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Sample records for random sample study

  1. Power and sample size calculations for Mendelian randomization studies using one genetic instrument.

    Science.gov (United States)

    Freeman, Guy; Cowling, Benjamin J; Schooling, C Mary

    2013-08-01

    Mendelian randomization, which is instrumental variable analysis using genetic variants as instruments, is an increasingly popular method of making causal inferences from observational studies. In order to design efficient Mendelian randomization studies, it is essential to calculate the sample sizes required. We present formulas for calculating the power of a Mendelian randomization study using one genetic instrument to detect an effect of a given size, and the minimum sample size required to detect effects for given levels of significance and power, using asymptotic statistical theory. We apply the formulas to some example data and compare the results with those from simulation methods. Power and sample size calculations using these formulas should be more straightforward to carry out than simulation approaches. These formulas make explicit that the sample size needed for Mendelian randomization study is inversely proportional to the square of the correlation between the genetic instrument and the exposure and proportional to the residual variance of the outcome after removing the effect of the exposure, as well as inversely proportional to the square of the effect size.

  2. Randomized controlled trials 5: Determining the sample size and power for clinical trials and cohort studies.

    Science.gov (United States)

    Greene, Tom

    2015-01-01

    Performing well-powered randomized controlled trials is of fundamental importance in clinical research. The goal of sample size calculations is to assure that statistical power is acceptable while maintaining a small probability of a type I error. This chapter overviews the fundamentals of sample size calculation for standard types of outcomes for two-group studies. It considers (1) the problems of determining the size of the treatment effect that the studies will be designed to detect, (2) the modifications to sample size calculations to account for loss to follow-up and nonadherence, (3) the options when initial calculations indicate that the feasible sample size is insufficient to provide adequate power, and (4) the implication of using multiple primary endpoints. Sample size estimates for longitudinal cohort studies must take account of confounding by baseline factors.

  3. Studies on spectral analysis of randomly sampled signals: Application to laser velocimetry data

    Science.gov (United States)

    Sree, David

    1992-01-01

    Spectral analysis is very useful in determining the frequency characteristics of many turbulent flows, for example, vortex flows, tail buffeting, and other pulsating flows. It is also used for obtaining turbulence spectra from which the time and length scales associated with the turbulence structure can be estimated. These estimates, in turn, can be helpful for validation of theoretical/numerical flow turbulence models. Laser velocimetry (LV) is being extensively used in the experimental investigation of different types of flows, because of its inherent advantages; nonintrusive probing, high frequency response, no calibration requirements, etc. Typically, the output of an individual realization laser velocimeter is a set of randomly sampled velocity data. Spectral analysis of such data requires special techniques to obtain reliable estimates of correlation and power spectral density functions that describe the flow characteristics. FORTRAN codes for obtaining the autocorrelation and power spectral density estimates using the correlation-based slotting technique were developed. Extensive studies have been conducted on simulated first-order spectrum and sine signals to improve the spectral estimates. A first-order spectrum was chosen because it represents the characteristics of a typical one-dimensional turbulence spectrum. Digital prefiltering techniques, to improve the spectral estimates from randomly sampled data were applied. Studies show that the spectral estimates can be increased up to about five times the mean sampling rate.

  4. Inflammatory Biomarkers and Risk of Schizophrenia: A 2-Sample Mendelian Randomization Study.

    Science.gov (United States)

    Hartwig, Fernando Pires; Borges, Maria Carolina; Horta, Bernardo Lessa; Bowden, Jack; Davey Smith, George

    2017-12-01

    Positive associations between inflammatory biomarkers and risk of psychiatric disorders, including schizophrenia, have been reported in observational studies. However, conventional observational studies are prone to bias, such as reverse causation and residual confounding, thus limiting our understanding of the effect (if any) of inflammatory biomarkers on schizophrenia risk. To evaluate whether inflammatory biomarkers have an effect on the risk of developing schizophrenia. Two-sample mendelian randomization study using genetic variants associated with inflammatory biomarkers as instrumental variables to improve inference. Summary association results from large consortia of candidate gene or genome-wide association studies, including several epidemiologic studies with different designs, were used. Gene-inflammatory biomarker associations were estimated in pooled samples ranging from 1645 to more than 80 000 individuals, while gene-schizophrenia associations were estimated in more than 30 000 cases and more than 45 000 ancestry-matched controls. In most studies included in the consortia, participants were of European ancestry, and the prevalence of men was approximately 50%. All studies were conducted in adults, with a wide age range (18 to 80 years). Genetically elevated circulating levels of C-reactive protein (CRP), interleukin-1 receptor antagonist (IL-1Ra), and soluble interleukin-6 receptor (sIL-6R). Risk of developing schizophrenia. Individuals with schizophrenia or schizoaffective disorders were included as cases. Given that many studies contributed to the analyses, different diagnostic procedures were used. The pooled odds ratio estimate using 18 CRP genetic instruments was 0.90 (random effects 95% CI, 0.84-0.97; P = .005) per 2-fold increment in CRP levels; consistent results were obtained using different mendelian randomization methods and a more conservative set of instruments. The odds ratio for sIL-6R was 1.06 (95% CI, 1.01-1.12; P = .02

  5. Airway hyperresponsiveness to mannitol and methacholine and exhaled nitric oxide: a random-sample population study

    DEFF Research Database (Denmark)

    Sverrild, Asger; Porsbjerg, Celeste; Thomsen, Simon Francis

    2010-01-01

    Studies of selected patient groups have shown that airway hyperresponsiveness (AHR) to mannitol is more specific than methacholine for the diagnosis of asthma, as well as more closely associated with markers of airway inflammation in asthma....

  6. Airway hyperresponsiveness to mannitol and methacholine and exhaled nitric oxide: a random-sample population study

    DEFF Research Database (Denmark)

    Sverrild, Asger; Porsbjerg, Celeste; Thomsen, Simon Francis

    2010-01-01

    Studies of selected patient groups have shown that airway hyperresponsiveness (AHR) to mannitol is more specific than methacholine for the diagnosis of asthma, as well as more closely associated with markers of airway inflammation in asthma.......Studies of selected patient groups have shown that airway hyperresponsiveness (AHR) to mannitol is more specific than methacholine for the diagnosis of asthma, as well as more closely associated with markers of airway inflammation in asthma....

  7. Estimating screening-mammography receiver operating characteristic (ROC) curves from stratified random samples of screening mammograms: a simulation study.

    Science.gov (United States)

    Zur, Richard M; Pesce, Lorenzo L; Jiang, Yulei

    2015-05-01

    To evaluate stratified random sampling (SRS) of screening mammograms by (1) Breast Imaging Reporting and Data System (BI-RADS) assessment categories, and (2) the presence of breast cancer in mammograms, for estimation of screening-mammography receiver operating characteristic (ROC) curves in retrospective observer studies. We compared observer study case sets constructed by (1) random sampling (RS); (2) SRS with proportional allocation (SRS-P) with BI-RADS 1 and 2 noncancer cases accounting for 90.6% of all noncancer cases; (3) SRS with disproportional allocation (SRS-D) with BI-RADS 1 and 2 noncancer cases accounting for 10%-80%; and (4) SRS-D and multiple imputation (SRS-D + MI) with missing BI-RADS 1 and 2 noncancer cases imputed to recover the 90.6% proportion. Monte Carlo simulated case sets were drawn from a large case population modeled after published Digital Mammography Imaging Screening Trial data. We compared the bias, root-mean-square error, and coverage of 95% confidence intervals of area under the ROC curve (AUC) estimates from the sampling methods (200-2000 cases, of which 25% were cancer cases) versus from the large case population. AUC estimates were unbiased from RS, SRS-P, and SRS-D + MI, but biased from SRS-D. AUC estimates from SRS-P and SRS-D + MI had 10% smaller root-mean-square error than RS. Both SRS-P and SRS-D + MI can be used to obtain unbiased and 10% more efficient estimate of screening-mammography ROC curves. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  8. Investigating causal associations between use of nicotine, alcohol, caffeine, and cannabis: A two-sample bidirectional Mendelian randomization study.

    Science.gov (United States)

    Verweij, Karin J H; Treur, Jorien L; Vink, Jacqueline M

    2018-01-15

    Epidemiological studies consistently show co-occurrence of use of different addictive substances. Whether these associations are causal or due to overlapping underlying influences remains an important question in addiction research. Methodological advances have made it possible to use published genetic associations to infer causal relationships between phenotypes. In this exploratory study, we used Mendelian randomization (MR) to examine the causality of well-established associations between nicotine, alcohol, caffeine, and cannabis use. Two-sample MR was employed to estimate bi-directional causal effects between four addictive substances: nicotine (smoking initiation and cigarettes smoked per day), caffeine (cups of coffee per day), alcohol (units per week), and cannabis (initiation). Based on existing genome-wide association results we selected genetic variants associated with the exposure measure as an instrument to estimate causal effects. Where possible we applied sensitivity analyses (MR-Egger and weighted median) more robust to horizontal pleiotropy. Most MR tests did not reveal causal associations. There was some weak evidence for a causal positive effect of genetically instrumented alcohol use on smoking initiation and of cigarettes per day on caffeine use, but these did not hold up with the sensitivity analyses. There was also some suggestive evidence for a positive effect of alcohol use on caffeine use (only with MR-Egger) and smoking initiation on cannabis initiation (only with weighted median). None of the suggestive causal associations survived corrections for multiple testing. Two-sample Mendelian randomization analyses found little evidence for causal relationships between nicotine, alcohol, caffeine, and cannabis use. This article is protected by copyright. All rights reserved.

  9. k-Means: Random Sampling Procedure

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. k-Means: Random Sampling Procedure. Optimal 1-Mean is. Approximation of Centroid (Inaba et al). S = random sample of size O(1/ ); Centroid of S is a (1+ )-approx centroid of P with constant probability.

  10. Rationale, design, methodology and sample characteristics for the Vietnam pre-conceptual micronutrient supplementation trial (PRECONCEPT: a randomized controlled study

    Directory of Open Access Journals (Sweden)

    Nguyen Phuong H

    2012-10-01

    Full Text Available Abstract Background Low birth weight and maternal anemia remain intractable problems in many developing countries. The adequacy of the current strategy of providing iron-folic acid (IFA supplements only during pregnancy has been questioned given many women enter pregnancy with poor iron stores, the substantial micronutrient demand by maternal and fetal tissues, and programmatic issues related to timing and coverage of prenatal care. Weekly IFA supplementation for women of reproductive age (WRA improves iron status and reduces the burden of anemia in the short term, but few studies have evaluated subsequent pregnancy and birth outcomes. The Preconcept trial aims to determine whether pre-pregnancy weekly IFA or multiple micronutrient (MM supplementation will improve birth outcomes and maternal and infant iron status compared to the current practice of prenatal IFA supplementation only. This paper provides an overview of study design, methodology and sample characteristics from baseline survey data and key lessons learned. Methods/design We have recruited 5011 WRA in a double-blind stratified randomized controlled trial in rural Vietnam and randomly assigned them to receive weekly supplements containing either: 1 2800 μg folic acid 2 60 mg iron and 2800 μg folic acid or 3 MM. Women who become pregnant receive daily IFA, and are being followed through pregnancy, delivery, and up to three months post-partum. Study outcomes include birth outcomes and maternal and infant iron status. Data are being collected on household characteristics, maternal diet and mental health, anthropometry, infant feeding practices, morbidity and compliance. Discussion The study is timely and responds to the WHO Global Expert Consultation which identified the need to evaluate the long term benefits of weekly IFA and MM supplementation in WRA. Findings will generate new information to help guide policy and programs designed to reduce the burden of anemia in women and

  11. K-Median: Random Sampling Procedure

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. K-Median: Random Sampling Procedure. Sample a set of 1/ + 1 points from P. Let Q = first 1/ points, p = last point. Let T = Avg. 1-Median cost of P, c=1-Median. Let B1 = B(c,T/ 2), B2 = B(p, T). Let P' = points in B1.

  12. Nutritional status and falls in community-dwelling older people: a longitudinal study of a population-based random sample.

    Science.gov (United States)

    Chien, Ming-Hung; Guo, How-Ran

    2014-01-01

    Falls are common in older people and may lead to functional decline, disability, and death. Many risk factors have been identified, but studies evaluating effects of nutritional status are limited. To determine whether nutritional status is a predictor of falls in older people living in the community, we analyzed data collected through the Survey of Health and Living Status of the Elderly in Taiwan (SHLSET). SHLSET include a series of interview surveys conducted by the government on a random sample of people living in community dwellings in the nation. We included participants who received nutritional status assessment using the Mini Nutritional Assessment Taiwan Version 2 (MNA-T2) in the 1999 survey when they were 53 years or older and followed up on the cumulative incidence of falls in the one-year period before the interview in the 2003 survey. At the beginning of follow-up, the 4440 participants had a mean age of 69.5 (standard deviation= 9.1) years, and 467 participants were "not well-nourished," which was defined as having an MNA-T2 score of 23 or less. In the one-year study period, 659 participants reported having at least one fall. After adjusting for other risk factors, we found the associated odds ratio for falls was 1.73 (95% confidence interval, 1.23, 2.42) for "not well-nourished," 1.57 (1.30, 1.90) for female gender, 1.03 (1.02, 1.04) for one-year older, 1.55 (1.22, 1.98) for history of falls, 1.34 (1.05, 1.72) for hospital stay during the past 12 months, 1.66 (1.07, 2.58) for difficulties in activities of daily living, and 1.53 (1.23, 1.91) for difficulties in instrumental activities of daily living. Nutritional status is an independent predictor of falls in older people living in the community. Further studies are warranted to identify nutritional interventions that can help prevent falls in the elderly.

  13. Acceptance sampling using judgmental and randomly selected samples

    Energy Technology Data Exchange (ETDEWEB)

    Sego, Landon H.; Shulman, Stanley A.; Anderson, Kevin K.; Wilson, John E.; Pulsipher, Brent A.; Sieber, W. Karl

    2010-09-01

    We present a Bayesian model for acceptance sampling where the population consists of two groups, each with different levels of risk of containing unacceptable items. Expert opinion, or judgment, may be required to distinguish between the high and low-risk groups. Hence, high-risk items are likely to be identifed (and sampled) using expert judgment, while the remaining low-risk items are sampled randomly. We focus on the situation where all observed samples must be acceptable. Consequently, the objective of the statistical inference is to quantify the probability that a large percentage of the unsampled items in the population are also acceptable. We demonstrate that traditional (frequentist) acceptance sampling and simpler Bayesian formulations of the problem are essentially special cases of the proposed model. We explore the properties of the model in detail, and discuss the conditions necessary to ensure that required samples sizes are non-decreasing function of the population size. The method is applicable to a variety of acceptance sampling problems, and, in particular, to environmental sampling where the objective is to demonstrate the safety of reoccupying a remediated facility that has been contaminated with a lethal agent.

  14. Assessing causality in associations between cannabis use and schizophrenia risk: a two-sample Mendelian randomization study.

    Science.gov (United States)

    Gage, S H; Jones, H J; Burgess, S; Bowden, J; Davey Smith, G; Zammit, S; Munafò, M R

    2017-04-01

    Observational associations between cannabis and schizophrenia are well documented, but ascertaining causation is more challenging. We used Mendelian randomization (MR), utilizing publicly available data as a method for ascertaining causation from observational data. We performed bi-directional two-sample MR using summary-level genome-wide data from the International Cannabis Consortium (ICC) and the Psychiatric Genomics Consortium (PGC2). Single nucleotide polymorphisms (SNPs) associated with cannabis initiation (p schizophrenia (p cannabis initiation on risk of schizophrenia [odds ratio (OR) 1.04 per doubling odds of cannabis initiation, 95% confidence interval (CI) 1.01-1.07, p = 0.019]. There was strong evidence consistent with a causal effect of schizophrenia risk on likelihood of cannabis initiation (OR 1.10 per doubling of the odds of schizophrenia, 95% CI 1.05-1.14, p = 2.64 × 10-5). Findings were as predicted for the negative control (height: OR 1.00, 95% CI 0.99-1.01, p = 0.90) but weaker than predicted for the positive control (years in education: OR 0.99, 95% CI 0.97-1.00, p = 0.066) analyses. Our results provide some that cannabis initiation increases the risk of schizophrenia, although the size of the causal estimate is small. We find stronger evidence that schizophrenia risk predicts cannabis initiation, possibly as genetic instruments for schizophrenia are stronger than for cannabis initiation.

  15. A double-blind randomized controlled trial to study the efficacy of topiramate in a civilian sample of PTSD.

    Science.gov (United States)

    Yeh, Mary S L; Mari, Jair Jesus; Costa, Mariana Caddrobi Pupo; Andreoli, Sergio Baxter; Bressan, Rodrigo Affonseca; Mello, Marcelo Feijó

    2011-10-01

    To evaluate the efficacy and tolerability of topiramate in patients with posttraumatic stress disorder (PTSD). We conducted a 12-week double-blind, randomized, placebo-controlled study comparing topiramate to placebo. Men and women aged 18-62 years with diagnosis of PTSD according to DSM-IV were recruited from the outpatient clinic of the violence program of Federal University of São Paulo Hospital (Prove-UNIFESP), São Paulo City, between April 2006 and December 2009. Subjects were assessed for the Clinician-Administered Posttraumatic Stress Scale (CAPS), Clinical Global Impression, and Beck Depression Inventory (BDI). After 1-week period of washout, 35 patients were randomized to either group. The primary outcome measure was the CAPS total score changes from baseline to the endpoint. 82.35% of patients in the topiramate group exhibited improvements in PTSD symptoms. The efficacy analysis demonstrated that patients in the topiramate group exhibited significant improvements in reexperiencing symptoms: flashbacks, intrusive memories, and nightmares of the trauma (CAPS-B; P= 0.04) and in avoidance/numbing symptoms associated with the trauma, social isolation, and emotional numbing (CAPS-C; P= 0.0001). Furthermore, the experimental group demonstrated a significant difference in decrease in CAPS total score (topiramate -57.78; placebo -32.41; P= 0.0076). Mean topiramate dose was 102.94 mg/d. Topiramate was generally well tolerated. Topiramate was effective in improving reexperiencing and avoidance/numbing symptom clusters in patients with PTSD. This study supports the use of anticonvulsants for the improvement of symptoms of PTSD. © 2010 Blackwell Publishing Ltd.

  16. Efficient sampling of complex network with modified random walk strategies

    Science.gov (United States)

    Xie, Yunya; Chang, Shuhua; Zhang, Zhipeng; Zhang, Mi; Yang, Lei

    2018-02-01

    We present two novel random walk strategies, choosing seed node (CSN) random walk and no-retracing (NR) random walk. Different from the classical random walk sampling, the CSN and NR strategies focus on the influences of the seed node choice and path overlap, respectively. Three random walk samplings are applied in the Erdös-Rényi (ER), Barabási-Albert (BA), Watts-Strogatz (WS), and the weighted USAir networks, respectively. Then, the major properties of sampled subnets, such as sampling efficiency, degree distributions, average degree and average clustering coefficient, are studied. The similar conclusions can be reached with these three random walk strategies. Firstly, the networks with small scales and simple structures are conducive to the sampling. Secondly, the average degree and the average clustering coefficient of the sampled subnet tend to the corresponding values of original networks with limited steps. And thirdly, all the degree distributions of the subnets are slightly biased to the high degree side. However, the NR strategy performs better for the average clustering coefficient of the subnet. In the real weighted USAir networks, some obvious characters like the larger clustering coefficient and the fluctuation of degree distribution are reproduced well by these random walk strategies.

  17. GSAMPLE: Stata module to draw a random sample

    OpenAIRE

    Jann, Ben

    2006-01-01

    gsample draws a random sample from the data in memory. Simple random sampling (SRS) is supported, as well as unequal probability sampling (UPS), of which sampling with probabilities proportional to size (PPS) is a special case. Both methods, SRS and UPS/PPS, provide sampling with replacement and sampling without replacement. Furthermore, stratified sampling and cluster sampling is supported.

  18. Novel approach to systematic random sampling in population surveys: Lessons from the United Arab Emirates National Diabetes Study (UAEDIAB).

    Science.gov (United States)

    Sulaiman, Nabil; Albadawi, Salah; Abusnana, Salah; Fikri, Mahmoud; Madani, Abdulrazzag; Mairghani, Maisoon; Alawadi, Fatheya; Zimmet, Paul; Shaw, Jonathan

    2015-09-01

    The prevalence of diabetes has risen rapidly in the Middle East, particularly in the Gulf Region. However, some prevalence estimates have not fully accounted for large migrant worker populations and have focused on minority indigenous populations. The objectives of the UAE National Diabetes and Lifestyle Study are to: (i) define the prevalence of, and risk factors for, T2DM; (ii) describe the distribution and determinants of T2DM risk factors; (iii) study health knowledge, attitudes, and (iv) identify gene-environment interactions; and (v) develop baseline data for evaluation of future intervention programs. Given the high burden of diabetes in the region and the absence of accurate data on non-UAE nationals in the UAE, a representative sample of the non-UAE nationals was essential. We used an innovative methodology in which non-UAE nationals were sampled when attending the mandatory biannual health check that is required for visa renewal. Such an approach could also be used in other countries in the region. Complete data were available for 2719 eligible non-UAE nationals (25.9% Arabs, 70.7% Asian non-Arabs, 1.1% African non-Arabs, and 2.3% Westerners). Most were men service and sales, and unskilled occupations. Most (37.4%) had completed high school and 4.1% had a postgraduate degree. This novel methodology could provide insights for epidemiological studies in the UAE and other Gulf States, particularly for expatriates. © 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

  19. Biological Sampling Variability Study

    Energy Technology Data Exchange (ETDEWEB)

    Amidan, Brett G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-11-08

    There are many sources of variability that exist in the sample collection and analysis process. This paper addresses many, but not all, sources of variability. The main focus of this paper was to better understand and estimate variability due to differences between samplers. Variability between days was also studied, as well as random variability within each sampler. Experiments were performed using multiple surface materials (ceramic and stainless steel), multiple contaminant concentrations (10 spores and 100 spores), and with and without the presence of interfering material. All testing was done with sponge sticks using 10-inch by 10-inch coupons. Bacillus atrophaeus was used as the BA surrogate. Spores were deposited using wet deposition. Grime was coated on the coupons which were planned to include the interfering material (Section 3.3). Samples were prepared and analyzed at PNNL using CDC protocol (Section 3.4) and then cultured and counted. Five samplers were trained so that samples were taken using the same protocol. Each sampler randomly sampled eight coupons each day, four coupons with 10 spores deposited and four coupons with 100 spores deposited. Each day consisted of one material being tested. The clean samples (no interfering materials) were run first, followed by the dirty samples (coated with interfering material). There was a significant difference in recovery efficiency between the coupons with 10 spores deposited (mean of 48.9%) and those with 100 spores deposited (mean of 59.8%). There was no general significant difference between the clean and dirty (containing interfering material) coupons or between the two surface materials; however, there was a significant interaction between concentration amount and presence of interfering material. The recovery efficiency was close to the same for coupons with 10 spores deposited, but for the coupons with 100 spores deposited, the recovery efficiency for the dirty samples was significantly larger (65

  20. Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling.

    Science.gov (United States)

    Biro, Peter A

    2013-02-01

    Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, 'hidden' trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

  1. Generation and Analysis of Constrained Random Sampling Patterns

    DEFF Research Database (Denmark)

    Pierzchlewski, Jacek; Arildsen, Thomas

    2016-01-01

    Random sampling is a technique for signal acquisition which is gaining popularity in practical signal processing systems. Nowadays, event-driven analog-to-digital converters make random sampling feasible in practical applications. A process of random sampling is defined by a sampling pattern, whi...

  2. Purposive versus random sampling for map validation: a case study on ecotope maps of floodplains in the Netherlands

    NARCIS (Netherlands)

    Knotters, M.; Brus, D.J.

    2013-01-01

    The quality of ecotope maps of five districts of main water courses in the Netherlands was assessed on the basis of independent validation samples of field observations. The overall proportion of area correctly classified, and user's and producer's accuracy for each map unit were estimated. In four

  3. HPV self-sampling or the Pap-smear: a randomized study among cervical screening nonattenders from lower socioeconomic groups in France.

    Science.gov (United States)

    Sancho-Garnier, H; Tamalet, C; Halfon, P; Leandri, F X; Le Retraite, L; Djoufelkit, K; Heid, P; Davies, P; Piana, L

    2013-12-01

    Today in France, low attendance to cervical screening by Papanicolaou cytology (Pap-smear) is a major contributor to the 3,000 new cervical cancer cases and 1,000 deaths that occur from this disease every year. Nonattenders are mostly from lower socioeconomic groups and testing of self-obtained samples for high-risk Human Papilloma virus (HPV) types has been proposed as a method to increase screening participation in these groups. In 2011, we conducted a randomized study of women aged 35-69 from very low-income populations around Marseille who had not responded to an initial invitation for a free Pap-smear. After randomization, one group received a second invitation for a free Pap-smear and the other group was offered a free self-sampling kit for HPV testing. Participation rates were significantly different between the two groups with only 2.0% of women attending for a Pap-smear while 18.3% of women returned a self-sample for HPV testing (p ≤ 0.001). The detection rate of high-grade lesions (≥CIN2) was 0.2‰ in the Pap-smear group and 1.25‰ in the self-sampling group (p = 0.01). Offering self-sampling increased participation rates while the use of HPV testing increased the detection of cervical lesions (≥CIN2) in comparison to the group of women receiving a second invitation for a Pap-smear. However, low compliance to follow-up in the self-sampling group reduces the effectiveness of this screening approach in nonattenders women and must be carefully managed. Copyright © 2013 UICC.

  4. A random spatial sampling method in a rural developing nation.

    Science.gov (United States)

    Kondo, Michelle C; Bream, Kent D W; Barg, Frances K; Branas, Charles C

    2014-04-10

    Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method using geographical information system (GIS) software and global positioning system (GPS) technology for application in a health survey in a rural region of Guatemala, as well as a qualitative study of the enumeration process. This method offers an alternative sampling technique that could reduce opportunities for bias in household selection compared to cluster methods. However, its use is subject to issues surrounding survey preparation, technological limitations and in-the-field household selection. Application of this method in remote areas will raise challenges surrounding the boundary delineation process, use and translation of satellite imagery between GIS and GPS, and household selection at each survey point in varying field conditions. This method favors household selection in denser urban areas and in new residential developments. Random spatial sampling methodology can be used to survey a random sample of population in a remote region of a developing nation. Although this method should be further validated and compared with more established methods to determine its utility in social survey applications, it shows promise for use in developing nations with resource-challenged environments where detailed geographic and human census data are less available.

  5. Power Spectrum Estimation of Randomly Sampled Signals

    DEFF Research Database (Denmark)

    Velte, Clara M.; Buchhave, Preben; K. George, William

    2014-01-01

    with high data rate and low inherent bias, respectively, while residence time weighting provides non-biased estimates regardless of setting. The free-running processor was also tested and compared to residence time weighting using actual LDA measurements in a turbulent round jet. Power spectra from...... of alternative methods attempting to produce correct power spectra have been invented andtested. The objective of the current study is to create a simple computer generated signal for baseline testing of residence time weighting and some of the most commonly proposed algorithms (or algorithms which most...... modernalgorithms ultimately are based on), sample-and-hold and the direct spectral estimator without residence time weighting, and compare how they perform in relation to power spectra based on the equidistantly sampled reference signal. The computer generated signal is a Poisson process with a sample rate...

  6. Generalized and synthetic regression estimators for randomized branch sampling

    Science.gov (United States)

    David L. R. Affleck; Timothy G. Gregoire

    2015-01-01

    In felled-tree studies, ratio and regression estimators are commonly used to convert more readily measured branch characteristics to dry crown mass estimates. In some cases, data from multiple trees are pooled to form these estimates. This research evaluates the utility of both tactics in the estimation of crown biomass following randomized branch sampling (...

  7. Access to medical care among persons with musculoskeletal conditions. A study using a random sample of households in San Mateo County, California.

    Science.gov (United States)

    Yelin, E; Bernhard, G; Pflugrad, D

    1995-08-01

    To study access to medical care services, including subspecialty care, among persons with musculoskeletal conditions. In early 1993, a random sample of households in San Mateo County, California, was screened for the presence of household members with musculoskeletal conditions, and a member of each household so identified was administered a structured survey about access to medical care and other related subjects. Eighty-six percent of all persons with a musculoskeletal condition had ever seen at least one physician for the condition, but only 6.5% had ever seen a rheumatologist. Those without health insurance were only 82% as likely as those with health insurance to have ever seen a physician. Most persons with a musculoskeletal condition have seen a physician for the condition, but lack of health insurance significantly reduces the proportion who have done so.

  8. A random spatial sampling method in a rural developing nation

    Science.gov (United States)

    Michelle C. Kondo; Kent D.W. Bream; Frances K. Barg; Charles C. Branas

    2014-01-01

    Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method...

  9. Random constraint sampling and duality for convex optimization

    OpenAIRE

    Haskell, William B.; Pengqian, Yu

    2016-01-01

    We are interested in solving convex optimization problems with large numbers of constraints. Randomized algorithms, such as random constraint sampling, have been very successful in giving nearly optimal solutions to such problems. In this paper, we combine random constraint sampling with the classical primal-dual algorithm for convex optimization problems with large numbers of constraints, and we give a convergence rate analysis. We then report numerical experiments that verify the effectiven...

  10. Random number datasets generated from statistical analysis of randomly sampled GSM recharge cards.

    Science.gov (United States)

    Okagbue, Hilary I; Opanuga, Abiodun A; Oguntunde, Pelumi E; Ugwoke, Paulinus O

    2017-02-01

    In this article, a random number of datasets was generated from random samples of used GSM (Global Systems for Mobile Communications) recharge cards. Statistical analyses were performed to refine the raw data to random number datasets arranged in table. A detailed description of the method and relevant tests of randomness were also discussed.

  11. Power Spectrum Estimation of Randomly Sampled Signals

    DEFF Research Database (Denmark)

    Velte, C. M.; Buchhave, P.; K. George, W.

    . Residence time weighting provides non-biased estimates regardless of setting. The free-running processor was also tested and compared to residence time weighting using actual LDA measurements in a turbulent round jet. Power spectra from measurements on the jet centerline and the outer part of the jet...... sine waves. The primary signal and the corresponding power spectrum are shown in Figure 1. The conventional spectrum shows multiple erroneous mixing frequencies and the peak values are too low. The residence time weighted spectrum is correct. The sample-and-hold spectrum has lower power than...... the correct spectrum, and the f -2-filtering effect appearing for low data densities is evident (Adrian and Yao 1987). The remaining tests also show that sample-and-hold and the free-running processor perform well only under very particular circumstances with high data rate and low inherent bias, respectively...

  12. Improved estimator of finite population mean using auxiliary attribute in stratified random sampling

    OpenAIRE

    Verma, Hemant K.; Sharma, Prayas; Singh, Rajesh

    2014-01-01

    The present study discuss the problem of estimating the finite population mean using auxiliary attribute in stratified random sampling. In this paper taking the advantage of point bi-serial correlation between the study variable and auxiliary attribute, we have improved the estimation of population mean in stratified random sampling. The expressions for Bias and Mean square error have been derived under stratified random sampling. In addition, an empirical study has been carried out to examin...

  13. SOME SYSTEMATIC SAMPLING STRATEGIES USING MULTIPLE RANDOM STARTS

    Directory of Open Access Journals (Sweden)

    Sampath Sundaram

    2010-09-01

    Full Text Available In this paper an attempt is made to extend linear systematic sampling using multiple random starts due to Gautschi(1957for various types of systematic sampling schemes available in literature, namely(i  Balanced Systematic Sampling (BSS of  Sethi (1965 and (ii Modified Systematic Sampling (MSS of Singh, Jindal, and Garg  (1968. Further, the proposed methods were compared with Yates corrected estimator developed with reference to Gautschi’s Linear systematic sampling (LSS with two random starts using appropriate super population models with the  help of R package for statistical computing.

  14. Analysis of a global random stratified sample of nurse legislation.

    Science.gov (United States)

    Benton, D C; Fernández-Fernández, M P; González-Jurado, M A; Beneit-Montesinos, J V

    2015-06-01

    To identify, compare and contrast the major component parts of heterogeneous stratified sample of nursing legislation. Nursing legislation varies from one jurisdiction to another. Up until now no research exists into whether the variations of such legislation are random or if variations are related to a set of key attributes. This mixed method study used a random stratified sample of legislation to map through documentary analysis the content of 14 nursing acts and then explored, using quantitative techniques, whether the material contained relates to a number of key attributes. These attributes include: legal tradition of the jurisdiction; model of regulation; administrative approach; area of the world; and the economic status of the jurisdiction. Twelve component parts of nursing legislation were identified. These were remarkably similar irrespective of attributes of interest. However, not all component parts were specified in the same level of detail and the manner by which the elements were addressed did vary. A number of potential relationships between the structure of the legislation and the key attributes of interest were identified. This study generated a comprehensive and integrated map of a global sample of nursing legislation. It provides a set of descriptors to be used to undertake further quantitative work and provides an important policy tool to facilitate dialogue between regulatory bodies. At the individual nurse level it offers insights that can help nurses pursue recognition of credentials across jurisdictions. © 2015 International Council of Nurses.

  15. 22G versus 25G biopsy needles for EUS-guided tissue sampling of solid pancreatic masses: a randomized controlled study.

    Science.gov (United States)

    Woo, Young Sik; Lee, Kwang Hyuck; Noh, Dong Hyo; Park, Joo Kyung; Lee, Kyu Taek; Lee, Jong Kyun; Jang, Kee-Taek

    2017-12-01

    No comparative study of 22-gauge biopsy needles (PC22) and 25-gauge biopsy needles (PC25) has been conducted. We prospectively compared the diagnostic accuracy of PC22 and PC25 in patients with pancreatic and peripancreatic solid masses. We conducted a randomized noninferiority clinical study from January 2013 to May 2014 at Samsung Medical Center. A cytological and histological specimen of each pass was analyzed separately by an experienced pathologist. The primary outcome was to assess the diagnostic accuracy using the PC22 or PC25. Secondary outcomes included the optimal number of passes for adequate diagnosis, core specimen yield, sample adequacy, and complication rates. Diagnostic accuracy of combining cytology with histology in three cumulative passes was 97.1% (100/103) for the PC22 and 91.3% (94/103) for the PC25 group. Thus, noninferiority of PC25 to PC22 was not shown with a 10% noninferiority margin (difference, -5.8%; 95% CI, -12.1 to -0.5%). In a pairwise comparison with each needle type, two passes was non-inferior to three passes in the PC22 (96.1% vs. 97.1%; difference, -0.97%; 95% CI -6.63 to 4.69%) but noninferiority of two passes to three passes was not shown in the PC25 group (87.4% vs. 91.3%; difference, -3.88%; 95% CI, -13.5 to 5.7%). Non-inferiority of PC25 to PC22 diagnostic accuracy was not observed for solid pancreatic or peripancreatic masses without on-site cytology. PC22 may be a more ideal device because only two PC22 needle passes was sufficient to establish an adequate diagnosis, whereas PC25 required three or more needle passes.

  16. Self-help interventions for adjustment disorder problems: a randomized waiting-list controlled study in a sample of burglary victims.

    Science.gov (United States)

    Bachem, Rahel; Maercker, Andreas

    2016-09-01

    Adjustment disorders (AjD) are among the most frequent mental disorders yet often remain untreated. The high prevalence, comparatively mild symptom impairment, and transient nature make AjD a promising target for low-threshold self-help interventions. Bibliotherapy represents a potential treatment for AjD problems. This study investigates the effectiveness of a cognitive behavioral self-help manual specifically directed at alleviating AjD symptoms in a homogenous sample of burglary victims. Participants with clinical or subclinical AjD symptoms following experience of burglary were randomized to an intervention group (n = 30) or waiting-list control group (n = 24). The new explicit stress response syndrome model for diagnosing AjD was applied. Participants received no therapist support and assessments took place at baseline, after the one-month intervention, and at three-month follow-up. Based on completer analyses, group by time interactions indicated that the intervention group showed more improvement in AjD symptoms of preoccupation and in post-traumatic stress symptoms. Post-intervention between-group effect sizes ranged from Cohen's d = .17 to .67 and the proportion of participants showing reliable change was consistently higher in the intervention group than in the control group. Engagement with the self-help manual was high: 87% of participants had worked through at least half the manual. This is the first published RCT of a bibliotherapeutic self-help intervention for AjD problems. The findings provide evidence that a low-threshold self-help intervention without therapist contact is a feasible and effective treatment for symptoms of AjD.

  17. Spatial Random Sampling: A Structure-Preserving Data Sketching Tool

    Science.gov (United States)

    Rahmani, Mostafa; Atia, George K.

    2017-09-01

    Random column sampling is not guaranteed to yield data sketches that preserve the underlying structures of the data and may not sample sufficiently from less-populated data clusters. Also, adaptive sampling can often provide accurate low rank approximations, yet may fall short of producing descriptive data sketches, especially when the cluster centers are linearly dependent. Motivated by that, this paper introduces a novel randomized column sampling tool dubbed Spatial Random Sampling (SRS), in which data points are sampled based on their proximity to randomly sampled points on the unit sphere. The most compelling feature of SRS is that the corresponding probability of sampling from a given data cluster is proportional to the surface area the cluster occupies on the unit sphere, independently from the size of the cluster population. Although it is fully randomized, SRS is shown to provide descriptive and balanced data representations. The proposed idea addresses a pressing need in data science and holds potential to inspire many novel approaches for analysis of big data.

  18. Methods for sample size determination in cluster randomized trials.

    Science.gov (United States)

    Rutterford, Clare; Copas, Andrew; Eldridge, Sandra

    2015-06-01

    The use of cluster randomized trials (CRTs) is increasing, along with the variety in their design and analysis. The simplest approach for their sample size calculation is to calculate the sample size assuming individual randomization and inflate this by a design effect to account for randomization by cluster. The assumptions of a simple design effect may not always be met; alternative or more complicated approaches are required. We summarise a wide range of sample size methods available for cluster randomized trials. For those familiar with sample size calculations for individually randomized trials but with less experience in the clustered case, this manuscript provides formulae for a wide range of scenarios with associated explanation and recommendations. For those with more experience, comprehensive summaries are provided that allow quick identification of methods for a given design, outcome and analysis method. We present first those methods applicable to the simplest two-arm, parallel group, completely randomized design followed by methods that incorporate deviations from this design such as: variability in cluster sizes; attrition; non-compliance; or the inclusion of baseline covariates or repeated measures. The paper concludes with methods for alternative designs. There is a large amount of methodology available for sample size calculations in CRTs. This paper gives the most comprehensive description of published methodology for sample size calculation and provides an important resource for those designing these trials. © The Author 2015. Published by Oxford University Press on behalf of the International Epidemiological Association.

  19. SOME SYSTEMATIC SAMPLING STRATEGIES USING MULTIPLE RANDOM STARTS

    OpenAIRE

    Sampath Sundaram; Ammani Sivaraman

    2010-01-01

    In this paper an attempt is made to extend linear systematic sampling using multiple random starts due to Gautschi(1957)for various types of systematic sampling schemes available in literature, namely(i)  Balanced Systematic Sampling (BSS) of  Sethi (1965) and (ii) Modified Systematic Sampling (MSS) of Singh, Jindal, and Garg  (1968). Further, the proposed methods were compared with Yates corrected estimator developed with reference to Gautschi’s Linear systematic samplin...

  20. Sampling large random knots in a confined space

    Energy Technology Data Exchange (ETDEWEB)

    Arsuaga, J [Department of Mathematics, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132 (United States); Blackstone, T [Department of Computer Science, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132 (United States); Diao, Y [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Hinson, K [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Karadayi, E [Department of Mathematics, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States); Saito, M [Department of Mathematics, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States)

    2007-09-28

    DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e{sup n{sup 2}}). We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n{sup 2}). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

  1. A Family of Estimators of a Sensitive Variable Using Auxiliary Information in Stratified Random Sampling

    Directory of Open Access Journals (Sweden)

    Nadia Mushtaq

    2017-03-01

    Full Text Available In this article, a combined general family of estimators is proposed for estimating finite population mean of a sensitive variable in stratified random sampling with non-sensitive auxiliary variable based on randomized response technique. Under stratified random sampling without replacement scheme, the expression of bias and mean square error (MSE up to the first-order approximations are derived. Theoretical and empirical results through a simulation study show that the proposed class of estimators is more efficient than the existing estimators, i.e., usual stratified random sample mean estimator, Sousa et al (2014 ratio and regression estimator of the sensitive variable in stratified sampling.

  2. The influence factors of medical professionalism: A stratified-random sampling study based on the physicians and patients in ambulatory care clinics of Chengdu, China.

    Science.gov (United States)

    Lin, Yifei; Yin, Senlin; Lai, Sike; Tang, Ji; Huang, Jin; Du, Liang

    2016-10-01

    As the relationship between physicians and patients deteriorated in China recently, medical conflicts occurred more frequently now. Physicians, to a certain extent, also take some responsibilities. Awareness of medical professionalism and its influence factors can be helpful to take targeted measures and alleviate the contradiction. Through a combination of physicians' self-assessment and patients' assessment in ambulatory care clinics in Chengdu, this research aims to evaluate the importance of medical professionalism in hospitals and explore the influence factors, hoping to provide decision-making references to improve this grim situation. From February to March, 2013, a cross-sectional study was conducted in 2 tier 3 hospitals, 5 tier 2 hospitals, and 10 community hospitals through a stratified-random sampling method on physicians and patients, at a ratio of 1/5. Questionnaires are adopted from a pilot study. A total of 382 physicians and 1910 patients were matched and surveyed. Regarding the medical professionalism, the scores of the self-assessment for physicians were 85.18 ± 7.267 out of 100 and the scores of patient-assessment were 57.66 ± 7.043 out of 70. The influence factors of self-assessment were physicians' working years (P = 0.003) and patients' complaints (P = 0.006), whereas the influence factors of patient-assessment were patients' ages (P = 0.001) and their physicians' working years (P < 0.01) and satisfaction on the payment mode (P = 0.006). Higher self-assessment on the medical professionalism was in accordance with physicians of more working years and no complaint history. Higher patient-assessment was in line with elder patients, the physicians' more working years, and higher satisfaction on the payment mode. Elder patients, encountering with physicians who worked more years in health care services or with higher satisfaction on the payment mode, contribute to higher scores in patient assessment part. The government should

  3. Sequential time interleaved random equivalent sampling for repetitive signal

    Science.gov (United States)

    Zhao, Yijiu; Liu, Jingjing

    2016-12-01

    Compressed sensing (CS) based sampling techniques exhibit many advantages over other existing approaches for sparse signal spectrum sensing; they are also incorporated into non-uniform sampling signal reconstruction to improve the efficiency, such as random equivalent sampling (RES). However, in CS based RES, only one sample of each acquisition is considered in the signal reconstruction stage, and it will result in more acquisition runs and longer sampling time. In this paper, a sampling sequence is taken in each RES acquisition run, and the corresponding block measurement matrix is constructed using a Whittaker-Shannon interpolation formula. All the block matrices are combined into an equivalent measurement matrix with respect to all sampling sequences. We implemented the proposed approach with a multi-cores analog-to-digital converter (ADC), whose ADC cores are time interleaved. A prototype realization of this proposed CS based sequential random equivalent sampling method has been developed. It is able to capture an analog waveform at an equivalent sampling rate of 40 GHz while sampled at 1 GHz physically. Experiments indicate that, for a sparse signal, the proposed CS based sequential random equivalent sampling exhibits high efficiency.

  4. Optimum allocation in multivariate stratified random sampling: Stochastic matrix optimisation

    OpenAIRE

    Diaz-Garcia, Jose A.; Ramos-Quiroga, Rogelio

    2011-01-01

    The allocation problem for multivariate stratified random sampling as a problem of stochastic matrix integer mathematical programming is considered. With these aims the asymptotic normality of sample covariance matrices for each strata is established. Some alternative approaches are suggested for its solution. An example is solved by applying the proposed techniques.

  5. Performance of Random Effects Model Estimators under Complex Sampling Designs

    Science.gov (United States)

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan

    2011-01-01

    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  6. Sample Selection in Randomized Experiments: A New Method Using Propensity Score Stratified Sampling

    Science.gov (United States)

    Tipton, Elizabeth; Hedges, Larry; Vaden-Kiernan, Michael; Borman, Geoffrey; Sullivan, Kate; Caverly, Sarah

    2014-01-01

    Randomized experiments are often seen as the "gold standard" for causal research. Despite the fact that experiments use random assignment to treatment conditions, units are seldom selected into the experiment using probability sampling. Very little research on experimental design has focused on how to make generalizations to well-defined…

  7. Random sampling and validation of covariance matrices of resonance parameters

    Science.gov (United States)

    Plevnik, Lucijan; Zerovnik, Gašper

    2017-09-01

    Analytically exact methods for random sampling of arbitrary correlated parameters are presented. Emphasis is given on one hand on the possible inconsistencies in the covariance data, concentrating on the positive semi-definiteness and consistent sampling of correlated inherently positive parameters, and on the other hand on optimization of the implementation of the methods itself. The methods have been applied in the program ENDSAM, written in the Fortran language, which from a file from a nuclear data library of a chosen isotope in ENDF-6 format produces an arbitrary number of new files in ENDF-6 format which contain values of random samples of resonance parameters (in accordance with corresponding covariance matrices) in places of original values. The source code for the program ENDSAM is available from the OECD/NEA Data Bank. The program works in the following steps: reads resonance parameters and their covariance data from nuclear data library, checks whether the covariance data is consistent, and produces random samples of resonance parameters. The code has been validated with both realistic and artificial data to show that the produced samples are statistically consistent. Additionally, the code was used to validate covariance data in existing nuclear data libraries. A list of inconsistencies, observed in covariance data of resonance parameters in ENDF-VII.1, JEFF-3.2 and JENDL-4.0 is presented. For now, the work has been limited to resonance parameters, however the methods presented are general and can in principle be extended to sampling and validation of any nuclear data.

  8. Effective sampling of random surfaces by baby universe surgery

    NARCIS (Netherlands)

    Ambjørn, J.; Białas, P.; Jurkiewicz, J.; Burda, Z.; Petersson, B.

    1994-01-01

    We propose a new, very efficient algorithm for sampling of random surfaces in the Monte Carlo simulations, based on so-called baby universe surgery, i.e. cutting and pasting of baby universe. It drastically reduces slowing down as compared to the standard local flip algorithm, thereby allowing

  9. Fast egg collection method greatly improves randomness of egg sampling in Drosophila melanogaster

    DEFF Research Database (Denmark)

    Schou, Mads Fristrup

    2013-01-01

    When obtaining samples for population genetic studies, it is essential that the sampling is random. For Drosophila, one of the crucial steps in sampling experimental flies is the collection of eggs. Here an egg collection method is presented, which randomizes the eggs in a water column and dimini......When obtaining samples for population genetic studies, it is essential that the sampling is random. For Drosophila, one of the crucial steps in sampling experimental flies is the collection of eggs. Here an egg collection method is presented, which randomizes the eggs in a water column...... and to obtain a representative collection of genotypes, the method presented here is strongly recommended when collecting eggs from Drosophila....

  10. Random-effects linear modeling and sample size tables for two special crossover designs of average bioequivalence studies: the four-period, two-sequence, two-formulation and six-period, three-sequence, three-formulation designs.

    Science.gov (United States)

    Diaz, Francisco J; Berg, Michel J; Krebill, Ron; Welty, Timothy; Gidal, Barry E; Alloway, Rita; Privitera, Michael

    2013-12-01

    Due to concern and debate in the epilepsy medical community and to the current interest of the US Food and Drug Administration (FDA) in revising approaches to the approval of generic drugs, the FDA is currently supporting ongoing bioequivalence studies of antiepileptic drugs, the EQUIGEN studies. During the design of these crossover studies, the researchers could not find commercial or non-commercial statistical software that quickly allowed computation of sample sizes for their designs, particularly software implementing the FDA requirement of using random-effects linear models for the analyses of bioequivalence studies. This article presents tables for sample-size evaluations of average bioequivalence studies based on the two crossover designs used in the EQUIGEN studies: the four-period, two-sequence, two-formulation design, and the six-period, three-sequence, three-formulation design. Sample-size computations assume that random-effects linear models are used in bioequivalence analyses with crossover designs. Random-effects linear models have been traditionally viewed by many pharmacologists and clinical researchers as just mathematical devices to analyze repeated-measures data. In contrast, a modern view of these models attributes an important mathematical role in theoretical formulations in personalized medicine to them, because these models not only have parameters that represent average patients, but also have parameters that represent individual patients. Moreover, the notation and language of random-effects linear models have evolved over the years. Thus, another goal of this article is to provide a presentation of the statistical modeling of data from bioequivalence studies that highlights the modern view of these models, with special emphasis on power analyses and sample-size computations.

  11. The potential of Virtual Reality as anxiety management tool: a randomized controlled study in a sample of patients affected by Generalized Anxiety Disorder

    Directory of Open Access Journals (Sweden)

    Gorini Alessandra

    2008-05-01

    Full Text Available Abstract Background Generalized anxiety disorder (GAD is a psychiatric disorder characterized by a constant and unspecific anxiety that interferes with daily-life activities. Its high prevalence in general population and the severe limitations it causes, point out the necessity to find new efficient strategies to treat it. Together with the cognitive-behavioural treatments, relaxation represents a useful approach for the treatment of GAD, but it has the limitation that it is hard to be learned. To overcome this limitation we propose the use of virtual reality (VR to facilitate the relaxation process by visually presenting key relaxing images to the subjects. The visual presentation of a virtual calm scenario can facilitate patients' practice and mastery of relaxation, making the experience more vivid and real than the one that most subjects can create using their own imagination and memory, and triggering a broad empowerment process within the experience induced by a high sense of presence. According to these premises, the aim of the present study is to investigate the advantages of using a VR-based relaxation protocol in reducing anxiety in patients affected by GAD. Methods/Design The trial is based on a randomized controlled study, including three groups of 25 patients each (for a total of 75 patients: (1 the VR group, (2 the non-VR group and (3 the waiting list (WL group. Patients in the VR group will be taught to relax using a VR relaxing environment and audio-visual mobile narratives; patients in the non-VR group will be taught to relax using the same relaxing narratives proposed to the VR group, but without the VR support, and patients in the WL group will not receive any kind of relaxation training. Psychometric and psychophysiological outcomes will serve as quantitative dependent variables, while subjective reports of participants will be used as qualitative dependent variables. Conclusion We argue that the use of VR for relaxation

  12. Comparative Study of element composition of some honey samples ...

    African Journals Online (AJOL)

    The study was carried out at the Federal College of Forestry, Ibadan with seven honey samples were randomly selected within Ibadan metropolis, labeled as: Sample A (Forestry Honey), Sample B(Pure Honey), Sample C (Mr. Honey), Sample D (Taraba Honey), Sample E (Sokoto Honey), Sample F (Saki Honey), and ...

  13. Random sampling and validation of covariance matrices of resonance parameters

    Directory of Open Access Journals (Sweden)

    Plevnik Lucijan

    2017-01-01

    Full Text Available Analytically exact methods for random sampling of arbitrary correlated parameters are presented. Emphasis is given on one hand on the possible inconsistencies in the covariance data, concentrating on the positive semi-definiteness and consistent sampling of correlated inherently positive parameters, and on the other hand on optimization of the implementation of the methods itself. The methods have been applied in the program ENDSAM, written in the Fortran language, which from a file from a nuclear data library of a chosen isotope in ENDF-6 format produces an arbitrary number of new files in ENDF-6 format which contain values of random samples of resonance parameters (in accordance with corresponding covariance matrices in places of original values. The source code for the program ENDSAM is available from the OECD/NEA Data Bank. The program works in the following steps: reads resonance parameters and their covariance data from nuclear data library, checks whether the covariance data is consistent, and produces random samples of resonance parameters. The code has been validated with both realistic and artificial data to show that the produced samples are statistically consistent. Additionally, the code was used to validate covariance data in existing nuclear data libraries. A list of inconsistencies, observed in covariance data of resonance parameters in ENDF-VII.1, JEFF-3.2 and JENDL-4.0 is presented. For now, the work has been limited to resonance parameters, however the methods presented are general and can in principle be extended to sampling and validation of any nuclear data.

  14. A New Estimator For Population Mean Using Two Auxiliary Variables in Stratified random Sampling

    OpenAIRE

    Singh, Rajesh; Malik, Sachin

    2014-01-01

    In this paper, we suggest an estimator using two auxiliary variables in stratified random sampling. The propose estimator has an improvement over mean per unit estimator as well as some other considered estimators. Expressions for bias and MSE of the estimator are derived up to first degree of approximation. Moreover, these theoretical findings are supported by a numerical example with original data. Key words: Study variable, auxiliary variable, stratified random sampling, bias and mean squa...

  15. Sampling Polymorphs of Ionic Solids using Random Superlattices.

    Science.gov (United States)

    Stevanović, Vladan

    2016-02-19

    Polymorphism offers rich and virtually unexplored space for discovering novel functional materials. To harness this potential approaches capable of both exploring the space of polymorphs and assessing their realizability are needed. One such approach devised for partially ionic solids is presented. The structure prediction part is carried out by performing local density functional theory relaxations on a large set of random supperlattices (RSLs) with atoms distributed randomly over different planes in a way that favors cation-anion coordination. Applying the RSL sampling on MgO, ZnO, and SnO_{2} reveals that the resulting probability of occurrence of a given structure offers a measure of its realizability explaining fully the experimentally observed, metastable polymorphs in these three systems.

  16. Misrepresenting random sampling? A systematic review of research papers in the Journal of Advanced Nursing.

    Science.gov (United States)

    Williamson, Graham R

    2003-11-01

    This paper discusses the theoretical limitations of the use of random sampling and probability theory in the production of a significance level (or P-value) in nursing research. Potential alternatives, in the form of randomization tests, are proposed. Research papers in nursing, medicine and psychology frequently misrepresent their statistical findings, as the P-values reported assume random sampling. In this systematic review of studies published between January 1995 and June 2002 in the Journal of Advanced Nursing, 89 (68%) studies broke this assumption because they used convenience samples or entire populations. As a result, some of the findings may be questionable. The key ideas of random sampling and probability theory for statistical testing (for generating a P-value) are outlined. The result of a systematic review of research papers published in the Journal of Advanced Nursing is then presented, showing how frequently random sampling appears to have been misrepresented. Useful alternative techniques that might overcome these limitations are then discussed. REVIEW LIMITATIONS: This review is limited in scope because it is applied to one journal, and so the findings cannot be generalized to other nursing journals or to nursing research in general. However, it is possible that other nursing journals are also publishing research articles based on the misrepresentation of random sampling. The review is also limited because in several of the articles the sampling method was not completely clearly stated, and in this circumstance a judgment has been made as to the sampling method employed, based on the indications given by author(s). Quantitative researchers in nursing should be very careful that the statistical techniques they use are appropriate for the design and sampling methods of their studies. If the techniques they employ are not appropriate, they run the risk of misinterpreting findings by using inappropriate, unrepresentative and biased samples.

  17. Randomly Sampled-Data Control Systems. Ph.D. Thesis

    Science.gov (United States)

    Han, Kuoruey

    1990-01-01

    The purpose is to solve the Linear Quadratic Regulator (LQR) problem with random time sampling. Such a sampling scheme may arise from imperfect instrumentation as in the case of sampling jitter. It can also model the stochastic information exchange among decentralized controllers to name just a few. A practical suboptimal controller is proposed with the nice property of mean square stability. The proposed controller is suboptimal in the sense that the control structure is limited to be linear. Because of i. i. d. assumption, this does not seem unreasonable. Once the control structure is fixed, the stochastic discrete optimal control problem is transformed into an equivalent deterministic optimal control problem with dynamics described by the matrix difference equation. The N-horizon control problem is solved using the Lagrange's multiplier method. The infinite horizon control problem is formulated as a classical minimization problem. Assuming existence of solution to the minimization problem, the total system is shown to be mean square stable under certain observability conditions. Computer simulations are performed to illustrate these conditions.

  18. A Table-Based Random Sampling Simulation for Bioluminescence Tomography

    Directory of Open Access Journals (Sweden)

    Xiaomeng Zhang

    2006-01-01

    Full Text Available As a popular simulation of photon propagation in turbid media, the main problem of Monte Carlo (MC method is its cumbersome computation. In this work a table-based random sampling simulation (TBRS is proposed. The key idea of TBRS is to simplify multisteps of scattering to a single-step process, through randomly table querying, thus greatly reducing the computing complexity of the conventional MC algorithm and expediting the computation. The TBRS simulation is a fast algorithm of the conventional MC simulation of photon propagation. It retained the merits of flexibility and accuracy of conventional MC method and adapted well to complex geometric media and various source shapes. Both MC simulations were conducted in a homogeneous medium in our work. Also, we present a reconstructing approach to estimate the position of the fluorescent source based on the trial-and-error theory as a validation of the TBRS algorithm. Good agreement is found between the conventional MC simulation and the TBRS simulation.

  19. A comparison of methods for representing sparsely sampled random quantities.

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Vicente Jose; Swiler, Laura Painton; Urbina, Angel; Mullins, Joshua

    2013-09-01

    This report discusses the treatment of uncertainties stemming from relatively few samples of random quantities. The importance of this topic extends beyond experimental data uncertainty to situations involving uncertainty in model calibration, validation, and prediction. With very sparse data samples it is not practical to have a goal of accurately estimating the underlying probability density function (PDF). Rather, a pragmatic goal is that the uncertainty representation should be conservative so as to bound a specified percentile range of the actual PDF, say the range between 0.025 and .975 percentiles, with reasonable reliability. A second, opposing objective is that the representation not be overly conservative; that it minimally over-estimate the desired percentile range of the actual PDF. The presence of the two opposing objectives makes the sparse-data uncertainty representation problem interesting and difficult. In this report, five uncertainty representation techniques are characterized for their performance on twenty-one test problems (over thousands of trials for each problem) according to these two opposing objectives and other performance measures. Two of the methods, statistical Tolerance Intervals and a kernel density approach specifically developed for handling sparse data, exhibit significantly better overall performance than the others.

  20. A randomized controlled trial of inhaled corticosteroids (ICS) on markers of epithelial–mesenchymal transition (EMT) in large airway samples in COPD: an exploratory proof of concept study

    Science.gov (United States)

    Sohal, Sukhwinder Singh; Soltani, Amir; Reid, David; Ward, Chris; Wills, Karen E; Muller, H Konrad; Walters, Eugene Haydn

    2014-01-01

    Background We recently reported that epithelial–mesenchymal transition (EMT) is active in the airways in chronic obstructive pulmonary disease (COPD), suggesting presence of an active profibrotic and promalignant stroma. With no data available on potential treatment effects, we undertook a blinded analysis of inhaled corticosteroids (ICS) effects versus placebo on EMT markers in previously obtained endobronchial biopsies in COPD patients, as a “proof of concept” study. Methods Assessment of the effects of inhaled fluticasone propionate (FP; 500 μg twice daily for 6 months) versus placebo in 34 COPD patients (23 on fluticasone propionate and eleven on placebo). The end points were epidermal growth factor receptor (EGFR; marker of epithelial activation) and the biomarkers of EMT: reticular basement membrane (Rbm) fragmentation (“hallmark” structural marker), matrix metalloproteinase-9 (MMP-9) cell expression, and S100A4 expression in basal epithelial and Rbm cells (mesenchymal transition markers). Results Epithelial activation, “clefts/fragmentation” in the Rbm, and changes in the other biomarkers all regressed on ICS, at or close to conventional levels of statistical significance. From these data, we have been able to nominate primary and secondary end points and develop power calculations that would be applicable to a definitive prospective study. Conclusion Although only a pilot “proof of concept” study, this trial provided strong suggestive support for an anti-EMT effect of ICS in COPD airways. A larger and fully powered prospective study is now indicated as this issue is likely to be extremely important. Such studies may clarify the links between ICS use and better clinical outcomes and protection against lung cancer in COPD. PMID:24920891

  1. Stratified random sampling for estimating billing accuracy in health care systems.

    Science.gov (United States)

    Buddhakulsomsiri, Jirachai; Parthanadee, Parthana

    2008-03-01

    This paper presents a stratified random sampling plan for estimating accuracy of bill processing performance for the health care bills submitted to third party payers in health care systems. Bill processing accuracy is estimated with two measures: percent accuracy and total dollar accuracy. Difficulties in constructing a sampling plan arise when the population strata structure is unknown, and when the two measures require different sampling schemes. To efficiently utilize sample resource, the sampling plan is designed to effectively estimate both measures from the same sample. The sampling plan features a simple but efficient strata construction method, called rectangular method, and two accuracy estimation methods, one for each measure. The sampling plan is tested on actual populations from an insurance company. Accuracy estimates obtained are then used to compare the rectangular method to other potential clustering methods for strata construction, and compare the accuracy estimation methods to other eligible methods. Computational study results show effectiveness of the proposed sampling plan.

  2. A randomized controlled trial of inhaled corticosteroids (ICS on markers of epithelial–mesenchymal transition (EMT in large airway samples in COPD: an exploratory proof of concept study

    Directory of Open Access Journals (Sweden)

    Sohal SS

    2014-05-01

    Full Text Available Sukhwinder Singh Sohal,1,* Amir Soltani,1,* David Reid,1,2 Chris Ward,1,3 Karen E Wills,1,4 H Konrad Muller,1 Eugene Haydn Walters1 1National Health and Medical Research Council Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia; 2Iron Metabolism Laboratory, Queensland Institute of Medical Research, Brisbane, Queensland, Australia; 3Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, Tyne and Wear, UK; 4Department of Biostatistics, Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia *These authors contributed equally to this workBackground: We recently reported that epithelial–mesenchymal transition (EMT is active in the airways in chronic obstructive pulmonary disease (COPD, suggesting presence of an active profibrotic and promalignant stroma. With no data available on potential treatment effects, we undertook a blinded analysis of inhaled corticosteroids (ICS effects versus placebo on EMT markers in previously obtained endobronchial biopsies in COPD patients, as a “proof of concept” study.Methods: Assessment of the effects of inhaled fluticasone propionate (FP; 500 µg twice daily for 6 months versus placebo in 34 COPD patients (23 on fluticasone propionate and eleven on placebo. The end points were epidermal growth factor receptor (EGFR; marker of epithelial activation and the biomarkers of EMT: reticular basement membrane (Rbm fragmentation (“hallmark” structural marker, matrix metalloproteinase-9 (MMP-9 cell expression, and S100A4 expression in basal epithelial and Rbm cells (mesenchymal transition markers.Results: Epithelial activation, “clefts/fragmentation” in the Rbm, and changes in the other biomarkers all regressed on ICS, at or close to conventional levels of statistical significance. From these data, we have been able to nominate primary and secondary end points and develop

  3. Body mass, fat-free body mass, and prognosis in patients with chronic obstructive pulmonary disease from a random population sample: findings from the Copenhagen City Heart Study

    DEFF Research Database (Denmark)

    Vestbo, Jørgen; Prescott, Eva; Almdal, Thomas Peter

    2006-01-01

    Rationale: Low body mass index (BMI) is a marker of poor prognosis in chronic obstructive pulmonary disease (COPD). In the general population the harmful effect of low BMI is due to the deleterious effects of a low fat free mass index (FFMI, fat free mass/weight(2)). Objectives: We explored...... distribution of low FFMI and its association with prognosis in a population based cohort of COPD patients. Methods: We used data on 1,898 COPD patients identified in a population-based epidemiological study in Copenhagen. Fat free mass was measured using bioelectrical impedance analysis. Patients were followed...... up for a mean of 7 years and the association between BMI and FFMI and mortality was examined taking age, gender, smoking and lung function into account. Main results: The mean FFMI was 16.0 kg/m(2) for women and 18.7 kg/m(2) for men. Among subjects with normal BMI, 26.1 % had an FFMI lower than...

  4. The Vermont Diabetes Information System (VDIS): Study Design and Subject Recruitment for a Cluster Randomized Trial of a Decision Support System in a Regional Sample of Primary Care Practices

    Science.gov (United States)

    MacLean, Charles D.; Littenberg, Benjamin; Gagnon, Michael; Reardon, Mimi; Turner, Paul D.; Jordan, Cy

    2008-01-01

    Background Despite evidence that optimal care for diabetes can result in reduced complications and improved economic outcomes, such care is often not achieved. The Vermont Diabetes Information System (VDIS) is a registry-based decision support and reminder system based on the Chronic Care Model and targeted to primary care physicians and their patients with diabetes. Purpose To develop and evaluate a regional decision support system for patients with diabetes. Methods Randomized trial of an information system with clustering at the practice level. Ten percent random sub sample of patients selected for a home interview. Subject and setting includes 10 hospitals, 121 primary care providers, and 7,348 patients in 55 Vermont and New York primary care practices. Results We report on the study design and baseline characteristics of the population. Patients have a mean age of 63 years and a mean glycosolated hemoglobin A1C of 7.1%. Sixty percent of the population has excellent glycemic control (A1C<7%); 45% have excellent lipid control (serum LDL-cholesterol < 100mg/dl and serum triglycerides < 400mg/dl). Twenty-five percent have excellent blood pressure control (<130/80 mm Hg). These results compare favorably to recent national reports. However, only 8% are in optimal control for all three of hyperglycemia, lipids and blood pressure. Conclusions Our experience to date indicates that a low cost decision support and information system based on the chronic care model is feasible in primary care practices that lack sophisticated electronic information systems. VDIS is well accepted by patients, providers, and laboratory staff. If proven beneficial in a rigorous, randomized, controlled evaluation, the intervention could be widely disseminated to practices across America and the world with a substantial impact on the outcomes and costs of diabetes. It could also be adapted to other chronic conditions. We anticipate the results of the study will be available in 2006. PMID

  5. A Comparison of the Number of Men Who Have Sex with Men among Rural-To-Urban Migrants with Non-Migrant Rural and Urban Residents in Wuhan, China: A GIS/GPS-Assisted Random Sample Survey Study.

    Directory of Open Access Journals (Sweden)

    Xinguang Chen

    Full Text Available Mobile populations and men who have sex with men (MSM play an increasing role in the current HIV epidemic in China and across the globe. While considerable research has addressed both of these at-risk populations, more effective HIV control requires accurate data on the number of MSM at the population level, particularly MSM among migrant populations.Survey data from a random sample of male rural-to-urban migrants (aged 18-45, n=572 in Wuhan, China were analyzed and compared with those of randomly selected non-migrant urban (n=566 and rural counterparts (580. The GIS/GPS technologies were used for sampling and the survey estimation method was used for data analysis.HIV-related risk behaviors among rural-to-urban migrants were similar to those among the two comparison groups. The estimated proportion of MSM among migrants [95% CI] was 5.8% [4.7, 6.8], higher than 2.8% [1.2, 4.5] for rural residents and 1.0% [0.0, 2.4] for urban residents, respectively. Among these migrants, the MSM were more likely than non-MSM to be older in age, married, and migrated to more cities. They were also more likely to co-habit with others in rental properties located in new town and neighborhoods with fewer old acquaintances and more entertainment establishments. In addition, they were more likely to engage in commercial sex and less likely to consistently use condoms.Findings of this study indicate that compared to rural and urban populations, the migrant population in Wuhan consists of a higher proportion of MSM who also exhibit higher levels of HIV-related risk behaviors. More effective interventions should target this population with a focus on neighborhood factors, social capital and collective efficacy for risk reduction.

  6. Flexible sampling large-scale social networks by self-adjustable random walk

    Science.gov (United States)

    Xu, Xiao-Ke; Zhu, Jonathan J. H.

    2016-12-01

    Online social networks (OSNs) have become an increasingly attractive gold mine for academic and commercial researchers. However, research on OSNs faces a number of difficult challenges. One bottleneck lies in the massive quantity and often unavailability of OSN population data. Sampling perhaps becomes the only feasible solution to the problems. How to draw samples that can represent the underlying OSNs has remained a formidable task because of a number of conceptual and methodological reasons. Especially, most of the empirically-driven studies on network sampling are confined to simulated data or sub-graph data, which are fundamentally different from real and complete-graph OSNs. In the current study, we propose a flexible sampling method, called Self-Adjustable Random Walk (SARW), and test it against with the population data of a real large-scale OSN. We evaluate the strengths of the sampling method in comparison with four prevailing methods, including uniform, breadth-first search (BFS), random walk (RW), and revised RW (i.e., MHRW) sampling. We try to mix both induced-edge and external-edge information of sampled nodes together in the same sampling process. Our results show that the SARW sampling method has been able to generate unbiased samples of OSNs with maximal precision and minimal cost. The study is helpful for the practice of OSN research by providing a highly needed sampling tools, for the methodological development of large-scale network sampling by comparative evaluations of existing sampling methods, and for the theoretical understanding of human networks by highlighting discrepancies and contradictions between existing knowledge/assumptions of large-scale real OSN data.

  7. a randomized, placebo- controlled study

    OpenAIRE

    Hall, Franziska van

    2012-01-01

    Introduction: Repetitive transcranial magnetic stimulation (rTMS) is a well-tolerated non-invasive method, which has also been proved to have mild antidepressant effects and is used as “add-on“-therapy in treating pharmaco-resistant major depression. Objective: The efficacy of an escitalopram plus rTMS-combination-treatment was evaluated and compared to escitalopram plus sham rTMS. Methods: We designed a four week-, randomized, rater-blinded, and controlled add-on study with two trea...

  8. Dealing with daily challenges in dementia (deal-id study): effectiveness of the experience sampling method intervention 'Partner in Sight' for spousal caregivers of people with dementia: design of a randomized controlled trial.

    Science.gov (United States)

    van Knippenberg, Rosalia J M; de Vugt, Marjolein E; Ponds, Rudolf W; Myin-Germeys, Inez; Verhey, Frans R J

    2016-05-11

    There is an urgent need for psychosocial interventions that effectively support dementia caregivers in daily life. The Experience Sampling Methodology (ESM) offers the possibility to provide a more dynamic view of caregiver functioning. ESM-derived feedback may help to redirect caregivers' behavior towards situations that elicit positive emotions and to increase their feelings of competence in the caretaking process. This paper presents the design of a study that evaluates the process characteristics and effects of the ESM-based intervention 'Partner in Sight'. A randomized controlled trial with 90 spousal caregivers of people with dementia will be conducted. Participants will be randomly assigned to the experimental (6-week ESM intervention including feedback), pseudo-experimental (6-week ESM intervention without feedback), or control group (care as usual). Assessments will be performed pre- and post-intervention and at 2-, and 6-month follow-up. Main outcomes will be sense of competence, perceived control, momentary positive affect, and psychological complaints (depressive symptoms, perceived stress, anxiety, momentary negative affect). In addition to the effect evaluation, a process and economic evaluation will be conducted to investigate the credibility and generalizability of the intervention, and its cost-effectiveness. The potential effects of the ESM intervention may help caregivers to endure their care responsibilities and prevent them from becoming overburdened. This is the first ESM intervention for caregivers of people with dementia. The results of this study, therefore, provide a valuable contribution to the growing knowledge on m-health interventions for dementia caregivers. Dutch Trial Register NTR4847 ; date registered Oct 9, 2014.

  9. Occupational position and its relation to mental distress in a random sample of Danish residents

    DEFF Research Database (Denmark)

    Rugulies, Reiner Ernst; Madsen, Ida E H; Nielsen, Maj Britt D

    2010-01-01

    somatization symptoms (OR = 6.28, 95% CI = 1.39-28.46). CONCLUSIONS: Unskilled manual workers, the unemployed, and, to a lesser extent, the low-grade self-employed showed an increased level of mental distress. Activities to promote mental health in the Danish population should be directed toward these groups.......PURPOSE: To analyze the distribution of depressive, anxiety, and somatization symptoms across different occupational positions in a random sample of Danish residents. METHODS: The study sample consisted of 591 Danish residents (50% women), aged 20-65, drawn from an age- and gender-stratified random...... sample of the Danish population. Participants filled out a survey that included the 92 item version of the Hopkins Symptom Checklist (SCL-92). We categorized occupational position into seven groups: high- and low-grade non-manual workers, skilled and unskilled manual workers, high- and low-grade self...

  10. Modified Exponential Type Estimator for Population Mean Using Auxiliary Variables in Stratified Random Sampling

    OpenAIRE

    Özel, Gamze

    2015-01-01

    In this paper, a new exponential type estimator is developed in the stratified random sampling for the population mean using auxiliary variable information. In order to evaluate efficiency of the introduced estimator, we first review some estimators and study the optimum property of the suggested strategy. To judge the merits of the suggested class of estimators over others under the optimal condition, simulation study and real data applications are conducted. The results show that the introduc...

  11. Sample size calculations for micro-randomized trials in mHealth.

    Science.gov (United States)

    Liao, Peng; Klasnja, Predrag; Tewari, Ambuj; Murphy, Susan A

    2016-05-30

    The use and development of mobile interventions are experiencing rapid growth. In "just-in-time" mobile interventions, treatments are provided via a mobile device, and they are intended to help an individual make healthy decisions 'in the moment,' and thus have a proximal, near future impact. Currently, the development of mobile interventions is proceeding at a much faster pace than that of associated data science methods. A first step toward developing data-based methods is to provide an experimental design for testing the proximal effects of these just-in-time treatments. In this paper, we propose a 'micro-randomized' trial design for this purpose. In a micro-randomized trial, treatments are sequentially randomized throughout the conduct of the study, with the result that each participant may be randomized at the 100s or 1000s of occasions at which a treatment might be provided. Further, we develop a test statistic for assessing the proximal effect of a treatment as well as an associated sample size calculator. We conduct simulation evaluations of the sample size calculator in various settings. Rules of thumb that might be used in designing a micro-randomized trial are discussed. This work is motivated by our collaboration on the HeartSteps mobile application designed to increase physical activity. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  12. Sample size calculations for 3-level cluster randomized trials

    NARCIS (Netherlands)

    Teerenstra, S.; Moerbeek, M.; Achterberg, T. van; Pelzer, B.J.; Borm, G.F.

    2008-01-01

    BACKGROUND: The first applications of cluster randomized trials with three instead of two levels are beginning to appear in health research, for instance, in trials where different strategies to implement best-practice guidelines are compared. In such trials, the strategy is implemented in health

  13. Sample size calculations for 3-level cluster randomized trials

    NARCIS (Netherlands)

    Teerenstra, S.; Moerbeek, M.; Achterberg, T. van; Pelzer, B.J.; Borm, G.F.

    2008-01-01

    Background The first applications of cluster randomized trials with three instead of two levels are beginning to appear in health research, for instance, in trials where different strategies to implement best-practice guidelines are compared. In such trials, the strategy is implemented in health

  14. Assessment of proteinuria by using protein: creatinine index in random urine sample.

    Science.gov (United States)

    Khan, Dilshad Ahmed; Ahmad, Tariq Mahmood; Qureshil, Ayaz Hussain; Halim, Abdul; Ahmad, Mumtaz; Afzal, Saeed

    2005-10-01

    To assess the quantitative measurement of proteinuria by using random urine protein:creatinine index/ratio in comparison with 24 hours urinary protein excretion in patients of renal diseases having normal glomerular filtration rate. One hundred and thirty patients, 94 males and 36 females, with an age range of 5 to 60 years; having proteinuria of more than 150 mg/day were included in this study. Qualitative urinary protein estimation was done on random urine specimen by dipstick. Quantitative measurement of protein in the random and 24 hours urine specimens were carried out by a method based on the formation of a red complex of protein with pyrogallal red in acid medium on Micro lab 200 (Merck). Estimation of creatinine was done on Selectra -2 (Merck) by Jaffe's reaction. The urine protein:creatinine index and ratio were calculated by dividing the urine protein concentration (mg/L) by urine creatinine concentration (mmol/L) multilplied by 10 and mg/mg respectively. The protein:creatinine index and ratio of more than 140 and 0.18 respectively in a random urine sample indicated pathological proteinuria. An excellent correlation (r=0.96) was found between random urine protein:creatinine index/ratio and standard 24 hours urinary protein excretion in these patients (pprotein:creatinine index in random urine is a convenient, quick and reliable method of estimation of proteinuria as compared to 24 hours of urinary protein excretion for diagnosis and monitoring of renal diseases in our medical setup.

  15. Random sampling for a mental health survey in a deprived multi-ethnic area of Berlin.

    Science.gov (United States)

    Mundt, Adrian P; Aichberger, Marion C; Kliewe, Thomas; Ignatyev, Yuriy; Yayla, Seda; Heimann, Hannah; Schouler-Ocak, Meryam; Busch, Markus; Rapp, Michael; Heinz, Andreas; Ströhle, Andreas

    2012-12-01

    The aim of the study was to assess the response to random sampling for a mental health survey in a deprived multi-ethnic area of Berlin, Germany, with a large Turkish-speaking population. A random list from the registration office with 1,000 persons stratified by age and gender was retrieved from the population registry and these persons were contacted using a three-stage design including written information, telephone calls and personal contact at home. A female bilingual interviewer contacted persons with Turkish names. Of the persons on the list, 202 were not living in the area, one was deceased, 502 did not respond. Of the 295 responders, 152 explicitly refused(51.5%) to participate. We retained a sample of 143 participants(48.5%) representing the rate of multi-ethnicity in the area (52.1% migrants in the sample vs. 53.5% in the population). Turkish migrants were over-represented(28.9% in the sample vs. 18.6% in the population). Polish migrants (2.1 vs. 5.3% in the population) and persons from the former Yugoslavia (1.4 vs. 4.8% in the population)were under-represented. Bilingual contact procedures can improve the response rates of the most common migrant populations to random sampling if migrants of the same origin gate the contact. High non-contact and non-response rates for migrant and non-migrant populations in deprived urban areas remain a challenge for obtaining representative random samples.

  16. Generalized essential energy space random walks to more effectively accelerate solute sampling in aqueous environment.

    Science.gov (United States)

    Lv, Chao; Zheng, Lianqing; Yang, Wei

    2012-01-28

    Molecular dynamics sampling can be enhanced via the promoting of potential energy fluctuations, for instance, based on a Hamiltonian modified with the addition of a potential-energy-dependent biasing term. To overcome the diffusion sampling issue, which reveals the fact that enlargement of event-irrelevant energy fluctuations may abolish sampling efficiency, the essential energy space random walk (EESRW) approach was proposed earlier. To more effectively accelerate the sampling of solute conformations in aqueous environment, in the current work, we generalized the EESRW method to a two-dimension-EESRW (2D-EESRW) strategy. Specifically, the essential internal energy component of a focused region and the essential interaction energy component between the focused region and the environmental region are employed to define the two-dimensional essential energy space. This proposal is motivated by the general observation that in different conformational events, the two essential energy components have distinctive interplays. Model studies on the alanine dipeptide and the aspartate-arginine peptide demonstrate sampling improvement over the original one-dimension-EESRW strategy; with the same biasing level, the present generalization allows more effective acceleration of the sampling of conformational transitions in aqueous solution. The 2D-EESRW generalization is readily extended to higher dimension schemes and employed in more advanced enhanced-sampling schemes, such as the recent orthogonal space random walk method. © 2012 American Institute of Physics

  17. Multilayer pixel super-resolution lensless in-line holographic microscope with random sample movement.

    Science.gov (United States)

    Wang, Mingjun; Feng, Shaodong; Wu, Jigang

    2017-10-06

    We report a multilayer lensless in-line holographic microscope (LIHM) with improved imaging resolution by using the pixel super-resolution technique and random sample movement. In our imaging system, a laser beam illuminated the sample and a CMOS imaging sensor located behind the sample recorded the in-line hologram for image reconstruction. During the imaging process, the sample was moved by hand randomly and the in-line holograms were acquired sequentially. Then the sample image was reconstructed from an enhanced-resolution hologram obtained from multiple low-resolution in-line holograms by applying the pixel super-resolution (PSR) technique. We studied the resolution enhancement effects by using the U.S. Air Force (USAF) target as the sample in numerical simulation and experiment. We also showed that multilayer pixel super-resolution images can be obtained by imaging a triple-layer sample made with the filamentous algae on the middle layer and microspheres with diameter of 2 μm on the top and bottom layers. Our pixel super-resolution LIHM provides a compact and low-cost solution for microscopic imaging and is promising for many biomedical applications.

  18. Effectiveness of hand hygiene education among a random sample of women from the community

    OpenAIRE

    Ubheeram, J.; Biranjia-Hurdoyal, S.D.

    2017-01-01

    Summary Objective. The effectiveness of hand hygiene education was investigated by studying the hand hygiene awareness and bacterial hand contamination among a random sample of 170 women in the community. Methods. Questionnaire was used to assess the hand hygiene awareness score, followed by swabbing of the dominant hand. Bacterial identification was done by conventional biochemical tests. Results. Better hand hygiene awareness score was significantly associated with age, scarce bacterial gro...

  19. Chi-Squared Test of Fit and Sample Size-A Comparison between a Random Sample Approach and a Chi-Square Value Adjustment Method.

    Science.gov (United States)

    Bergh, Daniel

    2015-01-01

    Chi-square statistics are commonly used for tests of fit of measurement models. Chi-square is also sensitive to sample size, which is why several approaches to handle large samples in test of fit analysis have been developed. One strategy to handle the sample size problem may be to adjust the sample size in the analysis of fit. An alternative is to adopt a random sample approach. The purpose of this study was to analyze and to compare these two strategies using simulated data. Given an original sample size of 21,000, for reductions of sample sizes down to the order of 5,000 the adjusted sample size function works as good as the random sample approach. In contrast, when applying adjustments to sample sizes of lower order the adjustment function is less effective at approximating the chi-square value for an actual random sample of the relevant size. Hence, the fit is exaggerated and misfit under-estimated using the adjusted sample size function. Although there are big differences in chi-square values between the two approaches at lower sample sizes, the inferences based on the p-values may be the same.

  20. Hemodynamic and glucometabolic factors fail to predict renal function in a random population sample

    DEFF Research Database (Denmark)

    Pareek, M.; Nielsen, M.; Olesen, Thomas Bastholm

    2015-01-01

    Objective: To determine whether baseline hemodynamic and/or glucometabolic risk factors could predict renal function at follow-up, independently of baseline serum creatinine, in survivors from a random population sample. Design and method: We examined associations between baseline serum creatinine...... indices of beta-cell function (HOMA-2B), insulin sensitivity (HOMA-2S), and insulin resistance (HOMA-2IR)), traditional cardiovascular risk factors (age, sex, smoking status, body mass index, diabetes mellitus, total serum cholesterol), and later renal function determined as serum cystatin C in 238 men...... and 7 women aged 38 to 49 years at the time of inclusion, using multivariable linear regression analysis (p-entry 0.05, p-removal 0.20). Study subjects came from a random population based sample and were included 1974-1992, whilst the follow-up with cystatin C measurement was performed 2002...

  1. Computer Corner: A Note on Pascal's Triangle and Simple Random Sampling.

    Science.gov (United States)

    Wright, Tommy

    1989-01-01

    Describes the algorithm used to select a simple random sample of certain size without having to list all possible samples and a justification based on Pascal's triangle. Provides testing results by various computers. (YP)

  2. Exponential ratio-product type estimators under second order approximation in stratified random sampling

    OpenAIRE

    Singh, Rajesh; Sharma, Prayas; Smarandache, Florentin

    2014-01-01

    Singh et al (20009) introduced a family of exponential ratio and product type estimators in stratified random sampling. Under stratified random sampling without replacement scheme, the expressions of bias and mean square error (MSE) of Singh et al (2009) and some other estimators, up to the first- and second-order approximations are derived. Also, the theoretical findings are supported by a numerical example.

  3. Query-Based Sampling: Can we do Better than Random?

    NARCIS (Netherlands)

    Tigelaar, A.S.; Hiemstra, Djoerd

    2010-01-01

    Many servers on the web offer content that is only accessible via a search interface. These are part of the deep web. Using conventional crawling to index the content of these remote servers is impossible without some form of cooperation. Query-based sampling provides an alternative to crawling

  4. Stratified random sampling plan for an irrigation customer telephone survey

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, J.W.; Davis, L.J.

    1986-05-01

    This report describes the procedures used to design and select a sample for a telephone survey of individuals who use electricity in irrigating agricultural cropland in the Pacific Northwest. The survey is intended to gather information on the irrigated agricultural sector that will be useful for conservation assessment, load forecasting, rate design, and other regional power planning activities.

  5. [A comparative study of different sampling designs in fish community estimation].

    Science.gov (United States)

    Zhao, Jing; Zhang, Shou-Yu; Lin, Jun; Zhou, Xi-Jie

    2014-04-01

    The study of fishery community ecology depends on quality and quantity of data collected from well-designed sampling programs. The optimal sampling design must be cost-efficient, and the sampling results have been recognized as a significant factor affecting resources management. In this paper, the performances of stationary sampling, simple random sampling and stratified random sampling in estimating fish community were compared based on computer simulation by design effect (De), relative error (REE) and relative bias (RB). The results showed that, De of stationary sampling (average De was 3.37) was worse than simple random sampling and stratified random sampling (average De was 0.961). Stratified random sampling performed best among the three designs in terms of De, REE and RB. With the sample size increased, the design effect of stratified random sampling decreased but the precision and accuracy increased.

  6. Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms.

    Science.gov (United States)

    McGarvey, Richard; Burch, Paul; Matthews, Janet M

    2016-01-01

    Natural populations of plants and animals spatially cluster because (1) suitable habitat is patchy, and (2) within suitable habitat, individuals aggregate further into clusters of higher density. We compare the precision of random and systematic field sampling survey designs under these two processes of species clustering. Second, we evaluate the performance of 13 estimators for the variance of the sample mean from a systematic survey. Replicated simulated surveys, as counts from 100 transects, allocated either randomly or systematically within the study region, were used to estimate population density in six spatial point populations including habitat patches and Matérn circular clustered aggregations of organisms, together and in combination. The standard one-start aligned systematic survey design, a uniform 10 x 10 grid of transects, was much more precise. Variances of the 10 000 replicated systematic survey mean densities were one-third to one-fifth of those from randomly allocated transects, implying transect sample sizes giving equivalent precision by random survey would need to be three to five times larger. Organisms being restricted to patches of habitat was alone sufficient to yield this precision advantage for the systematic design. But this improved precision for systematic sampling in clustered populations is underestimated by standard variance estimators used to compute confidence intervals. True variance for the survey sample mean was computed from the variance of 10 000 simulated survey mean estimates. Testing 10 published and three newly proposed variance estimators, the two variance estimators (v) that corrected for inter-transect correlation (ν₈ and ν(W)) were the most accurate and also the most precise in clustered populations. These greatly outperformed the two "post-stratification" variance estimators (ν₂ and ν₃) that are now more commonly applied in systematic surveys. Similar variance estimator performance rankings were found with

  7. Estimating the Size of a Large Network and its Communities from a Random Sample.

    Science.gov (United States)

    Chen, Lin; Karbasi, Amin; Crawford, Forrest W

    2016-01-01

    Most real-world networks are too large to be measured or studied directly and there is substantial interest in estimating global network properties from smaller sub-samples. One of the most important global properties is the number of vertices/nodes in the network. Estimating the number of vertices in a large network is a major challenge in computer science, epidemiology, demography, and intelligence analysis. In this paper we consider a population random graph G = (V, E) from the stochastic block model (SBM) with K communities/blocks. A sample is obtained by randomly choosing a subset W ⊆ V and letting G(W) be the induced subgraph in G of the vertices in W. In addition to G(W), we observe the total degree of each sampled vertex and its block membership. Given this partial information, we propose an efficient PopULation Size Estimation algorithm, called PULSE, that accurately estimates the size of the whole population as well as the size of each community. To support our theoretical analysis, we perform an exhaustive set of experiments to study the effects of sample size, K, and SBM model parameters on the accuracy of the estimates. The experimental results also demonstrate that PULSE significantly outperforms a widely-used method called the network scale-up estimator in a wide variety of scenarios.

  8. Improvement of sampling strategies for randomly distributed hotspots in soil applying a computerized simulation considering the concept of uncertainty.

    Science.gov (United States)

    Hildebrandt, Thomas; Pick, Denis; Einax, Jürgen W

    2012-02-01

    The pollution of soil and environment as a result of human activity is a major problem. Nowadays, the determination of local contaminations is of interest for environmental remediation. These hotspots can have various toxic effects on plants, animals, humans, and the whole ecological system. However, economical and juridical consequences are also possible, e.g., high costs for remediation measures. In this study three sampling strategies (simple random sampling, stratified sampling, and systematic sampling) were applied on randomly distributed hotspot contaminations to prove their efficiency in term of finding hotspots. The results were used for the validation of a computerized simulation. This application can simulate the contamination on a field, the sampling pattern, and a virtual sampling. A constant hit rate showed that none of the sampling patterns could reach better results than others. Furthermore, the uncertainty associated with the results is described by confidence intervals. It is to be considered that the uncertainty during sampling is enormous and will decrease slightly, even the number of samples applied was increased to an unreasonable amount. It is hardly possible to identify the exact number of randomly distributed hotspot contaminations by statistical sampling. But a range of possible results could be calculated. Depending on various parameters such as shape and size of the area, number of hotspots, and sample quantity, optimal sampling strategies could be derived. Furthermore, an estimation of bias arising from sampling methodology is possible. The developed computerized simulation is an innovative tool for optimizing sampling strategies in terrestrial compartments for hotspot distributions.

  9. Location and multi-depot vehicle routing for emergency vehicles using tour coverage and random sampling

    Directory of Open Access Journals (Sweden)

    Alireza Goli

    2015-09-01

    Full Text Available Distribution and optimum allocation of emergency resources are the most important tasks, which need to be accomplished during crisis. When a natural disaster such as earthquake, flood, etc. takes place, it is necessary to deliver rescue efforts as quickly as possible. Therefore, it is important to find optimum location and distribution of emergency relief resources. When a natural disaster occurs, it is not possible to reach some damaged areas. In this paper, location and multi-depot vehicle routing for emergency vehicles using tour coverage and random sampling is investigated. In this study, there is no need to visit all the places and some demand points receive their needs from the nearest possible location. The proposed study is implemented for some randomly generated numbers in different sizes. The preliminary results indicate that the proposed method was capable of reaching desirable solutions in reasonable amount of time.

  10. ESTIMATION OF FINITE POPULATION MEAN USING RANDOM NON–RESPONSE IN SURVEY SAMPLING

    Directory of Open Access Journals (Sweden)

    Housila P. Singh

    2010-12-01

    Full Text Available This paper consider the problem of estimating the population mean under three different situations of random non–response envisaged by Singh et al (2000. Some ratio and product type estimators have been proposed and their properties are studied under an assumption that the number of sampling units on which information can not be obtained owing to random non–response follows some distribution. The suggested estimators are compared with the usual ratio and product estimators. An empirical study is carried out to show the performance of the suggested estimators over usual unbiased estimator, ratio and product estimators. A generalized version of the proposed ratio and product estimators is also given.

  11. Self-reported knowledge and awareness about blood pressure and hypertension: a cross-sectional study of a random sample of men and women aged 60–74 years

    Directory of Open Access Journals (Sweden)

    Qvist I

    2014-02-01

    Full Text Available Ina Qvist,1 Marie D Thomsen,2 Jes S Lindholt,2,3 Hans Ibsen,4 Jeroen ML Hendriks,5 Lars Frost1 1Department of Medicine, Diagnostic Centre, University Research Clinic for Innovative Patient Pathways, Silkeborg Regional Hospital, Silkeborg, Denmark; 2Department of Vascular Surgery, Viborg Regional Hospital and Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark; 3Centre of Individualized Medicine in Arterial Diseases, Department of Cardiothoracic and Vascular Department T, Odense University Hospital, Odense, Denmark; 4Department of Medicine, Holbæk Hospital, Holbæk, Denmark; 5Department of Cardiology, Maastricht University Medical Centre, Maastricht, the Netherlands Background: In general, it is assumed that patient education, by increasing knowledge, may change behavior and lifestyle and promote health. In this context, it is a surprise that knowledge and awareness about blood pressure and hypertension among elderly people is poor. We hypothesized that knowledge about blood pressure and hypertension would be better among individuals with self-reported hypertension compared with subjects without self-reported hypertension. Methods: We mailed a questionnaire to a random sample of 1,000 subjects living in the municipality of Silkeborg, Denmark. The study sample was drawn from the Central Person Registry. Results: The response rate was 72%. Of these, 43% of responders had self-reported hypertension. The people with self-reported hypertension were older, less educated, had higher self-reported blood cholesterol levels, had higher body weight, and more often had a family history of hypertension. More than 80% reported that overweight and obesity increases blood pressure. More than 60% reported that untreated hypertension may cause heart disease or stroke. More than half of the responders did not know their blood pressure, and only 21% knew that hypertension can occur without symptoms. Knowledge about hypertension was

  12. Randomized, interventional, prospective, comparative study to ...

    African Journals Online (AJOL)

    Randomized, interventional, prospective, comparative study to evaluate the antihypertensive efficacy and tolerability of ramipril versus telmisartan in stage 1 hypertensive patients with diabetes mellitus.

  13. Prevalence and correlates of problematic smartphone use in a large random sample of Chinese undergraduates.

    Science.gov (United States)

    Long, Jiang; Liu, Tie-Qiao; Liao, Yan-Hui; Qi, Chang; He, Hao-Yu; Chen, Shu-Bao; Billieux, Joël

    2016-11-17

    Smartphones are becoming a daily necessity for most undergraduates in Mainland China. Because the present scenario of problematic smartphone use (PSU) is largely unexplored, in the current study we aimed to estimate the prevalence of PSU and to screen suitable predictors for PSU among Chinese undergraduates in the framework of the stress-coping theory. A sample of 1062 undergraduate smartphone users was recruited by means of the stratified cluster random sampling strategy between April and May 2015. The Problematic Cellular Phone Use Questionnaire was used to identify PSU. We evaluated five candidate risk factors for PSU by using logistic regression analysis while controlling for demographic characteristics and specific features of smartphone use. The prevalence of PSU among Chinese undergraduates was estimated to be 21.3%. The risk factors for PSU were majoring in the humanities, high monthly income from the family (≥1500 RMB), serious emotional symptoms, high perceived stress, and perfectionism-related factors (high doubts about actions, high parental expectations). PSU among undergraduates appears to be ubiquitous and thus constitutes a public health issue in Mainland China. Although further longitudinal studies are required to test whether PSU is a transient phenomenon or a chronic and progressive condition, our study successfully identified socio-demographic and psychological risk factors for PSU. These results, obtained from a random and thus representative sample of undergraduates, opens up new avenues in terms of prevention and regulation policies.

  14. Parameter Estimation in Stratified Cluster Sampling under Randomized Response Models for Sensitive Question Survey.

    Science.gov (United States)

    Pu, Xiangke; Gao, Ge; Fan, Yubo; Wang, Mian

    2016-01-01

    Randomized response is a research method to get accurate answers to sensitive questions in structured sample survey. Simple random sampling is widely used in surveys of sensitive questions but hard to apply on large targeted populations. On the other side, more sophisticated sampling regimes and corresponding formulas are seldom employed to sensitive question surveys. In this work, we developed a series of formulas for parameter estimation in cluster sampling and stratified cluster sampling under two kinds of randomized response models by using classic sampling theories and total probability formulas. The performances of the sampling methods and formulas in the survey of premarital sex and cheating on exams at Soochow University were also provided. The reliability of the survey methods and formulas for sensitive question survey was found to be high.

  15. Parameter Estimation in Stratified Cluster Sampling under Randomized Response Models for Sensitive Question Survey.

    Directory of Open Access Journals (Sweden)

    Xiangke Pu

    Full Text Available Randomized response is a research method to get accurate answers to sensitive questions in structured sample survey. Simple random sampling is widely used in surveys of sensitive questions but hard to apply on large targeted populations. On the other side, more sophisticated sampling regimes and corresponding formulas are seldom employed to sensitive question surveys. In this work, we developed a series of formulas for parameter estimation in cluster sampling and stratified cluster sampling under two kinds of randomized response models by using classic sampling theories and total probability formulas. The performances of the sampling methods and formulas in the survey of premarital sex and cheating on exams at Soochow University were also provided. The reliability of the survey methods and formulas for sensitive question survey was found to be high.

  16. Nicotine therapy sampling to induce quit attempts among smokers unmotivated to quit: a randomized clinical trial.

    Science.gov (United States)

    Carpenter, Matthew J; Hughes, John R; Gray, Kevin M; Wahlquist, Amy E; Saladin, Michael E; Alberg, Anthony J

    2011-11-28

    Rates of smoking cessation have not changed in a decade, accentuating the need for novel approaches to prompt quit attempts. Within a nationwide randomized clinical trial (N = 849) to induce further quit attempts and cessation, smokers currently unmotivated to quit were randomized to a practice quit attempt (PQA) alone or to nicotine replacement therapy (hereafter referred to as nicotine therapy), sampling within the context of a PQA. Following a 6-week intervention period, participants were followed up for 6 months to assess outcomes. The PQA intervention was designed to increase motivation, confidence, and coping skills. The combination of a PQA plus nicotine therapy sampling added samples of nicotine lozenges to enhance attitudes toward pharmacotherapy and to promote the use of additional cessation resources. Primary outcomes included the incidence of any ever occurring self-defined quit attempt and 24-hour quit attempt. Secondary measures included 7-day point prevalence abstinence at any time during the study (ie, floating abstinence) and at the final follow-up assessment. Compared with PQA intervention, nicotine therapy sampling was associated with a significantly higher incidence of any quit attempt (49% vs 40%; relative risk [RR], 1.2; 95% CI, 1.1-1.4) and any 24-hour quit attempt (43% vs 34%; 1.3; 1.1-1.5). Nicotine therapy sampling was marginally more likely to promote floating abstinence (19% vs 15%; RR, 1.3; 95% CI, 1.0-1.7); 6-month point prevalence abstinence rates were no different between groups (16% vs 14%; 1.2; 0.9-1.6). Nicotine therapy sampling during a PQA represents a novel strategy to motivate smokers to make a quit attempt. clinicaltrials.gov Identifier: NCT00706979.

  17. Sample size in usability studies

    NARCIS (Netherlands)

    Schmettow, Martin

    2012-01-01

    Usability studies are important for developing usable, enjoyable products, identifying design flaws (usability problems) likely to compromise the user experience. Usability testing is recommended for improving interactive design, but discovery of usability problems depends on the number of users

  18. Protein/creatinine ratio on random urine samples for prediction of proteinuria in preeclampsia.

    Science.gov (United States)

    Roudsari, F Vahid; Ayati, S; Ayatollahi, H; Shakeri, M T

    2012-01-01

    To evaluate Protein/Creatinine ratio on random urine samples for prediction of proteinuria in preeclampsia. This study was performed on 150 pregnant women who were hospitalized as preeclampsia in Ghaem Hospital during 2006. At first, a 24-hours urine sample was collected for each patient to determine protein/creatinine ratio. Then, 24-hours urine collection was analyzed for the evaluation of proteinuria. Statistical analysis was performed with SPSS software. A total of 150 patients entered the study. There was a significant relation between the 24-hours urine protein and protein/creatinine ratio (r = 0.659, P < 0.001). Since the measurement of protein/creatinine ratio is more accurate, reliable, and cost-effective, it can be replaced by the method of measurement the 24-hours urine protein.

  19. A Unified Approach to Power Calculation and Sample Size Determination for Random Regression Models

    Science.gov (United States)

    Shieh, Gwowen

    2007-01-01

    The underlying statistical models for multiple regression analysis are typically attributed to two types of modeling: fixed and random. The procedures for calculating power and sample size under the fixed regression models are well known. However, the literature on random regression models is limited and has been confined to the case of all…

  20. Understanding infidelity: correlates in a national random sample.

    Science.gov (United States)

    Atkins, D C; Baucom, D H; Jacobson, N S

    2001-12-01

    Infidelity is a common phenomenon in marriages but is poorly understood. The current study examined variables related to extramarital sex using data from the 1991-1996 General Social Surveys. Predictor variables were entered into a logistic regression with presence of extramarital sex as the dependent variable. Results demonstrated that divorce, education, age when first married, and 2 "opportunity" variables--respondent's income and work status--significantly affected the likelihood of having engaged in infidelity. Also, there were 3 significant interactions related to infidelity: (a) between age and gender, (b) between marital satisfaction and religious behavior, and (c) between past divorce and educational level. Implications of these findings and directions for future research are discussed.

  1. Estimating the Size of a Large Network and its Communities from a Random Sample

    CERN Document Server

    Chen, Lin; Crawford, Forrest W

    2016-01-01

    Most real-world networks are too large to be measured or studied directly and there is substantial interest in estimating global network properties from smaller sub-samples. One of the most important global properties is the number of vertices/nodes in the network. Estimating the number of vertices in a large network is a major challenge in computer science, epidemiology, demography, and intelligence analysis. In this paper we consider a population random graph G = (V;E) from the stochastic block model (SBM) with K communities/blocks. A sample is obtained by randomly choosing a subset W and letting G(W) be the induced subgraph in G of the vertices in W. In addition to G(W), we observe the total degree of each sampled vertex and its block membership. Given this partial information, we propose an efficient PopULation Size Estimation algorithm, called PULSE, that correctly estimates the size of the whole population as well as the size of each community. To support our theoretical analysis, we perform an exhausti...

  2. A Family of Estimators of a Sensitive Variable Using Auxiliary Information in Stratified Random Sampling

    National Research Council Canada - National Science Library

    Nadia Mushtaq; Noor Ul Amin; Muhammad Hanif

    2017-01-01

    In this article, a combined general family of estimators is proposed for estimating finite population mean of a sensitive variable in stratified random sampling with non-sensitive auxiliary variable...

  3. Conflict-cost based random sampling design for parallel MRI with low rank constraints

    Science.gov (United States)

    Kim, Wan; Zhou, Yihang; Lyu, Jingyuan; Ying, Leslie

    2015-05-01

    In compressed sensing MRI, it is very important to design sampling pattern for random sampling. For example, SAKE (simultaneous auto-calibrating and k-space estimation) is a parallel MRI reconstruction method using random undersampling. It formulates image reconstruction as a structured low-rank matrix completion problem. Variable density (VD) Poisson discs are typically adopted for 2D random sampling. The basic concept of Poisson disc generation is to guarantee samples are neither too close to nor too far away from each other. However, it is difficult to meet such a condition especially in the high density region. Therefore the sampling becomes inefficient. In this paper, we present an improved random sampling pattern for SAKE reconstruction. The pattern is generated based on a conflict cost with a probability model. The conflict cost measures how many dense samples already assigned are around a target location, while the probability model adopts the generalized Gaussian distribution which includes uniform and Gaussian-like distributions as special cases. Our method preferentially assigns a sample to a k-space location with the least conflict cost on the circle of the highest probability. To evaluate the effectiveness of the proposed random pattern, we compare the performance of SAKEs using both VD Poisson discs and the proposed pattern. Experimental results for brain data show that the proposed pattern yields lower normalized mean square error (NMSE) than VD Poisson discs.

  4. Sample size of the reference sample in a case-augmented study.

    Science.gov (United States)

    Ghosh, Palash; Dewanji, Anup

    2017-05-01

    The case-augmented study, in which a case sample is augmented with a reference (random) sample from the source population with only covariates information known, is becoming popular in different areas of applied science such as pharmacovigilance, ecology, and econometrics. In general, the case sample is available from some source (for example, hospital database, case registry, etc.); however, the reference sample is required to be drawn from the corresponding source population. The required minimum size of the reference sample is an important issue in this regard. In this work, we address the minimum sample size calculation and discuss related issues. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  5. Comparison of kriging interpolation precision between grid sampling scheme and simple random sampling scheme for precision agriculture

    Directory of Open Access Journals (Sweden)

    Jiang Houlong

    2016-01-01

    Full Text Available Sampling methods are important factors that can potentially limit the accuracy of predictions of spatial distribution patterns. A 10 ha tobacco-planted field was selected to compared the accuracy in predicting the spatial distribution of soil properties by using ordinary kriging and cross validation methods between grid sampling and simple random sampling scheme (SRS. To achieve this objective, we collected soil samples from the topsoil (0-20 cm in March 2012. Sample numbers of grid sampling and SRS were both 115 points each. Accuracies of spatial interpolation using the two sampling schemes were then evaluated based on validation samples (36 points and deviations of the estimates. The results suggested that soil pH and nitrate-N (NO3-N had low variation, whereas all other soil properties exhibited medium variation. Soil pH, organic matter (OM, total nitrogen (TN, cation exchange capacity (CEC, total phosphorus (TP and available phosphorus (AP matched the spherical model, whereas the remaining variables fit an exponential model with both sampling methods. The interpolation error of soil pH, TP, and AP was the lowest in SRS. The errors of interpolation for OM, CEC, TN, available potassium (AK and total potassium (TK were the lowest for grid sampling. The interpolation precisions of the soil NO3-N showed no significant differences between the two sampling schemes. Considering our data on interpolation precision and the importance of minerals for cultivation of flue-cured tobacco, the grid-sampling scheme should be used in tobacco-planted fields to determine the spatial distribution of soil properties. The grid-sampling method can be applied in a practical and cost-effective manner to facilitate soil sampling in tobacco-planted field.

  6. A descriptive analysis of a representative sample of pediatric randomized controlled trials published in 2007

    Directory of Open Access Journals (Sweden)

    Thomson Denise

    2010-12-01

    Full Text Available Abstract Background Randomized controlled trials (RCTs are the gold standard for trials assessing the effects of therapeutic interventions; therefore it is important to understand how they are conducted. Our objectives were to provide an overview of a representative sample of pediatric RCTs published in 2007 and assess the validity of their results. Methods We searched Cochrane Central Register of Controlled Trials using a pediatric filter and randomly selected 300 RCTs published in 2007. We extracted data on trial characteristics; outcomes; methodological quality; reporting; and registration and protocol characteristics. Trial registration and protocol availability were determined for each study based on the publication, an Internet search and an author survey. Results Most studies (83% were efficacy trials, 40% evaluated drugs, and 30% were placebo-controlled. Primary outcomes were specified in 41%; 43% reported on adverse events. At least one statistically significant outcome was reported in 77% of trials; 63% favored the treatment group. Trial registration was declared in 12% of publications and 23% were found through an Internet search. Risk of bias (ROB was high in 59% of trials, unclear in 33%, and low in 8%. Registered trials were more likely to have low ROB than non-registered trials (16% vs. 5%; p = 0.008. Effect sizes tended to be larger for trials at high vs. low ROB (0.28, 95% CI 0.21,0.35 vs. 0.16, 95% CI 0.07,0.25. Among survey respondents (50% response rate, the most common reason for trial registration was a publication requirement and for non-registration, a lack of familiarity with the process. Conclusions More than half of this random sample of pediatric RCTs published in 2007 was at high ROB and three quarters of trials were not registered. There is an urgent need to improve the design, conduct, and reporting of child health research.

  7. High tobacco consumption is causally associated with increased all-cause mortality in a general population sample of 55,568 individuals, but not with short telomeres: a Mendelian randomization study.

    Science.gov (United States)

    Rode, Line; Bojesen, Stig E; Weischer, Maren; Nordestgaard, Børge G

    2014-10-01

    High cumulative tobacco consumption is associated with short telomeres and with increased all-cause mortality. We tested the hypothesis that high tobacco consumption is causally associated with short telomeres and with increased all-cause mortality. We studied 55,568 individuals including 32,823 ever smokers from the Danish general population, of whom 3430 died during 10 years of follow-up. All had telomere length measured, detailed information on smoking history, and CHRNA3 rs1051730 genotype, which is associated with tobacco consumption, determined. In a Mendelian randomization study, we conducted observational, genetic, and mediation analyses. First, tobacco consumption was 21.1 pack-years in non-carriers, 22.8 in heterozygotes and 24.8 in homozygotes (P-trendMendelian randomization analysis, the hazard ratio was 1.08 (1.02, 1.14) per minor CHRNA3 allele in ever smokers. Third, in observational analysis telomeres shortened with -13 base pairs (-18, -8) per doubling in tobacco consumption. In Mendelian randomization analysis, the estimate was +3 base pairs (-10, +15) per minor CHRNA3 allele. Finally, individuals with the shortest vs longest telomeres had a multivariable adjusted hazard ratio of 1.30 (1.13, 1.50) for all-cause mortality; however, in mediation analysis short telomeres explained only +0.4% (-3.5%, +4.3%) of the association between high tobacco consumption and increased all-cause mortality. High tobacco consumption is causally associated with increased all-cause mortality. High cumulative tobacco consumption is associated with short telomeres observationally, but there is no clear genetic association. © The Author 2014; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.

  8. Calculating sample sizes for cluster randomized trials: we can keep it simple and efficient !

    NARCIS (Netherlands)

    van Breukelen, Gerard J.P.; Candel, Math J.J.M.

    2012-01-01

    Objective: Simple guidelines for efficient sample sizes in cluster randomized trials with unknown intraclass correlation and varying cluster sizes. Methods: A simple equation is given for the optimal number of clusters and sample size per cluster. Here, optimal means maximizing power for a given

  9. Survey research with a random digit dial national mobile phone sample in Ghana: Methods and sample quality

    Science.gov (United States)

    Sefa, Eunice; Adimazoya, Edward Akolgo; Yartey, Emmanuel; Lenzi, Rachel; Tarpo, Cindy; Heward-Mills, Nii Lante; Lew, Katherine; Ampeh, Yvonne

    2018-01-01

    Introduction Generating a nationally representative sample in low and middle income countries typically requires resource-intensive household level sampling with door-to-door data collection. High mobile phone penetration rates in developing countries provide new opportunities for alternative sampling and data collection methods, but there is limited information about response rates and sample biases in coverage and nonresponse using these methods. We utilized data from an interactive voice response, random-digit dial, national mobile phone survey in Ghana to calculate standardized response rates and assess representativeness of the obtained sample. Materials and methods The survey methodology was piloted in two rounds of data collection. The final survey included 18 demographic, media exposure, and health behavior questions. Call outcomes and response rates were calculated according to the American Association of Public Opinion Research guidelines. Sample characteristics, productivity, and costs per interview were calculated. Representativeness was assessed by comparing data to the Ghana Demographic and Health Survey and the National Population and Housing Census. Results The survey was fielded during a 27-day period in February-March 2017. There were 9,469 completed interviews and 3,547 partial interviews. Response, cooperation, refusal, and contact rates were 31%, 81%, 7%, and 39% respectively. Twenty-three calls were dialed to produce an eligible contact: nonresponse was substantial due to the automated calling system and dialing of many unassigned or non-working numbers. Younger, urban, better educated, and male respondents were overrepresented in the sample. Conclusions The innovative mobile phone data collection methodology yielded a large sample in a relatively short period. Response rates were comparable to other surveys, although substantial coverage bias resulted from fewer women, rural, and older residents completing the mobile phone survey in

  10. [Respondent-Driven Sampling: a new sampling method to study visible and hidden populations].

    Science.gov (United States)

    Mantecón, Alejandro; Juan, Montse; Calafat, Amador; Becoña, Elisardo; Román, Encarna

    2008-01-01

    The paper introduces a variant of chain-referral sampling: respondent-driven sampling (RDS). This sampling method shows that methods based on network analysis can be combined with the statistical validity of standard probability sampling methods. In this sense, RDS appears to be a mathematical improvement of snowball sampling oriented to the study of hidden populations. However, we try to prove its validity with populations that are not within a sampling frame but can nonetheless be contacted without difficulty. The basics of RDS are explained through our research on young people (aged 14 to 25) who go clubbing, consume alcohol and other drugs, and have sex. Fieldwork was carried out between May and July 2007 in three Spanish regions: Baleares, Galicia and Comunidad Valenciana. The presentation of the study shows the utility of this type of sampling when the population is accessible but there is a difficulty deriving from the lack of a sampling frame. However, the sample obtained is not a random representative one in statistical terms of the target population. It must be acknowledged that the final sample is representative of a 'pseudo-population' that approximates to the target population but is not identical to it.

  11. Sample size and power for a stratified doubly randomized preference design.

    Science.gov (United States)

    Cameron, Briana; Esserman, Denise A

    2016-11-21

    The two-stage (or doubly) randomized preference trial design is an important tool for researchers seeking to disentangle the role of patient treatment preference on treatment response through estimation of selection and preference effects. Up until now, these designs have been limited by their assumption of equal preference rates and effect sizes across the entire study population. We propose a stratified two-stage randomized trial design that addresses this limitation. We begin by deriving stratified test statistics for the treatment, preference, and selection effects. Next, we develop a sample size formula for the number of patients required to detect each effect. The properties of the model and the efficiency of the design are established using a series of simulation studies. We demonstrate the applicability of the design using a study of Hepatitis C treatment modality, specialty clinic versus mobile medical clinic. In this example, a stratified preference design (stratified by alcohol/drug use) may more closely capture the true distribution of patient preferences and allow for a more efficient design than a design which ignores these differences (unstratified version). © The Author(s) 2016.

  12. Sample size in qualitative interview studies

    DEFF Research Database (Denmark)

    Malterud, Kirsti; Siersma, Volkert Dirk; Guassora, Ann Dorrit Kristiane

    2016-01-01

    Sample sizes must be ascertained in qualitative studies like in quantitative studies but not by the same means. The prevailing concept for sample size in qualitative studies is “saturation.” Saturation is closely tied to a specific methodology, and the term is inconsistently applied. We propose...... the concept “information power” to guide adequate sample size for qualitative studies. Information power indicates that the more information the sample holds, relevant for the actual study, the lower amount of participants is needed. We suggest that the size of a sample with sufficient information power...... depends on (a) the aim of the study, (b) sample specificity, (c) use of established theory, (d) quality of dialogue, and (e) analysis strategy. We present a model where these elements of information and their relevant dimensions are related to information power. Application of this model in the planning...

  13. SNP selection and classification of genome-wide SNP data using stratified sampling random forests.

    Science.gov (United States)

    Wu, Qingyao; Ye, Yunming; Liu, Yang; Ng, Michael K

    2012-09-01

    For high dimensional genome-wide association (GWA) case-control data of complex disease, there are usually a large portion of single-nucleotide polymorphisms (SNPs) that are irrelevant with the disease. A simple random sampling method in random forest using default mtry parameter to choose feature subspace, will select too many subspaces without informative SNPs. Exhaustive searching an optimal mtry is often required in order to include useful and relevant SNPs and get rid of vast of non-informative SNPs. However, it is too time-consuming and not favorable in GWA for high-dimensional data. The main aim of this paper is to propose a stratified sampling method for feature subspace selection to generate decision trees in a random forest for GWA high-dimensional data. Our idea is to design an equal-width discretization scheme for informativeness to divide SNPs into multiple groups. In feature subspace selection, we randomly select the same number of SNPs from each group and combine them to form a subspace to generate a decision tree. The advantage of this stratified sampling procedure can make sure each subspace contains enough useful SNPs, but can avoid a very high computational cost of exhaustive search of an optimal mtry, and maintain the randomness of a random forest. We employ two genome-wide SNP data sets (Parkinson case-control data comprised of 408 803 SNPs and Alzheimer case-control data comprised of 380 157 SNPs) to demonstrate that the proposed stratified sampling method is effective, and it can generate better random forest with higher accuracy and lower error bound than those by Breiman's random forest generation method. For Parkinson data, we also show some interesting genes identified by the method, which may be associated with neurological disorders for further biological investigations.

  14. LONG-TERM VARIABILITY OF BRONCHIAL RESPONSIVENESS TO HISTAMINE IN A RANDOM-POPULATION SAMPLE OF ADULTS

    NARCIS (Netherlands)

    RIJCKEN, B; SCHOUTEN, JP; WEISS, ST; ROSNER, B; DEVRIES, K; VANDERLENDE, R

    1993-01-01

    Long-term variability of bronchial responsiveness has been studied in a random population sample of adults. During a follow-up period of 18 yr, 2,216 subjects contributed 5,012 observations to the analyses. Each subject could have as many as seven observations. Bronchial responsiveness was assessed

  15. Randomized study of zinc supplementation during pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Hambidge, K.M.; Oliva-Rasbach, J.; Jacobs, M.; Purcell, S.; Statland, C.; Poirier, J.

    1986-03-05

    The hypothesis underlying this study was that a daily dietary Zn supplement during pregnancy would be associated with higher values for selected indices of Zn nutriture than corresponding values for non-Zn-supplemented subjects, if, and only if, Zn status of the unsupplemented control group was sub-optimal. The 12 test and 17 control subjects were healthy, apparently well-nourished anglos who were enrolled before the 12th week of gestation. Mean age=29 yrs, mean parity=0.8. Test subjects received a daily supplement of 15 mg Zn (mean compliance=90%) from the time of enrollment until 3 months post-partum. The supplement was taken at bedtime while other vitamin/mineral preparations were taken before breakfast. Blood samples were obtained at 4 week intervals from enrollment. Selected preliminary results: plasma Zn declined progressively with length of gestation to a nadir of 53 +/- 6 ..mu..g/dl at 10 months. (Non-pregnant mean 77 +/- 7). As in a previous, non-randomized, study the rate of decline for the test group did not differ from that of the control group. Mean monthly neutrophil Zn ranged from 43 +/- 8 - 50 +/- 14 ..mu..g/10/sup 10/ cells; there was not consistent pattern across gestation. Serum alkaline phosphatase activity and pre-albumin of the test group did not differ from the control group. These data did not give any indication of sub-optimal Zn nutriture in this pregnant population.

  16. Notes on interval estimation of the generalized odds ratio under stratified random sampling.

    Science.gov (United States)

    Lui, Kung-Jong; Chang, Kuang-Chao

    2013-05-01

    It is not rare to encounter the patient response on the ordinal scale in a randomized clinical trial (RCT). Under the assumption that the generalized odds ratio (GOR) is homogeneous across strata, we consider four asymptotic interval estimators for the GOR under stratified random sampling. These include the interval estimator using the weighted-least-squares (WLS) approach with the logarithmic transformation (WLSL), the interval estimator using the Mantel-Haenszel (MH) type of estimator with the logarithmic transformation (MHL), the interval estimator using Fieller's theorem with the MH weights (FTMH) and the interval estimator using Fieller's theorem with the WLS weights (FTWLS). We employ Monte Carlo simulation to evaluate the performance of these interval estimators by calculating the coverage probability and the average length. To study the bias of these interval estimators, we also calculate and compare the noncoverage probabilities in the two tails of the resulting confidence intervals. We find that WLSL and MHL can generally perform well, while FTMH and FTWLS can lose either precision or accuracy. We further find that MHL is likely the least biased. Finally, we use the data taken from a study of smoking status and breathing test among workers in certain industrial plants in Houston, Texas, during 1974 to 1975 to illustrate the use of these interval estimators.

  17. Random Walks on Directed Networks: Inference and Respondent-driven Sampling

    CERN Document Server

    Malmros, Jens; Britton, Tom

    2013-01-01

    Respondent driven sampling (RDS) is a method often used to estimate population properties (e.g. sexual risk behavior) in hard-to-reach populations. It combines an effective modified snowball sampling methodology with an estimation procedure that yields unbiased population estimates under the assumption that the sampling process behaves like a random walk on the social network of the population. Current RDS estimation methodology assumes that the social network is undirected, i.e. that all edges are reciprocal. However, empirical social networks in general also have non-reciprocated edges. To account for this fact, we develop a new estimation method for RDS in the presence of directed edges on the basis of random walks on directed networks. We distinguish directed and undirected edges and consider the possibility that the random walk returns to its current position in two steps through an undirected edge. We derive estimators of the selection probabilities of individuals as a function of the number of outgoing...

  18. Sampling pig farms at the abattoir in a cross-sectional study − Evaluation of a sampling method

    DEFF Research Database (Denmark)

    Birkegård, Anna Camilla; Hisham Beshara Halasa, Tariq; Toft, Nils

    2017-01-01

    A cross-sectional study design is relatively inexpensive, fast and easy to conduct when compared to other study designs. Careful planning is essential to obtaining a representative sample of the population, and the recommended approach is to use simple random sampling from an exhaustive list of u...

  19. Estimation of Sensitive Proportion by Randomized Response Data in Successive Sampling

    Directory of Open Access Journals (Sweden)

    Bo Yu

    2015-01-01

    Full Text Available This paper considers the problem of estimation for binomial proportions of sensitive or stigmatizing attributes in the population of interest. Randomized response techniques are suggested for protecting the privacy of respondents and reducing the response bias while eliciting information on sensitive attributes. In many sensitive question surveys, the same population is often sampled repeatedly on each occasion. In this paper, we apply successive sampling scheme to improve the estimation of the sensitive proportion on current occasion.

  20. Random sampling of elementary flux modes in large-scale metabolic networks.

    Science.gov (United States)

    Machado, Daniel; Soons, Zita; Patil, Kiran Raosaheb; Ferreira, Eugénio C; Rocha, Isabel

    2012-09-15

    The description of a metabolic network in terms of elementary (flux) modes (EMs) provides an important framework for metabolic pathway analysis. However, their application to large networks has been hampered by the combinatorial explosion in the number of modes. In this work, we develop a method for generating random samples of EMs without computing the whole set. Our algorithm is an adaptation of the canonical basis approach, where we add an additional filtering step which, at each iteration, selects a random subset of the new combinations of modes. In order to obtain an unbiased sample, all candidates are assigned the same probability of getting selected. This approach avoids the exponential growth of the number of modes during computation, thus generating a random sample of the complete set of EMs within reasonable time. We generated samples of different sizes for a metabolic network of Escherichia coli, and observed that they preserve several properties of the full EM set. It is also shown that EM sampling can be used for rational strain design. A well distributed sample, that is representative of the complete set of EMs, should be suitable to most EM-based methods for analysis and optimization of metabolic networks. Source code for a cross-platform implementation in Python is freely available at http://code.google.com/p/emsampler. dmachado@deb.uminho.pt Supplementary data are available at Bioinformatics online.

  1. Sampling versus Random Binning for Multiple Descriptions of a Bandlimited Source

    DEFF Research Database (Denmark)

    Mashiach, Adam; Østergaard, Jan; Zamir, Ram

    2013-01-01

    Random binning is an efficient, yet complex, coding technique for the symmetric L-description source coding problem. We propose an alternative approach, that uses the quantized samples of a bandlimited source as "descriptions". By the Nyquist condition, the source can be reconstructed if enough s...

  2. Recidivism among Child Sexual Abusers: Initial Results of a 13-Year Longitudinal Random Sample

    Science.gov (United States)

    Patrick, Steven; Marsh, Robert

    2009-01-01

    In the initial analysis of data from a random sample of all those charged with child sexual abuse in Idaho over a 13-year period, only one predictive variable was found that related to recidivism of those convicted. Variables such as ethnicity, relationship, gender, and age differences did not show a significant or even large association with…

  3. HABITAT ASSESSMENT USING A RANDOM PROBABILITY BASED SAMPLING DESIGN: ESCAMBIA RIVER DELTA, FLORIDA

    Science.gov (United States)

    Smith, Lisa M., Darrin D. Dantin and Steve Jordan. In press. Habitat Assessment Using a Random Probability Based Sampling Design: Escambia River Delta, Florida (Abstract). To be presented at the SWS/GERS Fall Joint Society Meeting: Communication and Collaboration: Coastal Systems...

  4. Reinforcing Sampling Distributions through a Randomization-Based Activity for Introducing ANOVA

    Science.gov (United States)

    Taylor, Laura; Doehler, Kirsten

    2015-01-01

    This paper examines the use of a randomization-based activity to introduce the ANOVA F-test to students. The two main goals of this activity are to successfully teach students to comprehend ANOVA F-tests and to increase student comprehension of sampling distributions. Four sections of students in an advanced introductory statistics course…

  5. Notes on interval estimation of the gamma correlation under stratified random sampling.

    Science.gov (United States)

    Lui, Kung-Jong; Chang, Kuang-Chao

    2012-07-01

    We have developed four asymptotic interval estimators in closed forms for the gamma correlation under stratified random sampling, including the confidence interval based on the most commonly used weighted-least-squares (WLS) approach (CIWLS), the confidence interval calculated from the Mantel-Haenszel (MH) type estimator with the Fisher-type transformation (CIMHT), the confidence interval using the fundamental idea of Fieller's Theorem (CIFT) and the confidence interval derived from a monotonic function of the WLS estimator of Agresti's α with the logarithmic transformation (MWLSLR). To evaluate the finite-sample performance of these four interval estimators and note the possible loss of accuracy in application of both Wald's confidence interval and MWLSLR using pooled data without accounting for stratification, we employ Monte Carlo simulation. We use the data taken from a general social survey studying the association between the income level and job satisfaction with strata formed by genders in black Americans published elsewhere to illustrate the practical use of these interval estimators. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Predictive value of testing random urine sample to detect microalbuminuria in diabetic subjects during outpatient visit.

    Science.gov (United States)

    Bouhanick, B; Berrut, G; Chameau, A M; Hallar, M; Bled, F; Chevet, B; Vergely, J; Rohmer, V; Fressinaud, P; Marre, M

    1992-01-01

    The predictive value of random urine sample during outpatient visit to predict persistent microalbuminuria was studied in 76 Type 1, insulin-dependent diabetic subjects, 61 Type 2, non-insulin-dependent diabetic subjects, and 72 Type 2, insulin-treated diabetic subjects. Seventy-six patients attended outpatient clinic during morning, and 133 during afternoon. Microalbuminuria was suspected if Urinary Albumin Excretion (UAE) exceeded 20 mg/l. All patients were hospitalized within 6 months following outpatient visit, and persistent microalbuminuria was assessed then if UAE was between 30 and 300 mg/24 h on 2-3 occasions in 3 urines samples. Of these 209 subjects eighty-three were also screened with Microbumintest (Ames-Bayer), a semi-quantitative method. Among the 209 subjects, 71 were positive both for microalbuminuria during outpatient visit and a persistent microalbuminuria during hospitalization: sensitivity 91.0%, specificity 83.2%, concordance 86.1%, and positive predictive value 76.3% (chi-squared test: 191; p less than 10(-4)). Data were not different for subjects examined on morning, or on afternoon. Among the 83 subjects also screened with Microbumintest, 22 displayed both a positive reaction and a persistent microalbuminuria: sensitivity 76%, specificity 81%, concordance 80%, and positive predictive value 69% (chi-squared test: 126; p less than 10(-4)). Both types of screening appeared equally effective during outpatient visit. Hence, a persistent microalbuminuria can be predicted during an outpatient visit in a diabetic clinic.

  7. Effectiveness of hand hygiene education among a random sample of women from the community.

    Science.gov (United States)

    Ubheeram, J; Biranjia-Hurdoyal, S D

    2017-03-01

    The effectiveness of hand hygiene education was investigated by studying the hand hygiene awareness and bacterial hand contamination among a random sample of 170 women in the community. Questionnaire was used to assess the hand hygiene awareness score, followed by swabbing of the dominant hand. Bacterial identification was done by conventional biochemical tests. Better hand hygiene awareness score was significantly associated with age, scarce bacterial growth and absence of potential pathogen (p hand samples, bacterial growth was noted in 155 (91.2%), which included 91 (53.5%) heavy growth, 53 (31.2%) moderate growth and 11 (6.47%) scanty growth. The presence of enteric bacteria was associated with long nails (49.4% vs 29.2%; p = 0.007; OR = 2.3; 95% CI: 1.25-4.44) while finger rings were associated with higher bacterial load (p = 0.003). Coliforms was significantly higher among women who had a lower hand hygiene awareness score, washed their hands at lower frequency (59.0% vs 32.8%; p = 0.003; OR = 2.9; 95% CI: 1.41-6.13) and used common soap as compared to antiseptic soaps (69.7% vs 30.3%, p = 0.000; OR = 4.11; 95% CI: 1.67-10.12). Level of hand hygiene awareness among the participants was satisfactory but not the compliance of hand washing practice, especially among the elders.

  8. Association between stalking victimisation and psychiatric morbidity in a random community sample.

    Science.gov (United States)

    Purcell, Rosemary; Pathé, Michele; Mullen, Paul E

    2005-11-01

    No studies have assessed psychopathology among victims of stalking who have not sought specialist help. To examine the associations between stalking victimisation and psychiatric morbidity in a representative community sample. A random community sample (n=1844) completed surveys examining the experience of harassment and current mental health. The 28-item General Health Questionnaire (GHQ-28) and the Impact of Event Scale were used to assess symptomatology in those reporting brief harassment (n=196) or protracted stalking (n=236) and a matched control group reporting no harassment (n=432). Rates of caseness on the GHQ-28 were higher among stalking victims (36.4%) than among controls (19.3%) and victims of brief harassment (21.9%). Psychiatric morbidity did not differ according to the recency of victimisation, with 34.1% of victims meeting caseness criteria 1 year after stalking had ended. In a significant minority of victims, stalking victimisation is associated with psychiatric morbidity that may persist long after it has ceased. Recognition of the immediate and long-term impacts of stalking is necessary to assist victims and help alleviate distress and long-term disability.

  9. Sampling pig farms at the abattoir in a cross-sectional study - Evaluation of a sampling method.

    Science.gov (United States)

    Birkegård, Anna Camilla; Halasa, Tariq; Toft, Nils

    2017-09-15

    A cross-sectional study design is relatively inexpensive, fast and easy to conduct when compared to other study designs. Careful planning is essential to obtaining a representative sample of the population, and the recommended approach is to use simple random sampling from an exhaustive list of units in the target population. This approach is rarely feasible in practice, and other sampling procedures must often be adopted. For example, when slaughter pigs are the target population, sampling the pigs on the slaughter line may be an alternative to on-site sampling at a list of farms. However, it is difficult to sample a large number of farms from an exact predefined list, due to the logistics and workflow of an abattoir. Therefore, it is necessary to have a systematic sampling procedure and to evaluate the obtained sample with respect to the study objective. We propose a method for 1) planning, 2) conducting, and 3) evaluating the representativeness and reproducibility of a cross-sectional study when simple random sampling is not possible. We used an example of a cross-sectional study with the aim of quantifying the association of antimicrobial resistance and antimicrobial consumption in Danish slaughter pigs. It was not possible to visit farms within the designated timeframe. Therefore, it was decided to use convenience sampling at the abattoir. Our approach was carried out in three steps: 1) planning: using data from meat inspection to plan at which abattoirs and how many farms to sample; 2) conducting: sampling was carried out at five abattoirs; 3) evaluation: representativeness was evaluated by comparing sampled and non-sampled farms, and the reproducibility of the study was assessed through simulated sampling based on meat inspection data from the period where the actual data collection was carried out. In the cross-sectional study samples were taken from 681 Danish pig farms, during five weeks from February to March 2015. The evaluation showed that the sampling

  10. Evaluation of a Class of Simple and Effective Uncertainty Methods for Sparse Samples of Random Variables and Functions

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Vicente [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bonney, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schroeder, Benjamin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weirs, V. Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-11-01

    When very few samples of a random quantity are available from a source distribution of unknown shape, it is usually not possible to accurately infer the exact distribution from which the data samples come. Under-estimation of important quantities such as response variance and failure probabilities can result. For many engineering purposes, including design and risk analysis, we attempt to avoid under-estimation with a strategy to conservatively estimate (bound) these types of quantities -- without being overly conservative -- when only a few samples of a random quantity are available from model predictions or replicate experiments. This report examines a class of related sparse-data uncertainty representation and inference approaches that are relatively simple, inexpensive, and effective. Tradeoffs between the methods' conservatism, reliability, and risk versus number of data samples (cost) are quantified with multi-attribute metrics use d to assess method performance for conservative estimation of two representative quantities: central 95% of response; and 10-4 probability of exceeding a response threshold in a tail of the distribution. Each method's performance is characterized with 10,000 random trials on a large number of diverse and challenging distributions. The best method and number of samples to use in a given circumstance depends on the uncertainty quantity to be estimated, the PDF character, and the desired reliability of bounding the true value. On the basis of this large data base and study, a strategy is proposed for selecting the method and number of samples for attaining reasonable credibility levels in bounding these types of quantities when sparse samples of random variables or functions are available from experiments or simulations.

  11. Random sample community-based health surveys: does the effort to reach participants matter?

    Science.gov (United States)

    Messiah, Antoine; Castro, Grettel; Rodríguez de la Vega, Pura; Acuna, Juan M

    2014-12-15

    Conducting health surveys with community-based random samples are essential to capture an otherwise unreachable population, but these surveys can be biased if the effort to reach participants is insufficient. This study determines the desirable amount of effort to minimise such bias. A household-based health survey with random sampling and face-to-face interviews. Up to 11 visits, organised by canvassing rounds, were made to obtain an interview. Single-family homes in an underserved and understudied population in North Miami-Dade County, Florida, USA. Of a probabilistic sample of 2200 household addresses, 30 corresponded to empty lots, 74 were abandoned houses, 625 households declined to participate and 265 could not be reached and interviewed within 11 attempts. Analyses were performed on the 1206 remaining households. Each household was asked if any of their members had been told by a doctor that they had high blood pressure, heart disease including heart attack, cancer, diabetes, anxiety/ depression, obesity or asthma. Responses to these questions were analysed by the number of visit attempts needed to obtain the interview. Return per visit fell below 10% after four attempts, below 5% after six attempts and below 2% after eight attempts. As the effort increased, household size decreased, while household income and the percentage of interviewees active and employed increased; proportion of the seven health conditions decreased, four of which did so significantly: heart disease 20.4-9.2%, high blood pressure 63.5-58.1%, anxiety/depression 24.4-9.2% and obesity 21.8-12.6%. Beyond the fifth attempt, however, cumulative percentages varied by less than 1% and precision varied by less than 0.1%. In spite of the early and steep drop, sustaining at least five attempts to reach participants is necessary to reduce selection bias. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  12. The effect of a mindfulness-based intervention in cognitive functions and psychological well-being applied as an early intervention in schizophrenia and high-risk mental state in a Chilean sample: study protocol for a randomized controlled trial.

    Science.gov (United States)

    Langer, Álvaro I; Schmidt, Carlos; Mayol, Rocío; Díaz, Marcela; Lecaros, Javiera; Krogh, Edwin; Pardow, Aída; Vergara, Carolina; Vergara, Guillermo; Pérez-Herrera, Bernardita; Villar, María José; Maturana, Alejandro; Gaspar, Pablo A

    2017-05-25

    According to the projections of the World Health Organization, 15% of all disabilities will be associated with mental illnesses by 2020. One of the mental disorders with the largest social impacts due to high personal and family costs is psychosis. Among the most effective psychological approaches to treat schizophrenia and other psychotic disorders at the world level is cognitive behavioral therapy. Recently, cognitive behavioral therapy has introduced several tools and strategies that promote psychological processes based on acceptance and mindfulness. A large number of studies support the effectiveness of mindfulness in dealing with various mental health problems, including psychosis. This study is aimed at determining the efficiency of a mindfulness-based program in increasing cognitive function and psychological well-being in patients with a first episode of schizophrenia and a high risk mental state (those at risk of developing an episode of psychosis). This is an experimentally designed, multi-center randomized controlled trial, with a 3-month follow-up period. The study participants will be 48 patients diagnosed with schizophrenia (first episode) and 48 with a high-risk mental state, from Santiago, Chile, aged between 15 and 35 years. Participants will be submitted to a mindfulness-based intervention (MBI), which will involve taking part in eight mindfulness workshops adapted for people with psychosis. Workshops will last approximately 1.5 hours and take place once a week, over 8 weeks. The primary outcome will be the cognitive function through Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) and the secondary outcome will be psychological well-being measured by self-reporting questionnaires. The outcomes of this trial will add empirical evidence to the benefits and feasibility of MBIs for the psychotherapeutic treatment of patients with schizophrenia and high-risk mental states in reducing cognitive impairment in

  13. Characterization of Electron Microscopes with Binary Pseudo-random Multilayer Test Samples

    Energy Technology Data Exchange (ETDEWEB)

    V Yashchuk; R Conley; E Anderson; S Barber; N Bouet; W McKinney; P Takacs; D Voronov

    2011-12-31

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  14. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V., E-mail: VVYashchuk@lbl.gov [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Conley, Raymond [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States); Anderson, Erik H. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Barber, Samuel K. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bouet, Nathalie [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States); McKinney, Wayne R. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Takacs, Peter Z. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Voronov, Dmitriy L. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-09-01

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  15. Accounting for Sampling Error in Genetic Eigenvalues Using Random Matrix Theory.

    Science.gov (United States)

    Sztepanacz, Jacqueline L; Blows, Mark W

    2017-07-01

    The distribution of genetic variance in multivariate phenotypes is characterized by the empirical spectral distribution of the eigenvalues of the genetic covariance matrix. Empirical estimates of genetic eigenvalues from random effects linear models are known to be overdispersed by sampling error, where large eigenvalues are biased upward, and small eigenvalues are biased downward. The overdispersion of the leading eigenvalues of sample covariance matrices have been demonstrated to conform to the Tracy-Widom (TW) distribution. Here we show that genetic eigenvalues estimated using restricted maximum likelihood (REML) in a multivariate random effects model with an unconstrained genetic covariance structure will also conform to the TW distribution after empirical scaling and centering. However, where estimation procedures using either REML or MCMC impose boundary constraints, the resulting genetic eigenvalues tend not be TW distributed. We show how using confidence intervals from sampling distributions of genetic eigenvalues without reference to the TW distribution is insufficient protection against mistaking sampling error as genetic variance, particularly when eigenvalues are small. By scaling such sampling distributions to the appropriate TW distribution, the critical value of the TW statistic can be used to determine if the magnitude of a genetic eigenvalue exceeds the sampling error for each eigenvalue in the spectral distribution of a given genetic covariance matrix. Copyright © 2017 by the Genetics Society of America.

  16. Finite-sample corrected generalized estimating equation of population average treatment effects in stepped wedge cluster randomized trials.

    Science.gov (United States)

    Scott, JoAnna M; deCamp, Allan; Juraska, Michal; Fay, Michael P; Gilbert, Peter B

    2017-04-01

    Stepped wedge designs are increasingly commonplace and advantageous for cluster randomized trials when it is both unethical to assign placebo, and it is logistically difficult to allocate an intervention simultaneously to many clusters. We study marginal mean models fit with generalized estimating equations for assessing treatment effectiveness in stepped wedge cluster randomized trials. This approach has advantages over the more commonly used mixed models that (1) the population-average parameters have an important interpretation for public health applications and (2) they avoid untestable assumptions on latent variable distributions and avoid parametric assumptions about error distributions, therefore, providing more robust evidence on treatment effects. However, cluster randomized trials typically have a small number of clusters, rendering the standard generalized estimating equation sandwich variance estimator biased and highly variable and hence yielding incorrect inferences. We study the usual asymptotic generalized estimating equation inferences (i.e., using sandwich variance estimators and asymptotic normality) and four small-sample corrections to generalized estimating equation for stepped wedge cluster randomized trials and for parallel cluster randomized trials as a comparison. We show by simulation that the small-sample corrections provide improvement, with one correction appearing to provide at least nominal coverage even with only 10 clusters per group. These results demonstrate the viability of the marginal mean approach for both stepped wedge and parallel cluster randomized trials. We also study the comparative performance of the corrected methods for stepped wedge and parallel designs, and describe how the methods can accommodate interval censoring of individual failure times and incorporate semiparametric efficient estimators.

  17. On analysis-based two-step interpolation methods for randomly sampled seismic data

    Science.gov (United States)

    Yang, Pengliang; Gao, Jinghuai; Chen, Wenchao

    2013-02-01

    Interpolating the missing traces of regularly or irregularly sampled seismic record is an exceedingly important issue in the geophysical community. Many modern acquisition and reconstruction methods are designed to exploit the transform domain sparsity of the few randomly recorded but informative seismic data using thresholding techniques. In this paper, to regularize randomly sampled seismic data, we introduce two accelerated, analysis-based two-step interpolation algorithms, the analysis-based FISTA (fast iterative shrinkage-thresholding algorithm) and the FPOCS (fast projection onto convex sets) algorithm from the IST (iterative shrinkage-thresholding) algorithm and the POCS (projection onto convex sets) algorithm. A MATLAB package is developed for the implementation of these thresholding-related interpolation methods. Based on this package, we compare the reconstruction performance of these algorithms, using synthetic and real seismic data. Combined with several thresholding strategies, the accelerated convergence of the proposed methods is also highlighted.

  18. An inversion method based on random sampling for real-time MEG neuroimaging

    CERN Document Server

    Pascarella, Annalisa

    2016-01-01

    The MagnetoEncephaloGraphy (MEG) has gained great interest in neurorehabilitation training due to its high temporal resolution. The challenge is to localize the active regions of the brain in a fast and accurate way. In this paper we use an inversion method based on random spatial sampling to solve the real-time MEG inverse problem. Several numerical tests on synthetic but realistic data show that the method takes just a few hundredths of a second on a laptop to produce an accurate map of the electric activity inside the brain. Moreover, it requires very little memory storage. For this reasons the random sampling method is particularly attractive in real-time MEG applications.

  19. Control Capacity and A Random Sampling Method in Exploring Controllability of Complex Networks

    OpenAIRE

    Jia, Tao; Barab?si, Albert-L?szl?

    2013-01-01

    Controlling complex systems is a fundamental challenge of network science. Recent advances indicate that control over the system can be achieved through a minimum driver node set (MDS). The existence of multiple MDS's suggests that nodes do not participate in control equally, prompting us to quantify their participations. Here we introduce control capacity quantifying the likelihood that a node is a driver node. To efficiently measure this quantity, we develop a random sampling algorithm. Thi...

  20. Classification of epileptic EEG signals based on simple random sampling and sequential feature selection

    OpenAIRE

    Ghayab, Hadi Ratham Al; Li, Yan; Abdulla, Shahab; Diykh, Mohammed; Wan, Xiangkui

    2016-01-01

    Electroencephalogram (EEG) signals are used broadly in the medical fields. The main applications of EEG signals are the diagnosis and treatment of diseases such as epilepsy, Alzheimer, sleep problems and so on. This paper presents a new method which extracts and selects features from multi-channel EEG signals. This research focuses on three main points. Firstly, simple random sampling (SRS) technique is used to extract features from the time domain of EEG signals. Secondly, the sequential fea...

  1. Experiments with central-limit properties of spatial samples from locally covariant random fields

    Science.gov (United States)

    Barringer, T.H.; Smith, T.E.

    1992-01-01

    When spatial samples are statistically dependent, the classical estimator of sample-mean standard deviation is well known to be inconsistent. For locally dependent samples, however, consistent estimators of sample-mean standard deviation can be constructed. The present paper investigates the sampling properties of one such estimator, designated as the tau estimator of sample-mean standard deviation. In particular, the asymptotic normality properties of standardized sample means based on tau estimators are studied in terms of computer experiments with simulated sample-mean distributions. The effects of both sample size and dependency levels among samples are examined for various value of tau (denoting the size of the spatial kernel for the estimator). The results suggest that even for small degrees of spatial dependency, the tau estimator exhibits significantly stronger normality properties than does the classical estimator of standardized sample means. ?? 1992.

  2. Determining optimal sample sizes for multi-stage randomized clinical trials using value of information methods.

    Science.gov (United States)

    Willan, Andrew; Kowgier, Matthew

    2008-01-01

    Traditional sample size calculations for randomized clinical trials depend on somewhat arbitrarily chosen factors, such as Type I and II errors. An effectiveness trial (otherwise known as a pragmatic trial or management trial) is essentially an effort to inform decision-making, i.e., should treatment be adopted over standard? Taking a societal perspective and using Bayesian decision theory, Willan and Pinto (Stat. Med. 2005; 24:1791-1806 and Stat. Med. 2006; 25:720) show how to determine the sample size that maximizes the expected net gain, i.e., the difference between the cost of doing the trial and the value of the information gained from the results. These methods are extended to include multi-stage adaptive designs, with a solution given for a two-stage design. The methods are applied to two examples. As demonstrated by the two examples, substantial increases in the expected net gain (ENG) can be realized by using multi-stage adaptive designs based on expected value of information methods. In addition, the expected sample size and total cost may be reduced. Exact solutions have been provided for the two-stage design. Solutions for higher-order designs may prove to be prohibitively complex and approximate solutions may be required. The use of multi-stage adaptive designs for randomized clinical trials based on expected value of sample information methods leads to substantial gains in the ENG and reductions in the expected sample size and total cost.

  3. Sample size calculations for pilot randomized trials: a confidence interval approach.

    Science.gov (United States)

    Cocks, Kim; Torgerson, David J

    2013-02-01

    To describe a method using confidence intervals (CIs) to estimate the sample size for a pilot randomized trial. Using one-sided CIs and the estimated effect size that would be sought in a large trial, we calculated the sample size needed for pilot trials. Using an 80% one-sided CI, we estimated that a pilot trial should have at least 9% of the sample size of the main planned trial. Using the estimated effect size difference for the main trial and using a one-sided CI, this allows us to calculate a sample size for a pilot trial, which will make its results more useful than at present. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Neurofeedback Against Binge Eating: A Randomized Controlled Trial in a Female Subclinical Threshold Sample.

    Science.gov (United States)

    Schmidt, Jennifer; Martin, Alexandra

    2016-09-01

    Brain-directed treatment techniques, such as neurofeedback, have recently been proposed as adjuncts in the treatment of eating disorders to improve therapeutic outcomes. In line with this recommendation, a cue exposure EEG-neurofeedback protocol was developed. The present study aimed at the evaluation of the specific efficacy of neurofeedback to reduce subjective binge eating in a female subthreshold sample. A total of 75 subjects were randomized to EEG-neurofeedback, mental imagery with a comparable treatment set-up or a waitlist group. At post-treatment, only EEG-neurofeedback led to a reduced frequency of binge eating (p = .015, g = 0.65). The effects remained stable to a 3-month follow-up. EEG-neurofeedback further showed particular beneficial effects on perceived stress and dietary self-efficacy. Differences in outcomes did not arise from divergent treatment expectations. Because EEG-neurofeedback showed a specific efficacy, it may be a promising brain-directed approach that should be tested as a treatment adjunct in clinical groups with binge eating. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

  5. A coupled well-balanced and random sampling scheme for computing bubble oscillations*

    Directory of Open Access Journals (Sweden)

    Jung Jonathan

    2012-04-01

    Full Text Available We propose a finite volume scheme to study the oscillations of a spherical bubble of gas in a liquid phase. Spherical symmetry implies a geometric source term in the Euler equations. Our scheme satisfies the well-balanced property. It is based on the VFRoe approach. In order to avoid spurious pressure oscillations, the well-balanced approach is coupled with an ALE (Arbitrary Lagrangian Eulerian technique at the interface and a random sampling remap. Nous proposons un schéma de volumes finis pour étudier les oscillations d’une bulle sphérique de gaz dans l’eau. La symétrie sphérique fait apparaitre un terme source géométrique dans les équations d’Euler. Notre schéma est basé sur une approche VFRoe et préserve les états stationnaires. Pour éviter les oscillations de pression, l’approche well-balanced est couplée avec une approche ALE (Arbitrary Lagrangian Eulerian, et une étape de projection basée sur un échantillonage aléatoire.

  6. Accelerating Markov chain Monte Carlo simulation by differential evolution with self-adaptive randomized subspace sampling

    Energy Technology Data Exchange (ETDEWEB)

    Vrugt, Jasper A [Los Alamos National Laboratory; Hyman, James M [Los Alamos National Laboratory; Robinson, Bruce A [Los Alamos National Laboratory; Higdon, Dave [Los Alamos National Laboratory; Ter Braak, Cajo J F [NETHERLANDS; Diks, Cees G H [UNIV OF AMSTERDAM

    2008-01-01

    Markov chain Monte Carlo (MCMC) methods have found widespread use in many fields of study to estimate the average properties of complex systems, and for posterior inference in a Bayesian framework. Existing theory and experiments prove convergence of well constructed MCMC schemes to the appropriate limiting distribution under a variety of different conditions. In practice, however this convergence is often observed to be disturbingly slow. This is frequently caused by an inappropriate selection of the proposal distribution used to generate trial moves in the Markov Chain. Here we show that significant improvements to the efficiency of MCMC simulation can be made by using a self-adaptive Differential Evolution learning strategy within a population-based evolutionary framework. This scheme, entitled DiffeRential Evolution Adaptive Metropolis or DREAM, runs multiple different chains simultaneously for global exploration, and automatically tunes the scale and orientation of the proposal distribution in randomized subspaces during the search. Ergodicity of the algorithm is proved, and various examples involving nonlinearity, high-dimensionality, and multimodality show that DREAM is generally superior to other adaptive MCMC sampling approaches. The DREAM scheme significantly enhances the applicability of MCMC simulation to complex, multi-modal search problems.

  7. Sample-to-sample fluctuations of power spectrum of a random motion in a periodic Sinai model

    Science.gov (United States)

    Dean, David S.; Iorio, Antonio; Marinari, Enzo; Oshanin, Gleb

    2016-09-01

    The Sinai model of a tracer diffusing in a quenched Brownian potential is a much-studied problem exhibiting a logarithmically slow anomalous diffusion due to the growth of energy barriers with the system size. However, if the potential is random but periodic, the regime of anomalous diffusion crosses over to one of normal diffusion once a tracer has diffused over a few periods of the system. Here we consider a system in which the potential is given by a Brownian bridge on a finite interval (0 ,L ) and then periodically repeated over the whole real line and study the power spectrum S (f ) of the diffusive process x (t ) in such a potential. We show that for most of realizations of x (t ) in a given realization of the potential, the low-frequency behavior is S (f ) ˜A /f2 , i.e., the same as for standard Brownian motion, and the amplitude A is a disorder-dependent random variable with a finite support. Focusing on the statistical properties of this random variable, we determine the moments of A of arbitrary, negative, or positive order k and demonstrate that they exhibit a multifractal dependence on k and a rather unusual dependence on the temperature and on the periodicity L , which are supported by atypical realizations of the periodic disorder. We finally show that the distribution of A has a log-normal left tail and exhibits an essential singularity close to the right edge of the support, which is related to the Lifshitz singularity. Our findings are based both on analytic results and on extensive numerical simulations of the process x (t ) .

  8. Phootprint - A Phobos sample return mission study

    Science.gov (United States)

    Koschny, Detlef; Svedhem, Håkan; Rebuffat, Denis

    Introduction ESA is currently studying a mission to return a sample from Phobos, called Phootprint. This study is performed as part of ESA’s Mars Robotic Exploration Programme. Part of the mission goal is to prepare technology needed for a sample return mission from Mars itself; the mission should also have a strong scientific justification, which is described here. 1. Science goal The main science goal of this mission will be to Understand the formation of the Martian moons Phobos and put constraints on the evolution of the solar system. Currently, there are several possibilities for explaining the formation of the Martian moons: (a) co-formation with Mars (b) capture of objects coming close to Mars (c) Impact of a large body onto Mars and formation from the impact ejecta The main science goal of this mission is to find out which of the three scenarios is the most probable one. To do this, samples from Phobos would be returned to Earth and analyzed with extremely high precision in ground-based laboratories. An on-board payload is foreseen to provide information to put the sample into the necessary geological context. 2. Mission Spacecraft and payload will be based on experience gained from previous studies to Martian moons and asteroids. In particular the Marco Polo and MarcoPolo-R asteroid sample return mission studies performed at ESA were used as a starting point. Currently, industrial studies are ongoing. The initial starting assumption was to use a Soyuz launcher. Uunlike the initial Marco Polo and MarcoPolo-R studies to an asteroid, a transfer stage will be needed. Another main difference to an asteroid mission is the fact that the spacecraft actually orbits Mars, not Phobos or Deimos. It is possible to select a spacecraft orbit, which in a Phobos- or Deimos-centred reference system would give an ellipse around the moon. The following model payload is currently foreseen: - Wide Angle Camera, - Narrow Angle Camera, - Close-Up Camera, - Context camera for

  9. Using re-sampling methods in mortality studies.

    Directory of Open Access Journals (Sweden)

    Igor Itskovich

    Full Text Available Traditional methods of computing standardized mortality ratios (SMR in mortality studies rely upon a number of conventional statistical propositions to estimate confidence intervals for obtained values. Those propositions include a common but arbitrary choice of the confidence level and the assumption that observed number of deaths in the test sample is a purely random quantity. The latter assumption may not be fully justified for a series of periodic "overlapping" studies. We propose a new approach to evaluating the SMR, along with its confidence interval, based on a simple re-sampling technique. The proposed method is most straightforward and requires neither the use of above assumptions nor any rigorous technique, employed by modern re-sampling theory, for selection of a sample set. Instead, we include all possible samples that correspond to the specified time window of the study in the re-sampling analysis. As a result, directly obtained confidence intervals for repeated overlapping studies may be tighter than those yielded by conventional methods. The proposed method is illustrated by evaluating mortality due to a hypothetical risk factor in a life insurance cohort. With this method used, the SMR values can be forecast more precisely than when using the traditional approach. As a result, the appropriate risk assessment would have smaller uncertainties.

  10. Work Sampling Study of an Engineering Professor during a Regular Contract Period

    Science.gov (United States)

    Brink, Jan; McDonald, Dale B.

    2015-01-01

    Work sampling is a technique that has been employed in industry and fields such as healthcare for some time. It is a powerful technique, and an alternative to conventional stop watch time studies, used by industrial engineers to focus upon random work sampling observations. This study applies work sampling to the duties performed by an individual…

  11. Ghana randomized air pollution and health study (GRAPHS): study protocol for a randomized controlled trial

    OpenAIRE

    Jack, Darby W.; Asante, Kwaku Poku; Blair J. Wylie; Chillrud, Steve N.; Whyatt, Robin M.; Ae-Ngibise, Kenneth A.; Quinn, Ashlinn K.; Yawson, Abena Konadu; Boamah, Ellen Abrafi; Agyei, Oscar; Mujtaba, Mohammed; Kaali, Seyram; Kinney, Patrick; Owusu-Agyei, Seth

    2015-01-01

    Background: Household air pollution exposure is a major health risk, but validated interventions remain elusive. Methods/Design The Ghana Randomized Air Pollution and Health Study (GRAPHS) is a cluster-randomized trial that evaluates the efficacy of clean fuels (liquefied petroleum gas, or LPG) and efficient biomass cookstoves in the Brong-Ahafo region of central Ghana. We recruit pregnant women into LPG, efficient cookstove, and control arms and track birth weight and physician-assessed seve...

  12. Randomized controlled trial on timing and number of sampling for bile aspiration cytology.

    Science.gov (United States)

    Tsuchiya, Tomonori; Yokoyama, Yukihiro; Ebata, Tomoki; Igami, Tsuyoshi; Sugawara, Gen; Kato, Katsuyuki; Shimoyama, Yoshie; Nagino, Masato

    2014-06-01

    The issue on timing and number of bile sampling for exfoliative bile cytology is still unsettled. A total of 100 patients with cholangiocarcinoma undergoing resection after external biliary drainage were randomized into two groups: a 2-day group where bile was sampled five times per day for 2 days; and a 10-day group where bile was sampled once per day for 10 days (registered University Hospital Medical Information Network/ID 000005983). The outcome of 87 patients who underwent laparotomy was analyzed, 44 in the 2-day group and 43 in the 10-day group. There were no significant differences in patient characteristics between the two groups. Positivity after one sampling session was significantly lower in the 2-day group than in the 10-day group (17.0 ± 3.7% vs. 20.7 ± 3.5%, P = 0.034). However, cumulative positivity curves were similar and overlapped each other between both groups. The final cumulative positivity by the 10th sampling session was 52.3% in the 2-day group and 51.2% in the 10-day group. We observed a small increase in cumulative positivity after the 5th or 6th session in both groups. Bile cytology positivity is unlikely to be affected by sample time. © 2013 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  13. Use of protein: creatinine ratio in a random spot urine sample for predicting significant proteinuria in diabetes mellitus.

    Science.gov (United States)

    Yadav, B K; Adhikari, S; Gyawali, P; Shrestha, R; Poudel, B; Khanal, M

    2010-06-01

    Present study was undertaken during a period of 6 months (September 2008-February 2009) to see an correlation of 24 hours urine protein estimation with random spot protein-creatinine (P:C) ratio among a diabetic patients. The study comprised of 144 patients aged 30-70 years, recruited from Kantipur hospital, Kathmandu. The 24-hr urine sample was collected, followed by spot random urine sample. Both samples were analyzed for protein and creatinine excretion. An informed consent was taken from all participants. Sixteen inadequately collected urine samples as defined by (predicted creatinine--measured creatinine)/predicted creatinine > 0.2 were excluded from analysis. The Spearman's rank correlation between the spot urine P:C ratio and 24-hr total protein were performed by the Statistical Package for Social Service. At the P:C ratio cutoff of 0.15 and reference method (24-hr urine protein) cutoff of 150 mg/day, the correlation coefficient was found to be 0.892 (p urine collection but the cutoff should be carefully selected for different patients group under different laboratory procedures and settings.

  14. Relations among questionnaire and experience sampling measures of inner speech: a smartphone app study

    National Research Council Canada - National Science Library

    Alderson-Day, Ben; Fernyhough, Charles

    2015-01-01

    ... (which involve collecting data at random timepoints). The present study compared self-reporting of inner speech collected via a general questionnaire and experience sampling, using data from a custom-made smartphone app (Inner Life...

  15. Sampling estimators of total mill receipts for use in timber product output studies

    Science.gov (United States)

    John P. Brown; Richard G. Oderwald

    2012-01-01

    Data from the 2001 timber product output study for Georgia was explored to determine new methods for stratifying mills and finding suitable sampling estimators. Estimators for roundwood receipts totals comprised several types: simple random sample, ratio, stratified sample, and combined ratio. Two stratification methods were examined: the Dalenius-Hodges (DH) square...

  16. LOD score exclusion analyses for candidate QTLs using random population samples.

    Science.gov (United States)

    Deng, Hong-Wen

    2003-11-01

    While extensive analyses have been conducted to test for, no formal analyses have been conducted to test against, the importance of candidate genes as putative QTLs using random population samples. Previously, we developed an LOD score exclusion mapping approach for candidate genes for complex diseases. Here, we extend this LOD score approach for exclusion analyses of candidate genes for quantitative traits. Under this approach, specific genetic effects (as reflected by heritability) and inheritance models at candidate QTLs can be analyzed and if an LOD score is < or = -2.0, the locus can be excluded from having a heritability larger than that specified. Simulations show that this approach has high power to exclude a candidate gene from having moderate genetic effects if it is not a QTL and is robust to population admixture. Our exclusion analysis complements association analysis for candidate genes as putative QTLs in random population samples. The approach is applied to test the importance of Vitamin D receptor (VDR) gene as a potential QTL underlying the variation of bone mass, an important determinant of osteoporosis.

  17. A Combined Weighting Method Based on Hybrid of Interval Evidence Fusion and Random Sampling

    Directory of Open Access Journals (Sweden)

    Ying Yan

    2017-01-01

    Full Text Available Due to the complexity of system and lack of expertise, epistemic uncertainties may present in the experts’ judgment on the importance of certain indices during group decision-making. A novel combination weighting method is proposed to solve the index weighting problem when various uncertainties are present in expert comments. Based on the idea of evidence theory, various types of uncertain evaluation information are uniformly expressed through interval evidence structures. Similarity matrix between interval evidences is constructed, and expert’s information is fused. Comment grades are quantified using the interval number, and cumulative probability function for evaluating the importance of indices is constructed based on the fused information. Finally, index weights are obtained by Monte Carlo random sampling. The method can process expert’s information with varying degrees of uncertainties, which possesses good compatibility. Difficulty in effectively fusing high-conflict group decision-making information and large information loss after fusion is avertible. Original expert judgments are retained rather objectively throughout the processing procedure. Cumulative probability function constructing and random sampling processes do not require any human intervention or judgment. It can be implemented by computer programs easily, thus having an apparent advantage in evaluation practices of fairly huge index systems.

  18. The Study on Mental Health at Work: Design and sampling.

    Science.gov (United States)

    Rose, Uwe; Schiel, Stefan; Schröder, Helmut; Kleudgen, Martin; Tophoven, Silke; Rauch, Angela; Freude, Gabriele; Müller, Grit

    2017-08-01

    The Study on Mental Health at Work (S-MGA) generates the first nationwide representative survey enabling the exploration of the relationship between working conditions, mental health and functioning. This paper describes the study design, sampling procedures and data collection, and presents a summary of the sample characteristics. S-MGA is a representative study of German employees aged 31-60 years subject to social security contributions. The sample was drawn from the employment register based on a two-stage cluster sampling procedure. Firstly, 206 municipalities were randomly selected from a pool of 12,227 municipalities in Germany. Secondly, 13,590 addresses were drawn from the selected municipalities for the purpose of conducting 4500 face-to-face interviews. The questionnaire covers psychosocial working and employment conditions, measures of mental health, work ability and functioning. Data from personal interviews were combined with employment histories from register data. Descriptive statistics of socio-demographic characteristics and logistic regressions analyses were used for comparing population, gross sample and respondents. In total, 4511 face-to-face interviews were conducted. A test for sampling bias revealed that individuals in older cohorts participated more often, while individuals with an unknown educational level, residing in major cities or with a non-German ethnic background were slightly underrepresented. There is no indication of major deviations in characteristics between the basic population and the sample of respondents. Hence, S-MGA provides representative data for research on work and health, designed as a cohort study with plans to rerun the survey 5 years after the first assessment.

  19. The quality of the reported sample size calculations in randomized controlled trials indexed in PubMed.

    Science.gov (United States)

    Lee, Paul H; Tse, Andy C Y

    2017-05-01

    There are limited data on the quality of reporting of information essential for replication of the calculation as well as the accuracy of the sample size calculation. We examine the current quality of reporting of the sample size calculation in randomized controlled trials (RCTs) published in PubMed and to examine the variation in reporting across study design, study characteristics, and journal impact factor. We also reviewed the targeted sample size reported in trial registries. We reviewed and analyzed all RCTs published in December 2014 with journals indexed in PubMed. The 2014 Impact Factors for the journals were used as proxies for their quality. Of the 451 analyzed papers, 58.1% reported an a priori sample size calculation. Nearly all papers provided the level of significance (97.7%) and desired power (96.6%), and most of the papers reported the minimum clinically important effect size (73.3%). The median (inter-quartile range) of the percentage difference of the reported and calculated sample size calculation was 0.0% (IQR -4.6%;3.0%). The accuracy of the reported sample size was better for studies published in journals that endorsed the CONSORT statement and journals with an impact factor. A total of 98 papers had provided targeted sample size on trial registries and about two-third of these papers (n=62) reported sample size calculation, but only 25 (40.3%) had no discrepancy with the reported number in the trial registries. The reporting of the sample size calculation in RCTs published in PubMed-indexed journals and trial registries were poor. The CONSORT statement should be more widely endorsed. Copyright © 2016 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  20. The Move from Accuracy Studies to Randomized Trials in PET

    DEFF Research Database (Denmark)

    Siepe, Bettina; Hoilund-Carlsen, Poul Flemming; Gerke, Oke

    2014-01-01

    Since the influential study by van Tinteren et al. published in The Lancet in 2002, there have been an increasing number of diagnostic randomized controlled trials (RCTs) investigating the benefit of PET. If they provide valid and useful information on the benefit, these studies can play an impor...... evaluation. Choice of patient-important outcomes and sufficient sample sizes are crucial issues in planning RCTs to demonstrate the clinical benefit of using PET.......Since the influential study by van Tinteren et al. published in The Lancet in 2002, there have been an increasing number of diagnostic randomized controlled trials (RCTs) investigating the benefit of PET. If they provide valid and useful information on the benefit, these studies can play...... of diagnostic randomized trials, in which PET was applied in only one arm. We covered published studies as well as registered unpublished and planned studies. We considered 3 quality indicators related to the usefulness of a trial to generate evidence for a clinical benefit: use of patient-important outcome...

  1. Stemflow estimation in a redwood forest using model-based stratified random sampling

    Science.gov (United States)

    Jack Lewis

    2003-01-01

    Model-based stratified sampling is illustrated by a case study of stemflow volume in a redwood forest. The approach is actually a model-assisted sampling design in which auxiliary information (tree diameter) is utilized in the design of stratum boundaries to optimize the efficiency of a regression or ratio estimator. The auxiliary information is utilized in both the...

  2. GASOLINE VEHICLE EXHAUST PARTICLE SAMPLING STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Kittelson, D; Watts, W; Johnson, J; Zarling, D Schauer,J Kasper, K; Baltensperger, U; Burtscher, H

    2003-08-24

    The University of Minnesota collaborated with the Paul Scherrer Institute, the University of Wisconsin (UWI) and Ricardo, Inc to physically and chemically characterize the exhaust plume from recruited gasoline spark ignition (SI) vehicles. The project objectives were: (1) Measure representative particle size distributions from a set of on-road SI vehicles and compare these data to similar data collected on a small subset of light-duty gasoline vehicles tested on a chassis dynamometer with a dilution tunnel using the Unified Drive Cycle, at both room temperature (cold start) and 0 C (cold-cold start). (2) Compare data collected from SI vehicles to similar data collected from Diesel engines during the Coordinating Research Council E-43 project. (3) Characterize on-road aerosol during mixed midweek traffic and Sunday midday periods and determine fleet-specific emission rates. (4) Characterize bulk- and size-segregated chemical composition of the particulate matter (PM) emitted in the exhaust from the gasoline vehicles. Particle number concentrations and size distributions are strongly influenced by dilution and sampling conditions. Laboratory methods were evaluated to dilute SI exhaust in a way that would produce size distributions that were similar to those measured during laboratory experiments. Size fractionated samples were collected for chemical analysis using a nano-microorifice uniform deposit impactor (nano-MOUDI). In addition, bulk samples were collected and analyzed. A mixture of low, mid and high mileage vehicles were recruited for testing during the study. Under steady highway cruise conditions a significant particle signature above background was not measured, but during hard accelerations number size distributions for the test fleet were similar to modern heavy-duty Diesel vehicles. Number emissions were much higher at high speed and during cold-cold starts. Fuel specific number emissions range from 1012 to 3 x 1016 particles/kg fuel. A simple

  3. Validation of the 2008 Landsat Burned Area Ecv Product for North America Using Stratified Random Sampling

    Science.gov (United States)

    Brunner, N. M.; Mladinich, C. S.; Caldwell, M. K.; Beal, Y. J. G.

    2014-12-01

    The U.S. Geological Survey is generating a suite of Essential Climate Variables (ECVs) products, as defined by the Global Climate Observing System, from the Landsat data archive. Validation protocols for these products are being established, incorporating the Committee on Earth Observing Satellites Land Product Validation Subgroup's best practice guidelines and validation hierarchy stages. The sampling design and accuracy measures follow the methodology developed by the European Space Agency's Climate Change Initiative Fire Disturbance (fire_cci) project (Padilla and others, 2014). A rigorous validation was performed on the 2008 Burned Area ECV (BAECV) prototype product, using a stratified random sample of 48 Thiessen scene areas overlaying Landsat path/rows distributed across several terrestrial biomes throughout North America. The validation reference data consisted of fourteen sample sites acquired from the fire_cci project and the remaining new samples sites generated from a densification of the stratified sampling for North America. The reference burned area polygons were generated using the ABAMS (Automatic Burned Area Mapping) software (Bastarrika and others, 2011; Izagirre, 2014). Accuracy results will be presented indicating strengths and weaknesses of the BAECV algorithm.Bastarrika, A., Chuvieco, E., and Martín, M.P., 2011, Mapping burned areas from Landsat TM/ETM+ data with a two-phase algorithm: Balancing omission and commission errors: Remote Sensing of Environment, v. 115, no. 4, p. 1003-1012.Izagirre, A.B., 2014, Automatic Burned Area Mapping Software (ABAMS), Preliminary Documentation, Version 10 v4,: Vitoria-Gasteiz, Spain, University of Basque Country, p. 27.Padilla, M., Chuvieco, E., Hantson, S., Theis, R., and Sandow, C., 2014, D2.1 - Product Validation Plan: UAH - University of Alcalá de Henares (Spain), 37 p.

  4. Conic sampling: an efficient method for solving linear and quadratic programming by randomly linking constraints within the interior.

    Science.gov (United States)

    Serang, Oliver

    2012-01-01

    Linear programming (LP) problems are commonly used in analysis and resource allocation, frequently surfacing as approximations to more difficult problems. Existing approaches to LP have been dominated by a small group of methods, and randomized algorithms have not enjoyed popularity in practice. This paper introduces a novel randomized method of solving LP problems by moving along the facets and within the interior of the polytope along rays randomly sampled from the polyhedral cones defined by the bounding constraints. This conic sampling method is then applied to randomly sampled LPs, and its runtime performance is shown to compare favorably to the simplex and primal affine-scaling algorithms, especially on polytopes with certain characteristics. The conic sampling method is then adapted and applied to solve a certain quadratic program, which compute a projection onto a polytope; the proposed method is shown to outperform the proprietary software Mathematica on large, sparse QP problems constructed from mass spectometry-based proteomics.

  5. RANdom SAmple Consensus (RANSAC) algorithm for material-informatics: application to photovoltaic solar cells.

    Science.gov (United States)

    Kaspi, Omer; Yosipof, Abraham; Senderowitz, Hanoch

    2017-06-06

    An important aspect of chemoinformatics and material-informatics is the usage of machine learning algorithms to build Quantitative Structure Activity Relationship (QSAR) models. The RANdom SAmple Consensus (RANSAC) algorithm is a predictive modeling tool widely used in the image processing field for cleaning datasets from noise. RANSAC could be used as a "one stop shop" algorithm for developing and validating QSAR models, performing outlier removal, descriptors selection, model development and predictions for test set samples using applicability domain. For "future" predictions (i.e., for samples not included in the original test set) RANSAC provides a statistical estimate for the probability of obtaining reliable predictions, i.e., predictions within a pre-defined number of standard deviations from the true values. In this work we describe the first application of RNASAC in material informatics, focusing on the analysis of solar cells. We demonstrate that for three datasets representing different metal oxide (MO) based solar cell libraries RANSAC-derived models select descriptors previously shown to correlate with key photovoltaic properties and lead to good predictive statistics for these properties. These models were subsequently used to predict the properties of virtual solar cells libraries highlighting interesting dependencies of PV properties on MO compositions.

  6. Mendelian randomization studies in coronary artery disease.

    Science.gov (United States)

    Jansen, Henning; Samani, Nilesh J; Schunkert, Heribert

    2014-08-01

    Epidemiological research over the last 50 years has discovered a plethora of biomarkers (including molecules, traits or other diseases) that associate with coronary artery disease (CAD) risk. Even the strongest association detected in such observational research precludes drawing conclusions about the causality underlying the relationship between biomarker and disease. Mendelian randomization (MR) studies can shed light on the causality of associations, i.e whether, on the one hand, the biomarker contributes to the development of disease or, on the other hand, the observed association is confounded by unrecognized exogenous factors or due to reverse causation, i.e. due to the fact that prevalent disease affects the level of the biomarker. However, conclusions from a MR study are based on a number of important assumptions. A prerequisite for such studies is that the genetic variant employed affects significantly the biomarker under investigation but has no effect on other phenotypes that might confound the association between the biomarker and disease. If this biomarker is a true causal risk factor for CAD, genotypes of the variant should associate with CAD risk in the direction predicted by the association of the biomarker with CAD. Given a random distribution of exogenous factors in individuals carrying respective genotypes, groups represented by the genotypes are highly similar except for the biomarker of interest. Thus, the genetic variant converts into an unconfounded surrogate of the respective biomarker. This scenario is nicely exemplified for LDL cholesterol. Almost every genotype found to increase LDL cholesterol level by a sufficient amount has also been found to increase CAD risk. Pending a number of conditions that needed to be fulfilled by the genetic variant under investigation (e.g. no pleiotropic effects) and the experimental set-up of the study, LDL cholesterol can be assumed to act as the functional component that links genotypes and CAD risk and

  7. Control capacity and a random sampling method in exploring controllability of complex networks.

    Science.gov (United States)

    Jia, Tao; Barabási, Albert-László

    2013-01-01

    Controlling complex systems is a fundamental challenge of network science. Recent advances indicate that control over the system can be achieved through a minimum driver node set (MDS). The existence of multiple MDS's suggests that nodes do not participate in control equally, prompting us to quantify their participations. Here we introduce control capacity quantifying the likelihood that a node is a driver node. To efficiently measure this quantity, we develop a random sampling algorithm. This algorithm not only provides a statistical estimate of the control capacity, but also bridges the gap between multiple microscopic control configurations and macroscopic properties of the network under control. We demonstrate that the possibility of being a driver node decreases with a node's in-degree and is independent of its out-degree. Given the inherent multiplicity of MDS's, our findings offer tools to explore control in various complex systems.

  8. Classification of epileptic EEG signals based on simple random sampling and sequential feature selection.

    Science.gov (United States)

    Ghayab, Hadi Ratham Al; Li, Yan; Abdulla, Shahab; Diykh, Mohammed; Wan, Xiangkui

    2016-06-01

    Electroencephalogram (EEG) signals are used broadly in the medical fields. The main applications of EEG signals are the diagnosis and treatment of diseases such as epilepsy, Alzheimer, sleep problems and so on. This paper presents a new method which extracts and selects features from multi-channel EEG signals. This research focuses on three main points. Firstly, simple random sampling (SRS) technique is used to extract features from the time domain of EEG signals. Secondly, the sequential feature selection (SFS) algorithm is applied to select the key features and to reduce the dimensionality of the data. Finally, the selected features are forwarded to a least square support vector machine (LS_SVM) classifier to classify the EEG signals. The LS_SVM classifier classified the features which are extracted and selected from the SRS and the SFS. The experimental results show that the method achieves 99.90, 99.80 and 100 % for classification accuracy, sensitivity and specificity, respectively.

  9. Randomized Controlled Trial of Attention Bias Modification in a Racially Diverse, Socially Anxious, Alcohol Dependent Sample

    Science.gov (United States)

    Clerkin, Elise M.; Magee, Joshua C.; Wells, Tony T.; Beard, Courtney; Barnett, Nancy P.

    2016-01-01

    Objective Attention biases may be an important treatment target for both alcohol dependence and social anxiety. This is the first ABM trial to investigate two (vs. one) targets of attention bias within a sample with co-occurring symptoms of social anxiety and alcohol dependence. Additionally, we used trial-level bias scores (TL-BS) to capture the phenomena of attention bias in a more ecologically valid, dynamic way compared to traditional attention bias scores. Method Adult participants (N=86; 41% Female; 52% African American; 40% White) with elevated social anxiety symptoms and alcohol dependence were randomly assigned to an 8-session training condition in this 2 (Social Anxiety ABM vs. Social Anxiety Control) by 2 (Alcohol ABM vs. Alcohol Control) design. Symptoms of social anxiety, alcohol dependence, and attention bias were assessed across time. Results Multilevel models estimated the trajectories for each measure within individuals, and tested whether these trajectories differed according to the randomized training conditions. Across time, there were significant or trending decreases in all attention TL-BS parameters (but not traditional attention bias scores) and most symptom measures. However, there were not significant differences in the trajectories of change between any ABM and control conditions for any symptom measures. Conclusions These findings add to previous evidence questioning the robustness of ABM and point to the need to extend the effects of ABM to samples that are racially diverse and/or have co-occurring psychopathology. The results also illustrate the potential importance of calculating trial-level attention bias scores rather than only including traditional bias scores. PMID:27591918

  10. Random sampling or geostatistical modelling? Choosing between design-based and model-based sampling strategies for soil (with discussion)

    NARCIS (Netherlands)

    Brus, D.J.; Gruijter, de J.J.

    1997-01-01

    Classical sampling theory has been repeatedly identified with classical statistics which assumes that data are identically and independently distributed. This explains the switch of many soil scientists from design-based sampling strategies, based on classical sampling theory, to the model-based

  11. Random Photon Absorption Model Elucidates How Early Gain Control in Fly Photoreceptors Arises from Quantal Sampling

    Science.gov (United States)

    Song, Zhuoyi; Zhou, Yu; Juusola, Mikko

    2016-01-01

    Many diurnal photoreceptors encode vast real-world light changes effectively, but how this performance originates from photon sampling is unclear. A 4-module biophysically-realistic fly photoreceptor model, in which information capture is limited by the number of its sampling units (microvilli) and their photon-hit recovery time (refractoriness), can accurately simulate real recordings and their information content. However, sublinear summation in quantum bump production (quantum-gain-nonlinearity) may also cause adaptation by reducing the bump/photon gain when multiple photons hit the same microvillus simultaneously. Here, we use a Random Photon Absorption Model (RandPAM), which is the 1st module of the 4-module fly photoreceptor model, to quantify the contribution of quantum-gain-nonlinearity in light adaptation. We show how quantum-gain-nonlinearity already results from photon sampling alone. In the extreme case, when two or more simultaneous photon-hits reduce to a single sublinear value, quantum-gain-nonlinearity is preset before the phototransduction reactions adapt the quantum bump waveform. However, the contribution of quantum-gain-nonlinearity in light adaptation depends upon the likelihood of multi-photon-hits, which is strictly determined by the number of microvilli and light intensity. Specifically, its contribution to light-adaptation is marginal (≤ 1%) in fly photoreceptors with many thousands of microvilli, because the probability of simultaneous multi-photon-hits on any one microvillus is low even during daylight conditions. However, in cells with fewer sampling units, the impact of quantum-gain-nonlinearity increases with brightening light. PMID:27445779

  12. Permutation Test Approach for Ordered Alternatives in Randomized Complete Block Design: A Comparative Study

    OpenAIRE

    GOKPINAR, Esra; GUL, Hasan; GOKPINAR, Fikri; BAYRAK, Hülya; OZONUR, Deniz

    2013-01-01

    Randomized complete block design is one of the most used experimental designs in statistical analysis. For testing ordered alternatives in randomized complete block design, parametric tests are used if random sample are drawn from Normal distribution. If normality assumption is not provide, nonparametric methods are used. In this study, we are interested nonparametric tests and we introduce briefly the nonparametric tests, such as Page, Modified Page and Hollander tests. We also give Permutat...

  13. Generalized SAMPLE SIZE Determination Formulas for Investigating Contextual Effects by a Three-Level Random Intercept Model.

    Science.gov (United States)

    Usami, Satoshi

    2017-03-01

    Behavioral and psychological researchers have shown strong interests in investigating contextual effects (i.e., the influences of combinations of individual- and group-level predictors on individual-level outcomes). The present research provides generalized formulas for determining the sample size needed in investigating contextual effects according to the desired level of statistical power as well as width of confidence interval. These formulas are derived within a three-level random intercept model that includes one predictor/contextual variable at each level to simultaneously cover various kinds of contextual effects that researchers can show interest. The relative influences of indices included in the formulas on the standard errors of contextual effects estimates are investigated with the aim of further simplifying sample size determination procedures. In addition, simulation studies are performed to investigate finite sample behavior of calculated statistical power, showing that estimated sample sizes based on derived formulas can be both positively and negatively biased due to complex effects of unreliability of contextual variables, multicollinearity, and violation of assumption regarding the known variances. Thus, it is advisable to compare estimated sample sizes under various specifications of indices and to evaluate its potential bias, as illustrated in the example.

  14. Comparison of Detrusor Muscle Sampling Rate in Monopolar and Bipolar Transurethral Resection of Bladder Tumor: A Randomized Trial.

    Science.gov (United States)

    Teoh, Jeremy Yuen-Chun; Chan, Eddie Shu-Yin; Yip, Siu-Ying; Tam, Ho-Man; Chiu, Peter Ka-Fung; Yee, Chi-Hang; Wong, Hon-Ming; Chan, Chi-Kwok; Hou, Simon See-Ming; Ng, Chi-Fai

    2017-05-01

    Our aim was to investigate the detrusor muscle sampling rate after monopolar versus bipolar transurethral resection of bladder tumor (TURBT). This was a single-center, prospective, randomized, phase III trial on monopolar versus bipolar TURBT. Baseline patient characteristics, disease characteristics and perioperative outcomes were compared, with the primary outcome being the detrusor muscle sampling rate in the TURBT specimen. Multivariate logistic regression analyses on detrusor muscle sampling were performed. From May 2012 to December 2015, a total of 160 patients with similar baseline characteristics were randomized to receive monopolar or bipolar TURBT. Fewer patients in the bipolar TURBT group required postoperative irrigation than patients in the monopolar TURBT group (18.7 vs. 43%; p = 0.001). In the whole cohort, no significant difference in the detrusor muscle sampling rates was observed between the bipolar and monopolar TURBT groups (77.3 vs. 63.3%; p = 0.057). In patients with urothelial carcinoma, bipolar TURBT achieved a higher detrusor muscle sampling rate than monopolar TURBT (84.6 vs. 67.7%; p = 0.025). On multivariate analyses, bipolar TURBT (odds ratio [OR] 2.23, 95% confidence interval [CI] 1.03-4.81; p = 0.042) and larger tumor size (OR 1.04, 95% CI 1.01-1.08; p = 0.022) were significantly associated with detrusor muscle sampling in the whole cohort. In addition, bipolar TURBT (OR 2.88, 95% CI 1.10-7.53; p = 0.031), larger tumor size (OR 1.05, 95% CI 1.01-1.10; p = 0.035), and female sex (OR 3.25, 95% CI 1.10-9.59; p = 0.033) were significantly associated with detrusor muscle sampling in patients with urothelial carcinoma. There was a trend towards a superior detrusor muscle sampling rate after bipolar TURBT. Further studies are needed to determine its implications on disease recurrence and progression.

  15. Optimal Subset Selection of Time-Series MODIS Images and Sample Data Transfer with Random Forests for Supervised Classification Modelling

    Directory of Open Access Journals (Sweden)

    Fuqun Zhou

    2016-10-01

    Full Text Available Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS. It is challenging to efficiently use these time-series MODIS datasets for long-term environmental monitoring due to their vast volume and information redundancy. This challenge will be greater when Sentinel 2–3 data become available. Another challenge that researchers face is the lack of in-situ data for supervised modelling, especially for time-series data analysis. In this study, we attempt to tackle the two important issues with a case study of land cover mapping using CCRS 10-day MODIS composites with the help of Random Forests’ features: variable importance, outlier identification. The variable importance feature is used to analyze and select optimal subsets of time-series MODIS imagery for efficient land cover mapping, and the outlier identification feature is utilized for transferring sample data available from one year to an adjacent year for supervised classification modelling. The results of the case study of agricultural land cover classification at a regional scale show that using only about a half of the variables we can achieve land cover classification accuracy close to that generated using the full dataset. The proposed simple but effective solution of sample transferring could make supervised modelling possible for applications lacking sample data.

  16. Optimal Subset Selection of Time-Series MODIS Images and Sample Data Transfer with Random Forests for Supervised Classification Modelling.

    Science.gov (United States)

    Zhou, Fuqun; Zhang, Aining

    2016-10-25

    Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS) datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS). It is challenging to efficiently use these time-series MODIS datasets for long-term environmental monitoring due to their vast volume and information redundancy. This challenge will be greater when Sentinel 2-3 data become available. Another challenge that researchers face is the lack of in-situ data for supervised modelling, especially for time-series data analysis. In this study, we attempt to tackle the two important issues with a case study of land cover mapping using CCRS 10-day MODIS composites with the help of Random Forests' features: variable importance, outlier identification. The variable importance feature is used to analyze and select optimal subsets of time-series MODIS imagery for efficient land cover mapping, and the outlier identification feature is utilized for transferring sample data available from one year to an adjacent year for supervised classification modelling. The results of the case study of agricultural land cover classification at a regional scale show that using only about a half of the variables we can achieve land cover classification accuracy close to that generated using the full dataset. The proposed simple but effective solution of sample transferring could make supervised modelling possible for applications lacking sample data.

  17. (Sample) size matters! An examination of sample size from the SPRINT trial study to prospectively evaluate reamed intramedullary nails in patients with tibial fractures

    NARCIS (Netherlands)

    Bhandari, Mohit; Tornetta, Paul; Rampersad, Shelly-Ann; Sprague, Sheila; Heels-Ansdell, Diane; Sanders, David W.; Schemitsch, Emil H.; Swiontkowski, Marc; Walter, Stephen; Guyatt, Gordon; Buckingham, Lisa; Leece, Pamela; Viveiros, Helena; Mignott, Tashay; Ansell, Natalie; Sidorkewicz, Natalie; Agel, Julie; Bombardier, Claire; Berlin, Jesse A.; Bosse, Michael; Browner, Bruce; Gillespie, Brenda; O'Brien, Peter; Poolman, Rudolf; Macleod, Mark D.; Carey, Timothy; Leitch, Kellie; Bailey, Stuart; Gurr, Kevin; Konito, Ken; Bartha, Charlene; Low, Isolina; MacBean, Leila V.; Ramu, Mala; Reiber, Susan; Strapp, Ruth; Tieszer, Christina; Kreder, Hans; Stephen, David J. G.; Axelrod, Terry S.; Yee, Albert J. M.; Richards, Robin R.; Finkelstein, Joel; Holtby, Richard M.; Cameron, Hugh; Cameron, John; Gofton, Wade; Murnaghan, John; Schatztker, Joseph; Bulmer, Beverly; Conlan, Lisa; Laflamme, Yves; Berry, Gregory; Beaumont, Pierre; Ranger, Pierre; Laflamme, Georges-Henri; Jodoin, Alain; Renaud, Eric; Gagnon, Sylvain; Maurais, Gilles; Malo, Michel; Fernandes, Julio; Latendresse, Kim; Poirier, Marie-France; Daigneault, Gina; McKee, Michael M.; Waddell, James P.; Bogoch, Earl R.; Daniels, Timothy R.; McBroom, Robert R.; Vicente, Milena R.; Storey, Wendy; Wild, Lisa M.; McCormack, Robert; Perey, Bertrand; Goetz, Thomas J.; Pate, Graham; Penner, Murray J.; Panagiotopoulos, Kostas; Pirani, Shafique; Dommisse, Ian G.; Loomer, Richard L.; Stone, Trevor; Moon, Karyn; Zomar, Mauri; Webb, Lawrence X.; Teasdall, Robert D.; Birkedal, John Peter; Martin, David Franklin; Ruch, David S.; Kilgus, Douglas J.; Pollock, David C.; Harris, Mitchel Brion; Wiesler, Ethan Ron; Ward, William G.; Shilt, Jeffrey Scott; Koman, Andrew L.; Poehling, Gary G.; Kulp, Brenda; Creevy, William R.; Stein, Andrew B.; Bono, Christopher T.; Einhorn, Thomas A.; Brown, T. Desmond; Pacicca, Donna; Sledge, John B.; Foster, Timothy E.; Voloshin, Ilva; Bolton, Jill; Carlisle, Hope; Shaughnessy, Lisa; Ombremsky, William T.; LeCroy, C. Michael; Meinberg, Eric G.; Messer, Terry M.; Craig, William L.; Dirschl, Douglas R.; Caudle, Robert; Harris, Tim; Elhert, Kurt; Hage, William; Jones, Robert; Piedrahita, Luis; Schricker, Paul O.; Driver, Robin; Godwin, Jean; Hansley, Gloria; Obremskey, William Todd; Kregor, Philip James; Tennent, Gregory; Truchan, Lisa M.; Sciadini, Marcus; Shuler, Franklin D.; Driver, Robin E.; Nading, Mary Alice; Neiderstadt, Jacky; Vap, Alexander R.; Vallier, Heather A.; Patterson, Brendan M.; Wilber, John H.; Wilber, Roger G.; Sontich, John K.; Moore, Timothy Alan; Brady, Drew; Cooperman, Daniel R.; Davis, John A.; Cureton, Beth Ann; Mandel, Scott; Orr, R. Douglas; Sadler, John T. S.; Hussain, Tousief; Rajaratnam, Krishan; Petrisor, Bradley; Drew, Brian; Bednar, Drew A.; Kwok, Desmond C. H.; Pettit, Shirley; Hancock, Jill; Cole, Peter A.; Smith, Joel J.; Brown, Gregory A.; Lange, Thomas A.; Stark, John G.; Levy, Bruce; Swiontkowski, Marc F.; Garaghty, Mary J.; Salzman, Joshua G.; Schutte, Carol A.; Tastad, Linda Toddie; Vang, Sandy; Seligson, David; Roberts, Craig S.; Malkani, Arthur L.; Sanders, Laura; Gregory, Sharon Allen; Dyer, Carmen; Heinsen, Jessica; Smith, Langan; Madanagopal, Sudhakar; Coupe, Kevin J.; Tucker, Jeffrey J.; Criswell, Allen R.; Buckle, Rosemary; Rechter, Alan Jeffrey; Sheth, Dhiren Shaskikant; Urquart, Brad; Trotscher, Thea; Anders, Mark J.; Kowalski, Joseph M.; Fineberg, Marc S.; Bone, Lawrence B.; Phillips, Matthew J.; Rohrbacher, Bernard; Stegemann, Philip; Mihalko, William M.; Buyea, Cathy; Augustine, Stephen J.; Jackson, William Thomas; Solis, Gregory; Ero, Sunday U.; Segina, Daniel N.; Berrey, Hudson B.; Agnew, Samuel G.; Fitzpatrick, Michael; Campbell, Lakina C.; Derting, Lynn; McAdams, June; Goslings, J. Carel; Ponsen, Kees Jan; Luitse, Jan; Kloen, Peter; Joosse, Pieter; Winkelhagen, Jasper; Duivenvoorden, Raphaël; Teague, David C.; Davey, Joseph; Sullivan, J. Andy; Ertl, William J. J.; Puckett, Timothy A.; Pasque, Charles B.; Tompkins, John F.; Gruel, Curtis R.; Kammerlocher, Paul; Lehman, Thomas P.; Puffinbarger, William R.; Carl, Kathy L.; Weber, Donald W.; Jomha, Nadr M.; Goplen, Gordon R.; Masson, Edward; Beaupre, Lauren A.; Greaves, Karen E.; Schaump, Lori N.; Jeray, Kyle J.; Goetz, David R.; Westberry, Davd E.; Broderick, J. Scott; Moon, Bryan S.; Tanner, Stephanie L.; Powell, James N.; Buckley, Richard E.; Elves, Leslie; Connolly, Stephen; Abraham, Edward P.; Eastwood, Donna; Steele, Trudy; Ellis, Thomas; Herzberg, Alex; Brown, George A.; Crawford, Dennis E.; Hart, Robert; Hayden, James; Orfaly, Robert M.; Vigland, Theodore; Vivekaraj, Maharani; Bundy, Gina L.; Miclau, Theodore; Matityahu, Amir; Coughlin, R. Richard; Kandemir, Utku; McClellan, R. Trigg; Lin, Cindy Hsin-Hua; Karges, David; Cramer, Kathryn; Watson, J. Tracy; Moed, Berton; Scott, Barbara; Beck, Dennis J.; Orth, Carolyn; Puskas, David; Clark, Russell; Jones, Jennifer; Egol, Kenneth A.; Paksima, Nader; France, Monet; Wai, Eugene K.; Johnson, Garth; Wilkinson, Ross; Gruszczynski, Adam T.; Vexler, Liisa

    2013-01-01

    Inadequate sample size and power in randomized trials can result in misleading findings. This study demonstrates the effect of sample size in a large clinical trial by evaluating the results of the Study to Prospectively evaluate Reamed Intramedullary Nails in Patients with Tibial fractures (SPRINT)

  18. Variability Study of the S5 Sample

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We present the results of flux density monitoring of the S5 sample at 5GHz with the Urumqi 25-m radio telescope during Dec. 2008 and Nov. 2009. Most sources exhibited > 2% rms variation in our one-year monitoring. Twenty-five highly variable sources were detected at a confidence level of 99%. Weaker ...

  19. Sample Size Calculations for Population Size Estimation Studies Using Multiplier Methods With Respondent-Driven Sampling Surveys.

    Science.gov (United States)

    Fearon, Elizabeth; Chabata, Sungai T; Thompson, Jennifer A; Cowan, Frances M; Hargreaves, James R

    2017-09-14

    While guidance exists for obtaining population size estimates using multiplier methods with respondent-driven sampling surveys, we lack specific guidance for making sample size decisions. To guide the design of multiplier method population size estimation studies using respondent-driven sampling surveys to reduce the random error around the estimate obtained. The population size estimate is obtained by dividing the number of individuals receiving a service or the number of unique objects distributed (M) by the proportion of individuals in a representative survey who report receipt of the service or object (P). We have developed an approach to sample size calculation, interpreting methods to estimate the variance around estimates obtained using multiplier methods in conjunction with research into design effects and respondent-driven sampling. We describe an application to estimate the number of female sex workers in Harare, Zimbabwe. There is high variance in estimates. Random error around the size estimate reflects uncertainty from M and P, particularly when the estimate of P in the respondent-driven sampling survey is low. As expected, sample size requirements are higher when the design effect of the survey is assumed to be greater. We suggest a method for investigating the effects of sample size on the precision of a population size estimate obtained using multipler methods and respondent-driven sampling. Uncertainty in the size estimate is high, particularly when P is small, so balancing against other potential sources of bias, we advise researchers to consider longer service attendance reference periods and to distribute more unique objects, which is likely to result in a higher estimate of P in the respondent-driven sampling survey.

  20. Random Model Sampling: Making Craig Interpolation Work When It Should Not

    Directory of Open Access Journals (Sweden)

    Marat Akhin

    2014-01-01

    Full Text Available One of the most serious problems when doing program analyses is dealing with function calls. While function inlining is the traditional approach to this problem, it nonetheless suffers from the increase in analysis complexity due to the state space explosion. Craig interpolation has been successfully used in recent years in the context of bounded model checking to do function summarization which allows one to replace the complete function body with its succinct summary and, therefore, reduce the complexity. Unfortunately this technique can be applied only to a pair of unsatisfiable formulae.In this work-in-progress paper we present an approach to function summarization based on Craig interpolation that overcomes its limitation by using random model sampling. It captures interesting input/output relations, strengthening satisfiable formulae into unsatisfiable ones and thus allowing the use of Craig interpolation. Preliminary experiments show the applicability of this approach; in our future work we plan to do a full evaluation on real-world examples.

  1. Discriminative motif discovery via simulated evolution and random under-sampling.

    Directory of Open Access Journals (Sweden)

    Tao Song

    Full Text Available Conserved motifs in biological sequences are closely related to their structure and functions. Recently, discriminative motif discovery methods have attracted more and more attention. However, little attention has been devoted to the data imbalance problem, which is one of the main reasons affecting the performance of the discriminative models. In this article, a simulated evolution method is applied to solve the multi-class imbalance problem at the stage of data preprocessing, and at the stage of Hidden Markov Models (HMMs training, a random under-sampling method is introduced for the imbalance between the positive and negative datasets. It is shown that, in the task of discovering targeting motifs of nine subcellular compartments, the motifs found by our method are more conserved than the methods without considering data imbalance problem and recover the most known targeting motifs from Minimotif Miner and InterPro. Meanwhile, we use the found motifs to predict protein subcellular localization and achieve higher prediction precision and recall for the minority classes.

  2. Comparing cluster-level dynamic treatment regimens using sequential, multiple assignment, randomized trials: Regression estimation and sample size considerations.

    Science.gov (United States)

    NeCamp, Timothy; Kilbourne, Amy; Almirall, Daniel

    2017-08-01

    Cluster-level dynamic treatment regimens can be used to guide sequential treatment decision-making at the cluster level in order to improve outcomes at the individual or patient-level. In a cluster-level dynamic treatment regimen, the treatment is potentially adapted and re-adapted over time based on changes in the cluster that could be impacted by prior intervention, including aggregate measures of the individuals or patients that compose it. Cluster-randomized sequential multiple assignment randomized trials can be used to answer multiple open questions preventing scientists from developing high-quality cluster-level dynamic treatment regimens. In a cluster-randomized sequential multiple assignment randomized trial, sequential randomizations occur at the cluster level and outcomes are observed at the individual level. This manuscript makes two contributions to the design and analysis of cluster-randomized sequential multiple assignment randomized trials. First, a weighted least squares regression approach is proposed for comparing the mean of a patient-level outcome between the cluster-level dynamic treatment regimens embedded in a sequential multiple assignment randomized trial. The regression approach facilitates the use of baseline covariates which is often critical in the analysis of cluster-level trials. Second, sample size calculators are derived for two common cluster-randomized sequential multiple assignment randomized trial designs for use when the primary aim is a between-dynamic treatment regimen comparison of the mean of a continuous patient-level outcome. The methods are motivated by the Adaptive Implementation of Effective Programs Trial which is, to our knowledge, the first-ever cluster-randomized sequential multiple assignment randomized trial in psychiatry.

  3. Cluster-randomized Studies in Educational Research: Principles and Methodological Aspects

    Directory of Open Access Journals (Sweden)

    Dreyhaupt, Jens

    2017-05-01

    Full Text Available An increasing number of studies are being performed in educational research to evaluate new teaching methods and approaches. These studies could be performed more efficiently and deliver more convincing results if they more strictly applied and complied with recognized standards of scientific studies. Such an approach could substantially increase the quality in particular of prospective, two-arm (intervention studies that aim to compare two different teaching methods. A key standard in such studies is randomization, which can minimize systematic bias in study findings; such bias may result if the two study arms are not structurally equivalent. If possible, educational research studies should also achieve this standard, although this is not yet generally the case. Some difficulties and concerns exist, particularly regarding organizational and methodological aspects. An important point to consider in educational research studies is that usually individuals cannot be randomized, because of the teaching situation, and instead whole groups have to be randomized (so-called “cluster randomization”. Compared with studies with individual randomization, studies with cluster randomization normally require (significantly larger sample sizes and more complex methods for calculating sample size. Furthermore, cluster-randomized studies require more complex methods for statistical analysis. The consequence of the above is that a competent expert with respective special knowledge needs to be involved in all phases of cluster-randomized studies.Studies to evaluate new teaching methods need to make greater use of randomization in order to achieve scientifically convincing results. Therefore, in this article we describe the general principles of cluster randomization and how to implement these principles, and we also outline practical aspects of using cluster randomization in prospective, two-arm comparative educational research studies.

  4. Tobacco smoking surveillance: is quota sampling an efficient tool for monitoring national trends? A comparison with a random cross-sectional survey.

    Directory of Open Access Journals (Sweden)

    Romain Guignard

    Full Text Available OBJECTIVES: It is crucial for policy makers to monitor the evolution of tobacco smoking prevalence. In France, this monitoring is based on a series of cross-sectional general population surveys, the Health Barometers, conducted every five years and based on random samples. A methodological study has been carried out to assess the reliability of a monitoring system based on regular quota sampling surveys for smoking prevalence. DESIGN / OUTCOME MEASURES: In 2010, current and daily tobacco smoking prevalences obtained in a quota survey on 8,018 people were compared with those of the 2010 Health Barometer carried out on 27,653 people. Prevalences were assessed separately according to the telephone equipment of the interviewee (landline phone owner vs "mobile-only", and logistic regressions were conducted in the pooled database to assess the impact of the telephone equipment and of the survey mode on the prevalences found. Finally, logistic regressions adjusted for sociodemographic characteristics were conducted in the random sample in order to determine the impact of the needed number of calls to interwiew "hard-to-reach" people on the prevalence found. RESULTS: Current and daily prevalences were higher in the random sample (respectively 33.9% and 27.5% in 15-75 years-old than in the quota sample (respectively 30.2% and 25.3%. In both surveys, current and daily prevalences were lower among landline phone owners (respectively 31.8% and 25.5% in the random sample and 28.9% and 24.0% in the quota survey. The required number of calls was slightly related to the smoking status after adjustment for sociodemographic characteristics. CONCLUSION: Random sampling appears to be more effective than quota sampling, mainly by making it possible to interview hard-to-reach populations.

  5. A numerical study of rays in random media. [Monte Carlo method simulation

    Science.gov (United States)

    Youakim, M. Y.; Liu, C. H.; Yeh, K. C.

    1973-01-01

    Statistics of electromagnetic rays in a random medium are studied numerically by the Monte Carlo method. Two dimensional random surfaces with prescribed correlation functions are used to simulate the random media. Rays are then traced in these sample media. Statistics of the ray properties such as the ray positions and directions are computed. Histograms showing the distributions of the ray positions and directions at different points along the ray path as well as at given points in space are given. The numerical experiment is repeated for different cases corresponding to weakly and strongly random media with isotropic and anisotropic irregularities. Results are compared with those derived from theoretical investigations whenever possible.

  6. Distribution of peak expiratory flow variability by age, gender and smoking habits in a random population sample aged 20-70 yrs

    NARCIS (Netherlands)

    Boezen, H M; Schouten, J. P.; Postma, D S; Rijcken, B

    1994-01-01

    Peak expiratory flow (PEF) variability can be considered as an index of bronchial lability. Population studies on PEF variability are few. The purpose of the current paper is to describe the distribution of PEF variability in a random population sample of adults with a wide age range (20-70 yrs),

  7. From Planning to Implementation: An Examination of Changes in the Research Design, Sample Size, and Precision of Group Randomized Trials Launched by the Institute of Education Sciences

    Science.gov (United States)

    Spybrook, Jessaca; Puente, Anne Cullen; Lininger, Monica

    2013-01-01

    This article examines changes in the research design, sample size, and precision between the planning phase and implementation phase of group randomized trials (GRTs) funded by the Institute of Education Sciences. Thirty-eight GRTs funded between 2002 and 2006 were examined. Three studies revealed changes in the experimental design. Ten studies…

  8. Studies of heterogeneous samples and material composition by fluorescence XAFS

    Science.gov (United States)

    Tannazi, Firouzeh

    X-ray Absorption Fine Structure (XAFS) Spectroscopy has proven to be an important tool for studying the composition and structure of materials. One benefit of XAFS is that it can be applied to a wide variety of systems, including complex real-world samples such as those found in biology and the environment. Determination of the chemical speciation of toxic elements in the environment currently is an active area of research. This dissertation describes my application of XAFS to chemical speciation in environmental soil samples as well as synthetic samples. In situ experimental XAFS measurements of metal speciation in soil core samples were made and the results were correlated with speciation results from chemical extraction. Several numerical approaches were implemented and tested. A novel approach to determining speciation by a Linear Programming algorithm was developed and found to be the most successful method for dilute samples of small particle size, i.e. in the linear regime. However, discrepancies between the in situ speciation results and other methods led to a fundamental investigation of x-ray transport in heterogeneous samples in which the observed fluorescence spectrum no longer is a linear combination of the spectra of the constituents. Useful theoretical models of x-ray propagation through heterogeneous media were found in older x-ray spectrometry literature, corrected, adapted for the first time to XAFS spectra. A Monte Carlo method was developed to calculate the effect on spectra of the shape, size, and orientation of particles of arbitrary convex shape, and the results are parameterized so that the loss factors can be easily calculated. Combining these models permits one to compute the fluorescence from arbitrary randomly heterogeneous particulate samples. This work demonstrates that the particle size distribution and the solid packing fraction have an important effect on the resulting spectra, which, if neglected, can introduce significant errors

  9. Enhancing positive parent-child interactions and family functioning in a poverty sample: a randomized control trial.

    Science.gov (United States)

    Negrão, Mariana; Pereira, Mariana; Soares, Isabel; Mesman, Judi

    2014-01-01

    This study tested the attachment-based intervention program Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline (VIPP-SD) in a randomized controlled trial with poor families of toddlers screened for professional's concerns about the child's caregiving environment. The VIPP-SD is an evidence-based intervention, but has not yet been tested in the context of poverty. The sample included 43 families with 1- to 4-year-old children: mean age at the pretest was 29 months and 51% were boys. At the pretest and posttest, mother-child interactions were observed at home, and mothers reported on family functioning. The VIPP-SD proved to be effective in enhancing positive parent-child interactions and positive family relations in a severely deprived context. Results are discussed in terms of implications for support services provided to such poor families in order to reduce intergenerational risk transmission.

  10. Dual to Ratio-Cum-Product Estimator in Simple and Stratified Random Sampling

    OpenAIRE

    Yunusa Olufadi

    2013-01-01

    New estimators for estimating the finite population mean using two auxiliary variables under simple and stratified sampling design is proposed. Their properties (e.g., mean square error) are studied to the first order of approximation. More so, some estimators are shown to be a particular member of this estimator. Furthermore, comparison of the proposed estimator with the usual unbiased estimator and other estimators considered in this paper reveals interesting results. These results are fur...

  11. Ghana randomized air pollution and health study (GRAPHS): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Jack, Darby W; Asante, Kwaku Poku; Wylie, Blair J; Chillrud, Steve N; Whyatt, Robin M; Ae-Ngibise, Kenneth A; Quinn, Ashlinn K; Yawson, Abena Konadu; Boamah, Ellen Abrafi; Agyei, Oscar; Mujtaba, Mohammed; Kaali, Seyram; Kinney, Patrick; Owusu-Agyei, Seth

    2015-09-22

    Household air pollution exposure is a major health risk, but validated interventions remain elusive. The Ghana Randomized Air Pollution and Health Study (GRAPHS) is a cluster-randomized trial that evaluates the efficacy of clean fuels (liquefied petroleum gas, or LPG) and efficient biomass cookstoves in the Brong-Ahafo region of central Ghana. We recruit pregnant women into LPG, efficient cookstove, and control arms and track birth weight and physician-assessed severe pneumonia incidence in the first year of life. A woman is eligible to participate if she is in the first or second trimester of pregnancy and carrying a live singleton fetus, if she is the primary cook, and if she does not smoke. We hypothesize that babies born to intervention mothers will weigh more and will have fewer cases of physician-assessed severe pneumonia in the first year of life. Additionally, an extensive personal air pollution exposure monitoring effort opens the way for exposure-response analyses, which we will present alongside intention-to-treat analyses. Major funding was provided by the National Institute of Environmental Health Sciences, The Thrasher Research Fund, and the Global Alliance for Clean Cookstoves. Household air pollution exposure is a major health risk that requires well-tested interventions. GRAPHS will provide important new evidence on the efficacy of both efficient biomass cookstoves and LPG, and will thus help inform health and energy policies in developing countries. The trial was registered with clinicaltrials.gov on 13 April 2011 with the identifier NCT01335490 .

  12. Randomized controlled study of CBT in bronchial asthma

    OpenAIRE

    Grover Naveen; D′Souza G; Thennarasu K; Kumaraiah V

    2007-01-01

    The aim of the present study was to find out efficacy of cognitive behavior therapy, as an adjunct to standard pharmacotherapy, in bronchial asthma. In a random-ized two-group design with pre-and post assessments, forty asthma patients were randomly allotted to two groups: self management group and cognitive behavior therapy group. Both groups were exposed to 6-8 weeks of intervention, asthma self management program and cognitive behavior therapy. Assessment measures used were-Semi structured...

  13. Active Learning Not Associated with Student Learning in a Random Sample of College Biology Courses

    Science.gov (United States)

    Andrews, T. M.; Leonard, M. J.; Colgrove, C. A.; Kalinowski, S. T.

    2011-01-01

    Previous research has suggested that adding active learning to traditional college science lectures substantially improves student learning. However, this research predominantly studied courses taught by science education researchers, who are likely to have exceptional teaching expertise. The present study investigated introductory biology courses randomly selected from a list of prominent colleges and universities to include instructors representing a broader population. We examined the relationship between active learning and student learning in the subject area of natural selection. We found no association between student learning gains and the use of active-learning instruction. Although active learning has the potential to substantially improve student learning, this research suggests that active learning, as used by typical college biology instructors, is not associated with greater learning gains. We contend that most instructors lack the rich and nuanced understanding of teaching and learning that science education researchers have developed. Therefore, active learning as designed and implemented by typical college biology instructors may superficially resemble active learning used by education researchers, but lacks the constructivist elements necessary for improving learning. PMID:22135373

  14. The psychometric properties of the AUDIT: a survey from a random sample of elderly Swedish adults.

    Science.gov (United States)

    Källmén, Håkan; Wennberg, Peter; Ramstedt, Mats; Hallgren, Mats

    2014-07-01

    Increasing alcohol consumption and related harms have been reported among the elderly population of Europe. Consequently, it is important to monitor patterns of alcohol use, and to use a valid and reliable tool when screening for risky consumption in this age group. The aim was to evaluate the internal consistency reliability and construct validity of the Alcohol Use Disorders Identification Test (AUDIT) in elderly Swedish adults, and to compare the results with the general Swedish population. Another aim was to calculate the level of alcohol consumption (AUDIT-C) to be used for comparison in future studies. The questionnaire was sent to 1459 Swedish adults aged 79-80 years with a response rate of 73.3%. Internal consistency reliability, were assessed using Cronbach alpha, and confirmatory factor analysis assessed construct validity of the Alcohol Use Disorders Identification Test (AUDIT) in elderly population as compared to a Swedish general population sample. The results showed that AUDIT was more reliable and valid among the Swedish general population sample than among the elderly and that Item 1 and 4 in AUDIT was less reliable and valid among the elderly. While the AUDIT showed acceptable psychometric properties in the general population sample, it's performance was of less quality among the elderly respondents. Further psychometric assessments of the AUDIT in elderly populations are required before it is implemented more widely.

  15. Albumin to creatinine ratio in a random urine sample: Correlation with severity of preeclampsia

    Directory of Open Access Journals (Sweden)

    Fady S. Moiety

    2014-06-01

    Conclusions: Random urine ACR may be a reliable method for prediction and assessment of severity of preeclampsia. Using the estimated cut-off may add to the predictive value of such a simple quick test.

  16. Relations among questionnaire and experience sampling measures of inner speech: a smartphone app study.

    Science.gov (United States)

    Alderson-Day, Ben; Fernyhough, Charles

    2015-01-01

    Inner speech is often reported to be a common and central part of inner experience, but its true prevalence is unclear. Many questionnaire-based measures appear to lack convergent validity and it has been claimed that they overestimate inner speech in comparison to experience sampling methods (which involve collecting data at random timepoints). The present study compared self-reporting of inner speech collected via a general questionnaire and experience sampling, using data from a custom-made smartphone app (Inner Life). Fifty-one university students completed a generalized self-report measure of inner speech (the Varieties of Inner Speech Questionnaire, VISQ) and responded to at least seven random alerts to report on incidences of inner speech over a 2-week period. Correlations and pairwise comparisons were used to compare generalized endorsements and randomly sampled scores for each VISQ subscale. Significant correlations were observed between general and randomly sampled measures for only two of the four VISQ subscales, and endorsements of inner speech with evaluative or motivational characteristics did not correlate at all across different measures. Endorsement of inner speech items was significantly lower for random sampling compared to generalized self-report, for all VISQ subscales. Exploratory analysis indicated that specific inner speech characteristics were also related to anxiety and future-oriented thinking.

  17. Relations among questionnaire and experience sampling measures of inner speech: A smartphone app study

    Directory of Open Access Journals (Sweden)

    Ben eAlderson-Day

    2015-04-01

    Full Text Available Inner speech is often reported to be a common and central part of inner experience, but its true prevalence is unclear. Many questionnaire-based measures appear to lack convergent validity and it has been claimed that they overestimate inner speech in comparison to experience sampling methods (which involve collecting data at random timepoints. The present study compared self-reporting of inner speech collected via a general questionnaire and experience sampling, using data from a custom-made smartphone app (Inner Life. Fifty-one university students completed a generalized self-report measure of inner speech (the Varieties of Inner Speech Questionnaire, or VISQ and responded to at least 7 random alerts to report on incidences of inner speech over a 2-week period. Correlations and pairwise comparisons were used to compare generalized endorsements and randomly-sampled scores for each VISQ subscale. Significant correlations were observed between general and randomly sampled measures for only 2 of the 4 VISQ subscales, and endorsements of inner speech with evaluative or motivational characteristics did not correlate at all across different measures. Endorsement of inner speech items was significantly lower for random sampling compared to generalized self-report, for all VISQ subscales. Exploratory analysis indicated that specific inner speech characteristics were also related to anxiety and future-oriented thinking.

  18. Replicating studies in which samples of participants respond to samples of stimuli.

    Science.gov (United States)

    Westfall, Jacob; Judd, Charles M; Kenny, David A

    2015-05-01

    In a direct replication, the typical goal is to reproduce a prior experimental result with a new but comparable sample of participants in a high-powered replication study. Often in psychology, the research to be replicated involves a sample of participants responding to a sample of stimuli. In replicating such studies, we argue that the same criteria should be used in sampling stimuli as are used in sampling participants. Namely, a new but comparable sample of stimuli should be used to ensure that the original results are not due to idiosyncrasies of the original stimulus sample, and the stimulus sample must often be enlarged to ensure high statistical power. In support of the latter point, we discuss the fact that in experiments involving samples of stimuli, statistical power typically does not approach 1 as the number of participants goes to infinity. As an example of the importance of sampling new stimuli, we discuss the bygone literature on the risky shift phenomenon, which was almost entirely based on a single stimulus sample that was later discovered to be highly unrepresentative. We discuss the use of both resampled and expanded stimulus sets, that is, stimulus samples that include the original stimuli plus new stimuli. © The Author(s) 2015.

  19. Sampling

    CERN Document Server

    Thompson, Steven K

    2012-01-01

    Praise for the Second Edition "This book has never had a competitor. It is the only book that takes a broad approach to sampling . . . any good personal statistics library should include a copy of this book." —Technometrics "Well-written . . . an excellent book on an important subject. Highly recommended." —Choice "An ideal reference for scientific researchers and other professionals who use sampling." —Zentralblatt Math Features new developments in the field combined with all aspects of obtaining, interpreting, and using sample data Sampling provides an up-to-date treat

  20. A Prospective Randomized Clinical Study of the Influence of Primary ...

    African Journals Online (AJOL)

    A Prospective Randomized Clinical Study of the Influence of Primary Closure or Dressing on. Post‑operative Morbidity after Mandibular Third. Molar Surgery. Peter E Egbor, Birch ... third molar surgery. Materials and Methods: This was a randomized clinical .... three sided buccal mucoperiosteal flap was made and reflected.

  1. Evidentials and advertising: a sample study

    Directory of Open Access Journals (Sweden)

    Laura Cruz García

    2017-07-01

    Full Text Available This paper explores the use of evidential devices in press adverts in English in a compilation of original advertisements. Due to the appellative nature of advertising discourse, I think that these texts are likely to convey source of knowledge through evidentials as an advertising strategy in order to pragmatically manifest a higher level of credibility and reliability of the information presented concerning the products and the brands. The selected corpus of adverts will allow us to focus special attention on this particular genre and on how evidentials are used, in the fashion of other works carried out in other textual genres (cf. Fox, 2001; Kaplan, 2007; Marín-Arrese, 2004, 2007; Ortega-Barrera and Torres-Ramírez, 2010. Evidentials are studied as part of a set of persuasion strategies used by different linguistic communities in the discourse of advertising (Block de Behar, 1992; Cook, 1992; Cortés de los Ríos, 2001; Pavitt, 2000; Rein, 1982. Conclusions will report on how evidentials are used in print adverts, and whether a type of evidential device prevails over the rest.

  2. Beyond Random Walk and Metropolis-Hastings Samplers: Why You Should Not Backtrack for Unbiased Graph Sampling

    CERN Document Server

    Lee, Chul-Ho; Eun, Do Young

    2012-01-01

    Graph sampling via crawling has been actively considered as a generic and important tool for collecting uniform node samples so as to consistently estimate and uncover various characteristics of complex networks. The so-called simple random walk with re-weighting (SRW-rw) and Metropolis-Hastings (MH) algorithm have been popular in the literature for such unbiased graph sampling. However, an unavoidable downside of their core random walks -- slow diffusion over the space, can cause poor estimation accuracy. In this paper, we propose non-backtracking random walk with re-weighting (NBRW-rw) and MH algorithm with delayed acceptance (MHDA) which are theoretically guaranteed to achieve, at almost no additional cost, not only unbiased graph sampling but also higher efficiency (smaller asymptotic variance of the resulting unbiased estimators) than the SRW-rw and the MH algorithm, respectively. In particular, a remarkable feature of the MHDA is its applicability for any non-uniform node sampling like the MH algorithm,...

  3. Celiac Patients: A Randomized, Controlled Clinical Study

    Directory of Open Access Journals (Sweden)

    Giuseppe Mazzarella

    2012-01-01

    Full Text Available A lifelong gluten-free diet (GFD is mandatory for celiac disease (CD but has poor compliance, justifying novel strategies. We found that wheat flour transamidation inhibited IFN-γ secretion by intestinal T cells from CD patients. Herein, the primary endpoint was to evaluate the ability of transamidated gluten to maintain GFD CD patients in clinical remission. Secondary endpoints were efficacy in prevention of the inflammatory response and safety at the kidney level, where reaction products are metabolized. In a randomized single blinded, controlled 90-day trial, 47 GFD CD patients received 3.7 g/day of gluten from nontransamidated (12 or transamidated (35 flour. On day 15, 75% and 37% of patients in the control and experimental groups, respectively, showed clinical relapse (=0.04 whereas intestinal permeability was mainly altered in the control group (50% versus 20%, =0.06. On day 90, 0 controls and 14 patients in the experimental group completed the challenge with no variation of antitransglutaminase IgA (=0.63, Marsh-Oberhuber grading (=0.08, or intestinal IFN-γ mRNA (>0.05. Creatinine clearance did not vary after 90 days of treatment (=0.46. In conclusion, transamidated gluten reduced the number of clinical relapses in challenged patients with no changes of baseline values for serological/mucosal CD markers and an unaltered kidney function.

  4. Identifying the origin of groundwater samples in a multi-layer aquifer system with Random Forest classification

    Science.gov (United States)

    Baudron, Paul; Alonso-Sarría, Francisco; García-Aróstegui, José Luís; Cánovas-García, Fulgencio; Martínez-Vicente, David; Moreno-Brotóns, Jesús

    2013-08-01

    Accurate identification of the origin of groundwater samples is not always possible in complex multilayered aquifers. This poses a major difficulty for a reliable interpretation of geochemical results. The problem is especially severe when the information on the tubewells design is hard to obtain. This paper shows a supervised classification method based on the Random Forest (RF) machine learning technique to identify the layer from where groundwater samples were extracted. The classification rules were based on the major ion composition of the samples. We applied this method to the Campo de Cartagena multi-layer aquifer system, in southeastern Spain. A large amount of hydrogeochemical data was available, but only a limited fraction of the sampled tubewells included a reliable determination of the borehole design and, consequently, of the aquifer layer being exploited. Added difficulty was the very similar compositions of water samples extracted from different aquifer layers. Moreover, not all groundwater samples included the same geochemical variables. Despite of the difficulty of such a background, the Random Forest classification reached accuracies over 90%. These results were much better than the Linear Discriminant Analysis (LDA) and Decision Trees (CART) supervised classification methods. From a total of 1549 samples, 805 proceeded from one unique identified aquifer, 409 proceeded from a possible blend of waters from several aquifers and 335 were of unknown origin. Only 468 of the 805 unique-aquifer samples included all the chemical variables needed to calibrate and validate the models. Finally, 107 of the groundwater samples of unknown origin could be classified. Most unclassified samples did not feature a complete dataset. The uncertainty on the identification of training samples was taken in account to enhance the model. Most of the samples that could not be identified had an incomplete dataset.

  5. Soil map disaggregation improved by soil-landscape relationships, area-proportional sampling and random forest implementation

    DEFF Research Database (Denmark)

    Møller, Anders Bjørn; Malone, Brendan P.; Odgers, Nathan

    algorithm were evaluated. The resulting maps were validated on 777 soil profiles situated in a grid covering Denmark. The experiments showed that the results obtained with Jacobsen’s map were more accurate than the results obtained with the CEC map, despite a nominally coarser scale of 1:2,000,000 vs. 1...... of European Communities (CEC, 1985) respectively, both using the FAO 1974 classification. Furthermore, the effects of implementing soil-landscape relationships, using area proportional sampling instead of per polygon sampling, and replacing the default C5.0 classification tree algorithm with a random forest......:1,000,000. This finding is probably related to the fact that Jacobsen’s map was more detailed with a larger number of polygons, soil map units and soil types, despite its coarser scale. The results showed that the implementation of soil-landscape relationships, area-proportional sampling and the random forest...

  6. High Field In Vivo 13C Magnetic Resonance Spectroscopy of Brain by Random Radiofrequency Heteronuclear Decoupling and Data Sampling

    Science.gov (United States)

    Li, Ningzhi; Li, Shizhe; Shen, Jun

    2017-06-01

    In vivo 13C magnetic resonance spectroscopy (MRS) is a unique and effective tool for studying dynamic human brain metabolism and the cycling of neurotransmitters. One of the major technical challenges for in vivo 13C-MRS is the high radio frequency (RF) power necessary for heteronuclear decoupling. In the common practice of in vivo 13C-MRS, alkanyl carbons are detected in the spectra range of 10-65ppm. The amplitude of decoupling pulses has to be significantly greater than the large one-bond 1H-13C scalar coupling (1JCH=125-145 Hz). Two main proton decoupling methods have been developed: broadband stochastic decoupling and coherent composite or adiabatic pulse decoupling (e.g., WALTZ); the latter is widely used because of its efficiency and superb performance under inhomogeneous B1 field. Because the RF power required for proton decoupling increases quadratically with field strength, in vivo 13C-MRS using coherent decoupling is often limited to low magnetic fields (Drug Administration (FDA). Alternately, carboxylic/amide carbons are coupled to protons via weak long-range 1H-13C scalar couplings, which can be decoupled using low RF power broadband stochastic decoupling. Recently, the carboxylic/amide 13C-MRS technique using low power random RF heteronuclear decoupling was safely applied to human brain studies at 7T. Here, we review the two major decoupling methods and the carboxylic/amide 13C-MRS with low power decoupling strategy. Further decreases in RF power deposition by frequency-domain windowing and time-domain random under-sampling are also discussed. Low RF power decoupling opens the possibility of performing in vivo 13C experiments of human brain at very high magnetic fields (such as 11.7T), where signal-to-noise ratio as well as spatial and temporal spectral resolution are more favorable than lower fields.

  7. Comparing attitudes about legal sanctions and teratogenic effects for cocaine, alcohol, tobacco and caffeine: A randomized, independent samples design

    Directory of Open Access Journals (Sweden)

    Alanis Kelly L

    2006-02-01

    Full Text Available Abstract Background Establishing more sensible measures to treat cocaine-addicted mothers and their children is essential for improving U.S. drug policy. Favorable post-natal environments have moderated potential deleterious prenatal effects. However, since cocaine is an illicit substance having long been demonized, we hypothesized that attitudes toward prenatal cocaine exposure would be more negative than for licit substances, alcohol, nicotine and caffeine. Further, media portrayals about long-term outcomes were hypothesized to influence viewers' attitudes, measured immediately post-viewing. Reducing popular crack baby stigmas could influence future policy decisions by legislators. In Study 1, 336 participants were randomly assigned to 1 of 4 conditions describing hypothetical legal sanction scenarios for pregnant women using cocaine, alcohol, nicotine or caffeine. Participants rated legal sanctions against pregnant women who used one of these substances and risk potential for developing children. In Study 2, 139 participants were randomly assigned to positive, neutral and negative media conditions. Immediately post-viewing, participants rated prenatal cocaine-exposed or non-exposed teens for their academic performance and risk for problems at age18. Results Participants in Study 1 imposed significantly greater legal sanctions for cocaine, perceiving prenatal cocaine exposure as more harmful than alcohol, nicotine or caffeine. A one-way ANOVA for independent samples showed significant differences, beyond .0001. Post-hoc Sheffe test illustrated that cocaine was rated differently from other substances. In Study 2, a one-way ANOVA for independent samples was performed on difference scores for the positive, neutral or negative media conditions about prenatal cocaine exposure. Participants in the neutral and negative media conditions estimated significantly lower grade point averages and more problems for the teen with prenatal cocaine exposure

  8. Comparing attitudes about legal sanctions and teratogenic effects for cocaine, alcohol, tobacco and caffeine: A randomized, independent samples design

    Science.gov (United States)

    Ginsburg, Harvey J; Raffeld, Paul; Alanis, Kelly L; Boyce, Angela S

    2006-01-01

    Background Establishing more sensible measures to treat cocaine-addicted mothers and their children is essential for improving U.S. drug policy. Favorable post-natal environments have moderated potential deleterious prenatal effects. However, since cocaine is an illicit substance having long been demonized, we hypothesized that attitudes toward prenatal cocaine exposure would be more negative than for licit substances, alcohol, nicotine and caffeine. Further, media portrayals about long-term outcomes were hypothesized to influence viewers' attitudes, measured immediately post-viewing. Reducing popular crack baby stigmas could influence future policy decisions by legislators. In Study 1, 336 participants were randomly assigned to 1 of 4 conditions describing hypothetical legal sanction scenarios for pregnant women using cocaine, alcohol, nicotine or caffeine. Participants rated legal sanctions against pregnant women who used one of these substances and risk potential for developing children. In Study 2, 139 participants were randomly assigned to positive, neutral and negative media conditions. Immediately post-viewing, participants rated prenatal cocaine-exposed or non-exposed teens for their academic performance and risk for problems at age18. Results Participants in Study 1 imposed significantly greater legal sanctions for cocaine, perceiving prenatal cocaine exposure as more harmful than alcohol, nicotine or caffeine. A one-way ANOVA for independent samples showed significant differences, beyond .0001. Post-hoc Sheffe test illustrated that cocaine was rated differently from other substances. In Study 2, a one-way ANOVA for independent samples was performed on difference scores for the positive, neutral or negative media conditions about prenatal cocaine exposure. Participants in the neutral and negative media conditions estimated significantly lower grade point averages and more problems for the teen with prenatal cocaine exposure than for the non-exposed teen

  9. Effect of the Mediterranean diet on heart failure biomarkers: a randomized sample from the PREDIMED trial.

    Science.gov (United States)

    Fitó, Montserrat; Estruch, Ramón; Salas-Salvadó, Jordi; Martínez-Gonzalez, Miguel Angel; Arós, Fernando; Vila, Joan; Corella, Dolores; Díaz, Oscar; Sáez, Guillermo; de la Torre, Rafael; Mitjavila, María-Teresa; Muñoz, Miguel Angel; Lamuela-Raventós, Rosa-María; Ruiz-Gutierrez, Valentina; Fiol, Miquel; Gómez-Gracia, Enrique; Lapetra, José; Ros, Emilio; Serra-Majem, Lluis; Covas, María-Isabel

    2014-05-01

    Scarce data are available on the effect of the traditional Mediterranean diet (TMD) on heart failure biomarkers. We assessed the effect of TMD on biomarkers related to heart failure in a high cardiovascular disease risk population. A total of 930 subjects at high cardiovascular risk (420 men and 510 women) were recruited in the framework of a multicentre, randomized, controlled, parallel-group clinical trial directed at testing the efficacy of the TMD on the primary prevention of cardiovascular disease (The PREDIMED Study). Participants were assigned to a low-fat diet (control, n = 310) or one of two TMDs [TMD + virgin olive oil (VOO) or TMD + nuts]. Depending on group assignment, participants received free provision of extra-virgin olive oil, mixed nuts, or small non-food gifts. After 1 year of intervention, both TMDs decreased plasma N-terminal pro-brain natriuretic peptide, with changes reaching significance vs. control group (P cardiovascular disease (CVD) who improved their diet toward a TMD pattern reduced their N-terminal pro-brain natriuretic peptide compared with those assigned to a low-fat diet. The same was found for in vivo oxidized low-density lipoprotein and lipoprotein(a) plasma concentrations after the TMD + VOO diet. From our results TMD could be a useful tool to mitigate against risk factors for heart failure. From our results TMD could modify markers of heart failure towards a more protective mode. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

  10. Self-sampling is appropriate for detection of Staphylococcus aureus: a validation study

    Directory of Open Access Journals (Sweden)

    van Cleef Brigitte AGL

    2012-11-01

    Full Text Available Abstract Background Studies frequently use nasal swabs to determine Staphylococcus aureus carriage. Self-sampling would be extremely useful in an outhospital research situation, but has not been studied in a healthy population. We studied the similarity of self-samples and investigator-samples in nares and pharynxes of healthy study subjects (hospital staff in the Netherlands. Methods One hundred and five nursing personnel members were sampled 4 times in random order after viewing an instruction paper: 1 nasal self-sample, 2 pharyngeal self-sample, 3 nasal investigator-sample, and 4 pharyngeal investigator-sample. Results For nasal samples, agreement is 93% with a kappa coefficient of 0.85 (95% CI 0.74-0.96, indicating excellent agreement, for pharyngeal samples agreement is 83% and the kappa coefficient is 0.60 (95% CI 0.43-0.76, indicating good agreement. In both sampling sites self-samples even detected more S. aureus than investigator-samples. Conclusions This means that self-samples are appropriate for detection of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

  11. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  12. Studies in astronomical time series analysis: Modeling random processes in the time domain

    Science.gov (United States)

    Scargle, J. D.

    1979-01-01

    Random process models phased in the time domain are used to analyze astrophysical time series data produced by random processes. A moving average (MA) model represents the data as a sequence of pulses occurring randomly in time, with random amplitudes. An autoregressive (AR) model represents the correlations in the process in terms of a linear function of past values. The best AR model is determined from sampled data and transformed to an MA for interpretation. The randomness of the pulse amplitudes is maximized by a FORTRAN algorithm which is relatively stable numerically. Results of test cases are given to study the effects of adding noise and of different distributions for the pulse amplitudes. A preliminary analysis of the optical light curve of the quasar 3C 273 is given.

  13. Do Research Findings Apply to My Students? Examining Study Samples and Sampling

    Science.gov (United States)

    Cook, Bryan G.; Cook, Lysandra

    2017-01-01

    Special educators are urged to use research findings to inform their instruction in order to improve student outcomes. However, it can be difficult to tell whether and how research findings apply to one's own students. In this article, we discuss how special educators can consider the samples and the sampling methods in studies to examine the…

  14. Relations among questionnaire and experience sampling measures of inner speech: a smartphone app study

    OpenAIRE

    Ben eAlderson-Day; Charles eFernyhough

    2015-01-01

    Inner speech is often reported to be a common and central part of inner experience, but its true prevalence is unclear. Many questionnaire-based measures appear to lack convergent validity and it has been claimed that they overestimate inner speech in comparison to experience sampling methods (which involve collecting data at random timepoints). The present study compared self-reporting of inner speech collected via a general questionnaire and experience sampling, using data from a custom-mad...

  15. Use of pornography in a random sample of Norwegian heterosexual couples.

    Science.gov (United States)

    Daneback, Kristian; Traeen, Bente; Månsson, Sven-Axel

    2009-10-01

    This study examined the use of pornography in couple relationships to enhance the sex-life. The study contained a representative sample of 398 heterosexual couples aged 22-67 years. Data collection was carried out by self-administered postal questionnaires. The majority (77%) of the couples did not report any kind of pornography use to enhance the sex-life. In 15% of the couples, both had used pornography; in 3% of the couples, only the female partner had used pornography; and, in 5% of the couples, only the male partner had used pornography for this purpose. Based on the results of a discriminant function analysis, it is suggested that couples where one or both used pornography had a more permissive erotic climate compared to the couples who did not use pornography. In couples where only one partner used pornography, we found more problems related to arousal (male) and negative (female) self-perception. These findings could be of importance for clinicians who work with couples.

  16. Mental Health Impact of Hosting Disaster Refugees: Analyses from a Random Sample Survey Among Haitians Living in Miami.

    Science.gov (United States)

    Messiah, Antoine; Lacoste, Jérôme; Gokalsing, Erick; Shultz, James M; Rodríguez de la Vega, Pura; Castro, Grettel; Acuna, Juan M

    2016-08-01

    Studies on the mental health of families hosting disaster refugees are lacking. This study compares participants in households that hosted 2010 Haitian earthquake disaster refugees with their nonhost counterparts. A random sample survey was conducted from October 2011 through December 2012 in Miami-Dade County, Florida. Haitian participants were assessed regarding their 2010 earthquake exposure and impact on family and friends and whether they hosted earthquake refugees. Using standardized scores and thresholds, they were evaluated for symptoms of three common mental disorders (CMDs): posttraumatic stress disorder, generalized anxiety disorder, and major depressive disorder (MDD). Participants who hosted refugees (n = 51) had significantly higher percentages of scores beyond thresholds for MDD than those who did not host refugees (n = 365) and for at least one CMD, after adjusting for participants' earthquake exposures and effects on family and friends. Hosting refugees from a natural disaster appears to elevate the risk for MDD and possibly other CMDs, independent of risks posed by exposure to the disaster itself. Families hosting refugees deserve special attention.

  17. Prediction accuracy of a sample-size estimation method for ROC studies.

    Science.gov (United States)

    Chakraborty, Dev P

    2010-05-01

    Sample-size estimation is an important consideration when planning a receiver operating characteristic (ROC) study. The aim of this work was to assess the prediction accuracy of a sample-size estimation method using the Monte Carlo simulation method. Two ROC ratings simulators characterized by low reader and high case variabilities (LH) and high reader and low case variabilities (HL) were used to generate pilot data sets in two modalities. Dorfman-Berbaum-Metz multiple-reader multiple-case (DBM-MRMC) analysis of the ratings yielded estimates of the modality-reader, modality-case, and error variances. These were input to the Hillis-Berbaum (HB) sample-size estimation method, which predicted the number of cases needed to achieve 80% power for 10 readers and an effect size of 0.06 in the pivotal study. Predictions that generalized to readers and cases (random-all), to cases only (random-cases), and to readers only (random-readers) were generated. A prediction-accuracy index defined as the probability that any single prediction yields true power in the 75%-90% range was used to assess the HB method. For random-case generalization, the HB-method prediction-accuracy was reasonable, approximately 50% for five readers and 100 cases in the pilot study. Prediction-accuracy was generally higher under LH conditions than under HL conditions. Under ideal conditions (many readers in the pilot study) the DBM-MRMC-based HB method overestimated the number of cases. The overestimates could be explained by the larger modality-reader variance estimates when reader variability was large (HL). The largest benefit of increasing the number of readers in the pilot study was realized for LH, where 15 readers were enough to yield prediction accuracy >50% under all generalization conditions, but the benefit was lesser for HL where prediction accuracy was approximately 36% for 15 readers under random-all and random-reader conditions. The HB method tends to overestimate the number of cases

  18. Association of macronutrient intake patterns with being overweight in a population-based random sample of men in France.

    Science.gov (United States)

    Ahluwalia, N; Ferrières, J; Dallongeville, J; Simon, C; Ducimetière, P; Amouyel, P; Arveiler, D; Ruidavets, J-B

    2009-04-01

    Diet is considered an important modifiable factor in the overweight. The role of macronutrients in obesity has been examined in general in selected populations, but the results of these studies are mixed, depending on the potential confounders and adjustments for other macronutrients. For this reason, we examined the association between macronutrient intake patterns and being overweight in a population-based representative sample of middle-aged (55.1+/-6.1 years) men (n=966), using various adjustment modalities. The study subjects kept 3-day food-intake records, and the standard cardiovascular risk factors were assessed. Weight, height and waist circumference (WC) were also measured. Carbohydrate intake was negatively associated and fat intake was positively associated with body mass index (BMI) and WC in regression models adjusted for energy intake and other factors, including age, smoking and physical activity. However, with mutual adjustments for other energy-yielding nutrients, the negative association of carbohydrate intake with WC remained significant, whereas the associations between fat intake and measures of obesity did not. Adjusted odds ratios (95% confidence interval) comparing the highest and lowest quartiles of carbohydrate intake were 0.50 (0.25-0.97) for obesity (BMI>29.9) and 0.41 (0.23-0.73) for abdominal obesity (WC>101.9 cm). Consistent negative associations between carbohydrate intake and BMI and WC were seen in this random representative sample of the general male population. The associations between fat intake and these measures of being overweight were attenuated on adjusting for carbohydrate intake. Thus, the balance of carbohydrate-to-fat intake is an important element in obesity in a general male population, and should be highlighted in dietary guidelines.

  19. Securing image information using double random phase encoding and parallel compressive sensing with updated sampling processes

    Science.gov (United States)

    Hu, Guiqiang; Xiao, Di; Wang, Yong; Xiang, Tao; Zhou, Qing

    2017-11-01

    Recently, a new kind of image encryption approach using compressive sensing (CS) and double random phase encoding has received much attention due to the advantages such as compressibility and robustness. However, this approach is found to be vulnerable to chosen plaintext attack (CPA) if the CS measurement matrix is re-used. Therefore, designing an efficient measurement matrix updating mechanism that ensures resistance to CPA is of practical significance. In this paper, we provide a novel solution to update the CS measurement matrix by altering the secret sparse basis with the help of counter mode operation. Particularly, the secret sparse basis is implemented by a reality-preserving fractional cosine transform matrix. Compared with the conventional CS-based cryptosystem that totally generates all the random entries of measurement matrix, our scheme owns efficiency superiority while guaranteeing resistance to CPA. Experimental and analysis results show that the proposed scheme has a good security performance and has robustness against noise and occlusion.

  20. Alcohol and marijuana use in adolescents' daily lives: a random sample of experiences.

    Science.gov (United States)

    Larson, R; Csikszentmihalyi, M; Freeman, M

    1984-07-01

    High school students filled out reports on their experiences at random times during their daily lives, including 48 occasions when they were using alcohol or marijuana. Alcohol use was reported primarily in the context of Friday and Saturday night social gatherings and was associated with a happy and gregarious subjective state. Marijuana use was reported across a wider range of situations and was associated with an average state that differed much less from ordinary experience.

  1. Prediction Of Students’ Learning Study Periode By Using Random Forest Method (Case Study: Stikom Bali

    Directory of Open Access Journals (Sweden)

    I Made Budi Adnyana

    2016-10-01

    Full Text Available Graduation on time is one of the assessment elements of the college accreditation. Furthermore, graduation on time is an important issue because it indicates an effectiveness of college. Academic division of STIKOM Bali face many difficulties on predicting student graduation time because lack of information and analysis. Predictions of graduation time can help academic division in making appropriate strategy to shorten the study time. Data mining can be applied on this prediction problems using random forest classification methods. Random forest is a collection of of several tree, where each tree dependent on the pixels on each vector that selected randomly and independent .Sample data obtained from academic division of STIKOM Bali. This research use sample data of last 2 years graduated students, such as IPK, SKS, the number of inactive, and study time. The classification output consists of 2 class, “graduate on time” and “graduate over the time”. From the experimental result, 83.54 % accuracy value obtained.

  2. Random or systematic sampling to detect a localised microbial contamination within a batch of food

    NARCIS (Netherlands)

    Jongenburger, I.; Reij, M.W.; Boer, E.P.J.; Gorris, L.G.M.; Zwietering, M.H.

    2011-01-01

    Pathogenic microorganisms are known to be distributed heterogeneously in food products that are solid, semi-solid or powdered, like for instance peanut butter, cereals, or powdered milk. This complicates effective detection of the pathogens by sampling. Two-class sampling plans, which are deployed

  3. Multistage point relascope and randomized branch sampling for downed coarse woody debris estimation

    Science.gov (United States)

    Jeffrey H. Gove; Mark J. Ducey; Harry T. Valentine

    2002-01-01

    New sampling methods have recently been introduced that allow estimation of downed coarse woody debris using an angle gauge, or relascope. The theory behind these methods is based on sampling straight pieces of downed coarse woody debris. When pieces deviate from this ideal situation, auxillary methods must be employed. We describe a two-stage procedure where the...

  4. Mental health impact of the 2010 Haiti earthquake on the Miami Haitian population: A random-sample survey.

    Science.gov (United States)

    Messiah, Antoine; Acuna, Juan M; Castro, Grettel; de la Vega, Pura Rodríguez; Vaiva, Guillaume; Shultz, James; Neria, Yuval; De La Rosa, Mario

    2014-07-01

    This study examined the mental health consequences of the January 2010 Haiti earthquake on Haitians living in Miami-Dade County, Florida, 2-3 years following the event. A random-sample household survey was conducted from October 2011 through December 2012 in Miami-Dade County, Florida. Haitian participants (N = 421) were assessed for their earthquake exposure and its impact on family, friends, and household finances; and for symptoms of posttraumatic stress disorder (PTSD), anxiety, and major depression; using standardized screening measures and thresholds. Exposure was considered as "direct" if the interviewee was in Haiti during the earthquake. Exposure was classified as "indirect" if the interviewee was not in Haiti during the earthquake but (1) family members or close friends were victims of the earthquake, and/or (2) family members were hosted in the respondent's household, and/or (3) assets or jobs were lost because of the earthquake. Interviewees who did not qualify for either direct or indirect exposure were designated as "lower" exposure. Eight percent of respondents qualified for direct exposure, and 63% qualified for indirect exposure. Among those with direct exposure, 19% exceeded threshold for PTSD, 36% for anxiety, and 45% for depression. Corresponding percentages were 9%, 22% and 24% for respondents with indirect exposure, and 6%, 14%, and 10% for those with lower exposure. A majority of Miami Haitians were directly or indirectly exposed to the earthquake. Mental health distress among them remains considerable two to three years post-earthquake.

  5. Randomization modeling to ascertain clustering patterns of human papillomavirus types detected in cervicovaginal samples in the United States.

    Directory of Open Access Journals (Sweden)

    Troy David Querec

    Full Text Available Detection of multiple human papillomavirus (HPV types in the genital tract is common. Associations among HPV types may impact HPV vaccination modeling and type replacement. The objectives were to determine the distribution of concurrent HPV type infections in cervicovaginal samples and examine type-specific associations. We analyzed HPV genotyping results from 32,245 cervicovaginal specimens collected from women aged 11 to 83 years in the United States from 2001 through 2011. Statistical power was enhanced by combining 6 separate studies. Expected concurrent infection frequencies from a series of permutation models, each with increasing fidelity to the real data, were compared with the observed data. Statistics were computed based on the distributional properties of the randomized data. Concurrent detection occurred more than expected with 0 or ≥3 HPV types and less than expected with 1 and 2 types. Some women bear a disproportionate burden of the HPV type prevalence. Type associations were observed that exceeded multiple hypothesis corrected significance. Multiple HPV types were detected more frequently than expected by chance and associations among particular HPV types were detected. However vaccine-targeted types were not specifically affected, supporting the expectation that current bivalent/quadrivalent HPV vaccination will not result in type replacement with other high-risk types.

  6. Global Stratigraphy of Venus: Analysis of a Random Sample of Thirty-Six Test Areas

    Science.gov (United States)

    Basilevsky, Alexander T.; Head, James W., III

    1995-01-01

    The age relations between 36 impact craters with dark paraboloids and other geologic units and structures at these localities have been studied through photogeologic analysis of Magellan SAR images of the surface of Venus. Geologic settings in all 36 sites, about 1000 x 1000 km each, could be characterized using only 10 different terrain units and six types of structures. These units and structures form a major stratigraphic and geologic sequence (from oldest to youngest): (1) tessera terrain; (2) densely fractured terrains associated with coronae and in the form of remnants among plains; (3) fractured and ridged plains and ridge belts; (4) plains with wrinkle ridges; (5) ridges associated with coronae annulae and ridges of arachnoid annulae which are contemporary with wrinkle ridges of the ridged plains; (6) smooth and lobate plains; (7) fractures of coronae annulae, and fractures not related to coronae annulae, which disrupt ridged and smooth plains; (8) rift-associated fractures; and (9) craters with associated dark paraboloids, which represent the youngest 1O% of the Venus impact crater population (Campbell et al.), and are on top of all volcanic and tectonic units except the youngest episodes of rift-associated fracturing and volcanism; surficial streaks and patches are approximately contemporary with dark-paraboloid craters. Mapping of such units and structures in 36 randomly distributed large regions (each approximately 10(exp 6) sq km) shows evidence for a distinctive regional and global stratigraphic and geologic sequence. On the basis of this sequence we have developed a model that illustrates several major themes in the history of Venus. Most of the history of Venus (that of its first 80% or so) is not preserved in the surface geomorphological record. The major deformation associated with tessera formation in the period sometime between 0.5-1.0 b.y. ago (Ivanov and Basilevsky) is the earliest event detected. In the terminal stages of tessera fon

  7. Endothelial nitric oxide synthase (G894T) gene polymorphism in a random sample of the Egyptian population: comparison with myocardial infarction patients.

    Science.gov (United States)

    Gad, Mohamed Z; Abdel Rahman, Mohamed F; Hashad, Ingy M; Abdel-Maksoud, Sahar M; Farag, Nabil M; Abou-Aisha, Khaled

    2012-07-01

    The aim of this study was to detect endothelial nitric oxide synthase (eNOS) Glu298Asp gene variants in a random sample of the Egyptian population, compare it with those from other populations, and attempt to correlate these variants with serum levels of nitric oxide (NO). The association of eNOS genotypes or serum NO levels with the incidence of acute myocardial infarction (AMI) was also examined. One hundred one unrelated healthy subjects and 104 unrelated AMI patients were recruited randomly from the 57357 Hospital and intensive care units of El Demerdash Hospital and National Heart Institute, Cairo, Egypt. eNOS genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Serum NO was determined spectrophotometrically. The genotype distribution of eNOS Glu298Asp polymorphism determined for our sample was 58.42% GG (wild type), 33.66% GT, and 7.92% TT genotypes while allele frequencies were 75.25% and 24.75% for G and T alleles, respectively. No significant association between serum NO and specific eNOS genotype could be detected. No significant correlation between eNOS genotype distribution or allele frequencies and the incidence of AMI was observed. The present study demonstrated the predominance of the homozygous genotype GG over the heterozygous GT and homozygous TT in random samples of Egyptian population. It also showed the lack of association between eNOS genotypes and mean serum levels of NO, as well as the incidence of AMI.

  8. Random sampling technique for ultra-fast computations of molecular opacities for exoplanet atmospheres

    Science.gov (United States)

    Min, M.

    2017-10-01

    Context. Opacities of molecules in exoplanet atmospheres rely on increasingly detailed line-lists for these molecules. The line lists available today contain for many species up to several billions of lines. Computation of the spectral line profile created by pressure and temperature broadening, the Voigt profile, of all of these lines is becoming a computational challenge. Aims: We aim to create a method to compute the Voigt profile in a way that automatically focusses the computation time into the strongest lines, while still maintaining the continuum contribution of the high number of weaker lines. Methods: Here, we outline a statistical line sampling technique that samples the Voigt profile quickly and with high accuracy. The number of samples is adjusted to the strength of the line and the local spectral line density. This automatically provides high accuracy line shapes for strong lines or lines that are spectrally isolated. The line sampling technique automatically preserves the integrated line opacity for all lines, thereby also providing the continuum opacity created by the large number of weak lines at very low computational cost. Results: The line sampling technique is tested for accuracy when computing line spectra and correlated-k tables. Extremely fast computations ( 3.5 × 105 lines per second per core on a standard current day desktop computer) with high accuracy (≤1% almost everywhere) are obtained. A detailed recipe on how to perform the computations is given.

  9. Hybrid random walk-linear discriminant analysis method for unwrapping quantitative phase microscopy images of biological samples

    Science.gov (United States)

    Kim, Diane N. H.; Teitell, Michael A.; Reed, Jason; Zangle, Thomas A.

    2015-11-01

    Standard algorithms for phase unwrapping often fail for interferometric quantitative phase imaging (QPI) of biological samples due to the variable morphology of these samples and the requirement to image at low light intensities to avoid phototoxicity. We describe a new algorithm combining random walk-based image segmentation with linear discriminant analysis (LDA)-based feature detection, using assumptions about the morphology of biological samples to account for phase ambiguities when standard methods have failed. We present three versions of our method: first, a method for LDA image segmentation based on a manually compiled training dataset; second, a method using a random walker (RW) algorithm informed by the assumed properties of a biological phase image; and third, an algorithm which combines LDA-based edge detection with an efficient RW algorithm. We show that the combination of LDA plus the RW algorithm gives the best overall performance with little speed penalty compared to LDA alone, and that this algorithm can be further optimized using a genetic algorithm to yield superior performance for phase unwrapping of QPI data from biological samples.

  10. Considerations in determining sample size for pilot studies.

    Science.gov (United States)

    Hertzog, Melody A

    2008-04-01

    There is little published guidance concerning how large a pilot study should be. General guidelines, for example using 10% of the sample required for a full study, may be inadequate for aims such as assessment of the adequacy of instrumentation or providing statistical estimates for a larger study. This article illustrates how confidence intervals constructed around a desired or anticipated value can help determine the sample size needed. Samples ranging in size from 10 to 40 per group are evaluated for their adequacy in providing estimates precise enough to meet a variety of possible aims. General sample size guidelines by type of aim are offered.

  11. THE RHETORICAL USE OF RANDOM SAMPLING: CRAFTING AND COMMUNICATING THE PUBLIC IMAGE OF POLLS AS A SCIENCE (1935-1948).

    Science.gov (United States)

    Lusinchi, Dominic

    2017-03-01

    The scientific pollsters (Archibald Crossley, George H. Gallup, and Elmo Roper) emerged onto the American news media scene in 1935. Much of what they did in the following years (1935-1948) was to promote both the political and scientific legitimacy of their enterprise. They sought to be recognized as the sole legitimate producers of public opinion. In this essay I examine the, mostly overlooked, rhetorical work deployed by the pollsters to publicize the scientific credentials of their polling activities, and the central role the concept of sampling has had in that pursuit. First, they distanced themselves from the failed straw poll by claiming that their sampling methodology based on quotas was informed by science. Second, although in practice they did not use random sampling, they relied on it rhetorically to derive the symbolic benefits of being associated with the "laws of probability." © 2017 Wiley Periodicals, Inc.

  12. Multivariate Multi-Objective Allocation in Stratified Random Sampling: A Game Theoretic Approach.

    Science.gov (United States)

    Muhammad, Yousaf Shad; Hussain, Ijaz; Shoukry, Alaa Mohamd

    2016-01-01

    We consider the problem of multivariate multi-objective allocation where no or limited information is available within the stratum variance. Results show that a game theoretic approach (based on weighted goal programming) can be applied to sample size allocation problems. We use simulation technique to determine payoff matrix and to solve a minimax game.

  13. The effect of dead time on randomly sampled power spectral estimates

    DEFF Research Database (Denmark)

    Buchhave, Preben; Velte, Clara Marika; George, William K.

    2014-01-01

    consider both the effect on the measured spectrum of a finite sampling time, i.e., a finite time during which the signal is acquired, and a finite dead time, that is a time in which the signal processor is busy evaluating a data point and therefore unable to measure a subsequent data point arriving within...... the dead time delay....

  14. Phase microscopy of technical and biological samples through random phase modulation with a difuser

    DEFF Research Database (Denmark)

    Almoro, Percival; Pedrini, Giancarlo; Gundu, Phanindra Narayan

    2010-01-01

    A technique for phase microscopy using a phase diffuser and a reconstruction algorithm is proposed. A magnified specimen wavefront is projected on the diffuser plane that modulates the wavefront into a speckle field. The speckle patterns at axially displaced planes are sampled and used in an iter...

  15. Sample Size and Statistical Power Calculation in Genetic Association Studies

    Directory of Open Access Journals (Sweden)

    Eun Pyo Hong

    2012-06-01

    Full Text Available A sample size with sufficient statistical power is critical to the success of genetic association studies to detect causal genes of human complex diseases. Genome-wide association studies require much larger sample sizes to achieve an adequate statistical power. We estimated the statistical power with increasing numbers of markers analyzed and compared the sample sizes that were required in case-control studies and case-parent studies. We computed the effective sample size and statistical power using Genetic Power Calculator. An analysis using a larger number of markers requires a larger sample size. Testing a single-nucleotide polymorphism (SNP marker requires 248 cases, while testing 500,000 SNPs and 1 million markers requires 1,206 cases and 1,255 cases, respectively, under the assumption of an odds ratio of 2, 5% disease prevalence, 5% minor allele frequency, complete linkage disequilibrium (LD, 1:1 case/control ratio, and a 5% error rate in an allelic test. Under a dominant model, a smaller sample size is required to achieve 80% power than other genetic models. We found that a much lower sample size was required with a strong effect size, common SNP, and increased LD. In addition, studying a common disease in a case-control study of a 1:4 case-control ratio is one way to achieve higher statistical power. We also found that case-parent studies require more samples than case-control studies. Although we have not covered all plausible cases in study design, the estimates of sample size and statistical power computed under various assumptions in this study may be useful to determine the sample size in designing a population-based genetic association study.

  16. Random Evolutionary Dynamics Driven by Fitness and House-of-Cards Mutations: Sampling Formulae

    Science.gov (United States)

    Huillet, Thierry E.

    2017-07-01

    We first revisit the multi-allelic mutation-fitness balance problem, especially when mutations obey a house of cards condition, where the discrete-time deterministic evolutionary dynamics of the allelic frequencies derives from a Shahshahani potential. We then consider multi-allelic Wright-Fisher stochastic models whose deviation to neutrality is from the Shahshahani mutation/selection potential. We next focus on the weak selection, weak mutation cases and, making use of a Gamma calculus, we compute the normalizing partition functions of the invariant probability densities appearing in their Wright-Fisher diffusive approximations. Using these results, generalized Ewens sampling formulae (ESF) from the equilibrium distributions are derived. We start treating the ESF in the mixed mutation/selection potential case and then we restrict ourselves to the ESF in the simpler house-of-cards mutations only situation. We also address some issues concerning sampling problems from infinitely-many alleles weak limits.

  17. A Randomized Controlled Trial Study on the Effect of Adding ...

    African Journals Online (AJOL)

    A Randomized Controlled Trial Study on the Effect of Adding Dexmedetomidine to Bupivacaine in Supraclavicular Block Using Ultrasound Guidance. ... BACKGROUND: The benefits of regional anesthetic techniques are well established. Use of additives to local anesthetics can prolong these benefits. The aim of this study ...

  18. A Prospective Randomized Clinical Study of the Influence of Primary ...

    African Journals Online (AJOL)

    Objective: The aim of the following study is to determine the effect of primary closure or dressing on post‑operative morbidity after impacted lower third molar surgery. Materials and Methods: This was a randomized clinical study of 72 patients who had surgical extraction of impacted mandibular third molars. The subjects ...

  19. Sequential sampling model for multiattribute choice alternatives with random attention time and processing order.

    Science.gov (United States)

    Diederich, Adele; Oswald, Peter

    2014-01-01

    A sequential sampling model for multiattribute binary choice options, called multiattribute attention switching (MAAS) model, assumes a separate sampling process for each attribute. During the deliberation process attention switches from one attribute consideration to the next. The order in which attributes are considered as well for how long each attribute is considered-the attention time-influences the predicted choice probabilities and choice response times. Several probability distributions for the attention time with different variances are investigated. Depending on the time and order schedule the model predicts a rich choice probability/choice response time pattern including preference reversals and fast errors. Furthermore, the difference between finite and infinite decision horizons for the attribute considered last is investigated. For the former case the model predicts a probability p 0 > 0 of not deciding within the available time. The underlying stochastic process for each attribute is an Ornstein-Uhlenbeck process approximated by a discrete birth-death process. All predictions are also true for the widely applied Wiener process.

  20. Sequential sampling model for multiattribute choice alternatives with random attention time and processing order

    Directory of Open Access Journals (Sweden)

    Adele eDiederich

    2014-09-01

    Full Text Available A sequential sampling model for multiattribute binary choice options, called Multiattribute attention switching (MAAS model, assumes a separate sampling process for each attribute. During the deliberation process attention switches from one attribute consideration to the next. The order in which attributes are considered as well for how long each attribute is considered - the attention time - influences the predicted choice probabilities and choice response times. Several probability distributions for the attention time including deterministic, Poisson, binomial, geometric, and uniform with different variances are investigated. Depending on the time and order schedule the model predicts a rich choice probability/choice response time pattern including preference reversals and fast errors. Furthermore, the difference between a finite and infinite decision horizons for the attribute considered last is investigated. For the former case the model predicts a probability $p_0> 0$ of not deciding within the available time. The underlying stochastic process for each attribute is an Ornstein-Uhlenbeck process approximated by a discrete birth-death process. All predictions are also true for the widely applied Wiener process.

  1. Incorporating covariance estimation uncertainty in spatial sampling design for prediction with trans-Gaussian random fields

    Directory of Open Access Journals (Sweden)

    Gunter eSpöck

    2015-05-01

    Full Text Available Recently, Spock and Pilz [38], demonstratedthat the spatial sampling design problem forthe Bayesian linear kriging predictor can betransformed to an equivalent experimentaldesign problem for a linear regression modelwith stochastic regression coefficients anduncorrelated errors. The stochastic regressioncoefficients derive from the polar spectralapproximation of the residual process. Thus,standard optimal convex experimental designtheory can be used to calculate optimal spatialsampling designs. The design functionals ̈considered in Spock and Pilz [38] did nottake into account the fact that kriging isactually a plug-in predictor which uses theestimated covariance function. The resultingoptimal designs were close to space-fillingconfigurations, because the design criteriondid not consider the uncertainty of thecovariance function.In this paper we also assume that thecovariance function is estimated, e.g., byrestricted maximum likelihood (REML. Wethen develop a design criterion that fully takesaccount of the covariance uncertainty. Theresulting designs are less regular and space-filling compared to those ignoring covarianceuncertainty. The new designs, however, alsorequire some closely spaced samples in orderto improve the estimate of the covariancefunction. We also relax the assumption ofGaussian observations and assume that thedata is transformed to Gaussianity by meansof the Box-Cox transformation. The resultingprediction method is known as trans-Gaussiankriging. We apply the Smith and Zhu [37]approach to this kriging method and show thatresulting optimal designs also depend on theavailable data. We illustrate our results witha data set of monthly rainfall measurementsfrom Upper Austria.

  2. Sample size computation for association studies using case–parents ...

    Indian Academy of Sciences (India)

    sample size for case–control association studies is discussed. Materials and methods. Parameter settings. We consider a candidate locus with two alleles A and a where. A is putatively associated with the disease status (increasing. Keywords. sample size; association tests; genotype relative risk; power; autism. Journal of ...

  3. A Monte Carlo study of adsorption of random copolymers on random surfaces

    CERN Document Server

    Moghaddam, M S

    2003-01-01

    We study the adsorption problem of a random copolymer on a random surface in which a self-avoiding walk in three dimensions interacts with a plane defining a half-space to which the walk is confined. Each vertex of the walk is randomly labelled A with probability p sub p or B with probability 1 - p sub p , and only vertices labelled A are attracted to the surface plane. Each lattice site on the plane is also labelled either A with probability p sub s or B with probability 1 - p sub s , and only lattice sites labelled A interact with the walk. We study two variations of this model: in the first case the A-vertices of the walk interact only with the A-sites on the surface. In the second case the constraint of selective binding is removed; that is, any contact between the walk and the surface that involves an A-labelling, either from the surface or from the walk, is counted as a visit to the surface. The system is quenched in both cases, i.e. the labellings of the walk and of the surface are fixed as thermodynam...

  4. Randomized controlled study of CBT in bronchial asthma

    Directory of Open Access Journals (Sweden)

    Grover Naveen

    2007-01-01

    Full Text Available The aim of the present study was to find out efficacy of cognitive behavior therapy, as an adjunct to standard pharmacotherapy, in bronchial asthma. In a random-ized two-group design with pre-and post assessments, forty asthma patients were randomly allotted to two groups: self management group and cognitive behavior therapy group. Both groups were exposed to 6-8 weeks of intervention, asthma self management program and cognitive behavior therapy. Assessment measures used were-Semi structured interview schedule, Asthma Symptom Checklist, Asthma di-ary, Asthma Bother Profile, Hospital Anxiety & Depression Scale, AQLQ and Peak Expiratory Flow Rate. Within group comparison showed significant improvement in both groups at the post assessment. Between group comparisons showed that CBT group reported significantly greater change than that of SM group. Cognitive behavior therapy helps in improving the managment of asthma.

  5. Determining optimal sample sizes for multistage adaptive randomized clinical trials from an industry perspective using value of information methods.

    Science.gov (United States)

    Chen, Maggie H; Willan, Andrew R

    2013-02-01

    Most often, sample size determinations for randomized clinical trials are based on frequentist approaches that depend on somewhat arbitrarily chosen factors, such as type I and II error probabilities and the smallest clinically important difference. As an alternative, many authors have proposed decision-theoretic (full Bayesian) approaches, often referred to as value of information methods that attempt to determine the sample size that maximizes the difference between the trial's expected utility and its expected cost, referred to as the expected net gain. Taking an industry perspective, Willan proposes a solution in which the trial's utility is the increase in expected profit. Furthermore, Willan and Kowgier, taking a societal perspective, show that multistage designs can increase expected net gain. The purpose of this article is to determine the optimal sample size using value of information methods for industry-based, multistage adaptive randomized clinical trials, and to demonstrate the increase in expected net gain realized. At the end of each stage, the trial's sponsor must decide between three actions: continue to the next stage, stop the trial and seek regulatory approval, or stop the trial and abandon the drug. A model for expected total profit is proposed that includes consideration of per-patient profit, disease incidence, time horizon, trial duration, market share, and the relationship between trial results and probability of regulatory approval. The proposed method is extended to include multistage designs with a solution provided for a two-stage design. An example is given. Significant increases in the expected net gain are realized by using multistage designs. The complexity of the solutions increases with the number of stages, although far simpler near-optimal solutions exist. The method relies on the central limit theorem, assuming that the sample size is sufficiently large so that the relevant statistics are normally distributed. From a value of

  6. A Systematic Review of Randomized Controlled Studies of Art Therapy

    Science.gov (United States)

    Maujean, Annick; Pepping, Christopher A.; Kendall, Elizabeth

    2014-01-01

    This review article examines current knowledge about the efficacy of art therapy based on the findings of 8 randomized controlled trials (RCTs) conducted with adult populations from 2008-2013 that met a high standard of rigor. Of these studies, all but one reported beneficial effects of art therapy. Review findings suggest that art therapy may…

  7. A Prospective, Randomized Study Comparing 7-day and 14-day ...

    African Journals Online (AJOL)

    2018-02-07

    Feb 7, 2018 ... KEYWORDS: Duodenum, dyspepsia, Helicobacter pylori, gastritis, stomach. A Prospective, Randomized Study Comparing 7-day and 14-day. Quadruple Therapies as First-line Treatments for Helicobacter pylori. Infection in Patients with Functional Dyspepsia. A Yağbasan, DÖ Coşkun1, Ö Özbakir2, ...

  8. Astronaut Neil Armstrong studies rock samples during geological field trip

    Science.gov (United States)

    1969-01-01

    Astronaut Neil Armstrong, commander of the Apollo 11 lunar landing mission, studies rock samples during a geological field trip to the Quitman Mountains area near the Fort Quitman ruins in far west Texas.

  9. Study of kissing molars in Turkish population sample | Yanik ...

    African Journals Online (AJOL)

    Study of kissing molars in Turkish population sample. ... refers to contacting occlusal surfaces of the impacted mandibular second and third molars. ... was to report the incidence of kissing molars (KMs), classification, incorporated pathologies, ...

  10. Uncertainty Of Stream Nutrient Transport Estimates Using Random Sampling Of Storm Events From High Resolution Water Quality And Discharge Data

    Science.gov (United States)

    Scholefield, P. A.; Arnscheidt, J.; Jordan, P.; Beven, K.; Heathwaite, L.

    2007-12-01

    The uncertainties associated with stream nutrient transport estimates are frequently overlooked and the sampling strategy is rarely if ever investigated. Indeed, the impact of sampling strategy and estimation method on the bias and precision of stream phosphorus (P) transport calculations is little understood despite the use of such values in the calibration and testing of models of phosphorus transport. The objectives of this research were to investigate the variability and uncertainty in the estimates of total phosphorus transfers at an intensively monitored agricultural catchment. The Oona Water which is located in the Irish border region, is part of a long term monitoring program focusing on water quality. The Oona Water is a rural river catchment with grassland agriculture and scattered dwelling houses and has been monitored for total phosphorus (TP) at 10 min resolution for several years (Jordan et al, 2007). Concurrent sensitive measurements of discharge are also collected. The water quality and discharge data were provided at 1 hour resolution (averaged) and this meant that a robust estimate of the annual flow weighted concentration could be obtained by simple interpolation between points. A two-strata approach (Kronvang and Bruhn, 1996) was used to estimate flow weighted concentrations using randomly sampled storm events from the 400 identified within the time series and also base flow concentrations. Using a random stratified sampling approach for the selection of events, a series ranging from 10 through to the full 400 were used, each time generating a flow weighted mean using a load-discharge relationship identified through log-log regression and monte-carlo simulation. These values were then compared to the observed total phosphorus concentration for the catchment. Analysis of these results show the impact of sampling strategy, the inherent bias in any estimate of phosphorus concentrations and the uncertainty associated with such estimates. The

  11. Active Learning "Not" Associated with Student Learning in a Random Sample of College Biology Courses

    Science.gov (United States)

    Andrews, T. M.; Leonard, M. J.; Colgrove, C. A.; Kalinowski, S. T.

    2011-01-01

    Previous research has suggested that adding active learning to traditional college science lectures substantially improves student learning. However, this research predominantly studied courses taught by science education researchers, who are likely to have exceptional teaching expertise. The present study investigated introductory biology courses…

  12. Protocol for fir tree sampling for provenance studies

    Science.gov (United States)

    Meisel, Thomas; Bandoniene, Donata; Zettl, Daniela

    2014-05-01

    Isotopic (stable and radiogenic) as well as trace element fingerprinting methods used for tracing the geographical origin, rely on databases, that need to contain data sets representative of the measurands of the individual samples for a specific geographic entity. Through this work, we want to assess different sampling strategies for obtaining representative sample of fir trees (Abies sp.). Motivation for this work is the protection of the local Austrian Christmas tree market from wrongly tagged trees of non-Austrian origin. In particular, we studied three typical Christmas trees the most common species sold as Christmas tree, namely Abies nordmanniana (Nordmann Fir), from the same locality in lower Austria. For the initial tests we applied the elemental fingerprinting method, to study the suitability of the different parts of the tree applying ICP-MS analysis after complete acid digestion in a high pressure asher system (HPA-S).Needle samples from each year of life of the tree and stem wood from three different heights were analyzed for their trace element content to prove the repeatability and to find the best sampling protocol. For the analysis of the needles, the natural wax coating had to be removed in order to get reproducible results. For the analysis of stem wood only the bark was removed. As expected the data of all three trees allowed the differentiation of the individual needle ages, but interestingly enough also between the three sampling heights of the needs. Both needles and wood proved to be suitable for successful fingerprinting, but importantly, provided that sample of the same type and ages are compared. The same samples for the three trees will also be used for isotopic analysis studies to better understand the influence of age and sampling height on the representativeness of fir tree samples. Based on elemental fingerprinting alone, a successful discrimination between local (Austrian) and foreign (Danish, Irish) Christmas trees was possible.

  13. Sampling strategies for tropical forest nutrient cycling studies: a case study in São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    G. Sparovek

    1997-12-01

    Full Text Available The precise sampling of soil, biological or micro climatic attributes in tropical forests, which are characterized by a high diversity of species and complex spatial variability, is a difficult task. We found few basic studies to guide sampling procedures. The objective of this study was to define a sampling strategy and data analysis for some parameters frequently used in nutrient cycling studies, i. e., litter amount, total nutrient amounts in litter and its composition (Ca, Mg, Κ, Ν and P, and soil attributes at three depths (organic matter, Ρ content, cation exchange capacity and base saturation. A natural remnant forest in the West of São Paulo State (Brazil was selected as study area and samples were collected in July, 1989. The total amount of litter and its total nutrient amounts had a high spatial independent variance. Conversely, the variance of litter composition was lower and the spatial dependency was peculiar to each nutrient. The sampling strategy for the estimation of litter amounts and the amount of nutrient in litter should be different than the sampling strategy for nutrient composition. For the estimation of litter amounts and the amount of nutrients in litter (related to quantity a large number of randomly distributed determinations are needed. Otherwise, for the estimation of litter nutrient composition (related to quality a smaller amount of spatially located samples should be analyzed. The determination of sampling for soil attributes differed according to the depth. Overall, surface samples (0-5 cm showed high short distance spatial dependent variance, whereas, subsurface samples exhibited spatial dependency in longer distances. Short transects with sampling interval of 5-10 m are recommended for surface sampling. Subsurface samples must also be spatially located, but with transects or grids with longer distances between sampling points over the entire area. Composite soil samples would not provide a complete

  14. Loneliness and Ethnic Composition of the School Class : A Nationally Random Sample of Adolescents

    NARCIS (Netherlands)

    Madsen, Katrine Rich; Damsgaard, Mogens Trab; Rubin, Mark; Jervelund, Signe Smith; Lasgaard, Mathias; Walsh, Sophie; Stevens, Gonneke G W J M; Holstein, Bjørn E

    Loneliness is a public health concern that increases the risk for several health, behavioral and academic problems among adolescents. Some studies have suggested that adolescents with an ethnic minority background have a higher risk for loneliness than adolescents from the majority population. The

  15. Mendelian randomization studies of biomarkers and type 2 diabetes.

    Science.gov (United States)

    Abbasi, Ali

    2015-12-01

    Many biomarkers are associated with type 2 diabetes (T2D) risk in epidemiological observations. The aim of this study was to identify and summarize current evidence for causal effects of biomarkers on T2D. A systematic literature search in PubMed and EMBASE (until April 2015) was done to identify Mendelian randomization studies that examined potential causal effects of biomarkers on T2D. To replicate the findings of identified studies, data from two large-scale, genome-wide association studies (GWAS) were used: DIAbetes Genetics Replication And Meta-analysis (DIAGRAMv3) for T2D and the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) for glycaemic traits. GWAS summary statistics were extracted for the same genetic variants (or proxy variants), which were used in the original Mendelian randomization studies. Of the 21 biomarkers (from 28 studies), ten have been reported to be causally associated with T2D in Mendelian randomization. Most biomarkers were investigated in a single cohort study or population. Of the ten biomarkers that were identified, nominally significant associations with T2D or glycaemic traits were reached for those genetic variants related to bilirubin, pro-B-type natriuretic peptide, delta-6 desaturase and dimethylglycine based on the summary data from DIAGRAMv3 or MAGIC. Several Mendelian randomization studies investigated the nature of associations of biomarkers with T2D. However, there were only a few biomarkers that may have causal effects on T2D. Further research is needed to broadly evaluate the causal effects of multiple biomarkers on T2D and glycaemic traits using data from large-scale cohorts or GWAS including many different genetic variants. © 2015 The authors.

  16. Sample size and power calculation for molecular biology studies.

    Science.gov (United States)

    Jung, Sin-Ho

    2010-01-01

    Sample size calculation is a critical procedure when designing a new biological study. In this chapter, we consider molecular biology studies generating huge dimensional data. Microarray studies are typical examples, so that we state this chapter in terms of gene microarray data, but the discussed methods can be used for design and analysis of any molecular biology studies involving high-dimensional data. In this chapter, we discuss sample size calculation methods for molecular biology studies when the discovery of prognostic molecular markers is performed by accurately controlling false discovery rate (FDR) or family-wise error rate (FWER) in the final data analysis. We limit our discussion to the two-sample case.

  17. Neuromuscular dose-response studies: determining sample size.

    Science.gov (United States)

    Kopman, A F; Lien, C A; Naguib, M

    2011-02-01

    Investigators planning dose-response studies of neuromuscular blockers have rarely used a priori power analysis to determine the minimal sample size their protocols require. Institutional Review Boards and peer-reviewed journals now generally ask for this information. This study outlines a proposed method for meeting these requirements. The slopes of the dose-response relationships of eight neuromuscular blocking agents were determined using regression analysis. These values were substituted for γ in the Hill equation. When this is done, the coefficient of variation (COV) around the mean value of the ED₅₀ for each drug is easily calculated. Using these values, we performed an a priori one-sample two-tailed t-test of the means to determine the required sample size when the allowable error in the ED₅₀ was varied from ±10-20%. The COV averaged 22% (range 15-27%). We used a COV value of 25% in determining the sample size. If the allowable error in finding the mean ED₅₀ is ±15%, a sample size of 24 is needed to achieve a power of 80%. Increasing 'accuracy' beyond this point requires increasing greater sample sizes (e.g. an 'n' of 37 for a ±12% error). On the basis of the results of this retrospective analysis, a total sample size of not less than 24 subjects should be adequate for determining a neuromuscular blocking drug's clinical potency with a reasonable degree of assurance.

  18. Fasting time and lipid parameters: association with hepatic steatosis — data from a random population sample

    Science.gov (United States)

    2014-01-01

    Background Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels. Method Subjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1–4 h, 4–8 h and > 8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression. Results At multivariate analysis, fasting time was associated with elevated triglycerides (p = 0.0047 for 1–4 h and p = 0.0147 for 4–8 h among females; p fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis. PMID:24447492

  19. Fasting time and lipid parameters: association with hepatic steatosis--data from a random population sample.

    Science.gov (United States)

    Gruchot, Martin; Graeter, Tilmann; Oeztuerk, Suemeyra; Haenle, Mark Martin; Koenig, Wolfgang; Imhof, Armin; Boehm, Bernhard Otto; Mason, Richard Andrew; Kratzer, Wolfgang; Akinli, Atilla Serif

    2014-01-22

    Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels. Subjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1-4 h, 4-8 h and > 8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression. At multivariate analysis, fasting time was associated with elevated triglycerides (p = 0.0047 for 1-4 h and p = 0.0147 for 4-8 h among females; p fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis.

  20. Active versus Passive Sample Attrition: The Health and Retirement Study

    OpenAIRE

    Honggao Cao; Daniel H. Hill

    2005-01-01

    This paper investigates sample attrition in the Health and Retirement Study (HRS). We compare attrition behavior in two of the HRS cohorts: original HRS cohort and AHEAD cohort. We distinguish attrition due to death (passive attrition) from attrition due to other causes (active attrition), examining potential effects of different attrition modes on the representativeness of the remaining samples. This distinction is justified based on a specification test on a multinomial logistic regression ...

  1. Randomized Comparison of Two Vaginal Self-Sampling Methods for Human Papillomavirus Detection: Dry Swab versus FTA Cartridge.

    Directory of Open Access Journals (Sweden)

    Rosa Catarino

    Full Text Available Human papillomavirus (HPV self-sampling (self-HPV is valuable in cervical cancer screening. HPV testing is usually performed on physician-collected cervical smears stored in liquid-based medium. Dry filters and swabs are an alternative. We evaluated the adequacy of self-HPV using two dry storage and transport devices, the FTA cartridge and swab.A total of 130 women performed two consecutive self-HPV samples. Randomization determined which of the two tests was performed first: self-HPV using dry swabs (s-DRY or vaginal specimen collection using a cytobrush applied to an FTA cartridge (s-FTA. After self-HPV, a physician collected a cervical sample using liquid-based medium (Dr-WET. HPV types were identified by real-time PCR. Agreement between collection methods was measured using the kappa statistic.HPV prevalence for high-risk types was 62.3% (95%CI: 53.7-70.2 detected by s-DRY, 56.2% (95%CI: 47.6-64.4 by Dr-WET, and 54.6% (95%CI: 46.1-62.9 by s-FTA. There was overall agreement of 70.8% between s-FTA and s-DRY samples (kappa = 0.34, and of 82.3% between self-HPV and Dr-WET samples (kappa = 0.56. Detection sensitivities for low-grade squamous intraepithelial lesion or worse (LSIL+ were: 64.0% (95%CI: 44.5-79.8 for s-FTA, 84.6% (95%CI: 66.5-93.9 for s-DRY, and 76.9% (95%CI: 58.0-89.0 for Dr-WET. The preferred self-collection method among patients was s-DRY (40.8% vs. 15.4%. Regarding costs, FTA card was five times more expensive than the swab (~5 US dollars (USD/per card vs. ~1 USD/per swab.Self-HPV using dry swabs is sensitive for detecting LSIL+ and less expensive than s-FTA.International Standard Randomized Controlled Trial Number (ISRCTN: 43310942.

  2. Aerobic physical activity and resistance training: an application of the theory of planned behavior among adults with type 2 diabetes in a random, national sample of Canadians

    Directory of Open Access Journals (Sweden)

    Karunamuni Nandini

    2008-12-01

    Full Text Available Abstract Background Aerobic physical activity (PA and resistance training are paramount in the treatment and management of type 2 diabetes (T2D, but few studies have examined the determinants of both types of exercise in the same sample. Objective The primary purpose was to investigate the utility of the Theory of Planned Behavior (TPB in explaining aerobic PA and resistance training in a population sample of T2D adults. Methods A total of 244 individuals were recruited through a random national sample which was created by generating a random list of household phone numbers. The list was proportionate to the actual number of household telephone numbers for each Canadian province (with the exception of Quebec. These individuals completed self-report TPB constructs of attitude, subjective norm, perceived behavioral control and intention, and a 3-month follow-up that assessed aerobic PA and resistance training. Results TPB explained 10% and 8% of the variance respectively for aerobic PA and resistance training; and accounted for 39% and 45% of the variance respectively for aerobic PA and resistance training intentions. Conclusion These results may guide the development of appropriate PA interventions for aerobic PA and resistance training based on the TPB.

  3. Serum Dried Samples to Detect Dengue Antibodies: A Field Study

    Directory of Open Access Journals (Sweden)

    Angelica Maldonado-Rodríguez

    2017-01-01

    Full Text Available Background. Dried blood and serum samples are useful resources for detecting antiviral antibodies. The conditions for elution of the sample need to be optimized for each disease. Dengue is a widespread disease in Mexico which requires continuous surveillance. In this study, we standardized and validated a protocol for the specific detection of dengue antibodies from dried serum spots (DSSs. Methods. Paired serum and DSS samples from 66 suspected cases of dengue were collected in a clinic in Veracruz, Mexico. Samples were sent to our laboratory, where the conditions for optimal elution of DSSs were established. The presence of anti-dengue antibodies was determined in the paired samples. Results. DSS elution conditions were standardized as follows: 1 h at 4°C in 200 µl of DNase-, RNase-, and protease-free PBS (1x. The optimal volume of DSS eluate to be used in the IgG assay was 40 µl. Sensitivity of 94%, specificity of 93.3%, and kappa concordance of 0.87 were obtained when comparing the antidengue reactivity between DSSs and serum samples. Conclusion. DSS samples are useful for detecting anti-dengue IgG antibodies in the field.

  4. Changes in prevalence of, and risk factors for, lameness in random samples of English sheep flocks: 2004-2013.

    Science.gov (United States)

    Winter, Joanne R; Kaler, Jasmeet; Ferguson, Eamonn; KilBride, Amy L; Green, Laura E

    2015-11-01

    The aims of this study were to update the prevalence of lameness in sheep in England and identify novel risk factors. A total of 1260 sheep farmers responded to a postal survey. The survey captured detailed information on the period prevalence of lameness from May 2012-April 2013 and the prevalence and farmer naming of lesions attributable to interdigital dermatitis (ID), severe footrot (SFR), contagious ovine digital dermatitis (CODD) and shelly hoof (SH), management and treatment of lameness, and farm and flock details. The global mean period prevalence of lameness fell between 2004 and 2013 from 10.6% to 4.9% and the geometric mean period prevalence of lameness fell from 5.4% (95% CL: 4.7%-6.0%) to 3.5% (95% CI: 3.3%-3.7%). In 2013, more farmers were using vaccination and antibiotic treatment for ID and SFR and fewer farmers were using foot trimming as a routine or therapeutic treatment than in 2004. Two over-dispersed Poisson regression models were developed with the outcome the period prevalence of lameness, one investigated associations with farmer estimates of prevalence of the four foot lesions and one investigated associations with management practices to control and treat lameness and footrot. A prevalence of ID>10%, SFR>2.5% and CODD>2.5% were associated with a higher prevalence of lameness compared with those lesions being absent, however, the prevalence of SH was not associated with a change in risk of lameness. A key novel management risk associated with higher prevalence of lameness was the rate of feet bleeding/100 ewes trimmed/year. In addition, vaccination of ewes once per year and selecting breeding replacements from never-lame ewes were associated with a decreased risk of lameness. Other factors associated with a lower risk of lameness for the first time in a random sample of farmers and a full risk model were: recognising lameness in sheep at locomotion score 1 compared with higher scores, treatment of the first lame sheep in a group compared

  5. Appearance Investment and Everyday Interpersonal Functioning: An Experience Sampling Study

    Science.gov (United States)

    Forand, Nicholas R.; Gunthert, Kathleen C.; German, Ramaris E.; Wenze, Susan J.

    2010-01-01

    Several studies have shown that body satisfaction affects interpersonal functioning. However, few have studied the specific interpersonal correlates of another important body image dimension, appearance investment--that is, the importance a woman places on appearance. We used an experience sampling design with PDA (personal digital assistant)…

  6. Media Use and Source Trust among Muslims in Seven Countries: Results of a Large Random Sample Survey

    Directory of Open Access Journals (Sweden)

    Steven R. Corman

    2013-12-01

    Full Text Available Despite the perceived importance of media in the spread of and resistance against Islamist extremism, little is known about how Muslims use different kinds of media to get information about religious issues, and what sources they trust when doing so. This paper reports the results of a large, random sample survey among Muslims in seven countries Southeast Asia, West Africa and Western Europe, which helps fill this gap. Results show a diverse set of profiles of media use and source trust that differ by country, with overall low trust in mediated sources of information. Based on these findings, we conclude that mass media is still the most common source of religious information for Muslims, but that trust in mediated information is low overall. This suggests that media are probably best used to persuade opinion leaders, who will then carry anti-extremist messages through more personal means.

  7. Rationale, Design, Samples, and Baseline Sun Protection in a Randomized Trial on a Skin Cancer Prevention Intervention in Resort Environments

    Science.gov (United States)

    Buller, David B.; Andersen, Peter A.; Walkosz, Barbara J.; Scott, Michael D.; Beck, Larry; Cutter, Gary R.

    2016-01-01

    Introduction Exposure to solar ultraviolet radiation during recreation is a risk factor for skin cancer. A trial evaluating an intervention to promote advanced sun protection (sunscreen pre-application/reapplication; protective hats and clothing; use of shade) during vacations. Materials and Methods Adult visitors to hotels/resorts with outdoor recreation (i.e., vacationers) participated in a group-randomized pretest-posttest controlled quasi-experimental design in 2012–14. Hotels/resorts were pair-matched and randomly assigned to the intervention or untreated control group. Sun protection (e.g., clothing, hats, shade and sunscreen) was measured in cross-sectional samples by observation and a face-to-face intercept survey during two-day visits. Results Initially, 41 hotel/resorts (11%) participated but 4 dropped out before posttest. Hotel/resorts were diverse (employees=30 to 900; latitude=24o 78′ N to 50o 52′ N; elevation=2 ft. to 9,726 ft. above sea level), and had a variety of outdoor venues (beaches/pools, court/lawn games, golf courses, common areas, and chairlifts). At pretest, 4,347 vacationers were observed and 3,531 surveyed. More females were surveyed (61%) than observed (50%). Vacationers were mostly 35–60 years old, highly educated (college education = 68%) and non-Hispanic white (93%), with high-risk skin types (22%). Vacationers reported covering 60% of their skin with clothing. Also, 40% of vacationers used shade; 60% applied sunscreen; and 42% had been sunburned. Conclusions The trial faced challenges recruiting resorts but result show that the large, multi-state sample of vacationers were at high risk for solar UV exposure. PMID:26593781

  8. Sampling strategies to measure the prevalence of common recurrent infections in longitudinal studies

    Directory of Open Access Journals (Sweden)

    Luby Stephen P

    2010-08-01

    Full Text Available Abstract Background Measuring recurrent infections such as diarrhoea or respiratory infections in epidemiological studies is a methodological challenge. Problems in measuring the incidence of recurrent infections include the episode definition, recall error, and the logistics of close follow up. Longitudinal prevalence (LP, the proportion-of-time-ill estimated by repeated prevalence measurements, is an alternative measure to incidence of recurrent infections. In contrast to incidence which usually requires continuous sampling, LP can be measured at intervals. This study explored how many more participants are needed for infrequent sampling to achieve the same study power as frequent sampling. Methods We developed a set of four empirical simulation models representing low and high risk settings with short or long episode durations. The model was used to evaluate different sampling strategies with different assumptions on recall period and recall error. Results The model identified three major factors that influence sampling strategies: (1 the clustering of episodes in individuals; (2 the duration of episodes; (3 the positive correlation between an individual's disease incidence and episode duration. Intermittent sampling (e.g. 12 times per year often requires only a slightly larger sample size compared to continuous sampling, especially in cluster-randomized trials. The collection of period prevalence data can lead to highly biased effect estimates if the exposure variable is associated with episode duration. To maximize study power, recall periods of 3 to 7 days may be preferable over shorter periods, even if this leads to inaccuracy in the prevalence estimates. Conclusion Choosing the optimal approach to measure recurrent infections in epidemiological studies depends on the setting, the study objectives, study design and budget constraints. Sampling at intervals can contribute to making epidemiological studies and trials more efficient, valid

  9. Missing citations due to exact reference matching: Analysis of a random sample from WoS. Are publications from peripheral countries disadvantaged?

    Energy Technology Data Exchange (ETDEWEB)

    Donner, P.

    2016-07-01

    Citation counts of scientific research contributions are one fundamental data in scientometrics. Accuracy and completeness of citation links are therefore crucial data quality issues (Moed, 2005, Ch. 13). However, despite the known flaws of reference matching algorithms, usually no attempts are made to incorporate uncertainty about citation counts into indicators. This study is a step towards that goal. Particular attention is paid to the question whether publications from countries not using basic Latin script are differently affected by missed citations. The proprietary reference matching procedure of Web of Science (WoS) is based on (near) exact agreement of cited reference data (normalized during processing) to the target papers bibliographical data. Consequently, the procedure has near-optimal precision but incomplete recall - it is known to miss some slightly inaccurate reference links (Olensky, 2015). However, there has been no attempt so far to estimate the rate of missed citations by a principled method for a random sample. For this study a simple random sample of WoS source papers was drawn and it was attempted to find all reference strings of WoS indexed documents that refer to them, in particular inexact matches. The objective is to give a statistical estimate of the proportion of missed citations and to describe the relationship of the number of found citations to the number of missed citations, i.e. the conditional error distribution. The empirical error distribution is statistically analyzed and modelled. (Author)

  10. Acupuncture in alcoholism treatment: a randomized out-patient study.

    Science.gov (United States)

    Sapir-Weise, R; Berglund, M; Frank, A; Kristenson, H

    1999-01-01

    Seventy-two alcoholics were treated with acupuncture to the ear in a randomized single-blind controlled design over 10 weeks. Orthodox points and incorrect points 3-5 mm from orthodox points were used. No initial differences were found regarding social characteristics, the responses to the Swedish version of the Alcohol Use Inventory and the Three-dimensional Personality Questionnaire, indicating a successful randomization. There were non-significant tendencies towards gender differential response after acupuncture treatment (P = 0.07). There was no difference in the number of drinking days or level of craving between treatment and control patients. Among females, those in the treatment group reported reduction of anxiety after 1 month, more often than those in the control group (P < 0.05). Response to acupuncture was not related to personality or drinking pattern. Patients' experience of needle placement was similar in the study and control groups. The effects of acupuncture were less pronounced than those previously reported.

  11. WRAP Module 1 sampling strategy and waste characterization alternatives study

    Energy Technology Data Exchange (ETDEWEB)

    Bergeson, C.L.

    1994-09-30

    The Waste Receiving and Processing Module 1 Facility is designed to examine, process, certify, and ship drums and boxes of solid wastes that have a surface dose equivalent of less than 200 mrem/h. These wastes will include low-level and transuranic wastes that are retrievably stored in the 200 Area burial grounds and facilities in addition to newly generated wastes. Certification of retrievably stored wastes processing in WRAP 1 is required to meet the waste acceptance criteria for onsite treatment and disposal of low-level waste and mixed low-level waste and the Waste Isolation Pilot Plant Waste Acceptance Criteria for the disposal of TRU waste. In addition, these wastes will need to be certified for packaging in TRUPACT-II shipping containers. Characterization of the retrievably stored waste is needed to support the certification process. Characterization data will be obtained from historical records, process knowledge, nondestructive examination nondestructive assay, visual inspection of the waste, head-gas sampling, and analysis of samples taken from the waste containers. Sample characterization refers to the method or methods that are used to test waste samples for specific analytes. The focus of this study is the sample characterization needed to accurately identify the hazardous and radioactive constituents present in the retrieved wastes that will be processed in WRAP 1. In addition, some sampling and characterization will be required to support NDA calculations and to provide an over-check for the characterization of newly generated wastes. This study results in the baseline definition of WRAP 1 sampling and analysis requirements and identifies alternative methods to meet these requirements in an efficient and economical manner.

  12. Practical recommendations for population PK studies with sampling time errors.

    Science.gov (United States)

    Choi, Leena; Crainiceanu, Ciprian M; Caffo, Brian S

    2013-12-01

    Population pharmacokinetic (PK) data collected from routine clinical practice offers a rich source of valuable information. However, in observational population PK data, accurate time information for blood samples is often missing, resulting in measurement errors (ME) in the sampling time variable. The goal of this study was to investigate the effects on model parameters when a scheduled time is used instead of the actual blood sampling time, and to propose ME correction methods. Simulation studies were conducted based on two major factors: the curvature in PK profiles and the size of ME. As ME correction methods, transform both sides (TBS) models were developed with application of Box-Cox power transformation and Taylor expansion. The TBS models were compared to a conventional population PK model using simulations. The most important determinant of bias due to time ME was the degree of curvature (nonlinearity) in PK profiles; the smaller the curvature around sampling times, the smaller the associated bias. The second important determinant was the magnitude of ME; the larger the ME, the larger the bias. The proposed TBS models performed better than a conventional population PK modeling when curvature and ME were substantial. Time ME in sampling time can lead to bias on the parameter estimators. The following practical recommendations are provided: 1) when the curvature of PK profiles is small, conventional population PK modeling is robust to even large ME; and 2) when the curvature is moderate or large, the proposed methodology reduces bias in parameter estimates.

  13. Statistical inferences for data from studies conducted with an aggregated multivariate outcome-dependent sample design.

    Science.gov (United States)

    Lu, Tsui-Shan; Longnecker, Matthew P; Zhou, Haibo

    2017-03-15

    Outcome-dependent sampling (ODS) scheme is a cost-effective sampling scheme where one observes the exposure with a probability that depends on the outcome. The well-known such design is the case-control design for binary response, the case-cohort design for the failure time data, and the general ODS design for a continuous response. While substantial work has been carried out for the univariate response case, statistical inference and design for the ODS with multivariate cases remain under-developed. Motivated by the need in biological studies for taking the advantage of the available responses for subjects in a cluster, we propose a multivariate outcome-dependent sampling (multivariate-ODS) design that is based on a general selection of the continuous responses within a cluster. The proposed inference procedure for the multivariate-ODS design is semiparametric where all the underlying distributions of covariates are modeled nonparametrically using the empirical likelihood methods. We show that the proposed estimator is consistent and developed the asymptotically normality properties. Simulation studies show that the proposed estimator is more efficient than the estimator obtained using only the simple-random-sample portion of the multivariate-ODS or the estimator from a simple random sample with the same sample size. The multivariate-ODS design together with the proposed estimator provides an approach to further improve study efficiency for a given fixed study budget. We illustrate the proposed design and estimator with an analysis of association of polychlorinated biphenyl exposure to hearing loss in children born to the Collaborative Perinatal Study. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Hardy-Weinberg equilibrium testing of biological ascertainment for Mendelian randomization studies.

    Science.gov (United States)

    Rodriguez, Santiago; Gaunt, Tom R; Day, Ian N M

    2009-02-15

    Mendelian randomization (MR) permits causal inference between exposures and a disease. It can be compared with randomized controlled trials. Whereas in a randomized controlled trial the randomization occurs at entry into the trial, in MR the randomization occurs during gamete formation and conception. Several factors, including time since conception and sampling variation, are relevant to the interpretation of an MR test. Particularly important is consideration of the "missingness" of genotypes that can be originated by chance, genotyping errors, or clinical ascertainment. Testing for Hardy-Weinberg equilibrium (HWE) is a genetic approach that permits evaluation of missingness. In this paper, the authors demonstrate evidence of nonconformity with HWE in real data. They also perform simulations to characterize the sensitivity of HWE tests to missingness. Unresolved missingness could lead to a false rejection of causality in an MR investigation of trait-disease association. These results indicate that large-scale studies, very high quality genotyping data, and detailed knowledge of the life-course genetics of the alleles/genotypes studied will largely mitigate this risk. The authors also present a Web program (http://www.oege.org/software/hwe-mr-calc.shtml) for estimating possible missingness and an approach to evaluating missingness under different genetic models.

  15. Multimedia learning tools for teaching undergraduate ophthalmology: results of a randomized clinical study.

    Science.gov (United States)

    Steedman, Michael; Abouammoh, Marwan; Sharma, Sanjay

    2012-02-01

    To evaluate the effectiveness of a novel multimedia learning tool (MMLT) for teaching a method of approaching common ophthalmologic presentations. Randomized clinical study. 25 second-year medical students at Queen's University. We evaluated 2 MMLTs pertaining to common ophthalmologic presentations--acute visual loss and cataract--through the use of a randomized clinical study. Subjects were randomized either to watch a short-form video or to read a textbook excerpt for both cataract and acute visual loss. If randomized to one MMLT for the first module, the subject was allocated to the other modality for the second module. The main outcomes of interest were knowledge retention as measured by a short multiple-choice questionnaire, efficiency, and user preference. A trend was noted whereby subjects randomized to an MMLT had higher composite scores on multiple-choice questionnaires (mean score MMLT = 75.2% vs text = 67.5%; t test = 1.535; df = 22; p value = 0.139). Additionally, those who watched an MMLT spent 72% less time reviewing the education content (29 min vs 8 min; t test = 3.955, p value = 0.0003). Of the sample, 87% preferred the MMLT over the text. MMLTs can significantly reduce learning time without sacrificing knowledge retention in undergraduate students of ophthalmology. Copyright © 2012 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  16. Astronauts Armstrong and Aldrin study rock samples during field trip

    Science.gov (United States)

    1969-01-01

    Astronaut Neil Armstrong, commander of the Apollo 11 lunar landing mission, and Astronaut Edwin Aldrin, Lunar module pilot for Apollo 11, study rock samples during a geological field trip to the Quitman Mountains area near the Fort Quitman ruins in far west Texas.

  17. Genesis Solar Wind Collector Cleaning Assessment: 60366 Sample Case Study

    Science.gov (United States)

    Goreva, Y. S.; Gonzalez, C. P.; Kuhlman, K. R.; Burnett, D. S.; Woolum, D.; Jurewicz, A. J.; Allton, J. H.; Rodriguez, M. C.; Burkett, P. J.

    2014-01-01

    In order to recognize, localize, characterize and remove particle and thin film surface contamination, a small subset of Genesis mission collector fragments are being subjected to extensive study via various techniques [1-5]. Here we present preliminary results for sample 60336, a Czochralski silicon (Si-CZ) based wafer from the bulk array (B/C).

  18. Sampling challenges in a study examining refugee resettlement

    Directory of Open Access Journals (Sweden)

    Thompson Sandra C

    2011-03-01

    Full Text Available Abstract Background As almost half of all refugees currently under United Nations protection are from Afghanistan or Iraq and significant numbers have already been resettled outside the region of origin, it is likely that future research will examine their resettlement needs. A number of methodological challenges confront researchers working with culturally and linguistically diverse groups; however, few detailed articles are available to inform other studies. The aim of this paper is to outline challenges with sampling and recruitment of socially invisible refugee groups, describing the method adopted for a mixed methods exploratory study assessing mental health, subjective wellbeing and resettlement perspectives of Afghan and Kurdish refugees living in New Zealand and Australia. Sampling strategies used in previous studies with similar refugee groups were considered before determining the approach to recruitment Methods A snowball approach was adopted for the study, with multiple entry points into the communities being used to choose as wide a range of people as possible to provide further contacts and reduce selection bias. Census data was used to assess the representativeness of the sample. Results A sample of 193 former refugee participants was recruited in Christchurch (n = 98 and Perth (n = 95, 47% were of Afghan and 53% Kurdish ethnicity. A good gender balance (males 52%, females 48% was achieved overall, mainly as a result of the sampling method used. Differences in the demographic composition of groups in each location were observed, especially in relation to the length of time spent in a refugee situation and time since arrival, reflecting variations in national humanitarian quota intakes. Although some measures were problematic, Census data comparison to assess reasonable representativeness of the study sample was generally reassuring. Conclusions Snowball sampling, with multiple initiation points to reduce selection bias, was

  19. A study into the distribution of gunshot residue particles in the random population.

    Science.gov (United States)

    Lucas, Nick; Brown, Hayley; Cook, Michael; Redman, Kahlee; Condon, Tanith; Wrobel, Harald; Kirkbride, K Paul; Kobus, Hilton

    2016-05-01

    When considering the impact and value of gunshot residues (GSR) as forensic trace evidence, the likelihood of a suspect producing a positive GSR analysis result without having direct exposure to a firearm is a major consideration. Therefore, the random prevalence of GSR and 'GSR-like' residues in the wider population is a highly pertinent question when considering the probative value of such evidence. The random prevalence of GSR in two Australian jurisdictions - Victoria and South Australia - was assessed through the collection and analysis of GSR samples obtained from randomly selected members of the public. Volunteers were asked to declare any firearms use, hobbies or potential firearms exposure before allowing their hands to be sampled using aluminium GSR sample stubs coated in adhesive tape. A total of 289 samples, 120 from Victoria and 169 from South Australia were collected and analysed using scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDS). Across all samples, three 'characteristic' three-component Pb/Ba/Sb particles were detected from a single subject in South Australia, corresponding to an overall prevalence of 0.3%. Two-component 'consistent' particles were more prevalent, with Pb/Sb particles being the most frequently occurring, in 8% of samples, and in South Australia only. A number of samples, approximately 7%, showed populations of single element particles of Pb, Ba and Sb, which has the potential to generate a false positive for GSR if using a bulk analysis technique such as NAA or AAS. The prevalence of GSR or 'GSR like' particles in this study matches closely with similar surveys conducted in other jurisdictions. Such surveys are a useful foundation for the creation of a probabilistic method for the assessment of GSR evidence. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Study of β-NMR for Liquid Biological Samples

    CERN Document Server

    Beattie, Caitlin

    2017-01-01

    β-NMR is an exotic form of NMR spectroscopy that allows for the characterization of matter based on the anisotropic β-decay of radioactive probe nuclei. This has been shown to be an effective spectroscopic technique for many different compounds, but its use for liquid biological samples is relatively unexplored. The work at the VITO line of ISOLDE seeks to employ this technique to study such samples. Currently, preparations are being made for an experiment to characterize DNA G-quadruplexes and their interactions with stabilizing cations. More specifically, the work in which I engaged as a summer student focused on the experiment’s liquid handling system and the stability of the relevant biological samples under vacuum.

  1. Sample size considerations for clinical research studies in nuclear cardiology.

    Science.gov (United States)

    Chiuzan, Cody; West, Erin A; Duong, Jimmy; Cheung, Ken Y K; Einstein, Andrew J

    2015-12-01

    Sample size calculation is an important element of research design that investigators need to consider in the planning stage of the study. Funding agencies and research review panels request a power analysis, for example, to determine the minimum number of subjects needed for an experiment to be informative. Calculating the right sample size is crucial to gaining accurate information and ensures that research resources are used efficiently and ethically. The simple question "How many subjects do I need?" does not always have a simple answer. Before calculating the sample size requirements, a researcher must address several aspects, such as purpose of the research (descriptive or comparative), type of samples (one or more groups), and data being collected (continuous or categorical). In this article, we describe some of the most frequent methods for calculating the sample size with examples from nuclear cardiology research, including for t tests, analysis of variance (ANOVA), non-parametric tests, correlation, Chi-squared tests, and survival analysis. For the ease of implementation, several examples are also illustrated via user-friendly free statistical software.

  2. Stages of change of the readiness to quit smoking among a random sample of minority Arab male smokers in Israel.

    Science.gov (United States)

    Daoud, Nihaya; Hayek, Samah; Sheikh Muhammad, Ahmad; Abu-Saad, Kathleen; Osman, Amira; Thrasher, James F; Kalter-Leibovici, Ofra

    2015-07-16

    Despite advanced smoking prevention and cessation policies in many countries, the prevalence of cigarette smoking among indigenous and some ethnic minorities continues to be high. This study examined the stages of change (SOC) of the readiness to quit smoking among Arab men in Israel shortly after new regulations of free-of-charge smoking cessation workshops and subsidized medications were introduced through primary health care clinics. We conducted a countrywide study in Israel between 2012-2013. Participants, 735 current smokers; 18-64 years old; were recruited from a stratified random sample and interviewed face-to-face using a structured questionnaire in Arabic. We used ordered regression to examine the contribution of socio-economic position (SEP), health status, psychosocial attributes, smoking-related factors, and physician advice to the SOC of the readiness to quit smoking (pre-contemplation, contemplation and preparation). Of the current smokers, 61.8% were at the pre-contemplation stage, 23.8% were at the contemplation stage, and only 14.4% were at the preparation stage. In the multinomial analysis, factors significantly (P stage compared to pre-contemplation stage included [odds ratio (OR), 95% confidence interval (CI)]: chronic morbidity [0.52, (0.31-0.88)], social support [1.35, (1.07-1.70)], duration of smoking for 11-21 years [1.94, (1.07-3.50)], three or more previous attempts to quit [2.27, (1.26-4.01)], knowledge about smoking hazards [1.75, (1.29-2.35)], positive attitudes toward smoking prevention [1.44, (1.14-1.82)], and physician advice to quit smoking [1.88, (1.19-2.97)]. The factors significantly (P stage compared to pre-contemplation stage were [OR, (95 % CI)]: chronic morbidity [0.36, (0.20-0.67)], anxiety [1.07, (1.01-1.13)], social support [1.34, (1.01-1.78)], duration of smoking 5 years or less [2.93, (1.14-7.52)], three or more previous attempts to quit [3.16, (1.60-6.26)], knowledge about smoking hazards [1.57, (1.10-2.21)], and

  3. Two to five repeated measurements per patient reduced the required sample size considerably in a randomized clinical trial for patients with inflammatory rheumatic diseases

    Directory of Open Access Journals (Sweden)

    Smedslund Geir

    2013-02-01

    Full Text Available Abstract Background Patient reported outcomes are accepted as important outcome measures in rheumatology. The fluctuating symptoms in patients with rheumatic diseases have serious implications for sample size in clinical trials. We estimated the effects of measuring the outcome 1-5 times on the sample size required in a two-armed trial. Findings In a randomized controlled trial that evaluated the effects of a mindfulness-based group intervention for patients with inflammatory arthritis (n=71, the outcome variables Numerical Rating Scales (NRS (pain, fatigue, disease activity, self-care ability, and emotional wellbeing and General Health Questionnaire (GHQ-20 were measured five times before and after the intervention. For each variable we calculated the necessary sample sizes for obtaining 80% power (α=.05 for one up to five measurements. Two, three, and four measures reduced the required sample sizes by 15%, 21%, and 24%, respectively. With three (and five measures, the required sample size per group was reduced from 56 to 39 (32 for the GHQ-20, from 71 to 60 (55 for pain, 96 to 71 (73 for fatigue, 57 to 51 (48 for disease activity, 59 to 44 (45 for self-care, and 47 to 37 (33 for emotional wellbeing. Conclusions Measuring the outcomes five times rather than once reduced the necessary sample size by an average of 27%. When planning a study, researchers should carefully compare the advantages and disadvantages of increasing sample size versus employing three to five repeated measurements in order to obtain the required statistical power.

  4. Prevalence and predictors of Video Game Addiction: A study based on a national sample of Gamers.

    OpenAIRE

    Wittek, CT; Finserås, TR; Pallesen, S; Mentzoni, RA; Hanss, D; Griffiths, MD; Molde, H

    2015-01-01

    Video gaming has become a popular leisure activity in many parts of the world, and an increasing number of empirical studies examine the small minority that appears to develop problems as a result of excessive gaming. This study investigated prevalence rates and predictors of video game addiction in a sample of gamers, randomly selected from the National Population Registry of Norway (N?=?3389). Results showed there were 1.4 % addicted gamers, 7.3 % problem gamers, 3.9 % engaged gamers, and 8...

  5. Controlled samples for silicon defect and impurity studies

    Energy Technology Data Exchange (ETDEWEB)

    Ciszek, T.F. [National Renewable Energy Lab., Golden, CO (United States)

    1995-08-01

    Because of the diverse defects and impurities that are present in any given sample of silicon material, it can be extremely difficult to conduct a controlled experiment to study the influence of any particular defect or impurity on photovoltaic properties such as minority charge carrier lifetime {tau} or solar cell efficiency q. For example, the influence of iron may be different if boron is present, or the influence of silicon self interstitial clusters may be different if oxygen is present. It thus becomes important to conduct such studies on controlled samples where the influence of secondary effects is minimized. At NREL, over the past several years, we have focused on using the high-purity float-zone (FZ) growth method to obtain controlled samples. Because the silicon melt is not in contact with a container, and no heated components are in the growth region, very high purities and low defect levels can be achieved in baseline material. The baseline can be controllably perturbed by introduction of specific defects or impurities. The chart shown below lists some of the types of defect and impurity. combinations that can be studied in this way. The boxes marked with an {open_quotes}x{close_quotes} represent combinations we have studied to some extent.

  6. Microanalysis study of archaeological mural samples containing Maya blue pigment

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez del Rio, M. [ESRF, BP220, F-38043 Grenoble (France)]. E-mail: srio@esrf.fr; Martinetto, P. [Laboratoire de Cristallographie, CNRS, BP166 F-30842 Grenoble (France); Somogyi, A. [ESRF, BP220, F-38043 Grenoble (France); Reyes-Valerio, C. [INAH, Mexico DF (Mexico); Dooryhee, E. [Laboratoire de Cristallographie, CNRS, BP166 F-30842 Grenoble (France); Peltier, N. [Laboratoire de Cristallographie, CNRS, BP166 F-30842 Grenoble (France); Alianelli, L. [INFM-OGG c/o ESRF, BP220, F-38043 Grenoble Cedex (France); Moignard, B. [C2RMF, 6 Rue des Pyramides, F-75041 Paris Cedex 01 (France); Pichon, L. [C2RMF, 6 Rue des Pyramides, F-75041 Paris Cedex 01 (France); Calligaro, T. [C2RMF, 6 Rue des Pyramides, F-75041 Paris Cedex 01 (France); Dran, J.-C. [C2RMF, 6 Rue des Pyramides, F-75041 Paris Cedex 01 (France)

    2004-10-08

    Elemental analysis by X-ray fluorescence and particle induced X-ray emission is applied to the study of several Mesoamerican mural samples containing blue pigments. The most characteristic blue pigment is Maya blue, a very stable organo-clay complex original from Maya culture and widely used in murals, pottery and sculptures in a vast region of Mesoamerica during the pre-hispanic time (from VIII century) and during the colonization until 1580. The mural samples come from six different archaeological sites (four pre-hispanic and two from XVI century colonial convents). The correlation between the presence of some elements and the pigment colour is discussed. From the comparative study of the elemental concentration, some conclusions are drawn on the nature of the pigments and the technology used.

  7. A Randomized, Placebo-Controlled, Double-Blind Efficacy Study of Nefiracetam to Treat Poststroke Apathy.

    Science.gov (United States)

    Starkstein, Sergio E; Brockman, Simone; Hatch, Katherine K; Bruce, David G; Almeida, Osvaldo P; Davis, Wendy A; Robinson, Robert G

    2016-05-01

    To evaluate the efficacy of treatment with nefiracetam compared to placebo in poststroke apathy. A parallel group, randomized, placebo-controlled, double-blind two-center trial in patients with recent stroke and apathy was conducted in 2 tertiary teaching hospitals in Perth, Western Australia, between March 2010 and October 2014. Consenting patients hospitalized with stroke were screened for participation at the time of hospitalization and, if diagnosed with apathy 8-36 weeks later, they were randomized to 12 weeks of 900 mg/day nefiracetam or placebo. The primary efficacy parameter was change in apathy at 12 weeks defined by the 14-item Apathy Scale (AS). Of 2514 patients screened, only 377 (15%) were eligible for the study after the first screening, 233 declined further participation, and 144 were assessed for apathy at 8-36 weeks post stroke to confirm eligibility. Twenty patients out of 106 with a complete psychiatric assessment had apathy (19%). Of this sample, 13 patients were randomized. Overall, the AS score decreased by a mean of 7.0 points (95% CI = -14.6 to .6), but there was no significant between-group difference at week 12 (mean paired t-tests, P > .14). Treatment with nefiracetam did not prove to be more efficacious than placebo in ameliorating apathy in stroke. The main limitation was the very small sample randomized, highlighting the limitations of conducting drug trials for behavioral problems among stroke patients. Pharmacological studies of apathy in stroke will require a large multicenter study and a massive sample of patients. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  8. Genetically predicted body mass index and Alzheimer's disease-related phenotypes in three large samples: Mendelian randomization analyses.

    Science.gov (United States)

    Mukherjee, Shubhabrata; Walter, Stefan; Kauwe, John S K; Saykin, Andrew J; Bennett, David A; Larson, Eric B; Crane, Paul K; Glymour, M Maria

    2015-12-01

    Observational research shows that higher body mass index (BMI) increases Alzheimer's disease (AD) risk, but it is unclear whether this association is causal. We applied genetic variants that predict BMI in Mendelian randomization analyses, an approach that is not biased by reverse causation or confounding, to evaluate whether higher BMI increases AD risk. We evaluated individual-level data from the AD Genetics Consortium (ADGC: 10,079 AD cases and 9613 controls), the Health and Retirement Study (HRS: 8403 participants with algorithm-predicted dementia status), and published associations from the Genetic and Environmental Risk for AD consortium (GERAD1: 3177 AD cases and 7277 controls). No evidence from individual single-nucleotide polymorphisms or polygenic scores indicated BMI increased AD risk. Mendelian randomization effect estimates per BMI point (95% confidence intervals) were as follows: ADGC, odds ratio (OR) = 0.95 (0.90-1.01); HRS, OR = 1.00 (0.75-1.32); GERAD1, OR = 0.96 (0.87-1.07). One subscore (cellular processes not otherwise specified) unexpectedly predicted lower AD risk. Copyright © 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

  9. Family constellation seminars improve psychological functioning in a general population sample: results of a randomized controlled trial.

    Science.gov (United States)

    Weinhold, Jan; Hunger, Christina; Bornhäuser, Annette; Link, Leoni; Rochon, Justine; Wild, Beate; Schweitzer, Jochen

    2013-10-01

    The study examined the efficacy of nonrecurring family constellation seminars on psychological health. We conducted a monocentric, single-blind, stratified, and balanced randomized controlled trial (RCT). After choosing their roles for participating in a family constellation seminar as either active participant (AP) or observing participant (OP), 208 adults (M = 48 years, SD = 10; 79% women) from the general population were randomly allocated to the intervention group (IG; 3-day family constellation seminar; 64 AP, 40 OP) or a wait-list control group (WLG; 64 AP, 40 OP). It was predicted that family constellation seminars would improve psychological functioning (Outcome Questionnaire OQ-45.2) at 2-week and 4-month follow-ups. In addition, we assessed the impact of family constellation seminars on psychological distress and motivational incongruence. The IG showed significantly improved psychological functioning (d = 0.45 at 2-week follow-up, p = .003; d = 0.46 at 4-month follow-up, p = .003). Results were confirmed for psychological distress and motivational incongruence. No adverse events were reported. This RCT provides evidence for the efficacy of family constellation in a nonclinical population. The implications of the findings are discussed.

  10. Multiple-image authentication with a cascaded multilevel architecture based on amplitude field random sampling and phase information multiplexing.

    Science.gov (United States)

    Fan, Desheng; Meng, Xiangfeng; Wang, Yurong; Yang, Xiulun; Pan, Xuemei; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

    2015-04-10

    A multiple-image authentication method with a cascaded multilevel architecture in the Fresnel domain is proposed, in which a synthetic encoded complex amplitude is first fabricated, and its real amplitude component is generated by iterative amplitude encoding, random sampling, and space multiplexing for the low-level certification images, while the phase component of the synthetic encoded complex amplitude is constructed by iterative phase information encoding and multiplexing for the high-level certification images. Then the synthetic encoded complex amplitude is iteratively encoded into two phase-type ciphertexts located in two different transform planes. During high-level authentication, when the two phase-type ciphertexts and the high-level decryption key are presented to the system and then the Fresnel transform is carried out, a meaningful image with good quality and a high correlation coefficient with the original certification image can be recovered in the output plane. Similar to the procedure of high-level authentication, in the case of low-level authentication with the aid of a low-level decryption key, no significant or meaningful information is retrieved, but it can result in a remarkable peak output in the nonlinear correlation coefficient of the output image and the corresponding original certification image. Therefore, the method realizes different levels of accessibility to the original certification image for different authority levels with the same cascaded multilevel architecture.

  11. Empirical evidence of study design biases in randomized trials

    DEFF Research Database (Denmark)

    Page, Matthew J.; Higgins, Julian P. T.; Clayton, Gemma

    2016-01-01

    search September 2012), and searched Ovid MEDLINE and Ovid EMBASE for studies indexed from Jan 2012-May 2015. Data were extracted by one author and verified by another. We combined estimates of average bias (e.g. ratio of odds ratios (ROR) or difference in standardised mean differences (dSMD)) in meta......-analyses using the random-effects model. Analyses were stratified by type of outcome ("mortality" versus "other objective" versus "subjective"). Direction of effect was standardised so that ROR ...) characteristic. Results: We included 24 studies. The available evidence suggests that intervention effect estimates may be exaggerated in trials with inadequate/unclear (versus adequate) sequence generation (ROR 0.93, 95% CI 0.86 to 0.99; 7 studies) and allocation concealment (ROR 0.90, 95% CI 0.84 to 0.97; 7...

  12. Automatic sampling for unbiased and efficient stereological estimation using the proportionator in biological studies

    DEFF Research Database (Denmark)

    Gardi, Jonathan Eyal; Nyengaard, Jens Randel; Gundersen, Hans Jørgen Gottlieb

    2008-01-01

    and feature detection is clearly biased, the estimator is strictly unbiased. The proportionator is compared to the commonly applied sampling technique (systematic uniform random sampling in 2D space or so-called meander sampling) using three biological examples: estimating total number of granule cells in rat...

  13. Empirically simulated study to compare and validate sampling methods used in aerial surveys of wildlife populations

    NARCIS (Netherlands)

    Khaemba, W.M.; Stein, A.; Rasch, D.; Leeuw, de J.; Georgiadis, N.

    2001-01-01

    This paper compares the distribution, sampling and estimation of abundance for two animal species in an African ecosystem by means of an intensive simulation of the sampling process under a geographical information system (GIS) environment. It focuses on systematic and random sampling designs,

  14. Alcohol consumption and cognitive performance: a Mendelian randomization study.

    Science.gov (United States)

    Kumari, Meena; Holmes, Michael V; Dale, Caroline E; Hubacek, Jaroslav A; Palmer, Tom M; Pikhart, Hynek; Peasey, Anne; Britton, Annie; Horvat, Pia; Kubinova, Ruzena; Malyutina, Sofia; Pajak, Andrzej; Tamosiunas, Abdonas; Shankar, Aparna; Singh-Manoux, Archana; Voevoda, Mikhail; Kivimaki, Mika; Hingorani, Aroon D; Marmot, Michael G; Casas, Juan P; Bobak, Martin

    2014-09-01

    To use Mendelian randomization to assess whether alcohol intake was causally associated with cognitive function. Mendelian randomization using a genetic variant related to alcohol intake (ADH1B rs1229984) was used to obtain unbiased estimates of the association between alcohol intake and cognitive performance. Europe. More than 34 000 adults. Any versus no alcohol intake and units of intake in the previous week was measured by questionnaire. Cognitive function was assessed in terms of immediate and delayed word recall, verbal fluency and processing speed. Having consumed any versus no alcohol was associated with higher scores by 0.17 standard deviations (SD) [95% confidence interval (CI) = 0.15, 0.20] for immediate recall, 0.17 SD (95% CI = 0.14, 0.19) for delayed recall, 0.17 SD (95% CI = 0.14, 0.19) for verbal fluency and 0.12 SD (95% CI = 0.09, 0.15) for processing speed. The minor allele of rs1229984 was associated with reduced odds of consuming any alcohol (odds ratio = 0.87; 95% CI = 0.80, 0.95; P = 0.001; R(2)  = 0.1%; F-statistic = 47). In Mendelian randomization analysis, the minor allele was not associated with any cognitive test score, and instrumental variable analysis suggested no causal association between alcohol consumption and cognition: -0.74 SD (95% CI = -1.88, 0.41) for immediate recall, -1.09 SD (95% CI = -2.38, 0.21) for delayed recall, -0.63 SD (95% CI = -1.78, 0.53) for verbal fluency and -0.16 SD (95% CI = -1.29, 0.97) for processing speed. The Mendelian randomization analysis did not provide strong evidence of a causal association between alcohol consumption and cognitive ability. © 2014 The Authors. Addiction published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.

  15. TRU Waste Sampling Program: Volume II. Gas generation studies

    Energy Technology Data Exchange (ETDEWEB)

    Clements, T.L. Jr.; Kudera, D.E.

    1985-09-01

    Volume II of the TRU Waste Sampling Program report contains the data generated from evaluating the adequacy of venting/filtering devices for maintaining safe hydrogen levels in plutonium contaminated waste drums. Additional studies reported in this volume include gas generation rates, selected waste form monitoring, and evaluation of hydrogen migration from sealed 90-mil rigid polyethylene drum liners containing /sup 238/Pu-contaminated wastes. All wastes used in the studies were newly-generated, and the waste drums were under controlled, experimental conditions. Studies using /sup 239/Pu-contaminated wastes were conducted at the Rocky Flats Plant. Studies using /sup 238/Pu-contaminated wastes were conducted at the Los Alamos National Laboratory.

  16. [Acupuncture and moxibustion for peripheral facial palsy at different stages: multi-central large-sample randomized controlled trial].

    Science.gov (United States)

    Li, Ying; Li, Yan; Liu, Li-an; Zhao, Ling; Hu, Ka-ming; Wu, Xi; Chen, Xiao-qin; Li, Gui-ping; Mang, Ling-ling; Qi, Qi-hua

    2011-04-01

    To explore the best intervention time of acupuncture and moxibustion for peripheral facial palsy (Bell's palsy) and the clinical advantage program of selective treatment with acupuncture and moxibustion. Multi-central large-sample randomized controlled trial was carried out. Nine hundreds cases of Bell's palsy were randomized into 5 treatment groups, named selective filiform needle group (group A), selective acupuncture + moxibustion group (group B), selective acupuncture + electroacupuncture (group C), selective acupuncture + line-up needling on muscle region of meridian group (group D) and non-selective filiform needle group (group E). Four sessions of treatment were required in each group. Separately, during the enrollment, after 4 sessions of treatment, in 1 month and 3 months of follow-up after treatment, House-Brackmann Scale, Facial Disability Index Scale and Degree of Facial Nerve Paralysis (NFNP) were adopted for efficacy assessment. And the efficacy systematic analysis was provided in view of the intervention time and nerve localization of disease separately. The curative rates of intervention in acute stage and resting stage were 50.1% (223/445) and 52.1% (162/311), which were superior to recovery stage (25.9%, 35/135) separately. There were no statistical significant differences in efficacy in comparison among 5 treatment programs at the same stage (all P > 0.05). The efficacy of intervention of group A and group E in acute stage was superior to that in recovery stage (both P < 0.01). The difference was significant statistically between the efficacy on the localization above chorda tympani nerve and that on the localization below the nerve in group D (P < 0.01). The efficacy on the localization below chorda tympani nerve was superior to the localization above the nerve. The best intervention time for the treatment of Bell's palsy is in acute stage and resting stage, meaning 1 to 3 weeks after occurrence. All of the 5 treatment programs are advantageous

  17. Why choose Random Forest to predict rare species distribution with few samples in large undersampled areas? Three Asian crane species models provide supporting evidence

    Directory of Open Access Journals (Sweden)

    Chunrong Mi

    2017-01-01

    Full Text Available Species distribution models (SDMs have become an essential tool in ecology, biogeography, evolution and, more recently, in conservation biology. How to generalize species distributions in large undersampled areas, especially with few samples, is a fundamental issue of SDMs. In order to explore this issue, we used the best available presence records for the Hooded Crane (Grus monacha, n = 33, White-naped Crane (Grus vipio, n = 40, and Black-necked Crane (Grus nigricollis, n = 75 in China as three case studies, employing four powerful and commonly used machine learning algorithms to map the breeding distributions of the three species: TreeNet (Stochastic Gradient Boosting, Boosted Regression Tree Model, Random Forest, CART (Classification and Regression Tree and Maxent (Maximum Entropy Models. In addition, we developed an ensemble forecast by averaging predicted probability of the above four models results. Commonly used model performance metrics (Area under ROC (AUC and true skill statistic (TSS were employed to evaluate model accuracy. The latest satellite tracking data and compiled literature data were used as two independent testing datasets to confront model predictions. We found Random Forest demonstrated the best performance for the most assessment method, provided a better model fit to the testing data, and achieved better species range maps for each crane species in undersampled areas. Random Forest has been generally available for more than 20 years and has been known to perform extremely well in ecological predictions. However, while increasingly on the rise, its potential is still widely underused in conservation, (spatial ecological applications and for inference. Our results show that it informs ecological and biogeographical theories as well as being suitable for conservation applications, specifically when the study area is undersampled. This method helps to save model-selection time and effort, and allows robust and rapid

  18. Cognitive training in Alzheimer's disease: a controlled randomized study.

    Science.gov (United States)

    Giovagnoli, A R; Manfredi, V; Parente, A; Schifano, L; Oliveri, S; Avanzini, G

    2017-08-01

    This controlled randomized single-blind study evaluated the effects of cognitive training (CT), compared to active music therapy (AMT) and neuroeducation (NE), on initiative in patients with mild to moderate Alzheimer's disease (AD). Secondarily, we explored the effects of CT on episodic memory, mood, and social relationships. Thirty-nine AD patients were randomly assigned to CT, AMT, or NE. Each treatment lasted 3 months. Before, at the end, and 3 months after treatment, neuropsychological tests and self-rated scales assessed initiative, episodic memory, depression, anxiety, and social relationships. At the end of the CT, initiative significantly improved, whereas, at the end of AMT and NE, it was unchanged. Episodic memory showed no changes at the end of CT or AMT and a worsening after NE. The rates of the patients with clinically significant improvement of initiative were greater after CT (about 62%) than after AMT (about 8%) or NE (none). At the 3-month follow-up, initiative and episodic memory declined in all patients. Mood and social relationships improved in the three groups, with greater changes after AMT or NE. In patients with mild to moderate AD, CT can improve initiative and stabilize memory, while the non-cognitive treatments can ameliorate the psychosocial aspects. The combining of CT and non-cognitive treatments may have useful clinical implications.

  19. Early rehabilitation of cancer patients - a randomized controlled intervention study.

    Science.gov (United States)

    Arving, Cecilia; Thormodsen, Inger; Brekke, Guri; Mella, Olav; Berntsen, Sveinung; Nordin, Karin

    2013-01-07

    Faced with a life-threatening illness, such as cancer, many patients develop stress symptoms, i.e. avoidance behaviour, intrusive thoughts and worry. Stress management interventions have proven to be effective; however, they are mostly performed in group settings and it is commonly breast cancer patients who are studied. We hereby present the design of a randomized controlled trial (RCT) evaluating the effectiveness and cost-effectiveness of an individual stress-management intervention with a stepped-care approach in several cancer diagnoses. Patients (≥ 18 years) with a recent diagnosis of breast cancer, colorectal cancer, lymphoma, prostate cancer or testicle cancer and scheduled for adjuvant/curative oncology treatment, will consecutively be included in the study. In this prospective longitudinal intervention study with a stepped-care approach, patients will be randomized to control, treatment as usual, or an individual stress-management intervention in two steps. The first step is a low-intensity stress-management intervention, given to all patients randomized to intervention. Patients who continue to report stress symptoms after the first step will thereafter be given more intensive treatment at the second step of the programme. In the intervention patients will also be motivated to be physically active. Avoidance and intrusion are the primary outcomes. According to the power analyses, 300 patients are planned to be included in the study and will be followed for two years. Other outcomes are physical activity level, sleep duration and quality recorded objectively, and anxiety, depression, quality of life, fatigue, stress in daily living, and patient satisfaction assessed using valid and standardized psychometric tested questionnaires. Utilization of hospital services will be derived from the computerized patient administration systems used by the hospital. The cost-effectiveness of the intervention will be evaluated through a cost-utility analysis. This RCT

  20. [Identification and sampling of people with migration background for epidemiological studies in Germany].

    Science.gov (United States)

    Reiss, K; Makarova, N; Spallek, J; Zeeb, H; Razum, O

    2013-06-01

    In 2009, 19.6% of the population of Germany either had migrated themselves or were the offspring of people with migration experience. Migrants differ from the autochthonous German population in terms of health status, health awareness and health behaviour. To further investigate the health situation of migrants in Germany, epidemiological studies are needed. Such studies can employ existing databases which provide detailed information on migration status. Otherwise, onomastic or toponomastic procedures can be applied to identify people with migration background. If migrants have to be recruited into an epidemiological study, this can be done register-based (e. g., data from registration offices or telephone lists), based on residential location (random-route or random-walk procedure), via snowball sampling (e. g., through key persons) or via settings (e. g., school entry examination). An oversampling of people with migration background is not sufficient to avoid systematic bias in the sample due to non-participation. Additional measures have to be taken to increase access and raise participation rates. Personal contacting, multilingual instruments, multilingual interviewers and extensive public relations increase access and willingness to participate. Empirical evidence on 'successful' recruitment strategies for studies with migrants is still lacking in epidemiology and health sciences in Germany. The choice of the recruitment strategy as well as the measures to raise accessibility and willingness to participate depend on the available resources, the research question and the specific migrant target group. © Georg Thieme Verlag KG Stuttgart · New York.

  1. Salivary gland tumours in a Mexican sample. A retrospective study.

    Science.gov (United States)

    Ledesma-Montes, C; Garces-Ortiz, M

    2002-01-01

    Salivary gland tumours are an important part of the Oral and Maxillofacial Pathology, unfortunately, only few studies on these tumours have been done in Latin-American population. The aim of this study was to compare demographic data on salivary gland tumours in a Mexican sample with those previously published from Latin American and non-Latin American countries. All cases of salivary gland tumours or lesions diagnosed in our service were reviewed. Of the reviewed cases,67 were confirmed as salivary gland tumours. Out of these 64.2% were benign neoplasms, 35.8% were malignant and a slight female predominance (56.7%) was found. The most common location was palate followed by lips and floor of the mouth. Mean age for benign tumours was 40.6 years with female predominance (60.5%). Mean age for malignant tumours was 41 years and female predominance was found again. Palate followed by retromolar area were the usual locations. Pleomorphic adenoma (58.2%), mucoepidermoid carcinoma (17.9%) and adenoid cystic carcinoma (11.9%) were the more frequent neoplasms. All retromolar cases were malignant and all submandibular gland tumours were benign. We found a high proportion of salivary gland neoplasms in children. Our results showed that differences of the studied tumours among our sample and previously reported series exist. These differences can be related to race and geographical location.

  2. Cystatin C and Cardiovascular Disease: A Mendelian Randomization Study.

    Science.gov (United States)

    van der Laan, Sander W; Fall, Tove; Soumaré, Aicha; Teumer, Alexander; Sedaghat, Sanaz; Baumert, Jens; Zabaneh, Delilah; van Setten, Jessica; Isgum, Ivana; Galesloot, Tessel E; Arpegård, Johannes; Amouyel, Philippe; Trompet, Stella; Waldenberger, Melanie; Dörr, Marcus; Magnusson, Patrik K; Giedraitis, Vilmantas; Larsson, Anders; Morris, Andrew P; Felix, Janine F; Morrison, Alanna C; Franceschini, Nora; Bis, Joshua C; Kavousi, Maryam; O'Donnell, Christopher; Drenos, Fotios; Tragante, Vinicius; Munroe, Patricia B; Malik, Rainer; Dichgans, Martin; Worrall, Bradford B; Erdmann, Jeanette; Nelson, Christopher P; Samani, Nilesh J; Schunkert, Heribert; Marchini, Jonathan; Patel, Riyaz S; Hingorani, Aroon D; Lind, Lars; Pedersen, Nancy L; de Graaf, Jacqueline; Kiemeney, Lambertus A L M; Baumeister, Sebastian E; Franco, Oscar H; Hofman, Albert; Uitterlinden, André G; Koenig, Wolfgang; Meisinger, Christa; Peters, Annette; Thorand, Barbara; Jukema, J Wouter; Eriksen, Bjørn Odvar; Toft, Ingrid; Wilsgaard, Tom; Onland-Moret, N Charlotte; van der Schouw, Yvonne T; Debette, Stéphanie; Kumari, Meena; Svensson, Per; van der Harst, Pim; Kivimaki, Mika; Keating, Brendan J; Sattar, Naveed; Dehghan, Abbas; Reiner, Alex P; Ingelsson, Erik; den Ruijter, Hester M; de Bakker, Paul I W; Pasterkamp, Gerard; Ärnlöv, Johan; Holmes, Michael V; Asselbergs, Folkert W

    2016-08-30

    Epidemiological studies show that high circulating cystatin C is associated with risk of cardiovascular disease (CVD), independent of creatinine-based renal function measurements. It is unclear whether this relationship is causal, arises from residual confounding, and/or is a consequence of reverse causation. The aim of this study was to use Mendelian randomization to investigate whether cystatin C is causally related to CVD in the general population. We incorporated participant data from 16 prospective cohorts (n = 76,481) with 37,126 measures of cystatin C and added genetic data from 43 studies (n = 252,216) with 63,292 CVD events. We used the common variant rs911119 in CST3 as an instrumental variable to investigate the causal role of cystatin C in CVD, including coronary heart disease, ischemic stroke, and heart failure. Cystatin C concentrations were associated with CVD risk after adjusting for age, sex, and traditional risk factors (relative risk: 1.82 per doubling of cystatin C; 95% confidence interval [CI]: 1.56 to 2.13; p = 2.12 × 10(-14)). The minor allele of rs911119 was associated with decreased serum cystatin C (6.13% per allele; 95% CI: 5.75 to 6.50; p = 5.95 × 10(-211)), explaining 2.8% of the observed variation in cystatin C. Mendelian randomization analysis did not provide evidence for a causal role of cystatin C, with a causal relative risk for CVD of 1.00 per doubling cystatin C (95% CI: 0.82 to 1.22; p = 0.994), which was statistically different from the observational estimate (p = 1.6 × 10(-5)). A causal effect of cystatin C was not detected for any individual component of CVD. Mendelian randomization analyses did not support a causal role of cystatin C in the etiology of CVD. As such, therapeutics targeted at lowering circulating cystatin C are unlikely to be effective in preventing CVD. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Mental practice enhances surgical technical skills: a randomized controlled study.

    Science.gov (United States)

    Arora, Sonal; Aggarwal, Rajesh; Sirimanna, Pramudith; Moran, Aidan; Grantcharov, Teodor; Kneebone, Roger; Sevdalis, Nick; Darzi, Ara

    2011-02-01

    To assess the effects of mental practice on surgical performance. Increasing concerns for patient safety have highlighted a need for alternative training strategies outside the operating room. Mental practice (MP), "the cognitive rehearsal of a task before performance," has been successful in sport and music to enhance skill. This study investigates whether MP enhances performance in laparoscopic surgery. After baseline skills testing, 20 novice surgeons underwent training on an evidence-based virtual reality curriculum. After randomization using the closed envelope technique, all participants performed 5 Virtual Reality (VR) laparoscopic cholecystectomies (LC). Mental practice participants performed 30 minutes of MP before each LC; control participants viewed an online lecture. Technical performance was assessed using video Objective Structured Assessment of Technical Skills-based global ratings scale (scored from 7 to 35). Mental imagery was assessed using a previously validated Mental Imagery Questionnaire. Eighteen participants completed the study. There were no intergroup differences in baseline technical ability. Learning curves were demonstrated for both MP and control groups. Mental practice was superior to control (global ratings) for the first LC (median 20 vs 15, P = 0.005), second LC (20.5 vs 13.5, P = 0.001), third LC (24 vs 15.5, P imagery for the MP group was also significantly superior to the control group across all sessions (P imagery significantly correlated with better quality of performance (ρ 0.51–0.62, Ps < 0.05). This is the first randomized controlled study to show that MP enhances the quality of performance based on VR laparoscopic cholecystectomy. This may be a time- and cost-effective strategy to augment traditional training in the OR thus potentially improving patient care.

  4. Saliva sampling in global clinical studies: the impact of low sampling volume on performance of DNA in downstream genotyping experiments

    Science.gov (United States)

    2013-01-01

    Background The collection of viable DNA samples is an essential element of any genetics research programme. Biological samples for DNA purification are now routinely collected in many studies with a variety of sampling methods available. Initial observation in this study suggested a reduced genotyping success rate of some saliva derived DNA samples when compared to blood derived DNA samples prompting further investigation. Methods Genotyping success rate was investigated to assess the suitability of using saliva samples in future safety and efficacy pharmacogenetics experiments. The Oragene® OG-300 DNA Self-Collection kit was used to collect and extract DNA from saliva from 1468 subjects enrolled in global clinical studies. Statistical analysis evaluated the impact of saliva sample volume of collection on the quality, yield, concentration and performance of saliva DNA in genotyping assays. Results Across 13 global clinical studies that utilized the Oragene® OG-300 DNA Self-Collection kit there was variability in the volume of saliva sample collection with ~31% of participants providing 0.5 mL of saliva, rather than the recommended 2 mL. While the majority of saliva DNA samples provided high quality genotype data, collection of 0.5 mL volumes of saliva contributed to DNA samples being significantly less likely to pass genotyping quality control standards. Assessment of DNA sample characteristics that may influence genotyping outcomes indicated that saliva sample volume, DNA purity and turbidity were independently associated with sample genotype pass rate, but that saliva collection volume had the greatest effect. Conclusion When employing saliva sampling to obtain DNA, it is important to encourage all study participants to provide sufficient sample to minimize potential loss of data in downstream genotyping experiments. PMID:23759220

  5. Differentiating intraprofessional attitudes toward paradigms in health care delivery among chiropractic factions: results from a randomly sampled survey

    Science.gov (United States)

    2014-01-01

    Background As health care has increased in complexity and health care teams have been offered as a solution, so too is there an increased need for stronger interprofessional collaboration. However the intraprofessional factions that exist within every profession challenge interprofessional communication through contrary paradigms. As a contender in the conservative spinal health care market, factions within chiropractic that result in unorthodox practice behaviours may compromise interprofessional relations and that profession’s progress toward institutionalization. The purpose of this investigation was to quantify the professional stratification among Canadian chiropractic practitioners and evaluate the practice perceptions of those factions. Methods A stratified random sample of 740 Canadian chiropractors was surveyed to determine faction membership and how professional stratification could be related to views that could be considered unorthodox to current evidence-based care and guidelines. Stratification in practice behaviours is a stated concern of mainstream medicine when considering interprofessional referrals. Results Of 740 deliverable questionnaires, 503 were returned for a response rate of 68%. Less than 20% of chiropractors (18.8%) were aligned with a predefined unorthodox perspective of the conditions they treat. Prediction models suggest that unorthodox perceptions of health practice related to treatment choices, x-ray use and vaccinations were strongly associated with unorthodox group membership (X2 =13.4, p = 0.0002). Conclusion Chiropractors holding unorthodox views may be identified based on response to specific beliefs that appear to align with unorthodox health practices. Despite continued concerns by mainstream medicine, only a minority of the profession has retained a perspective in contrast to current scientific paradigms. Understanding the profession’s factions is important to the anticipation of care delivery when considering

  6. Humans cannot consciously generate random numbers sequences: Polemic study.

    Science.gov (United States)

    Figurska, Małgorzata; Stańczyk, Maciej; Kulesza, Kamil

    2008-01-01

    It is widely believed, that randomness exists in Nature. In fact such an assumption underlies many scientific theories and is embedded in the foundations of quantum mechanics. Assuming that this hypothesis is valid one can use natural phenomena, like radioactive decay, to generate random numbers. Today, computers are capable of generating the so-called pseudorandom numbers. Such series of numbers are only seemingly random (bias in the randomness quality can be observed). Question whether people can produce random numbers, has been investigated by many scientists in the recent years. The paper "Humans can consciously generate random numbers sequences..." published recently in Medical Hypotheses made claims that were in many ways contrary to state of art; it also stated far-reaching hypotheses. So, we decided to repeat the experiments reported, with special care being taken of proper laboratory procedures. Here, we present the results and discuss possible implications in computer and other sciences.

  7. Changes in brain volume and cognition in a randomized trial of exercise and social interaction in a community-based sample of non-demented Chinese elders.

    Science.gov (United States)

    Mortimer, James A; Ding, Ding; Borenstein, Amy R; DeCarli, Charles; Guo, Qihao; Wu, Yougui; Zhao, Qianhua; Chu, Shugang

    2012-01-01

    Physical exercise has been shown to increase brain volume and improve cognition in randomized trials of non-demented elderly. Although greater social engagement was found to reduce dementia risk in observational studies, randomized trials of social interventions have not been reported. A representative sample of 120 elderly from Shanghai, China was randomized to four groups (Tai Chi, Walking, Social Interaction, No Intervention) for 40 weeks. Two MRIs were obtained, one before the intervention period, the other after. A neuropsychological battery was administered at baseline, 20 weeks, and 40 weeks. Comparison of changes in brain volumes in intervention groups with the No Intervention group were assessed by t-tests. Time-intervention group interactions for neuropsychological measures were evaluated with repeated-measures mixed models. Compared to the No Intervention group, significant increases in brain volume were seen in the Tai Chi and Social Intervention groups (p < 0.05). Improvements also were observed in several neuropsychological measures in the Tai Chi group, including the Mattis Dementia Rating Scale score (p = 0.004), the Trailmaking Test A (p = 0.002) and B (p = 0.0002), the Auditory Verbal Learning Test (p = 0.009), and verbal fluency for animals (p = 0.01). The Social Interaction group showed improvement on some, but fewer neuropsychological indices. No differences were observed between the Walking and No Intervention groups. The findings differ from previous clinical trials in showing increases in brain volume and improvements in cognition with a largely non-aerobic exercise (Tai Chi). In addition, intellectual stimulation through social interaction was associated with increases in brain volume as well as with some cognitive improvements.

  8. Sample size requirement in analytical studies for similarity assessment.

    Science.gov (United States)

    Chow, Shein-Chung; Song, Fuyu; Bai, He

    2017-01-01

    For the assessment of biosimilar products, the FDA recommends a stepwise approach for obtaining the totality-of-the-evidence for assessing biosimilarity between a proposed biosimilar product and its corresponding innovative biologic product. The stepwise approach starts with analytical studies for assessing similarity in critical quality attributes (CQAs), which are relevant to clinical outcomes at various stages of the manufacturing process. For CQAs that are the most relevant to clinical outcomes, the FDA requires an equivalence test be performed for similarity assessment based on an equivalence acceptance criterion (EAC) that is obtained using a single test value of some selected reference lots. In practice, we often have extremely imbalanced numbers of reference and test lots available for the establishment of EAC. In this case, to assist the sponsors, the FDA proposed an idea for determining the number of reference lots and the number of test lots required in order not to have imbalanced sample sizes when establishing EAC for the equivalence test based on extensive simulation studies. Along this line, this article not only provides statistical justification of Dong, Tsong, and Weng's proposal, but also proposes an alternative method for sample size requirement for the Tier 1 equivalence test.

  9. HDL Cholesterol, LDL Cholesterol, and Triglycerides as Risk Factors for CKD: A Mendelian Randomization Study.

    Science.gov (United States)

    Lanktree, Matthew B; Thériault, Sébastien; Walsh, Michael; Paré, Guillaume

    2017-07-26

    High-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride concentrations are heritable risk factors for vascular disease, but their role in the progression of chronic kidney disease (CKD) is unclear. 2-sample Mendelian randomization analysis of data derived from the largest published lipid and CKD studies. Effect of independent genetic variants significantly associated with lipid concentrations was obtained from the Global Lipids Genetics Consortium (n=188,577), and the effect of these same variants on estimated glomerular filtration rate (eGFR), CKD (defined as eGFRGenetics Consortium (n=133,814). Using conventional, multivariable, and Egger Mendelian randomization approaches, we assessed the causal association between genetically determined lipid concentrations and kidney traits. eGFR, dichotomous eGFRGenetically higher triglyceride concentrations appeared associated with higher eGFRs, but this finding was driven by a single pleiotropic variant in the glucokinase regulator gene (GCKR). After exclusion, genetically higher triglyceride concentration was not associated with any kidney trait. Individual patient-level phenotype and genotype information were unavailable. 2-sample Mendelian randomization analysis of data from the largest lipid and CKD cohorts supports genetically higher HDL cholesterol concentration as causally associated with better kidney function. There was no association between genetically altered LDL cholesterol or triglyceride concentration and kidney function. Further analysis of CKD outcomes in HDL cholesterol intervention trials is warranted. Copyright © 2017 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  10. Sleep Promotion Program for Improving Sleep Behaviors in Adolescents: A Randomized Controlled Pilot Study.

    Science.gov (United States)

    John, Bindu; Bellipady, Sumanth Shetty; Bhat, Shrinivasa Undaru

    2016-01-01

    Aims. The purpose of this pilot trial was to determine the efficacy of sleep promotion program to adapt it for the use of adolescents studying in various schools of Mangalore, India, and evaluate the feasibility issues before conducting a randomized controlled trial in a larger sample of adolescents. Methods. A randomized controlled trial design with stratified random sampling method was used. Fifty-eight adolescents were selected (mean age: 14.02 ± 2.15 years; intervention group, n = 34; control group, n = 24). Self-report questionnaires, including sociodemographic questionnaire with some additional questions on sleep and activities, Sleep Hygiene Index, Pittsburgh Sleep Quality Index, The Cleveland Adolescent Sleepiness Questionnaire, and PedsQL™ Present Functioning Visual Analogue Scale, were used. Results. Insufficient weekday-weekend sleep duration with increasing age of adolescents was observed. The program revealed a significant effect in the experimental group over the control group in overall sleep quality, sleep onset latency, sleep duration, daytime sleepiness, and emotional and overall distress. No significant effect was observed in sleep hygiene and other sleep parameters. All target variables showed significant correlations with each other. Conclusion. The intervention holds a promise for improving the sleep behaviors in healthy adolescents. However, the effect of the sleep promotion program treatment has yet to be proven through a future research. This trial is registered with ISRCTN13083118.

  11. Sleep Promotion Program for Improving Sleep Behaviors in Adolescents: A Randomized Controlled Pilot Study

    Directory of Open Access Journals (Sweden)

    Bindu John

    2016-01-01

    Full Text Available Aims. The purpose of this pilot trial was to determine the efficacy of sleep promotion program to adapt it for the use of adolescents studying in various schools of Mangalore, India, and evaluate the feasibility issues before conducting a randomized controlled trial in a larger sample of adolescents. Methods. A randomized controlled trial design with stratified random sampling method was used. Fifty-eight adolescents were selected (mean age: 14.02 ± 2.15 years; intervention group, n=34; control group, n=24. Self-report questionnaires, including sociodemographic questionnaire with some additional questions on sleep and activities, Sleep Hygiene Index, Pittsburgh Sleep Quality Index, The Cleveland Adolescent Sleepiness Questionnaire, and PedsQL™ Present Functioning Visual Analogue Scale, were used. Results. Insufficient weekday-weekend sleep duration with increasing age of adolescents was observed. The program revealed a significant effect in the experimental group over the control group in overall sleep quality, sleep onset latency, sleep duration, daytime sleepiness, and emotional and overall distress. No significant effect was observed in sleep hygiene and other sleep parameters. All target variables showed significant correlations with each other. Conclusion. The intervention holds a promise for improving the sleep behaviors in healthy adolescents. However, the effect of the sleep promotion program treatment has yet to be proven through a future research. This trial is registered with ISRCTN13083118.

  12. A shared frailty model for case-cohort samples: parent and offspring relations in an adoption study

    DEFF Research Database (Denmark)

    Petersen, Liselotte; Sørensen, Thorkild I A; Andersen, Per Kragh

    2010-01-01

    probability weighting to account for the sampling in a conditional, shared frailty Poisson model and to use the robust variance estimator proposed by Moger et al. (Statist. Med. 2008; 27:1062-1074).To explore the performance of the estimation procedure, a simulation study was conducted. We studied situations......The Danish adoption register contains data on the 12 301 Danish nonfamilial adoptions during 1924-1947. From that register a case-cohort sample was selected consisting of all case adoptees, that is those adoptees dying before age 70 years, and a random sample of 1683 adoptees. The survival data...

  13. Comparison of Sampling Designs for Estimating Deforestation from Landsat TM and MODIS Imagery: A Case Study in Mato Grosso, Brazil

    Directory of Open Access Journals (Sweden)

    Shanyou Zhu

    2014-01-01

    Full Text Available Sampling designs are commonly used to estimate deforestation over large areas, but comparisons between different sampling strategies are required. Using PRODES deforestation data as a reference, deforestation in the state of Mato Grosso in Brazil from 2005 to 2006 is evaluated using Landsat imagery and a nearly synchronous MODIS dataset. The MODIS-derived deforestation is used to assist in sampling and extrapolation. Three sampling designs are compared according to the estimated deforestation of the entire study area based on simple extrapolation and linear regression models. The results show that stratified sampling for strata construction and sample allocation using the MODIS-derived deforestation hotspots provided more precise estimations than simple random and systematic sampling. Moreover, the relationship between the MODIS-derived and TM-derived deforestation provides a precise estimate of the total deforestation area as well as the distribution of deforestation in each block.

  14. Comparison of sampling designs for estimating deforestation from landsat TM and MODIS imagery: a case study in Mato Grosso, Brazil.

    Science.gov (United States)

    Zhu, Shanyou; Zhang, Hailong; Liu, Ronggao; Cao, Yun; Zhang, Guixin

    2014-01-01

    Sampling designs are commonly used to estimate deforestation over large areas, but comparisons between different sampling strategies are required. Using PRODES deforestation data as a reference, deforestation in the state of Mato Grosso in Brazil from 2005 to 2006 is evaluated using Landsat imagery and a nearly synchronous MODIS dataset. The MODIS-derived deforestation is used to assist in sampling and extrapolation. Three sampling designs are compared according to the estimated deforestation of the entire study area based on simple extrapolation and linear regression models. The results show that stratified sampling for strata construction and sample allocation using the MODIS-derived deforestation hotspots provided more precise estimations than simple random and systematic sampling. Moreover, the relationship between the MODIS-derived and TM-derived deforestation provides a precise estimate of the total deforestation area as well as the distribution of deforestation in each block.

  15. Study population, questionnaire, data management and sample description.

    Science.gov (United States)

    de Waure, Chiara; Poscia, Andrea; Virdis, Andrea; Di Pietro, Maria Luisa; Ricciardi, Walter

    2015-01-01

    This article describes methodological issues of the "Sportello Salute Giovani" project ("Youth Health Information Desk"), a multicenter study aimed at assessing the health status and attitudes and behaviours of university students in Italy. The questionnaire used to carry out the study was adapted from the Italian health behaviours in school-aged children (HBSC) project and consisted of 93 items addressing: demographics; nutritional habits and status; physical activity; lifestyles; reproductive and preconception health; health and satisfaction of life; attitudes and behaviours toward academic study and new technologies. The questionnaire was administered to a pool of 12 000 students from 18 to 30 years of age who voluntary decided to participate during classes held at different Italian faculties or at the three "Sportello Salute Giovani" centers which were established in the three sites of the Università Cattolica del Sacro Cuore (Catholic University of the Sacred Heart of Rome). The final study sample was composed by 8516 university students. The mean age of responders was 22.2 (Standard Deviation 2.0) and 5702 (67.0%) were females. According to the distribution in age classes, 3601 (43.3%) belonged to the 18-21 one, 3796 (44.5%) to the 22-24 class and 1019 (12.2%) to the 25-30 class. With respect to socio-economic status, data were available for 8410 responders and showed that 50.3% of students belonged to the middle class. The project took into consideration a large number of individuals from different regions of the country and therefore may be considered representative of the general population of Italian university students. Furthermore, it is the first to address, at the same time, several issues, in particular attitudes and behaviours toward health, in Italian university students. The analysis of data from such a large sample of university students sets the basis for identifying the most appropriate interventions in order to address the specific needs of

  16. Partner randomized controlled trial: study protocol and coaching intervention

    Directory of Open Access Journals (Sweden)

    Garbutt Jane M

    2012-04-01

    Full Text Available Abstract Background Many children with asthma live with frequent symptoms and activity limitations, and visits for urgent care are common. Many pediatricians do not regularly meet with families to monitor asthma control, identify concerns or problems with management, or provide self-management education. Effective interventions to improve asthma care such as small group training and care redesign have been difficult to disseminate into office practice. Methods and design This paper describes the protocol for a randomized controlled trial (RCT to evaluate a 12-month telephone-coaching program designed to support primary care management of children with persistent asthma and subsequently to improve asthma control and disease-related quality of life and reduce urgent care events for asthma care. Randomization occurred at the practice level with eligible families within a practice having access to the coaching program or to usual care. The coaching intervention was based on the transtheoretical model of behavior change. Targeted behaviors included 1 effective use of controller medications, 2 effective use of rescue medications and 3 monitoring to ensure optimal control. Trained lay coaches provided parents with education and support for asthma care, tailoring the information provided and frequency of contact to the parent's readiness to change their child's day-to-day asthma management. Coaching calls varied in frequency from weekly to monthly. For each participating family, follow-up measurements were obtained at 12- and 24-months after enrollment in the study during a telephone interview. The primary outcomes were the mean change in 1 the child's asthma control score, 2 the parent's quality of life score, and 3 the number of urgent care events assessed at 12 and 24 months. Secondary outcomes reflected adherence to guideline recommendations by the primary care pediatricians and included the proportion of children prescribed controller medications

  17. Using Environmental Variables for Studying of the Quality of Sampling in Soil Mapping

    Directory of Open Access Journals (Sweden)

    A. Jafari

    2016-02-01

    Full Text Available Introduction: Methods of soil survey are generally empirical and based on the mental development of the surveyor, correlating soil with underlying geology, landforms, vegetation and air-photo interpretation. Since there are no statistical criteria for traditional soil sampling; this may lead to bias in the areas being sampled. In digital soil mapping, soil samples may be used to elaborate quantitative relationships or models between soil attributes and soil covariates. Because the relationships are based on the soil observations, the quality of the resulting soil map depends also on the soil observation quality. An appropriate sampling design for digital soil mapping depends on how much data is available and where the data is located. Some statistical methods have been developed for optimizing data sampling for soil surveys. Some of these methods deal with the use of ancillary information. The purpose of this study was to evaluate the quality of sampling of existing data. Materials and Methods: The study area is located in the central basin of the Iranian plateau (Figure 1. The geologic infrastructure of the area is mainly Cretaceous limestone, Mesozoic shale and sandstone. Air photo interpretation (API was used to differentiate geomorphic patterns based on their formation processes, general structure and morphometry. The patterns were differentiated through a nested geomorphic hierarchy (Fig. 2. A four-level geomorphic hierarchy is used to breakdown the complexity of different landscapes of the study area. In the lower level of the hierarchy, the geomorphic surfaces, which were formed by a unique process during a specific geologic time, were defined. A stratified sampling scheme was designed based on geomorphic mapping. In the stratified simple random sampling, the area was divided into sub-areas referred to as strata based on geomorphic surfaces, and within each stratum, sampling locations were randomly selected (Figure 2. This resulted in 191

  18. Yoga in Correctional Settings: A Randomized Controlled Study

    Directory of Open Access Journals (Sweden)

    Nóra Kerekes

    2017-10-01

    Full Text Available BackgroundThe effect of yoga in the reduction of depressive symptoms, anxiety, stress, anger as well as in the increased ability of behavioral control has been shown. These effects of yoga are highly relevant for prison inmates who often have poor mental health and low impulse control. While it has been shown that yoga and meditation can be effective in improving subjective well-being, mental health, and executive functioning within prison populations, only a limited number of studies have proved this, using randomized controlled settings.MethodsA total of 152 participants from nine Swedish correctional facilities were randomly assigned to a 10-week yoga group (one class a week; N = 77 or a control group (N = 75. Before and after the intervention period, participants answered questionnaires measuring stress, aggression, affective states, sleep quality, and psychological well-being and completed a computerized test measuring attention and impulsivity.ResultsAfter the intervention period, significant improvements were found on 13 of the 16 variables within the yoga group (e.g., less perceived stress, better sleep quality, an increased psychological and emotional well-being, less aggressive, and antisocial behavior and on two within the control group. Compared to the control group, yoga class participants reported significantly improved emotional well-being and less antisocial behavior after 10 weeks of yoga. They also showed improved performance on the computerized test that measures attention and impulse control.ConclusionIt can be concluded that the yoga practiced in Swedish correctional facilities has positive effects on inmates’ well-being and on considerable risk factors associated with recidivism, such as impulsivity and antisocial behavior. Accordingly, the results show that yoga practice can play an important part in the rehabilitation of prison inmates.

  19. NSAID Use after Bariatric Surgery: a Randomized Controlled Intervention Study.

    Science.gov (United States)

    Yska, Jan Peter; Gertsen, Sanneke; Flapper, Gerbrich; Emous, Marloes; Wilffert, Bob; van Roon, Eric N

    2016-12-01

    Use of nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided in bariatric surgery patients. If use of an NSAID is inevitable, a proton pump inhibitor (PPI) should also be used. To determine the effect of an, compared to care-as-usual, additional intervention to reduce NSAID use in patients who underwent bariatric surgery, and to determine the use of PPIs in patients who use NSAIDs after bariatric surgery. A randomized controlled intervention study in patients after bariatric surgery. Patients were randomized to an intervention or a control group. The intervention consisted of sending a letter to patients and their general practitioners on the risks of use of NSAIDs after bariatric surgery and the importance of avoiding NSAID use. The control group received care-as-usual. Dispensing data of NSAIDs and PPIs were collected from patients' pharmacies: from a period of 6 months before and from 3 until 9 months after the intervention. Two hundred forty-eight patients were included (intervention group: 124; control group: 124). The number of users of NSAIDs decreased from 22 to 18 % in the intervention group and increased from 20 to 21 % in the control group (NS). The use of a PPI with an NSAID rose from 52 to 55 % in the intervention group, and from 52 to 69 % in the control group (NS). Informing patients and their general practitioners by letter, in addition to care-as-usual, is not an effective intervention to reduce the use of NSAIDs after bariatric surgery (trial number NTR3665).

  20. A randomized pilot study of naturopathic medicine in multiple sclerosis.

    Science.gov (United States)

    Shinto, Lynne; Calabrese, Carlo; Morris, Cynthia; Yadav, Vijayshree; Griffith, Debbie; Frank, Rachel; Oken, Barry S; Baldauf-Wagner, Sara; Bourdette, Dennis

    2008-06-01

    Complementary and alternative medicine (CAM) use is high in people with multiple sclerosis (MS), yet there are limited reports on safety and effectiveness of CAM in MS. Naturopathic medicine encompasses a broad range of CAM modalities and may improve quality of life in patients with MS. To assess quality of life in MS subjects who received interventions designed to "model" the "whole practice" of naturopathy. A pilot, randomized, controlled study with a 6-month intervention period. Participants who met criteria for clinically definite MS. The 3 intervention arms were usual care, naturopathic medicine plus usual care, and MS education plus usual care. The primary outcome measure was quality of life (36-item short form health survey [SF-36]). Secondary outcome measures included fatigue (Modified Fatigue Impact Scale); depression (Beck Depression Inventory); cognition battery (Stroop test and Paced Auditory Serial Addition Test 3), and neurologic impairment (Expanded Disability Status Scale [EDSS] and Multiple Sclerosis Functional Composite). Adverse event reporting and laboratory measures were used to assess safety. Forty-five (45) participants (15 per group) were randomized and all completed the 6-month intervention. There were no significant differences between groups on any outcome measure. There was a trend in favoring the naturopathic group in the General Health subscale of the SF-36 (p = 0.11), Timed Walk (p = 0.11), and neurologic impairment (EDSS) (p = 0.07). There was a trend favoring the Education group in the Stroop attention test (p = 0.07). There was no difference between groups in adverse events or laboratory changes. Naturopathic medicine combined with usual care for MS showed a trend in improvement in the General Health subscale of the SF-36, Timed Walk, and neurologic impairment. Evaluation of naturopathic medicine, as a multimodality regimen, warrants further investigation.

  1. The Analysis of Random Effects in Modeling Studies.

    Science.gov (United States)

    Scheirer, C. James; Geller, Sanford E.

    1979-01-01

    Argues that in research on the effects of modeling, models must be analyzed as a random factor in order to avoid a positive bias in the results. The concept of a random factor is discussed, worked examples are provided, and a practical solution to the problem is proposed. (JMB)

  2. Evaluating effectiveness of down-sampling for stratified designs and unbalanced prevalence in Random Forest models of tree species distributions in Nevada

    Science.gov (United States)

    Elizabeth A. Freeman; Gretchen G. Moisen; Tracy S. Frescino

    2012-01-01

    Random Forests is frequently used to model species distributions over large geographic areas. Complications arise when data used to train the models have been collected in stratified designs that involve different sampling intensity per stratum. The modeling process is further complicated if some of the target species are relatively rare on the landscape leading to an...

  3. Sample correlations of infinite variance time series models: an empirical and theoretical study

    Directory of Open Access Journals (Sweden)

    Jason Cohen

    1998-01-01

    Full Text Available When the elements of a stationary ergodic time series have finite variance the sample correlation function converges (with probability 1 to the theoretical correlation function. What happens in the case where the variance is infinite? In certain cases, the sample correlation function converges in probability to a constant, but not always. If within a class of heavy tailed time series the sample correlation functions do not converge to a constant, then more care must be taken in making inferences and in model selection on the basis of sample autocorrelations. We experimented with simulating various heavy tailed stationary sequences in an attempt to understand what causes the sample correlation function to converge or not to converge to a constant. In two new cases, namely the sum of two independent moving averages and a random permutation scheme, we are able to provide theoretical explanations for a random limit of the sample autocorrelation function as the sample grows.

  4. Prospective randomized clinical studies involving reirradiation. Lessons learned

    Energy Technology Data Exchange (ETDEWEB)

    Nieder, Carsten [Nordland Hospital, Department of Oncology and Palliative Medicine, Bodoe (Norway); University of Tromsoe, Department of Clinical Medicine, Faculty of Health Sciences, Tromsoe (Norway); Langendijk, Johannes A. [University Medical Centre Groningen, Department of Radiation Oncology, Groningen (Netherlands); Guckenberger, Matthias [University Hospital Zuerich, Department of Radiation Oncology, Zuerich (Switzerland); Grosu, Anca L. [University Hospital Freiburg, Department of Radiation Oncology, Freiburg (Germany)

    2016-10-15

    Reirradiation is a potentially useful option for many patients with recurrent cancer. The purpose of this study was to review all recently published randomized trials in order to identify methodological strengths and weaknesses, comment on the results, clinical implications and open questions, and give advice for the planning of future trials. Systematic review of trials published between 2000 and 2015 (databases searched were PubMed, Scopus and Web of Science). We reviewed 9 trials, most of which addressed reirradiation of head and neck tumours. The median number of patients was 69. Trial design, primary endpoint and statistical hypotheses varied widely. The results contribute mainly to decision making for reirradiation of nasopharynx cancer and bone metastases. The trials with relatively long median follow-up confirm that serious toxicity remains a concern after high cumulative total doses. Multi-institutional collaboration is encouraged to complete sufficiently large trials. Despite a paucity of large randomized studies, reirradiation has been adopted in different clinical scenarios by many institutions. Typically, the patients have been assessed by multidisciplinary tumour boards and advanced technologies are used to create highly conformal dose distributions. (orig.) [German] Eine Rebestrahlung kann fuer viele Patienten mit rezidivierenden Malignomen eine nuetzliche Option bieten. Der Zweck dieser Studie bestand darin, alle in der juengeren Vergangenheit publizierten randomisierten Studien zu beurteilen, da deren methodische Staerken und Schwaechen, Ergebnisse und resultierende Implikationen bzw. offene Fragen die Planung kuenftiger Studien wesentlich beeinflussen koennen. Systematische Uebersicht aller zwischen 2000 und 2015 veroeffentlichten Studien (Literatursuche ueber PubMed, Scopus und Web of Science). Ausgewertet wurden 9 Studien, in die vor allem Patienten mit Kopf-Hals-Tumoren eingeschlossen waren. Im Median hatten 69 Patienten teilgenommen. Das

  5. Study population, questionnaire, data management and sample description

    Directory of Open Access Journals (Sweden)

    Chiara de Waure

    2015-06-01

    Full Text Available INTRODUCTION: This article describes methodological issues of the "Sportello Salute Giovani" project ("Youth Health Information Desk", a multicenter study aimed at assessing the health status and attitudes and behaviours of university students in Italy. MATERIALS AND METHODS: The questionnaire used to carry out the study was adapted from the Italian health behaviours in school-aged children (HBSC project and consisted of 93 items addressing: demographics; nutritional habits and status; physical activity; lifestyles; reproductive and preconception health; health and satisfaction of life; attitudes and behaviours toward academic study and new technologies. The questionnaire was administered to a pool of 12 000 students from 18 to 30 years of age who voluntary decided to participate during classes held at different Italian faculties or at the three "Sportello Salute Giovani" centers which were established in the three sites of the Università Cattolica del Sacro Cuore (Catholic University of the Sacred Heart of Rome. RESULTS: The final study sample was composed by 8516 university students. The mean age of responders was 22.2 (Standard Deviation 2.0 and 5702 (67.0% were females. According to the distribution in age classes, 3601 (43.3% belonged to the 18-21 one, 3796 (44.5% to the 22-24 class and 1019 (12.2% to the 25-30 class. With respect to socio-economic status, data were available for 8410 responders and showed that 50.3% of students belonged to the middle class. DISCUSSION: The project took into consideration a large number of individuals from different regions of the country and therefore may be considered representative of the general population of Italian university students. Furthermore, it is the first to address, at the same time, several issues, in particular attitudes and behaviours toward health, in Italian university students. CONCLUSION: The analysis of data from such a large sample of university students sets the basis for

  6. Characterizing stand-level forest canopy cover and height using Landsat time series, samples of airborne LiDAR, and the Random Forest algorithm

    Science.gov (United States)

    Ahmed, Oumer S.; Franklin, Steven E.; Wulder, Michael A.; White, Joanne C.

    2015-03-01

    Many forest management activities, including the development of forest inventories, require spatially detailed forest canopy cover and height data. Among the various remote sensing technologies, LiDAR (Light Detection and Ranging) offers the most accurate and consistent means for obtaining reliable canopy structure measurements. A potential solution to reduce the cost of LiDAR data, is to integrate transects (samples) of LiDAR data with frequently acquired and spatially comprehensive optical remotely sensed data. Although multiple regression is commonly used for such modeling, often it does not fully capture the complex relationships between forest structure variables. This study investigates the potential of Random Forest (RF), a machine learning technique, to estimate LiDAR measured canopy structure using a time series of Landsat imagery. The study is implemented over a 2600 ha area of industrially managed coastal temperate forests on Vancouver Island, British Columbia, Canada. We implemented a trajectory-based approach to time series analysis that generates time since disturbance (TSD) and disturbance intensity information for each pixel and we used this information to stratify the forest land base into two strata: mature forests and young forests. Canopy cover and height for three forest classes (i.e. mature, young and mature and young (combined)) were modeled separately using multiple regression and Random Forest (RF) techniques. For all forest classes, the RF models provided improved estimates relative to the multiple regression models. The lowest validation error was obtained for the mature forest strata in a RF model (R2 = 0.88, RMSE = 2.39 m and bias = -0.16 for canopy height; R2 = 0.72, RMSE = 0.068% and bias = -0.0049 for canopy cover). This study demonstrates the value of using disturbance and successional history to inform estimates of canopy structure and obtain improved estimates of forest canopy cover and height using the RF algorithm.

  7. Acupuncture in Menopause (AIM) study: a pragmatic, randomized controlled trial.

    Science.gov (United States)

    Avis, Nancy E; Coeytaux, Remy R; Isom, Scott; Prevette, Kristen; Morgan, Timothy

    2016-06-01

    The aim of the study was to evaluate the short and long-term effects of acupuncture on vasomotor symptoms (VMS) and quality of life-related measures. A total of 209 perimenopausal and postmenopausal women aged 45 to 60 years, experiencing four or more VMS per day, were recruited from the community and randomized to receive up to 20 acupuncture treatments within the first 6 months (acupuncture group) or the second 6 months (waitlist control group) of the 12-month study period. The primary outcome was mean daily frequency of VMS. Secondary outcomes were VMS interference with daily life, sleep quality, depressive symptoms, somatic and other symptoms, anxiety, and quality of life. The VMS frequency declined by 36.7% at 6 months in the acupuncture group and increased by 6.0% in the control group (P acupuncture group was 29.4% (P acupuncture treatments, and maximal clinical effects occurred after a median of eight treatments. Persistent improvements were seen in many quality of life-related outcomes in the acupuncture group relative to the control group. We found that a course of acupuncture treatments was associated with significant reduction in VMS, and several quality-of-life measures, compared with no acupuncture, and that clinical benefit persisted for at least 6 months beyond the end of treatment.

  8. Glove failure in elective thyroid surgery: A prospective randomized study

    Directory of Open Access Journals (Sweden)

    Dariusz Timler

    2015-06-01

    Full Text Available Objectives: To analyze perforation rate in sterile gloves used by surgeons in the operating theatre of the Department of Endocrinological and General Surgery of Medical University of Lodz. Material and Methods: Randomized and controlled trial. This study analyses the incidents of tears in sterile surgical gloves used by surgeons during operations on 3 types of thyroid diseases according to the 10th revision of International Statistical Classification of Diseases and Related Health Problems (ICD-10 codes. Nine hundred seventy-two pairs (sets of gloves were collected from 321 surgical procedures. All gloves were tested immediately following surgery using the water leak test (EN455-1 to detect leakage. Results: Glove perforation was detected in 89 of 972 glove sets (9.2%. Statistically relevant more often glove tears occurred in operator than the 1st assistant (p < 0.001. The sites of perforation were localized mostly on the middle finger of the non-dominant hand (22.5%, and the non-dominant ring finger (17.9%. Conclusions: This study has proved that the role performed by the surgeon during the procedure (operator, 1st assistant has significant influence on the risk of glove perforations. Nearly 90% of glove perforations are unnoticed during surgery.

  9. Music and preoperative anxiety: a randomized, controlled study.

    Science.gov (United States)

    Wang, Shu-Ming; Kulkarni, Lina; Dolev, Jackqulin; Kain, Zeev N

    2002-06-01

    Music may decrease the anxiety experienced by patients before surgery. Previous studies of this issue were hindered with multiple methodological problems. In this investigation, we examined this hypothesis while using a rigorous study design and objective outcome measures. Adult patients undergoing anesthesia and surgery were randomly assigned to two study groups. Subjects in Group 1 (n = 48) listened to a 30-min patient-selected music session, and subjects in Group 2 (n = 45) received no intervention. By using self-report validated behavioral (State-Trait Anxiety Inventory) and physiological measures of anxiety (heart rate, blood pressure, and electrodermal activity and serum cortisol, epinephrine, and norepinephrine), patients were evaluated before, during, and after administration of the intervention. We found that after intervention, subjects in the Music group reported significantly lower anxiety levels as compared with the Control group (F(1,91) = 15.4, P = 0.001). That is, the postintervention anxiety level of subjects in the Music group decreased by 16% as compared with the preintervention level, whereas the anxiety level of the Control group did not change significantly. Two-way repeated-measures analysis of variance performed for the electrodermal activity, blood pressure, heart rate, cortisol, and catecholamine data demonstrated no group difference and no time x group interaction (P = not significant). In conclusion, under the conditions of this study, patients who listened to music before surgery reported lower levels of state anxiety. Physiological outcomes did not differ, however, between the two study groups. Patients who listen to music of their choice during the preoperative period report less anxiety.

  10. Employing a Multi-level Approach to Recruit a Representative Sample of Women with Recent Gestational Diabetes Mellitus into a Randomized Lifestyle Intervention Trial.

    Science.gov (United States)

    Nicklas, Jacinda M; Skurnik, Geraldine; Zera, Chloe A; Reforma, Liberty G; Levkoff, Sue E; Seely, Ellen W

    2016-02-01

    The postpartum period is a window of opportunity for diabetes prevention in women with recent gestational diabetes (GDM), but recruitment for clinical trials during this period of life is a major challenge. We adapted a social-ecologic model to develop a multi-level recruitment strategy at the macro (high or institutional level), meso (mid or provider level), and micro (individual) levels. Our goal was to recruit 100 women with recent GDM into the Balance after Baby randomized controlled trial over a 17-month period. Participants were asked to attend three in-person study visits at 6 weeks, 6, and 12 months postpartum. They were randomized into a control arm or a web-based intervention arm at the end of the baseline visit at six weeks postpartum. At the end of the recruitment period, we compared population characteristics of our enrolled subjects to the entire population of women with GDM delivering at Brigham and Women's Hospital (BWH). We successfully recruited 107 of 156 (69 %) women assessed for eligibility, with the majority (92) recruited during pregnancy at a mean 30 (SD ± 5) weeks of gestation, and 15 recruited postpartum, at a mean 2 (SD ± 3) weeks postpartum. 78 subjects attended the initial baseline visit, and 75 subjects were randomized into the trial at a mean 7 (SD ± 2) weeks postpartum. The recruited subjects were similar in age and race/ethnicity to the total population of 538 GDM deliveries at BWH over the 17-month recruitment period. Our multilevel approach allowed us to successfully meet our recruitment goal and recruit a representative sample of women with recent GDM. We believe that our most successful strategies included using a dedicated in-person recruiter, integrating recruitment into clinical flow, allowing for flexibility in recruitment, minimizing barriers to participation, and using an opt-out strategy with providers. Although the majority of women were recruited while pregnant, women recruited in the early postpartum period were

  11. Stop the pain: study protocol for a randomized-controlled trial.

    Science.gov (United States)

    Warschburger, Petra; Calvano, Claudia; Becker, Sebastian; Friedt, Michael; Hudert, Christian; Posovszky, Carsten; Schier, Maike; Wegscheider, Karl

    2014-09-11

    Functional abdominal pain (FAP) is not only a highly prevalent disease but also poses a considerable burden on children and their families. Untreated, FAP is highly persistent until adulthood, also leading to an increased risk of psychiatric disorders. Intervention studies underscore the efficacy of cognitive behavioral treatment approaches but are limited in terms of sample size, long-term follow-up data, controls and inclusion of psychosocial outcome data. In a multicenter randomized controlled trial, 112 children aged 7 to 12 years who fulfill the Rome III criteria for FAP will be allocated to an established cognitive behavioral training program for children with FAP (n = 56) or to an active control group (focusing on age-appropriate information delivery; n = 56). Randomization occurs centrally, blockwise and is stratified by center. This study is performed in five pediatric gastroenterology outpatient departments. Observer-blind assessments of outcome variables take place four times: pre-, post-, 3- and 12-months post-treatment. Primary outcome is the course of pain intensity and frequency. Secondary endpoints are health-related quality of life, pain-related coping and cognitions, as well as self-efficacy. This confirmatory randomized controlled clinical trial evaluates the efficacy of a cognitive behavioral intervention for children with FAP. By applying an active control group, time and attention processes can be controlled, and long-term follow-up data over the course of one year can be explored. DRKS00005038 (date: 25 July 2013); NCT02030392 (date: 7 January 2014).

  12. A prospective, randomized multicenter study comparing APD and CAPD treatment

    DEFF Research Database (Denmark)

    Bro, S; Bjorner, J B; Tofte-Jensen, P

    2000-01-01

    , dialysis-related complications, dialysis-related expenses. RESULTS: The quality-of-life studies showed that significantly more time for work, family, and social activities was available to patients on APD compared to those on CAPD (p .... With larger patient samples, it is possible, however, that a significant difference might have been achieved. The running costs for APD treatment were US $75 per day and for CAPD treatment US $61 per day. CONCLUSION: If APD treatment can help to keep selected patients vocationally or socially active, paying...

  13. Randomized multi-centre study on the effect of training on tooth shade matching.

    Science.gov (United States)

    Olms, C; Klinke, Th; Pirek, P; Hannak, W B

    2013-12-01

    The aim of this study was to find out whether Toothguide Trainer, TT, and Toothguide Training Box, TTB, show any training effects, independent of the shade guide chosen. Students from four dental schools (N=78) were included in this study. The participants were randomized into a study, 42 students (age range: 19-27 years; 69% female, 31% male) and a control group of 36 students (age range: 19-30 years; 57% female, 43% male). The study group started with a double blind introduction test, followed by the TT and TTB training, finishing with the final test. The control group only passed the introduction and - after a break - the final test. Eight randomly chosen samples, seven of the Vita classical and one of the 3D-Master colour scale, were marked by barcodes. Colour matching was arranged by the Vita classical scale. The results of the pre- and final tests of both groups were combined. For every sample, the value ΔE was determined. The summation of all eight samples from the introduction and final tests offered a summarized ΔE value. The differences between introduction and final tests revealed the individual learning success. 47.6% of the study group showed statistically significant better results than the control group, 33% (p=0.031). TT and TTB show a positive effect of training on tooth shade matching independent of the colour scale used. Visual shade taking is the most frequent clinical method for shade determination. To increase better results in visual colour matching, TT and TTB training is used. This is the first study examining the training effect of TT and TTB using Vita classical scale. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. A randomized, prospective study of adjunctive Ampicillin in preterm labor

    Directory of Open Access Journals (Sweden)

    Tehranian A

    1999-09-01

    Full Text Available Acute amniotic fluid infection has emerged as a possible cause of many heretofore unexplained preterm births. Our purpose was to determine the effect of ampicillin in the prolongation of pregnancies receiving tocolysis for preterm labor. A blinded, placebo-controlled, randomized trial was conducted to study ampicillin in women hospitalized for preterm labor between 24 and 37 weeks' gestation. A total of 60 patients with intact membranes and without chorioamnionitis who were receiving magnesium sulfate were screened. Thirty women with preterm labor received ampicillin, and 30 received placebos. The primary end point was prolongation of gestation. There was no difference in age of delivery (37.6±9.7 days vs 36.08±3.9 days, P=0.085 and no difference in retardation of delivery (4.7±3.1 vs 4.1±2.1, P=0.39. The mean degree of preterm delivery were 0.62±1.93 and 1.8±3.3 weeks in ampicillin and placebo groups, respectively (not significant, P>0.1. Conclusions: Ampicillin had no effect on interval to delivery or duration of pregnancy in women treated for preterm labor. So rotine clinical use of ampicillin during tocolysis should not be recommended.

  15. TVT versus TOT, 2-year prospective randomized study.

    Science.gov (United States)

    Wadie, Bassem S; El-Hefnawy, Ahmed S; Elhefnawy, Ahmed S

    2013-06-01

    To evaluate in a comprehensive way TVT in comparison with TOT, the results of a single-center RCT are presented. Many studies addressed efficacy and safety of TVT and TOT. Women included were adults having predominant SUI with positive stress test. They were randomized to get either TVT (Gynecare(®)) or TOT (Aris(®)). All women were seen 1 week, 3, 6, 12, 18, and 24 months. Seventy-one women completed 2-year follow-up. Median age was 47 (range 33-60 years). Mean ± SD BMI in TVT group was 34 ± 5 while in TOT group was 32 ± 5 kg/m(2). POP of any degree was seen in 50 % (35 women). At 1 year, pad test-negative women were 31 and 29 for TVT and TOT, respectively. At 2 years, figures became 28 in TVT group and 27 in TOT. At 1 year, UDI 6 and IIQ 7 decreased by 78.5 and 81 % for TVT and by 69 % and 75 % for TOT group. At 2 year, comparable percentages were 73 and 79 % for TVT and 69 and 82 % for TOT. Fifteen unique patients had adverse events, 10 of them had TOT. Both tapes have similar efficacy, regarding cure of incontinence. TVT is more effective, albeit insignificantly, than TOT at 2 years. However, serious adverse events were more frequent with TVT, yet TOT has more unique adverse events.

  16. Robotic telementoring/telesurgical system and randomized evaluation study.

    Science.gov (United States)

    Patriciu, Alexandru; Challacombe, Benjamin; Dasgupta, Prokar; Kavoussi, Louis; Stoianovici, Dan

    2005-01-01

    The paper presents a new telementoring system incorporating audio-video communication and remote robotic control. The system was developed around an off the shelf ISDN video conferencing system enhanced with video annotation and remote robot control features. The user can remotely control a robot of perform needle alignment and insertion in a Percutaneous access procedure. Particular attention was devoted to ensure the safety of the procedure. The data connection is continuously monitored and in the event of a failure the robot control is switched to the local operator. Two series of randomized trials were performed between Baltimore and London. The accuracy and procedure time were evaluated for manual needle placement, local robotic needle placement and remotely controlled robotic needle placement. The test showed that while the procedure time is not improved by the robotic approach there is an improvement in the accuracy of the procedure. The study showed also that there is no significant difference between the locally controlled robotic needled placement and the remotely controlled robotic needle placement. Thus, the proposed system can be safely used for remote robotic percutaneous access procedures.

  17. Retromolar laryngoscopy: a randomized crossover vocal cords visualization study.

    Science.gov (United States)

    Reiterer, Christian; Waltl, Barbara; Kabon, Barbara; Schramm, Wolfgang

    2017-08-01

    Vocal cords visualization is a major determinant for successful tracheal intubation. The aim of our study was to compare vocal cord visualization by using conventional direct laryngoscopy with retromolar direct laryngoscopy in patients with an existing retromolar gap at the right mandible. We enrolled 100 adults needing endotracheal intubation for elective surgery. In each patient, the vocal cords were visualized and scored according to Cormack and Lehane with a Macintosh blade #3 for conventional technique and with a Miller blade #4 for the retromolar technique in a randomized sequence. Finally, tracheal intubation was performed primarily by conventional laryngoscopy and in the case of failing retromolar laryngoscopy was used as the rescue method. Overall 100 laryngoscopies with the conventional method and 100 laryngoscopies with the retromolar method were scored according to Cormack and Lehane. The retromolar technique achieved significant (P=0.000003) lower Cormack and Lehane scores compared to the conventional technique. In eleven patients, intubation by conventional laryngoscopy failed and seven of those patients were successfully intubated by the retromolar technique. A BURP-maneuver significantly improved vocal cord visualization during both methods. In summary, laryngoscopy via the retromolar method by using a Miller blade #4 lead to a significantly better vocal cord visualization compared to the conventional method performed with a Macintosh blade #3 in patients with an existing retromolar gap on the right side.

  18. Microbiota-based Signature of Gingivitis Treatments: A Randomized Study.

    Science.gov (United States)

    Huang, Shi; Li, Zhen; He, Tao; Bo, Cunpei; Chang, Jinlan; Li, Lin; He, Yanyan; Liu, Jiquan; Charbonneau, Duane; Li, Rui; Xu, Jian

    2016-04-20

    Plaque-induced gingivitis can be alleviated by various treatment regimens. To probe the impacts of various anti-gingivitis treatments on plaque microflora, here a double blinded, randomized controlled trial of 91 adults with moderate gingivitis was designed with two anti-gingivitis regimens: the brush-alone treatment and the brush-plus-rinse treatment. In the later group, more reduction in both Plaque Index (TMQHI) and Gingival Index (mean MGI) at Day 3, Day 11 and Day 27 was evident, and more dramatic changes were found between baseline and other time points for both supragingival plaque microbiota structure and salivary metabonomic profiles. A comparison of plaque microbiota changes was also performed between these two treatments and a third dataset where 50 subjects received regimen of dental scaling. Only Actinobaculum, TM7 and Leptotrichia were consistently reduced by all the three treatments, whereas the different microbial signatures of the three treatments during gingivitis relieve indicate distinct mechanisms of action. Our study suggests that microbiota based signatures can serve as a valuable approach for understanding and potentially comparing the modes of action for clinical treatments and oral-care products in the future.

  19. A comparative study of sampling techniques for monitoring carcass contamination

    NARCIS (Netherlands)

    Snijders, J.M.A.; Janssen, M.H.W.; Gerats, G.E.; Corstiaensen, G.P.

    1984-01-01

    Four bacteriological sampling techniques i.e. the excision, double swab, agar contract and modified agar contact techniques were compared by sampling pig carcasses before and after chilling. As well as assessing the advantages and disadvantages of the techniques particular attention was paid to

  20. A cluster-randomized trial of a middle school gender violence prevention program: Design, rationale, and sample characteristics.

    Science.gov (United States)

    Abebe, Kaleab Z; Jones, Kelley A; Ciaravino, Samantha; Ripper, Lisa; Paglisotti, Taylor; Morrow, Sarah Elizabeth; Grafals, Melanie; Van Dusen, Courtney; Miller, Elizabeth

    2017-11-01

    High rates of adolescent relationship abuse (ARA) and sexual violence (SV) reported among adolescents point to the need for prevention among middle school-age youth. This is a cluster randomized controlled trial to test an athletic coach-delivered ARA/SV prevention program in 41 middle schools (38 clusters). Trained coaches talk to their male athletes about 1) what constitutes harmful vs. respectful relationship behaviors, 2) dispelling myths that glorify male sexual aggression and promoting more gender-equitable attitudes, and 3) positive bystander intervention when aggressive male behaviors toward females are witnessed. A total of 973 male athletes (ages 11-14, grades 6-8) are participating. Athletes complete surveys at the beginning and end of sports season (Time 2), and one year later (Time 3). The primary outcome is an increase in positive bystander behaviors (i.e., intervening in peers' disrespectful or harmful behaviors); secondary outcomes are changes in recognition of what constitutes abusive behavior, intentions to intervene, and gender equitable attitudes (Time 2 and 3) as well as reduction in abuse perpetration (Time 3). Participating schools have a greater proportion of non-White students and students on free/reduced lunch compared to schools that declined participation. Participants' self-reported ethnicities are 54.5% White, 29.0% Black, 1.4% Hispanic and the remainder, multi-racial, other, or not reported. This study will evaluate the effectiveness of a coach-delivered ARA/SV prevention program for middle school male athletes. Findings will add to the evidence base regarding developmentally appropriate violence prevention programs as well as the role of coaches in adolescent health promotion. Clinical Trials #: NCT02331238. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  1. The Statistical Power of the Cluster Randomized Block Design with Matched Pairs--A Simulation Study

    Science.gov (United States)

    Dong, Nianbo; Lipsey, Mark

    2010-01-01

    This study uses simulation techniques to examine the statistical power of the group- randomized design and the matched-pair (MP) randomized block design under various parameter combinations. Both nearest neighbor matching and random matching are used for the MP design. The power of each design for any parameter combination was calculated from…

  2. Perspectives on randomization and readiness for change in a workplace intervention study

    DEFF Research Database (Denmark)

    Nabe-Nielsen, Kirsten; Persson, Roger; Nielsen, Karina

    2015-01-01

    Randomization is often recommended above self-selection when allocating participants into intervention or control groups. One source of confounding in non-randomized studies is the participants’ attitudes towards the intervention. Because randomized workplace interventions are not always feasible...... refl ect the local leaders’ rather than the employees’ readiness for changes and that randomization may infl uence the participants’ attitude towards the intervention perhaps by evoking an experience of ‘winning or losing in the lottery’....

  3. Analytical decision model for sample size and effectiveness projections for use in planning a population-based randomized controlled trial of colorectal cancer screening.

    Science.gov (United States)

    Chiu, Sherry Y-H; Malila, Nea; Yen, Amy M-F; Anttila, Ahti; Hakama, Matti; Chen, H-H

    2011-02-01

    Population-based randomized controlled trials (RCTs) often involve enormous costs and long-term follow-up to evaluate primary end points. Analytical decision-simulated model for sample size and effectiveness projections based on primary and surrogate end points are necessary before planning a population-based RCT. Based on the study design similar to two previous RCTs, transition rates were estimated using a five-state natural history model [normal, preclinical detection phase (PCDP) Dukes' A/B, PCDP Dukes' C/D, Clinical Dukes' A/B and Clinical Dukes' C/D]. The Markov cycle tree was assigned transition parameters, variables related to screening and survival rate that simulated results of 10-year follow-up in the absence of screening for a hypothetical cohort aged 45-74 years. The corresponding screened arm was to simulate the results after the introduction of population-based screening for colorectal cancer with fecal occult blood test with stop screen design. The natural course of mean sojourn time for five-state Markov model were estimated as 2.75 years for preclinical Dukes' A/B and 1.38 years for preclinical Dukes' C/D. The expected reductions in mortality and Dukes' C/D were 13% (95% confidence intervals: 7-19%) and 26% (95% confidence intervals: 20-32%), respectively, given a 70% acceptance rate and a 90% colonoscopy referral rate. Sample sizes required were 86,150 and 65,592 subjects for the primary end point and the surrogate end point, respectively, given an incidence rate up to 0.0020 per year. The sample sizes required for primary and surrogate end points and the projection of effectiveness of fecal occult blood test for colorectal cancer screening were developed. Both are very important to plan a population-based RCT. © 2010 Blackwell Publishing Ltd.

  4. A large-scale study of the random variability of a coding sequence: a study on the CFTR gene.

    Science.gov (United States)

    Modiano, Guido; Bombieri, Cristina; Ciminelli, Bianca Maria; Belpinati, Francesca; Giorgi, Silvia; Georges, Marie des; Scotet, Virginie; Pompei, Fiorenza; Ciccacci, Cinzia; Guittard, Caroline; Audrézet, Marie Pierre; Begnini, Angela; Toepfer, Michael; Macek, Milan; Ferec, Claude; Claustres, Mireille; Pignatti, Pier Franco

    2005-02-01

    Coding single nucleotide substitutions (cSNSs) have been studied on hundreds of genes using small samples (n(g) approximately 100-150 genes). In the present investigation, a large random European population sample (average n(g) approximately 1500) was studied for a single gene, the CFTR (Cystic Fibrosis Transmembrane conductance Regulator). The nonsynonymous (NS) substitutions exhibited, in accordance with previous reports, a mean probability of being polymorphic (q > 0.005), much lower than that of the synonymous (S) substitutions, but they showed a similar rate of subpolymorphic (q < 0.005) variability. This indicates that, in autosomal genes that may have harmful recessive alleles (nonduplicated genes with important functions), genetic drift overwhelms selection in the subpolymorphic range of variability, making disadvantageous alleles behave as neutral. These results imply that the majority of the subpolymorphic nonsynonymous alleles of these genes are selectively negative or even pathogenic.

  5. Behavioral approach with or without surgical intervention to the vulvar vestibulitis syndrome : A prospective randomized and non randomized study

    NARCIS (Netherlands)

    Schultz, WCMW; Gianotten, WL; vanderMeijden, WI; vandeWiel, HBM; Blindeman, L; Chadha, S; Drogendijk, AC

    This article describes the outcome of a behavioral approach with or without preceding surgical intervention in 48 women with the vulvar vestibulitis syndrome. In the first part of the study, 14 women with the vulvar vestibulitis syndrome were randomly assigned to one of two treatment programs:

  6. Sugammadex versus neostigmine in pediatric patients: a prospective randomized study

    Directory of Open Access Journals (Sweden)

    Turhan Kara

    2014-12-01

    Full Text Available Background and objectives: Acetylcholinesterase inhibitors may cause postoperative residual curarization when they are used for reversal of neuromuscular blockade. Sugammadex reverses neuromuscular blockade by chemical encapsulation and is not associated with the side effects that may occur with the use of anticholinesterase agents. Because of increased outpatient surgical procedures postoperative residual curarization and rapid postoperative recovery have a greater importance in the pediatric patient population. The aim of this study was to compare the efficacy of sugammadex and neostigmine on reversing neuromuscular blockade in pediatric patients undergoing outpatient surgical procedures. Methods: 80 patients, aged 2-12 years, scheduled for outpatient surgery were enrolled in this randomized prospective study. Neuromuscular blockade was achieved with 0.6 mgkg−1 rocuronium and monitorized with train-of-four. Group RN (n = 40 received 0.03 mgkg−1 neostigmine, Group RS (n = 40 received 2 mgkg−1 sugammadex for reversal of rocuronium. Extubation time (time from the reversal of neuromuscular blockade to extubation, train-of-four ratio during this time, time to reach train-of-four > 0.9, and probable complications were recorded. Results: There was no significant difference between the patients' characteristics. Extubation time and time to reach train-of-four > 0.9 were significantly higher in Group RN (p = 0.001, p = 0.002. Train-of-four at the time of neostigmine/sugammadex injection in Group RN were significantly higher than in the RS group (p = 0.020. Extubation train-of-four ratio was significantly lower in Group RN (p = 0.002. Conclusion: Sugammadex provides safer extubation with a shorter recovery time than neostigmine in pediatric patients undergoing outpatient surgical procedures.

  7. Physical abuse of older adults in nursing homes: a random sample survey of adults with an elderly family member in a nursing home.

    Science.gov (United States)

    Schiamberg, Lawrence B; Oehmke, James; Zhang, Zhenmei; Barboza, Gia E; Griffore, Robert J; Von Heydrich, Levente; Post, Lori A; Weatherill, Robin P; Mastin, Teresa

    2012-01-01

    Few empirical studies have focused on elder abuse in nursing home settings. The present study investigated the prevalence and risk factors of staff physical abuse among elderly individuals receiving nursing home care in Michigan. A random sample of 452 adults with elderly relatives, older than 65 years, and in nursing home care completed a telephone survey regarding elder abuse and neglect experienced by this elder family member in the care setting. Some 24.3% of respondents reported at least one incident of physical abuse by nursing home staff. A logistic regression model was used to estimate the importance of various risk factors in nursing home abuse. Limitations in activities of daily living (ADLs), older adult behavioral difficulties, and previous victimization by nonstaff perpetrators were associated with a greater likelihood of physical abuse. Interventions that address these risk factors may be effective in reducing older adult physical abuse in nursing homes. Attention to the contextual or ecological character of nursing home abuse is essential, particularly in light of the findings of this study.

  8. The Accuracy of Pass/Fail Decisions in Random and Difficulty-Balanced Domain-Sampling Tests.

    Science.gov (United States)

    Schnipke, Deborah L.

    A common practice in some certification fields (e.g., information technology) is to draw items from an item pool randomly and apply a common passing score, regardless of the items administered. Because these tests are commonly used, it is important to determine how accurate the pass/fail decisions are for such tests and whether fairly small,…

  9. Single-blind, randomized, pilot study combining shiatsu and amitriptyline in refractory primary headaches.

    Science.gov (United States)

    Villani, Veronica; Prosperini, Luca; Palombini, Fulvio; Orzi, Francesco; Sette, Giuliano

    2017-06-01

    Complementary alternative medicine, such as shiatsu, can represent a suitable treatment for primary headaches. However, evidence-based data about the effect of combining shiatsu and pharmacological treatments are still not available. Therefore, we tested the efficacy and safety of combining shiatsu and amitriptyline to treat refractory primary headaches in a single-blind, randomized, pilot study. Subjects with a diagnosis of primary headache and who experienced lack of response to ≥2 different prophylactic drugs were randomized in a 1:1:1 ratio to receive shiatsu plus amitriptyline, shiatsu alone, or amitriptyline alone for 3 months. Primary endpoint was the proportion of patients experiencing ≥50%-reduction in headache days. Secondary endpoints were days with headache per month, visual analogue scale, and number of pain killers taken per month. After randomization, 37 subjects were allocated to shiatsu plus amitriptyline (n = 11), shiatsu alone (n = 13), and amitriptyline alone (n = 13). Randomization ensured well-balanced demographic and clinical characteristics at baseline. Although all the three groups improved in terms of headache frequency, visual analogue scale score, and number of pain killers (p < 0.05), there was no between-group difference in primary endpoint (p = ns). Shiatsu (alone or in combination) was superior to amitriptyline in reducing the number of pain killers taken per month (p < 0.05). Seven (19%) subjects reported adverse events, all attributable to amitriptyline, while no side effects were related with shiatsu treatment. Shiatsu is a safe and potentially useful alternative approach for refractory headache. However, there is no evidence of an additive or synergistic effect of combining shiatsu and amitriptyline. These findings are only preliminary and should be interpreted cautiously due to the small sample size of the population included in our study. Trial registration 81/2010 (Ethical Committee, S. Andrea Hospital

  10. Cannabis use and risk of schizophrenia: a Mendelian randomization study.

    Science.gov (United States)

    Vaucher, J; Keating, B J; Lasserre, A M; Gan, W; Lyall, D M; Ward, J; Smith, D J; Pell, J P; Sattar, N; Paré, G; Holmes, M V

    2017-01-24

    Cannabis use is observationally associated with an increased risk of schizophrenia, but whether the relationship is causal is not known. Using a genetic approach, we took 10 independent genetic variants previously identified to associate with cannabis use in 32 330 individuals to determine the nature of the association between cannabis use and risk of schizophrenia. Genetic variants were employed as instruments to recapitulate a randomized controlled trial involving two groups (cannabis users vs nonusers) to estimate the causal effect of cannabis use on risk of schizophrenia in 34 241 cases and 45 604 controls from predominantly European descent. Genetically-derived estimates were compared with a meta-analysis of observational studies reporting ever use of cannabis and risk of schizophrenia or related disorders. Based on the genetic approach, use of cannabis was associated with increased risk of schizophrenia (odds ratio (OR) of schizophrenia for users vs nonusers of cannabis: 1.37; 95% confidence interval (CI), 1.09-1.67; P-value=0.007). The corresponding estimate from observational analysis was 1.43 (95% CI, 1.19-1.67; P-value for heterogeneity =0.76). The genetic markers did not show evidence of pleiotropic effects and accounting for tobacco exposure did not alter the association (OR of schizophrenia for users vs nonusers of cannabis, adjusted for ever vs never smoker: 1.41; 95% CI, 1.09-1.83). This adds to the substantial evidence base that has previously identified cannabis use to associate with increased risk of schizophrenia, by suggesting that the relationship is causal. Such robust evidence may inform public health messages about cannabis use, especially regarding its potential mental health consequences.Molecular Psychiatry advance online publication, 24 January 2017; doi:10.1038/mp.2016.252.

  11. Study of probe-sample distance for biomedical spectra measurement

    Directory of Open Access Journals (Sweden)

    Li Lei

    2011-11-01

    Full Text Available Abstract Background Fiber-based optical spectroscopy has been widely used for biomedical applications. However, the effect of probe-sample distance on the collection efficiency has not been well investigated. Method In this paper, we presented a theoretical model to maximize the illumination and collection efficiency in designing fiber optic probes for biomedical spectra measurement. This model was in general applicable to probes with single or multiple fibers at an arbitrary incident angle. In order to demonstrate the theory, a fluorescence spectrometer was used to measure the fluorescence of human finger skin at various probe-sample distances. The fluorescence spectrum and the total fluorescence intensity were recorded. Results The theoretical results show that for single fiber probes, contact measurement always provides the best results. While for multi-fiber probes, there is an optimal probe distance. When a 400- μm excitation fiber is used to deliver the light to the skin and another six 400- μm fibers surrounding the excitation fiber are used to collect the fluorescence signal, the experimental results show that human finger skin has very strong fluorescence between 475 nm and 700 nm under 450 nm excitation. The fluorescence intensity is heavily dependent on the probe-sample distance and there is an optimal probe distance. Conclusions We investigated a number of probe-sample configurations and found that contact measurement could be the primary choice for single-fiber probes, but was very inefficient for multi-fiber probes. There was an optimal probe-sample distance for multi-fiber probes. By carefully choosing the probe-sample distance, the collection efficiency could be enhanced by 5-10 times. Our experiments demonstrated that the experimental results of the probe-sample distance dependence of collection efficiency in multi-fiber probes were in general agreement with our theory.

  12. Traditional acupuncture in migraine: a controlled, randomized study.

    Science.gov (United States)

    Facco, Enrico; Liguori, Aldo; Petti, Filomena; Zanette, Gastone; Coluzzi, Flaminia; De Nardin, Marco; Mattia, Consalvo

    2008-03-01

    To check the effectiveness of a true acupuncture treatment according to traditional Chinese medicine (TCM) in migraine without aura, comparing it to a standard mock acupuncture protocol, an accurate mock acupuncture healing ritual, and untreated controls. Migraine prevalence is high and affects a relevant rate of adults in the productive phase of their life. Acupuncture has been increasingly advocated and used in Western countries for migraine treatment, but the evidence of its effectiveness still remains weak. A large variability of treatments is present in published studies and no acupoint selection according to TCM has been investigated so far; therefore, the low level of evidence of acupuncture effectiveness might partly depend on inappropriate treatment. A prospective, randomized, controlled study was performed in 160 patients suffering from migraine without aura, assessed according to the ICD-10 classification. The patients were divided into the following 4 groups: (1) group TA, treated with true acupuncture (according to TCM) plus Rizatriptan; (2) group RMA, treated with ritualized mock acupuncture plus Rizatriptan; (3) group SMA, treated with standard mock acupuncture plus Rizatriptan; (4) group R, without prophylactic treatment with relief therapy only (Rizatriptan). The MIDAS Questionnaire was administered before treatment (T0), at 3 (T1) and 6 months (T2) from the beginning of treatment, and the MIDAS Index (MI) was calculated. Rizatriptan intake was also checked in all groups of patients at T0, T1, and T2. Group TA and RMA were evaluated according to TCM as well; then, the former was submitted to true acupuncture and the latter to mock acupuncture treatment resembling the same as TA. The statistical analysis was conducted with factorial ANOVA and multiple tests with a Bonferroni adjustment. A total of 127 patients completed the study (33 dropouts): 32 belonged to group TA, 30 to group RMA, 31 to group SMA, and 34 to group R. Before treatment the MI (T(0

  13. Randomized Controlled Studies and Alternative Designs in Outcome Studies: Challenges and Opportunities

    Science.gov (United States)

    Shadish, William R.

    2011-01-01

    This article reviews several decades of the author's meta-analytic and experimental research on the conditions under which nonrandomized experiments can approximate the results from randomized experiments (REs). Several studies make clear that we can expect accurate effect estimates from the regression discontinuity design, though its statistical…

  14. Study on genetic variability of Cassidula aurisfelis (snail) by random ...

    African Journals Online (AJOL)

    The genetic variability among individuals of Cassidula aurisfelis from Setiu Wetland, Terengganu Darul Iman was examined by using the random amplified polymorphic DNA (RAPD) technique. Ten oligonucleotide primers were screened and three primers were selected (OPA 02, OPA 04 and OPA 10) to amplify DNA from ...

  15. Randomized, Controlled Study of Adderall XR in ADHD

    OpenAIRE

    J Gordon Millichap

    2002-01-01

    The efficacy and safety of Adderall XR in the treatment of attention deficit/hyperactivity disorder and diurnal variation in responses were assessed by a multicenter, randomized, double-blind, parallel group, placebo-controlled trial at 47 sites, and reported from the Massachusetts General Hospital, Boston, MA.

  16. Randomized, Controlled Study of Adderall XR in ADHD

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2002-08-01

    Full Text Available The efficacy and safety of Adderall XR in the treatment of attention deficit/hyperactivity disorder and diurnal variation in responses were assessed by a multicenter, randomized, double-blind, parallel group, placebo-controlled trial at 47 sites, and reported from the Massachusetts General Hospital, Boston, MA.

  17. Study on genetic variability of Cassidula aurisfelis (snail) by random ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-16

    Nov 16, 2009 ... genetic variability is Random Amplified Polymorphic. DNAs (RAPD) (Williams et al., 1990). The technique requires no prior knowledge of the genome and it needs ... quantity of DNA was measured by obtaining the absorbance read- ... 1994) and Numerical taxonomy and Multivariate Analysis System.

  18. The Study of Suicidal Behaviors Rates in the Community Sample of Karaj City in 2005

    Directory of Open Access Journals (Sweden)

    S.K. Malakouti

    2008-04-01

    Full Text Available Introduction & Objective: Although many studies have been conducted in Iran, but because of the importance of suicide problem in the mental health programs, it is still necessary to do some epidemiologic study. This study has addressed to suicidal behaviors rates in a community sample of Karaj city.Materials & Methods: Karaj with 1,000,000 population was selected as the environment of study. Our subjects (no=2300 were 15 years and older that were selected by randomized sampling. SUPRE-MISS questionnaire was employed in this survey.Results: 65% of the subjects were female, 57.2% of them were married , and most of them had high school level of education (48%. Housewife women were the most common category among occupational groups (43.3%. According to the results the prevalence of positive history for suicide behaviors (idea, plan, attempt were 12.7%, 6.2% & 3.3% respectively, and for current year were 5.7%, 2.9% & 1%.Conclusion: Suicidal behaviors in Iran, in spite of suicide leading to death, have similar prevalence to western countries.

  19. Comparing cluster-level dynamic treatment regimens using sequential, multiple assignment, randomized trials: Regression estimation and sample size considerations

    OpenAIRE

    NeCamp, Timothy; Kilbourne, Amy; Almirall, Daniel

    2016-01-01

    Cluster-level dynamic treatment regimens can be used to guide sequential, intervention or treatment decision-making at the cluster level in order to improve outcomes at the individual or patient-level. In a cluster-level DTR, the intervention or treatment is potentially adapted and re-adapted over time based on changes in the cluster that could be impacted by prior intervention, including based on aggregate measures of the individuals or patients that comprise it. Cluster-randomized sequentia...

  20. Study of gastric cancer samples using terahertz techniques

    Science.gov (United States)

    Wahaia, Faustino; Kasalynas, Irmantas; Seliuta, Dalius; Molis, Gediminas; Urbanowicz, Andrzej; Carvalho Silva, Catia D.; Carneiro, Fatima; Valusis, Gintaras; Granja, Pedro L.

    2014-08-01

    In the present work, samples of healthy and adenocarcinoma-affected human gastric tissue were analyzed using transmission time-domain THz spectroscopy (THz-TDS) and spectroscopic THz imaging at 201 and 590 GHz. The work shows that it is possible to distinguish between normal and cancerous regions in dried and paraffin-embedded samples. Plots of absorption coefficient α and refractive index n of normal and cancer affected tissues, as well as 2-D transmission THz images are presented and the conditions for discrimination between normal and affected tissues are discussed.

  1. Approximating the variance of estimated means for systematic random sampling, illustrated with data of the French Soil Monitoring Network

    NARCIS (Netherlands)

    Brus, D.J.; Saby, N.P.A.

    2016-01-01

    In France like in many other countries, the soil is monitored at the locations of a regular, square grid thus forming a systematic sample (SY). This sampling design leads to good spatial coverage, enhancing the precision of design-based estimates of spatial means and totals. Design-based

  2. Sample size for regression analyses of theory of planned behaviour studies: case of prescribing in general practice.

    Science.gov (United States)

    Rashidian, Arash; Miles, Jeremy; Russell, Daphne; Russell, Ian

    2006-11-01

    Interest has been growing in the use of the theory of planned behaviour (TBP) in health services research. The sample sizes range from less than 50 to more than 750 in published TPB studies without sample size calculations. We estimate the sample size for a multi-stage random survey of prescribing intention and actual prescribing for asthma in British general practice. To our knowledge, this is the first systematic attempt to determine sample size for a TPB survey. We use two different approaches: reported values of regression models' goodness-of-fit (the lambda method) and zero-order correlations (the variance inflation factor or VIF method). Intra-cluster correlation coefficient (ICC) is estimated and a socioeconomic variable is used for stratification. We perform sensitivity analysis to estimate the effects of our decisions on final sample size. The VIF method is more sensitive to the requirements of a TPB study. Given a correlation of .25 between intention and behaviour, and of .4 between intention and perceived behavioural control, the proposed sample size is 148. We estimate the ICC for asthma prescribing to be around 0.07. If 10 general practitioners were sampled per cluster, the sample size would be 242. It is feasible to perform sophisticated sample size calculations for a TPB study. The VIF is the appropriate method. Our approach can be used with adjustments in other settings and for other regression models.

  3. Salacia Extract Improves Postprandial Glucose and Insulin Response: A Randomized Double-Blind, Placebo Controlled, Crossover Study in Healthy Volunteers

    Directory of Open Access Journals (Sweden)

    Shankaranarayanan Jeykodi

    2016-01-01

    Full Text Available Thirty-five healthy subjects were randomly assigned to different doses of Salacia chinensis extract (200 mg, 300 mg, and 500 mg SCE capsules and compared with placebo. It is a placebo controlled randomized crossover design study. Subjects were given oral sucrose solution along with capsules and plasma glucose and insulin responses were analyzed. Blood samples were collected at 0, 30, 60, 90, 120, and 180 minutes after administration. AUC insulin significantly lowered after ingestion of SCE. No significant adverse events were observed. Reducing glucose and insulin is very important in reducing postprandial hyperglycemia.

  4. [EFFICACY OF SELF-MONITORING IN WEIGHT LOSS: A SYSTEMATIC REVIEW OF RANDOMIZED CONTROLLED STUDIES].

    Science.gov (United States)

    Estrada Ruelas, Katia; Bacardí-Gascon, Montserrat; Jiménez-Cruz, Arturo

    2015-12-01

    different studies have shown a strong relationship between self-monitoring and weight loss. The objective of this review was to analyze randomized clinical trials using self-monitoring as a strategy for weight loss. a search was conducted in PubMed database of randomized controlled trials using self-monitoring for weight loss in adults, published in English and Spanish, from January 1st, 2009 to April 30th, 2015. The sample size, age, weight loss, BMI, intervention strategy, duration, and retention rate, were recorded. six studies met the selection criteria. The intervention and the follow-up ranged from 3 to 12 months. The study population ranged from 18-74 years of age and included subjects from 50-329. Weight loss ranged from 1.14 to 2.1 kg in the control group and -1.27 to -6.1 kg in the intervention group. The six studies determined a greater weight loss in the self-monitoring group with moderate to high evaluation evidence. greater weight loss was consistently found in the self-monitoring group. These results suggest the need to use self-monitoring as a strategy for weight loss. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  5. GY SAMPLING THEORY IN ENVIRONMENTAL STUDIES 2: SUBSAMPLING ERROR MEASUREMENTS

    Science.gov (United States)

    Sampling can be a significant source of error in the measurement process. The characterization and cleanup of hazardous waste sites require data that meet site-specific levels of acceptable quality if scientifically supportable decisions are to be made. In support of this effort,...

  6. Comparative Studies of Gasoline Samples Used in Nigeria | Faruq ...

    African Journals Online (AJOL)

    Comparative analysis was carried out on five samples of gasoline in the Nigerian market based on octane number, sulphur content, Reid vapour pressure, specific gravity, boiling point characteristics and chemical content. The result revealed that, Nigerian and Kuwait gasolines have low octane numbers in comparison to ...

  7. Planning Longitudinal Field Studies: Considerations in Determining Sample Size.

    Science.gov (United States)

    St.Pierre, Robert G.

    1980-01-01

    Factors that influence the sample size necessary for longitudinal evaluations include the nature of the evaluation questions, nature of available comparison groups, consistency of the treatment in different sites, effect size, attrition rate, significance level for statistical tests, and statistical power. (Author/GDC)

  8. Sampling considerations for demographic and habitat studies of Northern Goshawks

    Science.gov (United States)

    Richard T. Reynolds; J. David Wiens; Suzanne M. Joy; Susan R. Salafsky

    2005-01-01

    We used mark-recapture methods to monitor Northern Goshawks (Accipiter gentilis) and their nests over 12 yr in an increasing sample of breeding territories (37 in 1991 to 121 in 2002) in northern Arizona. As many as 8 yr of repeated nest searching were required to identify the population of breeders, as individuals skipped egg-laying on territories...

  9. Strip transect sampling and analysis for avian habitat studies

    Science.gov (United States)

    Richard N. Conner; James G. Dickson

    1980-01-01

    Censusing procedures that detect effects of habitat treatment on birds are outlined. We suggest that only relative values of bird species diversity, equitability, abundance, and species richness need be obtained. We also suggest that 4, 250-m strip transects per treatment and 8-10 trips over each transect are adequate. Aspects of sampling design that affect within-...

  10. Audio-recorded information to patients considering participation in cancer clinical trials - a randomized study.

    Science.gov (United States)

    Bergenmar, Mia; Johansson, Hemming; Wilking, Nils; Hatschek, Thomas; Brandberg, Yvonne

    2014-09-01

    Patient information in cancer clinical trial is challenging. The value of audio-recording interventions for patients considering participating in clinical trials is unclear. The primary aim of this randomized study was to investigate effects of audio-recorded information on knowledge and understanding in patients considering participation in a clinical trial. Patients scheduled for information about a phases 2 or 3 trial by one of the 13 participating oncologists at the Department of Oncology during the study period (2008-2013) were eligible. The intervention consisted of an audio-recording on compact disc (CD) of the information at the medical consultation in which the patients were informed about a trial. Knowledge and understanding was measured by the questionnaire, Quality of Informed Consent. A total of 130 patients were randomized, 70% of the calculated sample size (n = 186). Sixty-seven patients were randomized to the intervention. In total, 101 patients (78%) completed questionnaires. No statistical significant differences were found between the groups with respect to knowledge and understanding. The level of knowledge was relatively high, with the exceptions of the risks associated with, and the unproven nature of, the trial. Overall, patients who declined participation scored statistically significant lower on knowledge. The present study was underpowered and the results should therefore be interpreted with caution. Still, 130 patients were included with a response rate of 78%. A CD including the oral information about a clinical trial did not show any effects on knowledge or understanding. However, the levels of knowledge were high, possible due to the high levels of education in the study group. Information on risks associated with the trial is still an area for improvement.

  11. A description of the demographic characteristics of the New Zealand non-commercial horse population with data collected using a generalised random-tessellation stratified sampling design.

    Science.gov (United States)

    Rosanowski, S M; Cogger, N; Rogers, C W; Benschop, J; Stevenson, M A

    2012-12-01

    We conducted a cross-sectional survey to determine the demographic characteristics of non-commercial horses in New Zealand. A sampling frame of properties with non-commercial horses was derived from the national farms database, AgriBase™. Horse properties were stratified by property size and a generalised random-tessellated stratified (GRTS) sampling strategy was used to select properties (n=2912) to take part in the survey. The GRTS sampling design allowed for the selection of properties that were spatially balanced relative to the distribution of horse properties throughout the country. The registered decision maker of the property, as identified in AgriBase™, was sent a questionnaire asking them to describe the demographic characteristics of horses on the property, including the number and reason for keeping horses, as well as information about other animals kept on the property and the proximity of boundary neighbours with horses. The response rate to the survey was 38% (1044/2912) and the response rate was not associated with property size or region. A total of 5322 horses were kept for recreation, competition, racing, breeding, stock work, or as pets. The reasons for keeping horses and the number and class of horses varied significantly between regions and by property size. Of the properties sampled, less than half kept horses that could have been registered with Equestrian Sports New Zealand or either of the racing codes. Of the respondents that reported knowing whether their neighbours had horses, 58.6% (455/776) of properties had at least one boundary neighbour that kept horses. The results of this study have important implications for New Zealand, which has an equine population that is naïve to many equine diseases considered endemic worldwide. The ability to identify, and apply accurate knowledge of the population at risk to infectious disease control strategies would lead to more effective strategies to control and prevent disease spread during an

  12. A randomized controlled trial of smartphone-based mindfulness training for smoking cessation: a study protocol.

    Science.gov (United States)

    Garrison, Kathleen A; Pal, Prasanta; Rojiani, Rahil; Dallery, Jesse; O'Malley, Stephanie S; Brewer, Judson A

    2015-04-14

    Tobacco use is responsible for the death of about 1 in 10 individuals worldwide. Mindfulness training has shown preliminary efficacy as a behavioral treatment for smoking cessation. Recent advances in mobile health suggest advantages to smartphone-based smoking cessation treatment including smartphone-based mindfulness training. This study evaluates the efficacy of a smartphone app-based mindfulness training program for improving smoking cessation rates at 6-months follow-up. A two-group parallel-randomized clinical trial with allocation concealment will be conducted. Group assignment will be concealed from study researchers through to follow-up. The study will be conducted by smartphone and online. Daily smokers who are interested in quitting smoking and own a smartphone (n = 140) will be recruited through study advertisements posted online. After completion of a baseline survey, participants will be allocated randomly to the control or intervention group. Participants in both groups will receive a 22-day smartphone-based treatment program for smoking. Participants in the intervention group will receive mobile mindfulness training plus experience sampling. Participants in the control group will receive experience sampling-only. The primary outcome measure will be one-week point prevalence abstinence from smoking (at 6-months follow-up) assessed using carbon monoxide breath monitoring, which will be validated through smartphone-based video chat. This is the first intervention study to evaluate smartphone-based delivery of mindfulness training for smoking cessation. Such an intervention may provide treatment in-hand, in real-world contexts, to help individuals quit smoking. Clinicaltrials.gov NCT02134509 . Registered 7 May 2014.

  13. Whose sample is it anyway? Widespread misannotation of samples in transcriptomics studies [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Lilah Toker

    2016-08-01

    Full Text Available Concern about the reproducibility and reliability of biomedical research has been rising. An understudied issue is the prevalence of sample mislabeling, one impact of which would be invalid comparisons. We studied this issue in a corpus of human transcriptomics studies by comparing the provided annotations of sex to the expression levels of sex-specific genes. We identified apparent mislabeled samples in 46% of the datasets studied, yielding a 99% confidence lower-bound estimate for all studies of 33%. In a separate analysis of a set of datasets concerning a single cohort of subjects, 2/4 had mislabeled samples, indicating laboratory mix-ups rather than data recording errors. While the number of mixed-up samples per study was generally small, because our method can only identify a subset of potential mix-ups, our estimate is conservative for the breadth of the problem. Our findings emphasize the need for more stringent sample tracking, and that re-users of published data must be alert to the possibility of annotation and labelling errors.

  14. A profile of US-Mexico border mobility among a stratified random sample of Hispanics living in the El Paso-Juarez area.

    Science.gov (United States)

    Lapeyrouse, L M; Morera, O; Heyman, J M C; Amaya, M A; Pingitore, N E; Balcazar, H

    2012-04-01

    Examination of border-specific characteristics such as trans-border mobility and transborder health service illuminates the heterogeneity of border Hispanics and may provide greater insight toward understanding differential health behaviors and status among these populations. In this study, we create a descriptive profile of the concept of trans-border mobility by exploring the relationship between mobility status and a series of demographic, economic and socio-cultural characteristics among mobile and non-mobile Hispanics living in the El Paso-Juarez border region. Using a two-stage stratified random sampling design, bilingual interviewers collected survey data from border residents (n = 1,002). Findings show that significant economic, cultural, and behavioral differences exist between mobile and non-mobile respondents. While non-mobile respondents were found to have higher social economic status than their mobile counterparts, mobility across the border was found to offer less acculturated and poorer Hispanics access to alternative sources of health care and other services.

  15. Thermal discomfort with cold extremities in relation to age, gender, and body mass index in a random sample of a Swiss urban population

    Directory of Open Access Journals (Sweden)

    Orgül Selim

    2010-06-01

    Full Text Available Abstract Background The aim of this epidemiological study was to investigate the relationship of thermal discomfort with cold extremities (TDCE to age, gender, and body mass index (BMI in a Swiss urban population. Methods In a random population sample of Basel city, 2,800 subjects aged 20-40 years were asked to complete a questionnaire evaluating the extent of cold extremities. Values of cold extremities were based on questionnaire-derived scores. The correlation of age, gender, and BMI to TDCE was analyzed using multiple regression analysis. Results A total of 1,001 women (72.3% response rate and 809 men (60% response rate returned a completed questionnaire. Statistical analyses revealed the following findings: Younger subjects suffered more intensely from cold extremities than the elderly, and women suffered more than men (particularly younger women. Slimmer subjects suffered significantly more often from cold extremities than subjects with higher BMIs. Conclusions Thermal discomfort with cold extremities (a relevant symptom of primary vascular dysregulation occurs at highest intensity in younger, slimmer women and at lowest intensity in elderly, stouter men.

  16. Glutamine Randomized Studies in Early Life: The Unsolved Riddle of Experimental and Clinical Studies

    Directory of Open Access Journals (Sweden)

    Efrossini Briassouli

    2012-01-01

    Full Text Available Glutamine may have benefits during immaturity or critical illness in early life but its effects on outcome end hardpoints are controversial. Our aim was to review randomized studies on glutamine supplementation in pups, infants, and children examining whether glutamine affects outcome. Experimental work has proposed various mechanisms of glutamine action but none of the randomized studies in early life showed any effect on mortality and only a few showed some effect on inflammatory response, organ function, and a trend for infection control. Although apparently safe in animal models (pups, premature infants, and critically ill children, glutamine supplementation does not reduce mortality or late onset sepsis, and its routine use cannot be recommended in these sensitive populations. Large prospectively stratified trials are needed to better define the crucial interrelations of “glutamine-heat shock proteins-stress response” in critical illness and to identify the specific subgroups of premature neonates and critically ill infants or children who may have a greater need for glutamine and who may eventually benefit from its supplementation. The methodological problems noted in the reviewed randomized experimental and clinical trials should be seriously considered in any future well-designed large blinded randomized controlled trial involving glutamine supplementation in critical illness.

  17. A robust and efficient statistical method for genetic association studies using case and control samples from multiple cohorts.

    Science.gov (United States)

    Wang, Minghui; Wang, Lin; Jiang, Ning; Jia, Tianye; Luo, Zewei

    2013-02-08

    The theoretical basis of genome-wide association studies (GWAS) is statistical inference of linkage disequilibrium (LD) between any polymorphic marker and a putative disease locus. Most methods widely implemented for such analyses are vulnerable to several key demographic factors and deliver a poor statistical power for detecting genuine associations and also a high false positive rate. Here, we present a likelihood-based statistical approach that accounts properly for non-random nature of case-control samples in regard of genotypic distribution at the loci in populations under study and confers flexibility to test for genetic association in presence of different confounding factors such as population structure, non-randomness of samples etc. We implemented this novel method together with several popular methods in the literature of GWAS, to re-analyze recently published Parkinson's disease (PD) case-control samples. The real data analysis and computer simulation show that the new method confers not only significantly improved statistical power for detecting the associations but also robustness to the difficulties stemmed from non-randomly sampling and genetic structures when compared to its rivals. In particular, the new method detected 44 significant SNPs within 25 chromosomal regions of size methods. It discovered two SNPs located 1.18 Mb and 0.18 Mb from the PD candidates, FGF20 and PARK8, without invoking false positive risk. We developed a novel likelihood-based method which provides adequate estimation of LD and other population model parameters by using case and control samples, the ease in integration of these samples from multiple genetically divergent populations and thus confers statistically robust and powerful analyses of GWAS. On basis of simulation studies and analysis of real datasets, we demonstrated significant improvement of the new method over the non-parametric trend test, which is the most popularly implemented in the literature of GWAS.

  18. Study of an RF Direct Sampling Technique for Geodetic VLBI

    Science.gov (United States)

    Takefuji, K.; Kondo, T.; Sekido, M.; Ichikawa, R.; Kurihara, S.; Kokado, K.; Kawabata, R.

    2012-12-01

    Recently some digital samplers, which involve high RF frequency sensitivity, have been developed. We installed such samplers (sensitivity up to 24 GHz) at the Kashima 11-m station and the Tsukuba 32-m station (about 50 km baseline) in Japan and directly sampled X-band without any frequency conversion such as analog mixers. After the correlation process, we successfully detected first fringes at X-band. For the purpose of observing geodetic VLBI, we mixed signals of the S-band and the X-band just after the low noise amplifier. The mixed signal became overlapped and aliased baseband signals after 1024 MHz, 2-bit sampling. We could obtain four fringes (one from S-band and three from X-band), which came from the overlapped baseband signals, and successfully determined the baseline length.

  19. Multiwavelength studies of X-ray selected extragalactic sample

    OpenAIRE

    Mickaelian, A. M.; Paronyan, G. M.; Harutyunyan, G. S.; Abrahamyan, H. V.; Gyulzadyan, M. V.

    2015-01-01

    The joint catalogue of Active Galactic Nuclei selected from optical identifications of X-ray sources was created as a combination of two samples: Hamburg-ROSAT Catalogue (HRC) and Byurakan-Hamburg-ROSAT Catalogue (BHRC). Both are based on optical identifications of X-ray sources from ROSAT catalogues using low-dispersion spectra of Hamburg Quasar Survey (HQS). However, HRC and BHRC contain a number of misidentifications and using the recent optical and multiwavelength (MW) catalogues we have ...

  20. Differentiating emotions across contexts: comparing adults with and without social anxiety disorder using random, social interaction, and daily experience sampling.

    Science.gov (United States)

    Kashdan, Todd B; Farmer, Antonina S

    2014-06-01

    The ability to recognize and label emotional experiences has been associated with well-being and adaptive functioning. This skill is particularly important in social situations, as emotions provide information about the state of relationships and help guide interpersonal decisions, such as whether to disclose personal information. Given the interpersonal difficulties linked to social anxiety disorder (SAD), deficient negative emotion differentiation may contribute to impairment in this population. We hypothesized that people with SAD would exhibit less negative emotion differentiation in daily life, and these differences would translate to impairment in social functioning. We recruited 43 people diagnosed with generalized SAD and 43 healthy adults to describe the emotions they experienced over 14 days. Participants received palmtop computers for responding to random prompts and describing naturalistic social interactions; to complete end-of-day diary entries, they used a secure online website. We calculated intraclass correlation coefficients to capture the degree of differentiation of negative and positive emotions for each context (random moments, face-to-face social interactions, and end-of-day reflections). Compared to healthy controls, the SAD group exhibited less negative (but not positive) emotion differentiation during random prompts, social interactions, and (at trend level) end-of-day assessments. These differences could not be explained by emotion intensity or variability over the 14 days, or to comorbid depression or anxiety disorders. Our findings suggest that people with generalized SAD have deficits in clarifying specific negative emotions felt at a given point of time. These deficits may contribute to difficulties with effective emotion regulation and healthy social relationship functioning.

  1. Differentiating Emotions Across Contexts: Comparing Adults with and without Social Anxiety Disorder Using Random, Social Interaction, and Daily Experience Sampling

    Science.gov (United States)

    Kashdan, Todd B.; Farmer, Antonina S.

    2014-01-01

    The ability to recognize and label emotional experiences has been associated with well-being and adaptive functioning. This skill is particularly important in social situations, as emotions provide information about the state of relationships and help guide interpersonal decisions, such as whether to disclose personal information. Given the interpersonal difficulties linked to social anxiety disorder (SAD), deficient negative emotion differentiation may contribute to impairment in this population. We hypothesized that people with SAD would exhibit less negative emotion differentiation in daily life, and these differences would translate to impairment in social functioning. We recruited 43 people diagnosed with generalized SAD and 43 healthy adults to describe the emotions they experienced over 14 days. Participants received palmtop computers for responding to random prompts and describing naturalistic social interactions; to complete end-of-day diary entries, they used a secure online website. We calculated intraclass correlation coefficients to capture the degree of differentiation of negative and positive emotions for each context (random moments, face-to-face social interactions, and end-of-day reflections). Compared to healthy controls, the SAD group exhibited less negative (but not positive) emotion differentiation during random prompts, social interactions, and (at trend level) end-of-day assessments. These differences could not be explained by emotion intensity or variability over the 14 days, or to comorbid depression or anxiety disorders. Our findings suggest that people with generalized SAD have deficits in clarifying specific negative emotions felt at a given point of time. These deficits may contribute to difficulties with effective emotion regulation and healthy social relationship functioning. PMID:24512246

  2. Age at menarche and lung function: a Mendelian randomization study

    OpenAIRE

    Gill, Dipender; Sheehan, Nuala A; Wielscher, Matthias; Shrine, Nick; Amaral, Andre F. S.; Thompson, John R.; Granell, Raquel; Leynaert, Bénédicte; Real, Francisco Gómez; Hall, Ian P.; Tobin, Martin D; Auvinen, Juha; Ring, Susan M.; Jarvelin, Marjo-Riitta; Wain, Louise V

    2017-01-01

    A trend towards earlier menarche in women has been associated with childhood factors (e.g. obesity) and hypothesised environmental exposures (e.g. endocrine disruptors present in household products). Observational evidence has shown detrimental effects of early menarche on various health outcomes including adult lung function, but these might represent spurious associations due to confounding. To address this we used Mendelian randomization where genetic variants are used as proxies for age a...

  3. Childhood adiposity and risk of type 1 diabetes: A Mendelian randomization study.

    Science.gov (United States)

    Censin, J C; Nowak, Christoph; Cooper, Nicholas; Bergsten, Peter; Todd, John A; Fall, Tove

    2017-08-01

    The incidence of type 1 diabetes (T1D) is increasing globally. One hypothesis is that increasing childhood obesity rates may explain part of this increase, but, as T1D is rare, intervention studies are challenging to perform. The aim of this study was to assess this hypothesis with a Mendelian randomization approach that uses genetic variants as instrumental variables to test for causal associations. We created a genetic instrument of 23 single nucleotide polymorphisms (SNPs) associated with childhood adiposity in children aged 2-10 years. Summary-level association results for these 23 SNPs with childhood-onset (Mendelian randomization analysis, we found support for an effect of childhood adiposity on T1D risk (odds ratio 1.32, 95% CI 1.06-1.64 per standard deviation score in body mass index [SDS-BMI]). A sensitivity analysis provided evidence of horizontal pleiotropy bias (p = 0.04) diluting the estimates towards the null. We therefore applied Egger regression and multivariable Mendelian randomization methods to control for this type of bias and found evidence in support of a role of childhood adiposity in T1D (odds ratio in Egger regression, 2.76, 95% CI 1.40-5.44). Limitations of our study include that underlying genes and their mechanisms for most of the genetic variants included in the score are not known. Mendelian randomization requires large sample sizes, and power was limited to provide precise estimates. This research has been conducted using data from the Early Growth Genetics (EGG) Consortium, the Genetic Investigation of Anthropometric Traits (GIANT) Consortium, the Tobacco and Genetics (TAG) Consortium, and the Social Science Genetic Association Consortium (SSGAC), as well as meta-analysis results from a T1D genome-wide association study. This study provides genetic support for a link between childhood adiposity and T1D risk. Together with evidence from observational studies, our findings further emphasize the importance of measures to reduce the

  4. Exploring the Causal Pathway From Telomere Length to Coronary Heart Disease: A Network Mendelian Randomization Study.

    Science.gov (United States)

    Zhan, Yiqiang; Karlsson, Ida K; Karlsson, Robert; Tillander, Annika; Reynolds, Chandra A; Pedersen, Nancy L; Hägg, Sara

    2017-07-21

    Observational studies have found shorter leukocyte telomere length (TL) to be a risk factor for coronary heart disease (CHD), and recently the association was suggested to be causal. However, the relationship between TL and common metabolic risk factors for CHD is not well understood. Whether these risk factors could explain pathways from TL to CHD warrants further attention. To examine whether metabolic risk factors for CHD mediate the causal pathway from short TL to increased risk of CHD using a network Mendelian randomization design. Summary statistics from several genome-wide association studies were used in a 2-sample Mendelian randomization study design. Network Mendelian randomization analysis-an approach using genetic variants as the instrumental variables for both the exposure and mediator to infer causality-was performed to examine the causal association between telomeres and CHD and metabolic risk factors. Summary statistics from the ENGAGE Telomere Consortium were used (n=37 684) as a TL genetic instrument, CARDIoGRAMplusC4D Consortium data were used (case=22 233 and control=64 762) for CHD, and other consortia data were used for metabolic traits (fasting insulin, triglyceride, total cholesterol, low-density lipoprotein cholesterol, fasting glucose, diabetes mellitus, glycohemoglobin, body mass index, waist circumference, and waist:hip ratio). One-unit increase of genetically determined TL was associated with -0.07 (95% confidence interval, -0.01 to -0.12; P=0.01) lower log-transformed fasting insulin (pmol/L) and 21% lower odds (95% confidence interval, 3-35; P=0.02) of CHD. Higher genetically determined log-transformed fasting insulin level was associated with higher CHD risk (odds ratio, 1.86; 95% confidence interval, 1.01-3.41; P=0.04). Overall, our findings support a role of insulin as a mediator on the causal pathway from shorter telomeres to CHD pathogenesis. © 2017 American Heart Association, Inc.

  5. Managing mobility outcomes in vulnerable seniors ( MMOVeS): a randomized controlled pilot study.

    Science.gov (United States)

    Figueiredo, Sabrina; Morais, Jose A; Mayo, Nancy

    2017-12-01

    To estimate feasibility and potential for efficacy of an individualized, exercise-focused, self-management program (i.e. Managing Mobility Outcomes In Vulnerable Seniors ( MMOVeS)), in comparison to exercise information in improving mobility after six months among seniors recently discharged from hospital. Randomized pilot study. Two McGill University-teaching hospitals. Community dwelling seniors, aged 70 years and older, recently discharged from either participating hospitals. The physiotherapy-facilitated intervention consisted of (1) evaluation of mobility capacity, (2) setting short- and long-term goals, (3) delineation of an exercise treatment plan, (4) an educational booklet to enhance mobility self-management skills, and (5) six monthly telephone calls. Control group received a booklet with information on exercises targeting mobility limitations in seniors. Mobility, pain, and health status were assessed at baseline and at six months using multiple indicators drawn from Disabilities of the Arm, Shoulder, and Hand (DASH) Score, Lower Extremity Functional Scale (LEFS) and Short-Form (SF)-36. In all, 26 people were randomized to the intervention (mean age: 81 ± 8; 39% women), and 23 were randomized to the control (mean age: 79 ± 7; 33% women). The odds ratio for the mobility outcomes combined was 3.08 and the 95% confidence interval excluded 1 (1.65-5.77). The odds ratio for pain and health perception favored the MMOVeS group, but the 95% confidence interval included the null value. This feasibility study highlights the potential for efficacy of an individualized, exercise-focused, self-management program in comparison to exercise information in improving mobility outcome for seniors. Furthermore, a home-program combining self-management skills and exercise taught with minimal supervision prove to be feasible. Finally, data from this study can be used to estimate sample size for a confirmatory trial.

  6. A double SIMEX approach for bivariate random-effects meta-analysis of diagnostic accuracy studies

    Directory of Open Access Journals (Sweden)

    Annamaria Guolo

    2017-01-01

    Full Text Available Abstract Background Bivariate random-effects models represent a widely accepted and recommended approach for meta-analysis of test accuracy studies. Standard likelihood methods routinely used for inference are prone to several drawbacks. Small sample size can give rise to unreliable inferential conclusions and convergence issues make the approach unappealing. This paper suggests a different methodology to address such difficulties. Methods A SIMEX methodology is proposed. The method is a simulation-based technique originally developed as a correction strategy within the measurement error literature. It suits the meta-analysis framework as the diagnostic accuracy measures provided by each study are prone to measurement error. SIMEX can be straightforwardly adapted to cover different measurement error structures and to deal with covariates. The effortless implementation with standard software is an interesting feature of the method. Results Extensive simulation studies highlight the improvement provided by SIMEX over likelihood approach in terms of empirical coverage probabilities of confidence intervals under different scenarios, independently of the sample size and the values of the correlation between sensitivity and specificity. A remarkable amelioration is obtained in case of deviations from the normality assumption for the random-effects distribution. From a computational point of view, the application of SIMEX is shown to be neither involved nor subject to the convergence issues affecting likelihood-based alternatives. Application of the method to a diagnostic review of the performance of transesophageal echocardiography for assessing ascending aorta atherosclerosis enables overcoming limitations of the likelihood procedure. Conclusions The SIMEX methodology represents an interesting alternative to likelihood-based procedures for inference in meta-analysis of diagnostic accuracy studies. The approach can provide more accurate inferential

  7. Effects of delayed compared with early umbilical cord clamping on maternal postpartum hemorrhage and cord blood gas sampling: a randomized trial.

    Science.gov (United States)

    Andersson, Ola; Hellström-Westas, Lena; Andersson, Dan; Clausen, Jesper; Domellöf, Magnus

    2013-05-01

    To investigate the effect of delayed cord clamping (DCC) compared with early cord clamping (ECC) on maternal postpartum hemorrhage (PPH) and umbilical cord blood gas sampling. Secondary analysis of a parallel-group, single-center, randomized controlled trial. Swedish county hospital. 382 term deliveries after a low-risk pregnancy. Deliveries were randomized to DCC (≥180 seconds, n = 193) or ECC (≤10 seconds, n = 189). Maternal blood loss was estimated by the midwife. Samples for blood gas analysis were taken from one umbilical artery and the umbilical vein, from the pulsating unclamped cord in the DCC group and from the double-clamped cord in the ECC group. Samples were classified as valid when the arterial-venous difference was -0.02 or less for pH and 0.5 kPa or more for pCO2 . Main outcome measures. PPH and proportion of valid blood gas samples. The differences between the DCC and ECC groups with regard to PPH (1.2%, p = 0.8) and severe PPH (-2.7%, p = 0.3) were small and non-significant. The proportion of valid blood gas samples was similar between the DCC (67%, n = 130) and ECC (74%, n = 139) groups, with 6% (95% confidence interval: -4%-16%, p = 0.2) fewer valid samples after DCC. Delayed cord clamping, compared with early, did not have a significant effect on maternal postpartum hemorrhage or on the proportion of valid blood gas samples. We conclude that delayed cord clamping is a feasible method from an obstetric perspective. © 2012 The Authors Acta Obstetricia et Gynecologica Scandinavica© 2012 Nordic Federation of Societies of Obstetrics and Gynecology.

  8. Sample size determination for assessing equivalence based on proportion ratio under a randomized trial with non-compliance and missing outcomes.

    Science.gov (United States)

    Lui, Kung-Jong; Chang, Kuang-Chao

    2008-01-15

    When a generic drug is developed, it is important to assess the equivalence of therapeutic efficacy between the new and the standard drugs. Although the number of publications on testing equivalence and its relevant sample size determination is numerous, the discussion on sample size determination for a desired power of detecting equivalence under a randomized clinical trial (RCT) with non-compliance and missing outcomes is limited. In this paper, we derive under the compound exclusion restriction model the maximum likelihood estimator (MLE) for the ratio of probabilities of response among compliers between two treatments in a RCT with both non-compliance and missing outcomes. Using the MLE with the logarithmic transformation, we develop an asymptotic test procedure for assessing equivalence and find that this test procedure can perform well with respect to type I error based on Monte Carlo simulation. We further develop a sample size calculation formula for a desired power of detecting equivalence at a nominal alpha-level. To evaluate the accuracy of the sample size calculation formula, we apply Monte Carlo simulation again to calculate the simulated power of the proposed test procedure corresponding to the resulting sample size for a desired power of 80 per cent at 0.05 level in a variety of situations. We also include a discussion on determining the optimal ratio of sample size allocation subject to a desired power to minimize a linear cost function and provide a sensitivity analysis of the sample size formula developed here under an alterative model with missing at random. Copyright (c) 2007 John Wiley & Sons, Ltd.

  9. Can we rely on out-of-hospital blood samples? A prospective interventional study on the pre-analytical stability of blood samples under prehospital emergency medicine conditions.

    Science.gov (United States)

    Prottengeier, Johannes; Jess, Nicola; Harig, Frank; Gall, Christine; Schmidt, Joachim; Birkholz, Torsten

    2017-03-04

    Prehospital intravenous access provides the opportunity to sample blood from an emergency patient at the earliest possible moment in the course of acute illness and in a state prior to therapeutic interventions. Our study investigates the pre-analytical stability of biomarkers in prehospital emergency medicine and will answer the question whether an approach of blood sampling out in the field will deliver valid laboratory results. We prepared pairs of blood samples from healthy volunteers and volunteering patients post cardio-thoracic surgery. While one sample set was analysed immediately, the other one was subjected to a worse-than-reality treatment of 60 min time-lapse and standardized mechanical forces outside of the hospital through actual ambulance transport. We investigated 21 parameters comprising blood cells, coagulation tests, electrolytes, markers of haemolysis and markers of cardiac ischemia. Bland-Altman analysis was used to investigate differences between test groups. Differences between test groups were set against the official margins of test accuracy as given by the German Requirements for Quality Assurance of Medical Laboratory Examinations. Agreement between immediate analysis and our prehospital treatment is high as demonstrated by Bland-Altman plotting. Mechanical stress and time delay do not produce a systematic bias but only random inaccuracy. The limits of agreement for the tested parameters are generally within clinically acceptable ranges of variation and within the official margins as set by the German Requirements for Quality Assurance of Medical Laboratory Examinations. We subjected blood samples to a standardized treatment marking a worse-than-reality scenario of prehospital time delay and transport. Biomarkers including indicators of myocardial ischemia showed high pre-analytical stability. We conclude the validity of blood samples from a prehospital environment.

  10. Interstitial water studies on small core samples, Leg 9

    Science.gov (United States)

    Sayles, F.L.; Waterman, L.S.; Manheim, F. T.

    1972-01-01

    The chemistry of the pore fluids obtained on Leg 9 is remarkable primarily in its constancy. Excepting silicon and strontium, only at one site do the concentrations of the major and minor constituents deviate notably from sea water concentrations (see Tables 1 and 2). The trends, or lack of them, seen in these samples have been discussed previously and only references will be given here. The constancy of composition and similarity to sea water is particularly noteworthy, as the sediments at all of the 9 sites are thought to be intruded by the basal basalt. The pore fluid chemistry exhibits no evidence of intrusion except possibly at Site 84.

  11. Variance results for the second and third reduced sample moments in neutron multiplicity counting for randomly triggered or signal-triggered counting gates

    Energy Technology Data Exchange (ETDEWEB)

    Burr, T. [Statistical Sciences Group, Los Alamos National Laboratory, Mail Stop F600, Los Alamos, NM 87545 (United States)], E-mail: tburr@lanl.gov; Butterfield, K. [Advanced Nuclear Technology Group, Los Alamos National Laboratory, Mail Stop F600, Los Alamos, NM 87545 (United States)

    2008-09-01

    Neutron multiplicity counting is an established method to estimate the spontaneous fission rate, and therefore also the plutonium mass for example, in a sample that includes other neutron sources. The extent to which the sample and detector obey the 'point model' assumptions impacts the estimate's total measurement error, but, in nearly all cases, for the random error contribution, it is useful to evaluate the variances of the second and third reduced sample moments of the neutron source strength. Therefore, this paper derives exact expressions for the variances and covariances of the second and third reduced sample moments for either randomly triggered or signal-triggered non-overlapping counting gates, and compares them to the corresponding variances in simulated data. Approximate expressions are also provided for the case of overlapping counting gates. These variances and covariances are useful in figure of merit calculations to predict assay performance prior to data collection. In addition, whenever real data are available, a bootstrap method is presented as an alternate but effective way to estimate these variances.

  12. Choice of Moisturiser for Eczema Treatment (COMET): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Ridd, Matthew J; Redmond, Niamh M; Hollinghurst, Sandra; Ball, Nicola; Shaw, Lindsay; Guy, Richard; Wilson, Victoria; Metcalfe, Chris; Purdy, Sarah

    2015-07-15

    Eczema is common in children and in the UK most cases are managed in primary care. The foundation of all treatment is the regular use of leave-on emollients to preserve and restore moisture to the skin. This not only improves comfort but may also reduce the need for rescue treatment for 'flares', such as topical corticosteroids. However, clinicians can prescribe many different types of emollient and there is a paucity of evidence to guide this choice. One reason for this may be the challenges of conducting a clinical trial: are parents or carers of young children willing to be randomly allocated an emollient and followed up for a meaningful amount of time? This is a single-centre feasibility study of a pragmatic, four-arm, single-masked, randomized trial. Children with eczema who are eligible (from 1 month to less than 5 years of age, not known to be sensitive or allergic to any of study emollients or their constituents) are recruited via their general practices. Participants are allocated Aveeno® lotion, Diprobase® cream, Doublebase® gel or Hydromol® ointment via a web-based system, using a simple randomization process in a 1:1:1:1 fashion. Researchers are masked to the study emollient. Participants are assessed at baseline and followed up for 3 months. Data are collected by daily diaries, monthly researcher visits and review of electronic medical records. Because this is a feasibility study, a formal sample size calculation for the estimation of treatment effectiveness has not be made but we aim to recruit 160 participants. Recruitment is on-going. At the end of the study, as well as being able to answer the question, 'Is it is possible to recruit and retain children with eczema from primary care into a four-arm randomized trial of emollients?', we will also have collected important data on the acceptability and effectiveness of four commonly used emollients. Current Controlled Trials ISRCTN21828118 and Clinical Trials Register EudraCT2013-003001-26.

  13. Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling.

    Science.gov (United States)

    Rao, Amrita; Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Kochelani, Duncan; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

    2017-10-20

    In using regularly collected or existing surveillance data to characterize engagement in human immunodeficiency virus (HIV) services among marginalized populations, differences in sampling methods may produce different pictures of the target population and may therefore result in different priorities for response. The objective of this study was to use existing data to evaluate the sample distribution of eight studies of female sex workers (FSW) and men who have sex with men (MSM), who were recruited using different sampling approaches in two locations within Sub-Saharan Africa: Manzini, Swaziland and Yaoundé, Cameroon. MSM and FSW participants were recruited using either respondent-driven sampling (RDS) or venue-based snowball sampling. Recruitment took place between 2011 and 2016. Participants at each study site were administered a face-to-face survey to assess sociodemographics, along with the prevalence of self-reported HIV status, frequency of HIV testing, stigma, and other HIV-related characteristics. Crude and RDS-adjusted prevalence estimates were calculated. Crude prevalence estimates from the venue-based snowball samples were compared with the overlap of the RDS-adjusted prevalence estimates, between both FSW and MSM in Cameroon and Swaziland. RDS samples tended to be younger (MSM aged 18-21 years in Swaziland: 47.6% [139/310] in RDS vs 24.3% [42/173] in Snowball, in Cameroon: 47.9% [99/306] in RDS vs 20.1% [52/259] in Snowball; FSW aged 18-21 years in Swaziland 42.5% [82/325] in RDS vs 8.0% [20/249] in Snowball; in Cameroon 15.6% [75/576] in RDS vs 8.1% [25/306] in Snowball). They were less educated (MSM: primary school completed or less in Swaziland 42.6% [109/310] in RDS vs 4.0% [7/173] in Snowball, in Cameroon 46.2% [138/306] in RDS vs 14.3% [37/259] in Snowball; FSW: primary school completed or less in Swaziland 86.6% [281/325] in RDS vs 23.9% [59/247] in Snowball, in Cameroon 87.4% [520/576] in RDS vs 77.5% [238/307] in Snowball) than the snowball

  14. A randomized controlled pilot study of motivational interviewing for patients with psychotic and drug use disorders.

    Science.gov (United States)

    Martino, Steve; Carroll, Kathleen M; Nich, Charla; Rounsaville, Bruce J

    2006-10-01

    This pilot study examined the efficacy of a two-session motivational interview adapted for dually diagnosed psychotic and drug-related disordered patients (DDMI) in comparison to a two-session standard psychiatric interview (SI). The study used a randomized controlled trial design. Participants received either DDMI or SI and were assessed at baseline, 4-, 8- and 12-week follow-up points. The principal analysis for examination of treatment effects across time was a random effects regression model. Both DDMI and SI interviews served as pre-admission intake interventions to an ambulatory specialty dual diagnosis intensive out-patient and partial hospital program. Forty-four treatment-seeking participants (DDMI = 24; SI = 20) who had co-occurring psychotic and drug-related disorders were assigned randomly to the treatment conditions. Measurements Primary outcomes were days of primary drug use, secondary drug use, alcohol use and psychotropic medication adherence, proportion of participants admitted into the program and days of attendance. DDMI and SI resulted in improved treatment outcomes, but there were no main effects for the sample as a whole. Separate examination of primary cocaine and primary marijuana using subsamples, however, suggested that DDMI resulted in significantly better primary drug treatment outcomes for the cocaine-using group, whereas SI resulted in significantly better primary drug treatment outcomes for the marijuana-using group. These findings indicate that MI may not work equally well for all types of psychotic disordered dually diagnosed patients and that alternative approaches may be as effective in fostering improved substance use treatment outcomes for subgroups of these individuals.

  15. n4Studies: Sample Size Calculation for an Epidemiological Study on a Smart Device

    Directory of Open Access Journals (Sweden)

    Chetta Ngamjarus

    2016-05-01

    Full Text Available Objective: This study was to develop a sample size application (called “n4Studies” for free use on iPhone and Android devices and to compare sample size functions between n4Studies with other applications and software. Methods: Objective-C programming language was used to create the application for the iPhone OS (operating system while javaScript, jquery mobile, PhoneGap and jstat were used to develop it for Android phones. Other sample size applications were searched from the Apple app and Google play stores. The applications’ characteristics and sample size functions were collected. Spearman’s rank correlation was used to investigate the relationship between number of sample size functions and price. Results: “n4Studies” provides several functions for sample size and power calculations for various epidemiological study designs. It can be downloaded from the Apple App and Google play store. Comparing n4Studies with other applications, it covers several more types of epidemiological study designs, gives similar results for estimation of infinite/finite population mean and infinite/finite proportion from GRANMO, for comparing two independent means from BioStats, for comparing two independent proportions from EpiCal application. When using the same parameters, n4Studies gives similar results to STATA, epicalc package in R, PS, G*Power, and OpenEpi. Conclusion: “n4Studies” can be an alternative tool for calculating the sample size. It may be useful to students, lecturers and researchers in conducting their research projects.

  16. Financial ties of principal investigators and randomized controlled trial outcomes: cross sectional study.

    Science.gov (United States)

    Ahn, Rosa; Woodbridge, Alexandra; Abraham, Ann; Saba, Susan; Korenstein, Deborah; Madden, Erin; Boscardin, W John; Keyhani, Salomeh

    2017-01-17

     To examine the association between the presence of individual principal investigators' financial ties to the manufacturer of the study drug and the trial's outcomes after accounting for source of research funding.  Cross sectional study of randomized controlled trials (RCTs).  Studies published in "core clinical" journals, as identified by Medline, between 1 January 2013 and 31 December 2013.  Random sample of RCTs focused on drug efficacy.  Association between financial ties of principal investigators and study outcome.  A total of 190 papers describing 195 studies met inclusion criteria. Financial ties between principal investigators and the pharmaceutical industry were present in 132 (67.7%) studies. Of 397 principal investigators, 231 (58%) had financial ties and 166 (42%) did not. Of all principal investigators, 156 (39%) reported advisor/consultancy payments, 81 (20%) reported speakers' fees, 81 (20%) reported unspecified financial ties, 52 (13%) reported honorariums, 52 (13%) reported employee relationships, 52 (13%) reported travel fees, 41 (10%) reported stock ownership, and 20 (5%) reported having a patent related to the study drug. The prevalence of financial ties of principal investigators was 76% (103/136) among positive studies and 49% (29/59) among negative studies. In unadjusted analyses, the presence of a financial tie was associated with a positive study outcome (odds ratio 3.23, 95% confidence interval 1.7 to 6.1). In the primary multivariate analysis, a financial tie was significantly associated with positive RCT outcome after adjustment for the study funding source (odds ratio 3.57 (1.7 to 7.7). The secondary analysis controlled for additional RCT characteristics such as study phase, sample size, country of first authors, specialty, trial registration, study design, type of analysis, comparator, and outcome measure. These characteristics did not appreciably affect the relation between financial ties and study outcomes (odds ratio 3.37, 1

  17. Rugae pattern in a sample of population of Meerut - An institutional study.

    Science.gov (United States)

    Bhagwath, S; Chandra, L

    2014-05-01

    Many studies on rugae pattern have been done on various samples of population, but no study has so far been done to assess the rugae pattern of population of western Uttar radesh, especially Meerut. This study was aimed to assess the rugae pattern in males and females of a sample of population of Meerut, which may be an additional method of determining gender when dealing with any crime or with mutilated bodies that have undergone damage beyond recognition. A total of 100 Class I dentulous subjects, 50 male and 50 female patients reporting to the outpatient department of Kalka Dental College, Meerut, Uttar Pradesh were randomly selected with an age range between 20-30 years. Exclusion criteria were subjects >14 years of age, congenital malformations, previous orthognathic surgery, allergy to impression material, bony and soft tissue protuberances, active lesions, deformity or scars and trauma of the palate. Prior approval from the Institutional Ethical Committee was taken. Alginate impressions of palate of selected patients were poured in dental stone and rugae pattern was identified and analyzed by a single rater employing Thomas and Kotze's (1983) method. Two-sample t-test and Chi-Square tests were used for comparison of means and relationship between the attributes. A significance level of 5% was considered as critical value. No significant difference was noted in total number or length of rugae between the genders. However, statistically significant difference in the circular type in males and converge type in females was observed. Rugae pattern can be used as a method of differentiation between males and females to corroborate the findings of other methods such as anthropometric evaluation of the cranium and dental characteristics.

  18. Chronic kidney disease in the type 2 diabetic patients: prevalence and associated variables in a random sample of 2642 patients of a Mediterranean area

    Directory of Open Access Journals (Sweden)

    Coll-de-Tuero Gabriel

    2012-08-01

    Full Text Available Abstract Background Kidney disease is associated with an increased total mortality and cardiovascular morbimortality in the general population and in patients with Type 2 diabetes. The aim of this study is to determine the prevalence of kidney disease and different types of renal disease in patients with type 2 diabetes (T2DM. Methods Cross-sectional study in a random sample of 2,642 T2DM patients cared for in primary care during 2007. Studied variables: demographic and clinical characteristics, pharmacological treatments and T2DM complications (diabetic foot, retinopathy, coronary heart disease and stroke. Variables of renal function were defined as follows: 1 Microalbuminuria: albumin excretion rate & 30 mg/g or 3.5 mg/mmol, 2 Macroalbuminuria: albumin excretion rate & 300 mg/g or 35 mg/mmol, 3 Kidney disease (KD: glomerular filtration rate according to Modification of Diet in Renal Disease 2 and/or the presence of albuminuria, 4 Renal impairment (RI: glomerular filtration rate 2, 5 Nonalbuminuric RI: glomerular filtration rate 2 without albuminuria and, 5 Diabetic nephropathy (DN: macroalbuminuria or microalbuminuria plus diabetic retinopathy. Results The prevalence of different types of renal disease in patients was: 34.1% KD, 22.9% RI, 19.5% albuminuria and 16.4% diabetic nephropathy (DN. The prevalence of albuminuria without RI (13.5% and nonalbuminuric RI (14.7% was similar. After adjusting per age, BMI, cholesterol, blood pressure and macrovascular disease, RI was significantly associated with the female gender (OR 2.20; CI 95% 1.86–2.59, microvascular disease (OR 2.14; CI 95% 1.8–2.54 and insulin treatment (OR 1.82; CI 95% 1.39–2.38, and inversely associated with HbA1c (OR 0.85 for every 1% increase; CI 95% 0.80–0.91. Albuminuria without RI was inversely associated with the female gender (OR 0.27; CI 95% 0.21–0.35, duration of diabetes (OR 0.94 per year; CI 95% 0.91–0.97 and directly associated with HbA1c (OR 1.19 for every

  19. Multiscale study for stochastic characterization of shale samples

    Science.gov (United States)

    Tahmasebi, Pejman; Javadpour, Farzam; Sahimi, Muhammad; Piri, Mohammad

    2016-03-01

    Characterization of shale reservoirs, which are typically of low permeability, is very difficult because of the presence of multiscale structures. While three-dimensional (3D) imaging can be an ultimate solution for revealing important complexities of such reservoirs, acquiring such images is costly and time consuming. On the other hand, high-quality 2D images, which are widely available, also reveal useful information about shales' pore connectivity and size. Most of the current modeling methods that are based on 2D images use limited and insufficient extracted information. One remedy to the shortcoming is direct use of qualitative images, a concept that we introduce in this paper. We demonstrate that higher-order statistics (as opposed to the traditional two-point statistics, such as variograms) are necessary for developing an accurate model of shales, and describe an efficient method for using 2D images that is capable of utilizing qualitative and physical information within an image and generating stochastic realizations of shales. We then further refine the model by describing and utilizing several techniques, including an iterative framework, for removing some possible artifacts and better pattern reproduction. Next, we introduce a new histogram-matching algorithm that accounts for concealed nanostructures in shale samples. We also present two new multiresolution and multiscale approaches for dealing with distinct pore structures that are common in shale reservoirs. In the multiresolution method, the original high-quality image is upscaled in a pyramid-like manner in order to achieve more accurate global and long-range structures. The multiscale approach integrates two images, each containing diverse pore networks - the nano- and microscale pores - using a high-resolution image representing small-scale pores and, at the same time, reconstructing large pores using a low-quality image. Eventually, the results are integrated to generate a 3D model. The methods

  20. An econometric method for estimating population parameters from non-random samples: An application to clinical case finding.

    Science.gov (United States)

    Burger, Rulof P; McLaren, Zoë M

    2017-09-01

    The problem of sample selection complicates the process of drawing inference about populations. Selective sampling arises in many real world situations when agents such as doctors and customs officials search for targets with high values of a characteristic. We propose a new method for estimating population characteristics from these types of selected samples. We develop a model that captures key features of the agent's sampling decision. We use a generalized method of moments with instrumental variables and maximum likelihood to estimate the population prevalence of the characteristic of interest and the agents' accuracy in identifying targets. We apply this method to tuberculosis (TB), which is the leading infectious disease cause of death worldwide. We use a national database of TB test data from South Africa to examine testing for multidrug resistant TB (MDR-TB). Approximately one quarter of MDR-TB cases was undiagnosed between 2004 and 2010. The official estimate of 2.5% is therefore too low, and MDR-TB prevalence is as high as 3.5%. Signal-to-noise ratios are estimated to be between 0.5 and 1. Our approach is widely applicable because of the availability of routinely collected data and abundance of potential instruments. Using routinely collected data to monitor population prevalence can guide evidence-based policy making. Copyright © 2017 John Wiley & Sons, Ltd.

  1. Estimation of the Box Correction for Degrees of Freedom from Sample Data in Randomized Block and Split-Plot Designs

    Science.gov (United States)

    Huynh, Huynh; Feldt, Leonard S.

    1976-01-01

    When the variance assumptions of a repeated measures ANOVA are not met, the F distribution of the mean square ratio should be adjusted by the sample estimate of the Box correction factor. An alternative is proposed which is shown by Monte Carlo methods to be less biased for a moderately large factor. (RC)

  2. Randomized controlled trial of endoscopic ultrasound-guided fine-needle sampling with or without suction for better cytological diagnosis

    DEFF Research Database (Denmark)

    Puri, Rajesh; Vilmann, Peter; Saftoiu, Adrian

    2009-01-01

    ). The samples were characterized for cellularity and bloodiness, with a final cytology diagnosis established blindly. The final diagnosis was reached either by EUS-FNA if malignancy was definite, or by surgery and/or clinical follow-up of a minimum of 6 months in the cases of non-specific benign lesions...

  3. Loss to follow-up in a randomized controlled trial study for pediatric weight management (EPOC)

    National Research Council Canada - National Science Library

    Warschburger, Petra; Kröller, Katja

    2016-01-01

      Background Attrition is a serious problem in intervention studies. The current study analyzed the attrition rate during follow-up in a randomized controlled pediatric weight management program (EPOC study...

  4. Efficacy of short-term adjunctive subantimicrobial dose doxycycline in diabetic patients--randomized study.

    Science.gov (United States)

    Gilowski, L; Kondzielnik, P; Wiench, R; Płocica, I; Strojek, K; Krzemiński, T F

    2012-11-01

    To investigate the effectiveness of short-term adjunctive subantimicrobial dose doxycycline (SDD) treatment in patients with diabetes mellitus type 2 and chronic periodontitis (CP). Thirty-four patients with CP and type 2 diabetes mellitus were included in the placebo-controlled, double-blind study. After scaling and root planing (SRP), patients were randomly assigned to two groups, receiving either SDD or placebo bid for 3 months. The probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), approximal plaque index, glycated hemoglobin (HbA1c) level were recorded and gingival crevicular fluid (GCF) samples were collected at baseline and after 3-month therapy for the estimation of matrix metalloproteinase-8 levels. Clinical attachment level, PD, and BOP improved significantly in both groups after therapy (P diabetes and CP. © 2012 John Wiley & Sons A/S.

  5. The effect of a biological explanation on attitudes towards homosexual persons. A Swedish national sample study.

    Science.gov (United States)

    Landén, Mikael; Innala, Sune

    2002-01-01

    Studies assessing attitudes towards homosexuals have revealed widespread homophobia. The first aim of this study was to assess potential changes in public attitudes after important legislative changes related to homosexuals in Sweden. The second aim was to test whether the attitudes differ: 1) between people who believe in biological vs. people who believe in psychological theories in explanation of homosexuality, 2) between men and women, and 3) between the older and younger age groups. To this end, a questionnaire survey of a representative, randomly selected, national sample of 992 adult Swedish residents was carried out. The response rate was 67%, which is considered high in this context. In conclusion, this study demonstrates a clear-cut change towards more tolerant attitudes towards homosexual men and women compared to earlier studies. The reasons for this change is discussed; among factors of importance are anti-discrimination legislation, increased visibility of homosexual people, and that more people currently regard homosexuality as a biologically determined, natural variant of human sexuality than was the case 10 years ago. In accordance, this study gave further support to the notion that those who believe that homosexuality is caused by biological factors have a less restrictive view on homosexuality than do people who hold a psychological view.

  6. WWC Quick Review of the Article "Outcomes of a Prospective Trial of Student-Athlete Drug Testing: The Student Athlete Testing Using Random Notification ('SATURN') Study"

    Science.gov (United States)

    What Works Clearinghouse, 2008

    2008-01-01

    This study examines whether the Student Athlete Testing Using Random Notification ("SATURN") program affects illicit drug and alcohol use among student athletes. The study experienced high rates of sample attrition. Seven of the 18 study schools (39%) left the study and were not included in the analysis. Some students at the remaining…

  7. Empirical Evidence of Study Design Biases in Randomized Trials: Systematic Review of Meta-Epidemiological Studies.

    Science.gov (United States)

    Page, Matthew J; Higgins, Julian P T; Clayton, Gemma; Sterne, Jonathan A C; Hróbjartsson, Asbjørn; Savović, Jelena

    2016-01-01

    To synthesise evidence on the average bias and heterogeneity associated with reported methodological features of randomized trials. Systematic review of meta-epidemiological studies. We retrieved eligible studies included in a recent AHRQ-EPC review on this topic (latest search September 2012), and searched Ovid MEDLINE and Ovid EMBASE for studies indexed from Jan 2012-May 2015. Data were extracted by one author and verified by another. We combined estimates of average bias (e.g. ratio of odds ratios (ROR) or difference in standardised mean differences (dSMD)) in meta-analyses using the random-effects model. Analyses were stratified by type of outcome ("mortality" versus "other objective" versus "subjective"). Direction of effect was standardised so that ROR studies. The available evidence suggests that intervention effect estimates may be exaggerated in trials with inadequate/unclear (versus adequate) sequence generation (ROR 0.93, 95% CI 0.86 to 0.99; 7 studies) and allocation concealment (ROR 0.90, 95% CI 0.84 to 0.97; 7 studies). For these characteristics, the average bias appeared to be larger in trials of subjective outcomes compared with other objective outcomes. Also, intervention effects for subjective outcomes appear to be exaggerated in trials with lack of/unclear blinding of participants (versus blinding) (dSMD -0.37, 95% CI -0.77 to 0.04; 2 studies), lack of/unclear blinding of outcome assessors (ROR 0.64, 95% CI 0.43 to 0.96; 1 study) and lack of/unclear double blinding (ROR 0.77, 95% CI 0.61 to 0.93; 1 study). The influence of other characteristics (e.g. unblinded trial personnel, attrition) is unclear. Certain characteristics of randomized trials may exaggerate intervention effect estimates. The average bias appears to be greatest in trials of subjective outcomes. More research on several characteristics, particularly attrition and selective reporting, is needed.

  8. Assessing the precision of a time-sampling-based study among GPs: balancing sample size and measurement frequency.

    Science.gov (United States)

    van Hassel, Daniël; van der Velden, Lud; de Bakker, Dinny; van der Hoek, Lucas; Batenburg, Ronald

    2017-12-04

    Our research is based on a technique for time sampling, an innovative method for measuring the working hours of Dutch general practitioners (GPs), which was deployed in an earlier study. In this study, 1051 GPs were questioned about their activities in real time by sending them one SMS text message every 3 h during 1 week. The required sample size for this study is important for health workforce planners to know if they want to apply this method to target groups who are hard to reach or if fewer resources are available. In this time-sampling method, however, standard power analyses is not sufficient for calculating the required sample size as this accounts only for sample fluctuation and not for the fluctuation of measurements taken from every participant. We investigated the impact of the number of participants and frequency of measurements per participant upon the confidence intervals (CIs) for the hours worked per week. Statistical analyses of the time-use data we obtained from GPs were performed. Ninety-five percent CIs were calculated, using equations and simulation techniques, for various different numbers of GPs included in the dataset and for various frequencies of measurements per participant. Our results showed that the one-tailed CI, including sample and measurement fluctuation, decreased from 21 until 3 h between one and 50 GPs. As a result of the formulas to calculate CIs, the increase of the precision continued and was lower with the same additional number of GPs. Likewise, the analyses showed how the number of participants required decreased if more measurements per participant were taken. For example, one measurement per 3-h time slot during the week requires 300 GPs to achieve a CI of 1 h, while one measurement per hour requires 100 GPs to obtain the same result. The sample size needed for time-use research based on a time-sampling technique depends on the design and aim of the study. In this paper, we showed how the precision of the

  9. Safety and feasibility of transcranial direct current stimulation in pediatric hemiparesis: randomized controlled preliminary study.

    Science.gov (United States)

    Gillick, Bernadette T; Feyma, Tim; Menk, Jeremiah; Usset, Michelle; Vaith, Amy; Wood, Teddi Jean; Worthington, Rebecca; Krach, Linda E

    2015-03-01

    Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation that has shown improved adult stroke outcomes. Applying tDCS in children with congenital hemiparesis has not yet been explored. The primary objective of this study was to explore the safety and feasibility of single-session tDCS through an adverse events profile and symptom assessment within a double-blind, randomized placebo-controlled preliminary study in children with congenital hemiparesis. A secondary objective was to assess the stability of hand and cognitive function. A double-blind, randomized placebo-controlled pretest/posttest/follow-up study was conducted. The study was conducted in a university pediatric research laboratory. Thirteen children, ages 7 to 18 years, with congenital hemiparesis participated. Adverse events/safety assessment and hand function were measured. Participants were randomly assigned to either an intervention group or a control group, with safety and functional assessments at pretest, at posttest on the same day, and at a 1-week follow-up session. An intervention of 10 minutes of 0.7 mA tDCS was applied to bilateral primary motor cortices. The tDCS intervention was considered safe if there was no individual decline of 25% or group decline of 2 standard deviations for motor evoked potentials (MEPs) and behavioral data and no report of adverse events. No major adverse events were found, including no seizures. Two participants did not complete the study due to lack of MEP and discomfort. For the 11 participants who completed the study, group differences in MEPs and behavioral data did not exceed 2 standard deviations in those who received the tDCS (n=5) and those in the control group (n=6). The study was completed without the need for stopping per medical monitor and biostatisticial analysis. A limitation of the study was the small sample size, with data available for 11 participants. Based on the results of this study, tDCS appears to be safe

  10. Gambling problems in the family – A stratified probability sample study of prevalence and reported consequences

    Directory of Open Access Journals (Sweden)

    Øren Anita

    2008-12-01

    Full Text Available Abstract Background Prior studies on the impact of problem gambling in the family mainly include help-seeking populations with small numbers of participants. The objective of the present stratified probability sample study was to explore the epidemiology of problem gambling in the family in the general population. Methods Men and women 16–74 years-old randomly selected from the Norwegian national population database received an invitation to participate in this postal questionnaire study. The response rate was 36.1% (3,483/9,638. Given the lack of validated criteria, two survey questions ("Have you ever noticed that a close relative spent more and more money on gambling?" and "Have you ever experienced that a close relative lied to you about how much he/she gambles?" were extrapolated from the Lie/Bet Screen for pathological gambling. Respondents answering "yes" to both questions were defined as Concerned Significant Others (CSOs. Results Overall, 2.0% of the study population was defined as CSOs. Young age, female gender, and divorced marital status were factors positively associated with being a CSO. CSOs often reported to have experienced conflicts in the family related to gambling, worsening of the family's financial situation, and impaired mental and physical health. Conclusion Problematic gambling behaviour not only affects the gambling individual but also has a strong impact on the quality of life of family members.

  11. Randomized Double-Blind Study of the Efficacy, Safety and ...

    African Journals Online (AJOL)

    Pre- and post-treatment blood samples were collected from each patient for the evaluation of blood chemistry, haemogram profile and other laboratory parameters. ... Laboratory findings showed that tenoxicam had no adverse effect on haematological, homeostasis and biochemical values with a statistically significant ...

  12. Bayesian Inference for Multivariate Meta-regression with a Partially Observed Within-Study Sample Covariance Matrix

    Science.gov (United States)

    Yao, Hui; Kim, Sungduk; Chen, Ming-Hui; Ibrahim, Joseph G.; Shah, Arvind K.; Lin, Jianxin

    2015-01-01

    Summary Multivariate meta-regression models are commonly used in settings where the response variable is naturally multi-dimensional. Such settings are common in cardiovascular and diabetes studies where the goal is to study cholesterol levels once a certain medication is given. In this setting, the natural multivariate endpoint is Low Density Lipoprotein Cholesterol (LDL-C), High Density Lipoprotein Cholesterol (HDL-C), and Triglycerides (TG) (LDL-C, HDL-C, TG). In this paper, we examine study level (aggregate) multivariate meta-data from 26 Merck sponsored double-blind, randomized, active or placebo-controlled clinical trials on adult patients with primary hypercholesterolemia. Our goal is to develop a methodology for carrying out Bayesian inference for multivariate meta-regression models with study level data when the within-study sample covariance matrix S for the multivariate response data is partially observed. Specifically, the proposed methodology is based on postulating a multivariate random effects regression model with an unknown within-study covariance matrix Σ in which we treat the within-study sample correlations as missing data, the standard deviations of the within-study sample covariance matrix S are assumed observed, and given Σ, S follows a Wishart distribution. Thus, we treat the off-diagonal elements of S as missing data, and these missing elements are sampled from the appropriate full conditional distribution in a Markov chain Monte Carlo (MCMC) sampling scheme via a novel transformation based on partial correlations. We further propose several structures (models) for Σ, which allow for borrowing strength across different treatment arms and trials. The proposed methodology is assessed using simulated as well as real data, and the results are shown to be quite promising. PMID:26257452

  13. Northeast Cooperative Research Study Fleet (SF) Program Biological Sampling Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Northeast Cooperative Research Study Fleet (SF) Program partners with a subset of commercial fishermen to collect high quality, high resolution, haul by haul...

  14. Study population, questionnaire, data management and sample description

    OpenAIRE

    Chiara de Waure; Andrea Poscia; Andrea Virdis; Maria Luisa Di Pietro; Walter Ricciardi

    2015-01-01

    INTRODUCTION: This article describes methodological issues of the "Sportello Salute Giovani" project ("Youth Health Information Desk"), a multicenter study aimed at assessing the health status and attitudes and behaviours of university students in Italy. MATERIALS AND METHODS: The questionnaire used to carry out the study was adapted from the Italian health behaviours in school-aged children (HBSC) project and consisted of 93 items addressing: demographics; nutritional habits and status; phys...

  15. A Study of MAC Address Randomization in Mobile Devices and When it Fails

    Directory of Open Access Journals (Sweden)

    Martin Jeremy

    2017-10-01

    Full Text Available Media Access Control (MAC address randomization is a privacy technique whereby mobile devices rotate through random hardware addresses in order to prevent observers from singling out their traffic or physical location from other nearby devices. Adoption of this technology, however, has been sporadic and varied across device manufacturers. In this paper, we present the first wide-scale study of MAC address randomization in the wild, including a detailed breakdown of different randomization techniques by operating system, manufacturer, and model of device.

  16. Disparities in sleep characteristics by race/ethnicity in a population-based sample: Chicago Area Sleep Study.

    Science.gov (United States)

    Carnethon, Mercedes R; De Chavez, Peter John; Zee, Phyllis C; Kim, Kwang-Youn A; Liu, Kiang; Goldberger, Jeffrey J; Ng, Jason; Knutson, Kristen L

    2016-02-01

    Prior studies report less favorable sleep characteristics among non-Whites as compared with non-Hispanic Whites. However, few population-based studies have used objective measures of sleep duration, especially in more than two racial/ethnic groups. We tested whether objectively estimated sleep duration and self-reported sleep quality varied by race and whether differences were at least partially explained by the variability in clinical, psychological, and behavioral covariates. Adults aged 35-64 years who self-identified as White, Black, Asian, or Hispanic were randomly sampled from Chicago, IL, and the surrounding suburbs. Our analytic sample included adults who had an apnea-hypopnea index sample of adults with a low probability of sleep apnea and following adjustment for known confounders. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Japan Unified Protocol Clinical Trial for Depressive and Anxiety Disorders (JUNP study): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Ito, Masaya; Okumura, Yasuyuki; Horikoshi, Masaru; Kato, Noriko; Oe, Yuki; Miyamae, Mitsuhiro; Hirabayashi, Naotsugu; Kanie, Ayako; Nakagawa, Atsuo; Ono, Yutaka

    2016-03-18

    The unified protocol for the transdiagnostic treatment of emotional disorders is a promising treatment approach that could be applicable to a broad range of mental disorders, including depressive, anxiety, trauma-related, and obsessive-compulsive disorders. However, no randomized controlled trial has been conducted to verify the efficacy of the unified protocol on the heterogeneous clinical population with depressive and anxiety disorders. The trial was designed as a single-center, assessor-blinded, randomized, 20-week, parallel-group superiority study in order to compare the efficacy of the combination of unified protocol and treatment-as-usual versus waiting-list with treatment-as-usual for patients with depressive and/or anxiety disorders. The primary outcome was depression at 21 weeks, assessed by the 17-item version of the GRID-Hamilton Rating Scale for Depression. Estimated minimum sample size was 27 participants in each group. We will also examine the treatment mechanisms, treatment processes, and neuropsychological correlates. The results of this study will clarify the efficacy of the unified protocol for depressive and anxiety disorders, and the treatment mechanism, process, and neurological correlates for the effectiveness of the unified protocol. If its efficacy can be confirmed, the unified protocol may be of high clinical value for Japan, a country in which cognitive behavioral treatment has not yet been widely adopted. ClinicalTrials.gov NCT02003261 (registered on December 2, 2013).

  18. Reducing eating disorder onset in a very high risk sample with significant comorbid depression: A randomized controlled trial.

    Science.gov (United States)

    Taylor, C Barr; Kass, Andrea E; Trockel, Mickey; Cunning, Darby; Weisman, Hannah; Bailey, Jakki; Sinton, Meghan; Aspen, Vandana; Schecthman, Kenneth; Jacobi, Corinna; Wilfley, Denise E

    2016-05-01

    Eating disorders (EDs) are serious problems among college-age women and may be preventable. An indicated online eating disorder (ED) intervention, designed to reduce ED and comorbid pathology, was evaluated. 206 women (M age = 20 ± 1.8 years; 51% White/Caucasian, 11% African American, 10% Hispanic, 21% Asian/Asian American, 7% other) at very high risk for ED onset (i.e., with high weight/shape concerns plus a history of being teased, current or lifetime depression, and/or nonclinical levels of compensatory behaviors) were randomized to a 10-week, Internet-based, cognitive-behavioral intervention or waitlist control. Assessments included the Eating Disorder Examination (EDE, to assess ED onset), EDE-Questionnaire, Structured Clinical Interview for DSM Disorders, and Beck Depression Inventory-II. ED attitudes and behaviors improved more in the intervention than control group (p = .02, d = 0.31); although ED onset rate was 27% lower, this difference was not significant (p = .28, NNT = 15). In the subgroup with highest shape concerns, ED onset rate was significantly lower in the intervention than control group (20% vs. 42%, p = .025, NNT = 5). For the 27 individuals with depression at baseline, depressive symptomatology improved more in the intervention than control group (p = .016, d = 0.96); although ED onset rate was lower in the intervention than control group, this difference was not significant (25% vs. 57%, NNT = 4). An inexpensive, easily disseminated intervention might reduce ED onset among those at highest risk. Low adoption rates need to be addressed in future research. (c) 2016 APA, all rights reserved).

  19. The Impact of Child Sexual Abuse--A Study of a Random Sample of Norwegian Students.

    Science.gov (United States)

    Bendixen, Mons; And Others

    1994-01-01

    In a survey of 510 female and 486 male Norwegian college students, almost 12% reported child sexual abuse. Abuse was associated with health problems such as genital pain/infections and headache/abdominal/muscular pain as well as psychological disorders such as anxiety and suicidal ideation. A relationship was demonstrated between abuse severity…

  20. Practical Approaches For Determination Of Sample Size In Paired Case-Control Studies

    OpenAIRE

    Demirel, Neslihan; Ozlem EGE ORUC; Gurler, Selma

    2016-01-01

    Objective: Cross-over design or paired case control studies that are using in clinical studies are the methods of design of experiments which requires dependent samples. The problem of sample size determination is generally difficult step of planning the statistical design. The aim of this study is to provide the researchers a practical approach for determining the sample size in paired control studies. Material and Methods: In this study, determination of sample size is mentioned in detail i...

  1. Children's Quality of Life Based on the KIDSCREEN-27: Child Self-Report, Parent Ratings and Child-Parent Agreement in a Swedish Random Population Sample.

    Directory of Open Access Journals (Sweden)

    Anne H Berman

    Full Text Available The KIDSCREEN-27 is a measure of child and adolescent quality of life (QoL, with excellent psychometric properties, available in child-report and parent-rating versions in 38 languages. This study provides child-reported and parent-rated norms for the KIDSCREEN-27 among Swedish 11-16 year-olds, as well as child-parent agreement. Sociodemographic correlates of self-reported wellbeing and parent-rated wellbeing were also measured.A random population sample consisting of 600 children aged 11-16, 100 per age group and one of their parents (N = 1200, were approached for response to self-reported and parent-rated versions of the KIDSCREEN-27. Parents were also asked about their education, employment status and their own QoL based on the 26-item WHOQOL-Bref. Based on the final sampling pool of 1158 persons, a 34.8% response rate of 403 individuals was obtained, including 175 child-parent pairs, 27 child singleton responders and 26 parent singletons. Gender and age differences for parent ratings and child-reported data were analyzed using t-tests and the Mann-Whitney U-test. Post-hoc Dunn tests were conducted for pairwise comparisons when the p-value for specific subscales was 0.05 or lower. Child-parent agreement was tested item-by-item, using the Prevalence- and Bias-Adjusted Kappa (PABAK coefficient for ordinal data (PABAK-OS; dimensional and total score agreement was evaluated based on dichotomous cut-offs for lower well-being, using the PABAK and total, continuous scores were evaluated using Bland-Altman plots.Compared to European norms, Swedish children in this sample scored lower on Physical wellbeing (48.8 SE/49.94 EU but higher on the other KIDSCREEN-27 dimensions: Psychological wellbeing (53.4/49.77, Parent relations and autonomy (55.1/49.99, Social Support and peers (54.1/49.94 and School (55.8/50.01. Older children self-reported lower wellbeing than younger children. No significant self-reported gender differences occurred and parent ratings

  2. Children’s Quality of Life Based on the KIDSCREEN-27: Child Self-Report, Parent Ratings and Child-Parent Agreement in a Swedish Random Population Sample

    Science.gov (United States)

    Berman, Anne H.; Liu, Bojing; Ullman, Sara; Jadbäck, Isabel; Engström, Karin

    2016-01-01

    Background The KIDSCREEN-27 is a measure of child and adolescent quality of life (QoL), with excellent psychometric properties, available in child-report and parent-rating versions in 38 languages. This study provides child-reported and parent-rated norms for the KIDSCREEN-27 among Swedish 11–16 year-olds, as well as child-parent agreement. Sociodemographic correlates of self-reported wellbeing and parent-rated wellbeing were also measured. Methods A random population sample consisting of 600 children aged 11–16, 100 per age group and one of their parents (N = 1200), were approached for response to self-reported and parent-rated versions of the KIDSCREEN-27. Parents were also asked about their education, employment status and their own QoL based on the 26-item WHOQOL-Bref. Based on the final sampling pool of 1158 persons, a 34.8% response rate of 403 individuals was obtained, including 175 child-parent pairs, 27 child singleton responders and 26 parent singletons. Gender and age differences for parent ratings and child-reported data were analyzed using t-tests and the Mann-Whitney U-test. Post-hoc Dunn tests were conducted for pairwise comparisons when the p-value for specific subscales was 0.05 or lower. Child-parent agreement was tested item-by-item, using the Prevalence- and Bias-Adjusted Kappa (PABAK) coefficient for ordinal data (PABAK-OS); dimensional and total score agreement was evaluated based on dichotomous cut-offs for lower well-being, using the PABAK and total, continuous scores were evaluated using Bland-Altman plots. Results Compared to European norms, Swedish children in this sample scored lower on Physical wellbeing (48.8 SE/49.94 EU) but higher on the other KIDSCREEN-27 dimensions: Psychological wellbeing (53.4/49.77), Parent relations and autonomy (55.1/49.99), Social Support and peers (54.1/49.94) and School (55.8/50.01). Older children self-reported lower wellbeing than younger children. No significant self-reported gender differences

  3. Children's Quality of Life Based on the KIDSCREEN-27: Child Self-Report, Parent Ratings and Child-Parent Agreement in a Swedish Random Population Sample.

    Science.gov (United States)

    Berman, Anne H; Liu, Bojing; Ullman, Sara; Jadbäck, Isabel; Engström, Karin

    2016-01-01

    The KIDSCREEN-27 is a measure of child and adolescent quality of life (QoL), with excellent psychometric properties, available in child-report and parent-rating versions in 38 languages. This study provides child-reported and parent-rated norms for the KIDSCREEN-27 among Swedish 11-16 year-olds, as well as child-parent agreement. Sociodemographic correlates of self-reported wellbeing and parent-rated wellbeing were also measured. A random population sample consisting of 600 children aged 11-16, 100 per age group and one of their parents (N = 1200), were approached for response to self-reported and parent-rated versions of the KIDSCREEN-27. Parents were also asked about their education, employment status and their own QoL based on the 26-item WHOQOL-Bref. Based on the final sampling pool of 1158 persons, a 34.8% response rate of 403 individuals was obtained, including 175 child-parent pairs, 27 child singleton responders and 26 parent singletons. Gender and age differences for parent ratings and child-reported data were analyzed using t-tests and the Mann-Whitney U-test. Post-hoc Dunn tests were conducted for pairwise comparisons when the p-value for specific subscales was 0.05 or lower. Child-parent agreement was tested item-by-item, using the Prevalence- and Bias-Adjusted Kappa (PABAK) coefficient for ordinal data (PABAK-OS); dimensional and total score agreement was evaluated based on dichotomous cut-offs for lower well-being, using the PABAK and total, continuous scores were evaluated using Bland-Altman plots. Compared to European norms, Swedish children in this sample scored lower on Physical wellbeing (48.8 SE/49.94 EU) but higher on the other KIDSCREEN-27 dimensions: Psychological wellbeing (53.4/49.77), Parent relations and autonomy (55.1/49.99), Social Support and peers (54.1/49.94) and School (55.8/50.01). Older children self-reported lower wellbeing than younger children. No significant self-reported gender differences occurred and parent ratings showed

  4. Thermoluminescent properties studies of spodumene lilac sample to dosimetric applications

    Science.gov (United States)

    Lima, L. L.; Oliveira, R. A. P.; Lima, H. R. B. R.; Santos, H. N.; Santos, J. O.; Lima, A. F.; Souza, S. O.

    2010-11-01

    This work investigates the thermoluminescent (TL) dosimetric properties in natural spodumene, LiAlSi2O6, called kunzite, from Minas Gerais State, Brazil. The mineralogical and chemical composition of this material was identified by means X-ray fluorescence and X-ray diffraction. Some dosimetric properties were studied, such as thermoluminescent emission curves as function of gamma dose. The glow curves of annealed kunzite presented two very intense TL peaks at 215 °C (peak II) and 350 °C (peak III), after gamma irradiation, being both of first kinetic order. These two most prominent peaks analyzed do not presented a linear growth in the range of 50 to 5000 Gy in the range of doses studied. The peak II also presented a very short calculated lifetime, which means it is hardly can be used in dosimetry, while the peak III has a longer lifetime and could be used in some applications for high doses dosimetry.

  5. The Aggression Questionnaire: a validation study in student samples.

    Science.gov (United States)

    García-León, Ana; Reyes, Gustavo A; Vila, Jaime; Pérez, Nieves; Robles, Humbelina; Ramos, Manuel M

    2002-05-01

    The goal of this study was to examine the psychometric properties of the Aggression Questionnaire (AQ) in Spain. The AQ is a 29-item instrument designed to measure the different dimensions of the hostility/anger/aggression construct. It consists of 4 subscales that assess: (a) anger, (b) hostility, (c) verbal aggression, and (d) physical aggression. In Study 1, reliability, construct validity, and convergent validity were evaluated in a group of 384 male and female university students. Test-retest reliability was evaluated using a group of 154 male and female university students. The results of the factor analysis were similar to the scale structure claimed for this instrument. The subscales also showed internal consistency and stability over time. The AQ and its subscales were also compared with the scales and subscales of the Spielberger State-Trait Anger Expression Inventory (STAXI), the Cook-Medley Hostility Scale (Ho), the Buss-Durkee Hostility Inventory (BDHI), and the Jenkins Activity Survey-Form H (JASE-H). The results show that the AQ evaluates some aspects of anger, such as Anger-Trait and Anger-Out, rather than other elements, such as Anger-In or Anger-State. In Study 2, two new male groups were used to evaluate the criterion validity of the AQ: 57 prison inmates and 93 university students, finding that this instrument discriminated between the scores obtained by common offenders and university students.

  6. Quantification of damage in DNA recovered from highly degraded samples – a case study on DNA in faeces

    Directory of Open Access Journals (Sweden)

    Eveson J Paige

    2006-08-01

    Full Text Available Abstract Background Poorly preserved biological tissues have become an important source of DNA for a wide range of zoological studies. Measuring the quality of DNA obtained from these samples is often desired; however, there are no widely used techniques available for quantifying damage in highly degraded DNA samples. We present a general method that can be used to determine the frequency of polymerase blocking DNA damage in specific gene-regions in such samples. The approach uses quantitative PCR to measure the amount of DNA present at several fragment sizes within a sample. According to a model of random degradation the amount of available template will decline exponentially with increasing fragment size in damaged samples, and the frequency of DNA damage (λ can be estimated by determining the rate of decline. Results The method is illustrated through the analysis of DNA extracted from sea lion faecal samples. Faeces contain a complex mixture of DNA from several sources and different components are expected to be differentially degraded. We estimated the frequency of DNA damage in both predator and prey DNA within individual faecal samples. The distribution of fragment lengths for each target fit well with the assumption of a random degradation process and, in keeping with our expectations, the estimated frequency of damage was always less in predator DNA than in prey DNA within the same sample (mean λpredator = 0.0106 per nucleotide; mean λprey = 0.0176 per nucleotide. This study is the first to explicitly define the amount of template damage in any DNA extracted from faeces and the first to quantify the amount of predator and prey DNA present within individual faecal samples. Conclusion We present an approach for characterizing mixed, highly degraded PCR templates such as those often encountered in ecological studies using non-invasive samples as a source of DNA, wildlife forensics investigations and ancient DNA research. This method will

  7. Metaphor use and health literacy: a pilot study of strategies to explain randomization in cancer clinical trials.

    Science.gov (United States)

    Krieger, Janice L; Parrott, Roxanne L; Nussbaum, Jon F

    2011-01-01

    Patients often have difficulty understanding what randomization is and why it is needed in Phase III clinical trials. Physicians commonly report using metaphorical language to convey the role of chance in being assignment to treatment; however, the effectiveness of this strategy as an educational tool has not been explored. Guided by W. McGuire's (1972) information-processing model, the purpose of this pilot study was to explore effects of metaphors to explain randomization on message acceptance and behavioral intention to participate in a Phase III clinical trial among a sample of low-income, rural women (N = 64). Participants were randomly assigned to watch a video that explained randomization using 1 of 3 message strategies: a low-literacy definition, standard metaphor (i.e., flip of a coin), or a culturally derived metaphor (i.e., sex of a baby). The influence of attention on behavioral intentions to participate in clinical trials was partially moderated by message strategy. Under conditions of low attention, participants in the culturally derived metaphor condition experienced significantly higher intentions to participate in clinical trials compared with participants in the standard metaphor condition. However, as attention increased, differences in intentions among the conditions diminished. Having a positive affective response to the randomization message was a strong, positive predictor of behavioral intentions to participate in clinical trials. The authors discuss the theoretical and practical implications of these findings.

  8. Universal-Based Prevention of Syndromal and Subsyndromal Social Anxiety: A Randomized Controlled Study

    Science.gov (United States)

    Aune, Tore; Stiles, Tore C.

    2009-01-01

    This article reports results from a universal preventive program aimed at (a) reducing social anxiety and (b) preventing the development of syndromal social anxiety among a population-based sample of older children and young adolescents during a 1-year period. Pupils (N = 1,748) from 2 counties were cluster randomized to either an intervention or…

  9. Using music to reduce anxiety among older adults in the emergency department: a randomized pilot study.

    Science.gov (United States)

    Belland, Laura; Rivera-Reyes, Laura; Hwang, Ula

    2017-11-01

    An emergency department (ED) visit may be distressing and anxiety-provoking for older adults (age > 65 years). No studies have specifically evaluated the effect of music listening on anxiety in older adults in the ED. The objective of this pilot study was to evaluate the effect of music listening on anxiety levels in older ED patients. This was a randomized pilot study in the geriatric ED of an urban academic tertiary medical center. This was a sample of English-speaking adults (age > 65 years) who were not deaf (n = 35). Subjects consented to participate and were randomized to receive up to 60 min of music listening with routine care, while the control group received routine care with no music. Subjects in the music treatment group received headphones and an electronic tablet with pre-downloaded music, and were allowed to choose from 5 selections. The primary outcome was change in anxiety levels, measured by the state-trait anxiety inventory (STAI), at enrollment and 1 h later. A total of 35 participants were enrolled: 74% were female, 40% were white, and 40% were black; of these, 32 subjects completed the study protocol. When comparing control (n = 18) against intervention subjects (n = 17), there were no significant differences in enrollment STAI scores (43.00 ± 15.00 vs. 40.30 ± 12.80, P = 0.57). STAI scores 1 hour after enrollment (after the music intervention) were significantly reduced in the intervention subjects compared to the control subjects (with reduction of 10.00 ± 12.29 vs. 1.88 ± 7.97, P = 0.03). These pilot results suggest that music listening may be an effective tool for reducing anxiety among older adults in the ED.

  10. Acupuncture for the treatment of phantom limb pain in lower limb amputees: study protocol for a randomized controlled feasibility trial.

    Science.gov (United States)

    Trevelyan, Esmé G; Turner, Warren A; Robinson, Nicola

    2015-04-12

    Phantom limb pain is a prevalent condition that is difficult to manage, with a lack of robust evidence to support the use of many adjunctive treatments. Acupuncture can be effective in the management of many painful conditions but little is known about its effectiveness in treating phantom limb pain. The aim of this study is to explore the feasibility of conducting a randomized controlled trial comparing acupuncture and routine care in a group of lower limb amputees with phantom limb pain. An unstratified, pragmatic, randomized, two-armed, controlled trial of parallel design comparing acupuncture and usual care control will be conducted. A total of 20 participants will be randomly assigned to receive either usual care or usual care plus acupuncture. Acupuncture will include eight 1 hour treatments delivered pragmatically over 4 weeks by practitioners trained in traditional Chinese medicine. As outcome measures, the Numerical Pain Rating Scale, short-form McGill Pain Questionnaire 2, EQ-5D-5 L, Hospital Anxiety and Depression Scale, 10-Item Perceived Stress Scale, Insomnia Severity Index, and Patient Global Impression of Change will be completed at baseline, weekly for the duration of the study and at 1 month after completion of the study. After completion of the trial, participants will provide feedback though semi-structured interviews. Feasibility will be determined through the ability to recruit to the study, success of the randomization process, completion of acupuncture intervention, acceptability of random allocation and completion of outcome measures. Acceptability of the acupuncture intervention will be determined through semi-structured interviews with participants. The appropriateness of outcome measures for a future trial will be addressed through completion rates of questionnaires and participant feedback. Data generated on effect size will be used for future sample size calculations and will inform the development of an appropriate and feasible

  11. A randomized RSA study concentrating especially on continuous migration.

    Science.gov (United States)

    Molt, Mats; Ryd, Leif; Toksvig-Larsen, Sören

    2016-06-01

    Background and purpose - There is a general call for phased introduction of new implants, and one step in the introduction is an early evaluation of micromotion. We compared the micromotion in the Triathlon and its predecessor, the Duracon total knee prosthesis, concentrating especially on continuous migration over 5 years of follow-up. Patients and methods - 60 patients were randomized to receive either a cemented Triathlon total knee prosthesis or a cemented Duracon total knee prosthesis. 3-D tibial component migration was measured by radiostereometric analysis (RSA) at 3 months and at 1, 2, and 5 years. Results - There was no statistically significant difference in maximum total point motion (MTPM) between the 2 groups (p = 0.1). The mean MTPM at 5 years for the Duracon was 1.10 (SD 1.21) mm and for the Triathlon it was 0.66 (SD 0.38) mm. The numbers of continuously migrating prostheses were similar in the groups at the fifth year of follow-up; 6 of 21 prostheses in the Duracon group and 3 of 21 in the Triathlon group had migrated more than 0.3 mm between the second year and the fifth year of follow-up (p = 0.2). Interpretation - The Triathlon has a micromotion pattern similar to that of the Duracon total knee system at both short-term and medium-term follow-up, and may therefore, over time, show the same good long-term mechanical stability.

  12. Oral leukoplakia in a South African sample: a clinicopathological study.

    Science.gov (United States)

    Chandran, R; Meer, S; Feller, L

    2013-09-01

    This study analysed differences in clinicopathological features of oral leukoplakia in different racial groups in the greater Johannesburg area of South Africa, with emphasis on the black population. The retrospective review included cases diagnosed clinically as oral leukoplakia and histologically as hyperkeratosis without dysplasia, hyperkeratosis with mild, moderate or severe dysplasia, and carcinoma in situ from 1990 to 2010. Age, gender, ethnicity, clinical appearance, site of lesion and tobacco smoking habit were recorded. Fourteen per cent of oral leukoplakia occurred in black South Africans compared with 80% in white South Africans. In contrast to whites, blacks were diagnosed with oral leukoplakia at a younger age; there were more men affected than women; and the proportion of idiopathic leukoplakia was greater. There were significantly more blacks (23%) than whites (13%) with non-homogenous leukoplakia and significantly more whites (51%) than blacks (23%) with dysplastic oral leukoplakia. This study suggests that oral leukoplakia, especially non-homogenous and idiopathic forms affects South African blacks less frequently than white South Africans; and in the former, it occurs more in men and at a younger age. These findings may provide some guidance in establishing screening policies for oral cancer, particularly suited for blacks. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Thermoluminescent properties studies of spodumene lilac sample to dosimetric applications

    Energy Technology Data Exchange (ETDEWEB)

    Lima, L L; Oliveira, R A P; Lima, H R B R; Santos, H N; Santos, J O; Lima, A F; Souza, S O, E-mail: sosouza@fisica.ufs.b

    2010-11-01

    This work investigates the thermoluminescent (TL) dosimetric properties in natural spodumene, LiAlSi{sub 2}O{sub 6}, called kunzite, from Minas Gerais State, Brazil. The mineralogical and chemical composition of this material was identified by means X-ray fluorescence and X-ray diffraction. Some dosimetric properties were studied, such as thermoluminescent emission curves as function of gamma dose. The glow curves of annealed kunzite presented two very intense TL peaks at 215 {sup 0}C (peak II) and 350 {sup 0}C (peak III), after gamma irradiation, being both of first kinetic order. These two most prominent peaks analyzed do not presented a linear growth in the range of 50 to 5000 Gy in the range of doses studied. The peak II also presented a very short calculated lifetime, which means it is hardly can be used in dosimetry, while the peak III has a longer lifetime and could be used in some applications for high doses dosimetry.

  14. A work sampling study of provider activities in school-based health centers.

    Science.gov (United States)

    Mavis, Brian; Pearson, Rachel; Stewart, Gail; Keefe, Carole

    2009-06-01

    The purpose of this study was to describe provider activities in a convenience sample of School-Based Health Centers (SBHCs). The goal was to determine the relative proportion of time that clinic staff engaged in various patient care and non-patient care activities. All provider staff at 4 urban SBHCs participated in this study; 2 were in elementary schools, 1 in a middle school, and 1 in a school with kindergarten through grade 8. The study examined provider activity from 6 days sampled at random from the school year. Participants were asked to document their activities in 15-minute intervals from 8:00 a.m. to 5:00 p.m. A structured recording form was used that included 35 activity categories. Overall, 1492 records were completed, accounting for 2708 coded activities. Almost half (48%) of all staff activities were coded as direct patient contact, with clinic operations the second largest category. Limited variations in activities were found across clinic sites and according to season. A significant amount of provider activity was directed at the delivery of health care; direct patient care and clinic operations combined accounted for approximately 75% of clinic activity. Patient, classroom, and group education activities, as well as contacts with parents and school staff accounted for 20% of all clinic activity and represent important SBHC functions that other productivity measures such as billing data might not consistently track. Overall, the method was acceptable to professional staff as a means of tracking activity and was adaptable to meet their needs.

  15. Effectiveness of quadrat sampling on terrestrial cave fauna survey - a case study in a Neotropical cave

    OpenAIRE

    Maria Elina Bichuette; Luiza Bertelli Simões; Diego Monteiro von Schimonsky; Jonas Eduardo Gallão

    2015-01-01

    Quadrat sampling is a method used for a long time in plant ecology studies but only recently it has been used with focus on fauna. For the cave fauna samplings, there are rare works applying this methodology. The present study compared the methods of quadrat sampling with direct search qualitative for terrestrial cave fauna. For this, we conducted five sampling collections in a limestone cave in central Brazil. Quadrat sampling contributed with 121 exclusive species and 716 specimens and dire...

  16. Mediterranean versus vegetarian diet for cardiovascular disease prevention (the CARDIVEG study): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Sofi, Francesco; Dinu, Monica; Pagliai, Giuditta; Cesari, Francesca; Marcucci, Rossella; Casini, Alessandro

    2016-05-04

    Nutrition is able to alter the cardiovascular health of the general population. However, the optimal dietary strategy for cardiovascular disease prevention is still far from being defined. Mediterranean and vegetarian diets are those reporting the greatest grade of evidence in the literature, but no experimental studies comparing these two dietary patterns are available. This is an open randomized crossover clinical trial including healthy subjects with a low-to-medium cardiovascular risk profile, characterized by being overweight and by the presence of at least an additional metabolic risk factor (abdominal obesity, high total cholesterol, high LDL cholesterol, high triglycerides, impaired glucose fasting levels) but free from medications. A total of 100 subjects will be included and randomly assigned to two groups: Mediterranean calorie-restricted diet (n = 50) and vegetarian calorie-restricted diet (n = 50). The intervention phases will last 3 months each, and at the end of intervention phase I the groups will be crossed over. The two diets will be isocaloric and of three different sizes (1400 - 1600 - 1800 kcal/day), according to specific energy requirements. Adherence to the dietary intervention will be established through questionnaires and 24-h dietary recall. Anthropometric measurements, body composition, blood samples and stool samples will be obtained from each participant at the beginning and at the end of each intervention phase. The primary outcome measure will be change in weight from baseline. The secondary outcome measures will be variations of anthropometric and bioelectrical impedance variables as well as traditional and innovative cardiovascular biomarkers. Despite all the data supporting the efficacy of Mediterranean and vegetarian diets on the prevention of cardiovascular diseases, no studies have directly compared these two dietary profiles. The trial will test whether there are statistically significant differences between these

  17. Multivariate stratified sampling by stochastic multiobjective optimisation

    OpenAIRE

    Diaz-Garcia, Jose A.; Ramos-Quiroga, Rogelio

    2011-01-01

    This work considers the allocation problem for multivariate stratified random sampling as a problem of integer non-linear stochastic multiobjective mathematical programming. With this goal in mind the asymptotic distribution of the vector of sample variances is studied. Two alternative approaches are suggested for solving the allocation problem for multivariate stratified random sampling. An example is presented by applying the different proposed techniques.

  18. Study on MAX-MIN Ant System with Random Selection in Quadratic Assignment Problem

    Science.gov (United States)

    Iimura, Ichiro; Yoshida, Kenji; Ishibashi, Ken; Nakayama, Shigeru

    Ant Colony Optimization (ACO), which is a type of swarm intelligence inspired by ants' foraging behavior, has been studied extensively and its effectiveness has been shown by many researchers. The previous studies have reported that MAX-MIN Ant System (MMAS) is one of effective ACO algorithms. The MMAS maintains the balance of intensification and diversification concerning pheromone by limiting the quantity of pheromone to the range of minimum and maximum values. In this paper, we propose MAX-MIN Ant System with Random Selection (MMASRS) for improving the search performance even further. The MMASRS is a new ACO algorithm that is MMAS into which random selection was newly introduced. The random selection is one of the edgechoosing methods by agents (ants). In our experimental evaluation using ten quadratic assignment problems, we have proved that the proposed MMASRS with the random selection is superior to the conventional MMAS without the random selection in the viewpoint of the search performance.

  19. Study of interaction between croscarmellose and escitalopram during sample preparation.

    Science.gov (United States)

    Larsen, Jesper; Melander, Claes

    2012-10-01

    During routine analysis of an escitalopram tablet formulation, it was seen that there was a systematic deviation between content uniformity (CU - one tablet analysis) and assay analysis (ten pooled tablets). In the presence of the excipients from the tablet, it was found that the extraction of the active pharmaceutical ingredient (API) was incomplete. It was shown that the commonly used tablet disintegrant croscarmellose sodium (crosslinked carboxy-methyl cellulose) had a significant interaction with escitalopram. This was later found to be the explanation for the lower extraction during assay testing. Under normal conditions, the extraction took place in acidic medium which caused protonation of the amine and thereby the interaction of charged species in solution. The interaction of API was studied further with pure croscarmellose and the entire tablet matrix. A range of conditions was considered, including altering extraction volumes, organic solvents, pH of the extraction solvent, and addition of competitive binder in various concentrations. It was seen that arginine was the most effective cationic competitive binder of those tested and that adding it at a suitable concentration level could significantly improve the analytical methods. In the present case, an improvement in recovery was from 98.5% to almost 100% was achieved.

  20. Acupuncture, Counseling, and Usual care for Depression (ACUDep: study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    MacPherson Hugh

    2012-11-01

    Full Text Available Abstract Background The evidence on the effect of acupuncture or counseling for depression is not conclusive yet is sufficient to warrant further research. Our aim is to conduct a full-scale RCT to determine the clinical and cost effectiveness of acupuncture and counseling compared to usual care alone. We will explore the experiences and perspectives of patients and practitioners. Methods/Design Randomized controlled trial with three parallel arms: acupuncture plus usual care, counseling plus usual care, and usual care alone, in conjunction with a nested qualitative study using in-depth interviews with purposive samples of trial participants. Participants: Patients aged over 18 years diagnosed with depression or mood disorder by their GP and with a score of 20 or above on the Beck Depression Inventory (BDI-II. Randomization: Computer randomization by York Trials Unit to acupuncture, counseling, and usual care alone in proportions of 2:2:1, respectively, with secure allocation concealment. Interventions: Patients allocated to acupuncture and counseling groups receive the offer of up to 12 weekly sessions. Both interventions allow flexibility to address patient variation, yet are constrained within defined protocols. Acupuncture is based on traditional Chinese medicine and counseling is non-directive within the humanistic tradition. Outcome: The PHQ-9 is the primary outcome measure, collected at baseline, 3, 6, 9, and 12 months. Also measured is BDI-II, SF-36 Bodily pain subscale, and EQ-5D. Texted mood scores are collected weekly over the first 15 weeks. Health-related resource use is collected over 12 months. Analysis: The sample size target was for 640 participants, calculated for an effect size of 0.32 on the PHQ-9 when comparing acupuncture with counseling given 90% power, 5% significance, and 20% loss to follow-up. Analysis of covariance will be used on an intention-to-treat basis. Thematic analysis will be used for qualitative data. We will

  1. Rapid, easy, and cheap randomization: prospective evaluation in a study cohort

    Directory of Open Access Journals (Sweden)

    Parker Melissa J

    2012-06-01

    Full Text Available Abstract Background When planning a randomized controlled trial (RCT, investigators must select randomization and allocation procedures based upon a variety of factors. While third party randomization is cited as being among the most desirable randomization processes, many third party randomization procedures are neither feasible nor cost-effective for small RCTs, including pilot RCTs. In this study we present our experience with a third party randomization and allocation procedure that utilizes current technology to achieve randomization in a rapid, reliable, and cost-effective manner. Methods This method was developed by the investigators for use in a small 48-participant parallel group RCT with four study arms. As a nested study, the reliability of this randomization procedure was prospectively evaluated in this cohort. The primary outcome of this nested study was the proportion of subjects for whom allocation information was obtained by the Research Assistant within 15 min of the initial participant randomization request. A secondary outcome was the average time for communicating participant group assignment back to the Research Assistant. Descriptive information regarding any failed attempts at participant randomization as well as costs attributable to use of this method were also recorded. Statistical analyses included the calculation of simple proportions and descriptive statistics. Results Forty-eight participants were successfully randomized and group allocation instruction was received for 46 (96% within 15 min of the Research Assistant placing the initial randomization request. Time elapsed in minutes until receipt of participant allocation instruction was Mean (SD 3.1 +/− 3.6; Median (IQR 2 (2,3; Range (1–20 for the entire cohort of 48. For the two participants for whom group allocation information was not received by the Research Assistant within the 15-min pass threshold, this information was obtained following a second

  2. Table 1. Description of samples used for simulation study with S1, 2 ...

    Indian Academy of Sciences (India)

    priyanka

    Description of samples used for simulation study with S1, 2, 3. Sample name Treatment_time Treatment_agent Sample source. GEO sample. (GSM) file Ids. 1. Lm_Adult1. 0 h. Listeria monocytogenes. Peripheral blood. GSM1467819. 2 h. GSM1467820. 6 h. GSM1467821. 2. Lm_Adult2. 0 h. Peripheral blood. GSM1467822.

  3. Pilot study of the Korean Parent Training Program using a partial group randomized experimental study

    Science.gov (United States)

    Kim, Eunjung; Cain, Kevin; Boutain, Doris; Chun, Jin-Joo; Kim, Sangho; Im, Hyesang

    2017-01-01

    Problems Korean American (KA) children experience mental health problems due to difficulties in parenting dysfunction complicated by living in two cultures. Methods Korean Parent Training Program (KPTP) was pilot tested with 48 KA mothers of children (ages 3–8) using partial group randomized controlled experimental study design. Self-report survey and observation data were gathered. Findings Analyses using generalized estimating equation indicated the intervention group mothers increased effective parenting and their children decreased behavior problems and reported less acculturation conflict with mothers. Conclusions The KPTP is a promising way to promote effective parenting and increase positive child mental health in KA families. PMID:24645901

  4. Methodology Series Module 5: Sampling Strategies.

    Science.gov (United States)

    Setia, Maninder Singh

    2016-01-01

    Once the research question and the research design have been finalised, it is important to select the appropriate sample for the study. The method by which the researcher selects the sample is the ' Sampling Method'. There are essentially two types of sampling methods: 1) probability sampling - based on chance events (such as random numbers, flipping a coin etc.); and 2) non-probability sampling - based on researcher's choice, population that accessible & available. Some of the non-probability sampling methods are: purposive sampling, convenience sampling, or quota sampling. Random sampling method (such as simple random sample or stratified random sample) is a form of probability sampling. It is important to understand the different sampling methods used in clinical studies and mention this method clearly in the manuscript. The researcher should not misrepresent the sampling method in the manuscript (such as using the term ' random sample' when the researcher has used convenience sample). The sampling method will depend on the research question. For instance, the researcher may want to understand an issue in greater detail for one particular population rather than worry about the ' generalizability' of these results. In such a scenario, the researcher may want to use ' purposive sampling' for the study.

  5. Methodology series module 5: Sampling strategies

    Directory of Open Access Journals (Sweden)

    Maninder Singh Setia

    2016-01-01

    Full Text Available Once the research question and the research design have been finalised, it is important to select the appropriate sample for the study. The method by which the researcher selects the sample is the 'Sampling Method'. There are essentially two types of sampling methods: 1 probability sampling – based on chance events (such as random numbers, flipping a coin etc.; and 2 non-probability sampling – based on researcher's choice, population that accessible & available. Some of the non-probability sampling methods are: purposive sampling, convenience sampling, or quota sampling. Random sampling method (such as simple random sample or stratified random sample is a form of probability sampling. It is important to understand the different sampling methods used in clinical studies and mention this method clearly in the manuscript. The researcher should not misrepresent the sampling method in the manuscript (such as using the term 'random sample' when the researcher has used convenience sample. The sampling method will depend on the research question. For instance, the researcher may want to understand an issue in greater detail for one particular population rather than worry about the 'generalizability' of these results. In such a scenario, the researcher may want to use 'purposive sampling' for the study.

  6. Trial registration in Latin America and the Caribbean's: study of randomized trials published in 2010.

    Science.gov (United States)

    Reveiz, Ludovic; Bonfill, Xavier; Glujovsky, Demian; Pinzon, Carlos E; Asenjo-Lobos, Claudia; Cortes, Marcela; Canon, Martin; Bardach, Ariel; Comandé, Daniel; Cardona, Andrés F

    2012-05-01

    To determine the prevalence of trial registration in randomized controlled trials (RCTs) published in 2010 (PUBMED/LILACS) from Latin America and the Caribbean's (LAC) and to compare methodological characteristics between registered and nonregistered RCTs. A search for detecting RCTs in which at least the first/contact author had a LAC's affiliation was made. We determined if RCTs were registered in the International Clinical Trial Registry Platform (ICTRP). Data were independently extracted by two authors. The risk of bias (RoB) was assessed in all registered RCTs (n=89) and in a sample of nonregistered RCTs (n=237). The search identified 1,695 references; 526 RCTs from 19 countries were included. 16.9% (89/526) of RCTs were registered in the ICTRP; however, only 21 (4.0%) were prospectively registered. A significant difference was found in the overall assessment of the RoB between registered and nonregistered RCTs. Overall, registered RCTs were multinational, had larger sample size and longer follow-up, and reported more frequently information on funding, conflict of interests, and ethic issues. No significant differences were found when analyzing prospectively registered RCTs. This study shows that trial registration rates are still low in LAC and the quality of reporting needs to be improved. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. SAMPLE SIZE DETERMINATION IN NON-RADOMIZED SURVIVAL STUDIES WITH NON-CENSORED AND CENSORED DATA

    Directory of Open Access Journals (Sweden)

    S FAGHIHZADEH

    2003-06-01

    likelihood function, when data has censored cases an estimate of the probability of censorship should be considered, after obtaining the varince of maximum likelihood estimator and considering its asymptotic normal distribution and by using coefficient of determination, formulas have been derived. The derived sample size formulas could attain the required power for a test adjuasted for effect of other explanatory covariates. Discussion: application of regression model in non-randomnized survival analysis helps to derive suitable formulas to determin sample size in both randomized and non-randomnized studies in a error level, to attain necessary statistical power. In Coxs semiparametric proportional hazard model ,since the varince of the parameter can not be stated in a simple form ,a simulation model can be used. When the coefficient of determination is partialy large the power bassed on log-rank test overestimates the true value of power, but when coefficient of determination is near to difference between powers decreases zero. By increasing of regression coefficient of determination, the difference between the log-rank test and adjusted coefficient of determination of this paper increases.

  8. Working memory and processing speed training in schizophrenia: study protocol for a randomized controlled trial.

    Science.gov (United States)

    Cassetta, Briana D; Goghari, Vina M

    2016-01-26

    In most domains of cognition, individuals with schizophrenia are generally found to be one standard deviation below the mean of the controls. As a result, examining the impact of cognitive remediation in individuals with schizophrenia has been a burgeoning area of research. However, the state of the literature remains unclear as to which domains of cognition should be targeted to produce the most widespread and durable benefits for individuals with schizophrenia. One suggestion is that targeting lower-level cognitive processes that are important for higher-level and more complex aspects of cognition may produce the most widespread benefits in cognition and everyday functioning. Relatively few studies have examined the effects of working memory or processing speed training in schizophrenia, as most studies examine broad-based remediation programs. Thus, a need exists for targeted working memory and processing speed training studies to better understand the mechanisms of cognitive enhancement in patients. This study aims to 1) investigate near-transfer gains (that is, the transfer of learning to related contexts) associated with working memory and processing speed training in schizophrenia patients; 2) investigate far-transfer gains (that is, the transfer of learning to new contexts) associated with working memory and processing speed training (that is, gains in other neurocognitive domains and social cognition); and 3) investigate real-world gains associated with training (that is, gains in daily functioning). A double-blind randomized controlled trial with a three parallel group design will be conducted. A random sample of 81 patients with schizophrenia or schizoaffective disorder will be recruited through outpatient clinics at Foothills Hospital and community support programs in Calgary, Alberta. Participants will be randomly assigned using a computer-generated program in a 1:1:1 ratio to a working memory-training group, a processing speed-training group, or a no

  9. A randomized, controlled pilot study of mindfulness-based stress reduction for pediatric chronic pain.

    Science.gov (United States)

    Jastrowski Mano, Kristen E; Salamon, Katherine S; Hainsworth, Keri R; Anderson Khan, Kimberly J; Ladwig, Renee J; Davies, W Hobart; Weisman, Steven J

    2013-01-01

    It is estimated that 1 in 5 children in the United States is affected by chronic pain. Increasing adaptive coping strategies and decreasing stress may be important in treatment. Research has suggested that mindfulness can help alleviate symptoms associated with medical illnesses and increase quality of life. Little is known about the effectiveness of mindfulness-based stress reduction (MBSR) in youth, partly due to insufficient methodological rigor in related studies. The primary purpose of the present study was to examine the feasibility, acceptability, and effectiveness of MBSR for a treatment-seeking sample of youth with chronic pain. The current study was the first randomized, controlled pilot study of MBSR for pediatric chronic pain. The research team had intended to use block randomization involving a total of five recruitment waves, with each wave consisting of one MBSR group and one psychoeducation group. Due to difficulties with recruitment and attrition before the start of either group, however, only MBSR was conducted at each wave after the first wave. Participants were recruited from a multidisciplinary pain clinic in a large, Midwestern children's hospital. The final sample included six adolescents between the ages of 12 and 17 y, four in the MBSR group and two in the psychoeducation group. Weekly sessions for the MBSR group were 90 min in length and followed a structured protocol. Sessions included a review of homework, an introduction to and practice of meditation, discussion of the session, and a review of the home practice assignment. The psychoeducation group participated in six group sessions, which were based on a cognitive-behavioral model of pain, and discussion topics included the nature of chronic pain and stress management. Health-related quality of life, pain catastrophizing, anxiety, functional disability, mindfulness, and treatment acceptability were all assessed pre- and postintervention as well as at follow-up. Recruitment and

  10. Empirical Evidence of Study Design Biases in Randomized Trials: Systematic Review of Meta-Epidemiological Studies.

    Directory of Open Access Journals (Sweden)

    Matthew J Page

    Full Text Available To synthesise evidence on the average bias and heterogeneity associated with reported methodological features of randomized trials.Systematic review of meta-epidemiological studies.We retrieved eligible studies included in a recent AHRQ-EPC review on this topic (latest search September 2012, and searched Ovid MEDLINE and Ovid EMBASE for studies indexed from Jan 2012-May 2015. Data were extracted by one author and verified by another. We combined estimates of average bias (e.g. ratio of odds ratios (ROR or difference in standardised mean differences (dSMD in meta-analyses using the random-effects model. Analyses were stratified by type of outcome ("mortality" versus "other objective" versus "subjective". Direction of effect was standardised so that ROR < 1 and dSMD < 0 denotes a larger intervention effect estimate in trials with an inadequate or unclear (versus adequate characteristic.We included 24 studies. The available evidence suggests that intervention effect estimates may be exaggerated in trials with inadequate/unclear (versus adequate sequence generation (ROR 0.93, 95% CI 0.86 to 0.99; 7 studies and allocation concealment (ROR 0.90, 95% CI 0.84 to 0.97; 7 studies. For these characteristics, the average bias appeared to be larger in trials of subjective outcomes compared with other objective outcomes. Also, intervention effects for subjective outcomes appear to be exaggerated in trials with lack of/unclear blinding of participants (versus blinding (dSMD -0.37, 95% CI -0.77 to 0.04; 2 studies, lack of/unclear blinding of outcome assessors (ROR 0.64, 95% CI 0.43 to 0.96; 1 study and lack of/unclear double blinding (ROR 0.77, 95% CI 0.61 to 0.93; 1 study. The influence of other characteristics (e.g. unblinded trial personnel, attrition is unclear.Certain characteristics of randomized trials may exaggerate intervention effect estimates. The average bias appears to be greatest in trials of subjective outcomes. More research on several

  11. Effect of oil pulling on plaque induced gingivitis: A randomized, controlled, triple-blind study

    Directory of Open Access Journals (Sweden)

    Asokan Sharath

    2009-01-01

    Full Text Available Background: Oil pulling has been used extensively as a traditional Indian folk remedy for many years for strengthening teeth, gums, and the jaw and to prevent decay, oral malodor, bleeding gums, dryness of the throat, and cracked lips. Aims: The aim of this study was to evaluate the effect of oil pulling with sesame oil on plaque-induced gingivitis and to compare its efficacy with chlorhexidine mouthwash. Materials and Methods : A total of 20 age-matched adolescent boys with plaque-induced gingivitis were selected for this study. They were divided randomly into the study or oil pulling group (Group I and the control or chlorhexidine group (Group II with 10 subjects in each group. Plaque index and modified gingival index scores were recorded for the 20 subjects and baseline plaque samples were also collected. The plaque samples were used to identify the microorganisms and to measure the total colony count of the aerobic microorganisms present. The study group was subjected to oil pulling with sesame oil and the control group was given chlorhexidine mouthwash everyday in the morning before brushing. Reassessment of the index scores and collection of plaque for measuring the colony count of the aerobic microorganisms was done after 10 days. Results: There was a statistically significant reduction of the pre- and post-values of the plaque and modified gingival index scores in both the study and control groups ( P < 0.001 in both. There was a considerable reduction in the total colony count of aerobic microorganisms present in both the groups. Conclusion: The oil pulling therapy showed a reduction in the plaque index, modified gingival scores, and total colony count of aerobic microorganisms in the plaque of adolescents with plaque-induced gingivitis.

  12. Myofascial Release Therapy in the Treatment of Occupational Mechanical Neck Pain: A Randomized Parallel Group Study.

    Science.gov (United States)

    Rodríguez-Fuentes, Iván; De Toro, Francisco Javier; Rodríguez-Fuentes, Gustavo; de Oliveira, Iris Machado; Meijide-Faílde, Rosa; Fuentes-Boquete, Isaac Manuel

    2016-07-01

    As myofascial release therapy is currently under development, the objective of this study was to compare the effectiveness of myofascial release therapy with manual therapy for treating occupational mechanical neck pain. A randomized, single-blind parallel group study was developed. The sample (n = 59) was divided into GI, treated with manual therapy, and GII, treated with myofascial release therapy. Variables studied were intensity of neck pain, cervical disability, quality of life, craniovertebral angle, and ranges of cervical motion. At five sessions, clinical significance was observed in both groups for all the variables studied, except for flexion in GI. At this time point, an intergroup statistical difference was observed, which showed that GII had better craniovertebral angle (P = 0.014), flexion (P = 0.021), extension (P = 0.003), right side bending (P = 0.001), and right rotation (P = 0.031). A comparative analysis between therapies after intervention showed statistical differences indicating that GII had better craniovertebral angle (P = 0.000), right (P = 0.000) and left (P = 0.009) side bending, right (P = 0.024) and left (P = 0.046) rotations, and quality of life. The treatment of occupational mechanical neck pain by myofascial release therapy seems to be more effective than manual therapy for correcting the advanced position of the head, recovering range of motion in side bending and rotation, and improving quality of life.

  13. Prednisolone and acupuncture in Bell's palsy: study protocol for a randomized, controlled trial

    Directory of Open Access Journals (Sweden)

    Wang Kangjun

    2011-06-01

    Full Text Available Abstract Background There are a variety of treatment options for Bell's palsy. Evidence from randomized controlled trials indicates corticosteroids can be used as a proven therapy for Bell's palsy. Acupuncture is one of the most commonly used methods to treat Bell's palsy in China. Recent studies suggest that staging treatment is more suitable for Bell's palsy, according to different path-stages of this disease. The aim of this study is to compare the effects of prednisolone and staging acupuncture in the recovery of the affected facial nerve, and to verify whether prednisolone in combination with staging acupuncture is more effective than prednisolone alone for Bell's palsy in a large number of patients. Methods/Design In this article, we report the design and protocol of a large sample multi-center randomized controlled trial to treat Bell's palsy with prednisolone and/or acupuncture. In total, 1200 patients aged 18 to 75 years within 72 h of onset of acute, unilateral, peripheral facial palsy will be assessed. There are six treatment groups, with four treated according to different path-stages and two not. These patients are randomly assigned to be in one of the following six treatment groups, i.e. 1 placebo prednisolone group, 2 prednisolone group, 3 placebo prednisolone plus acute stage acupuncture group, 4 prednisolone plus acute stage acupuncture group, 5 placebo prednisolone plus resting stage acupuncture group, 6 prednisolone plus resting stage acupuncture group. The primary outcome is the time to complete recovery of facial function, assessed by Sunnybrook system and House-Brackmann scale. The secondary outcomes include the incidence of ipsilateral pain in the early stage of palsy (and the duration of this pain, the proportion of patients with severe pain, the occurrence of synkinesis, facial spasm or contracture, and the severity of residual facial symptoms during the study period. Discussion The result of this trial will assess the

  14. The Effects of Experimentally Manipulated Social Status on Acute Eating Behavior: A Randomized, Crossover Pilot Study

    Science.gov (United States)

    Cardel, MI; Johnson, SL; Beck, J; Dhurandhar, E; Keita, AD; Tomczik, AC; Pavela, G; Huo, T; Janicke, DM; Muller, K; Piff, PK; Peters, JC; Hill, JO; Allison, DB

    2016-01-01

    Both subjective and objectively measured social status has been associated with multiple health outcomes, including weight status, but the mechanism for this relationship remains unclear. Experimental studies may help identify the causal mechanisms underlying low social standing as a pathway for obesity. Our objective was to investigate the effects of experimentally manipulated social status on ad libitum acute dietary intakes and stress-related outcomes as potential mechanisms relating social status and weight. This was a pilot feasibility, randomized, crossover study in Hispanic young adults (n=9; age 19–25; 67% female; BMI ≥18.5 and ≤30 kg/m2). At visit 1, participants consumed a standardized breakfast and were randomized to a high social status position (HIGH) or low social status position (LOW) in a rigged game of Monopoly™. The rules for the game differed substantially in terms of degree of ‘privilege’ depending on randomization to HIGH or LOW. Following Monopoly™, participants were given an ad libitum buffet meal and energy intakes (kcal) were estimated by pre- and post-weighing foods consumed. Stress-related markers were measured at baseline, after the game of Monopoly™, and after lunch. Visit 2 used the same standardized protocol; however, participants were exposed to the opposite social status condition. When compared to HIGH, participants in LOW consumed 130 more calories (p=0.07) and a significantly higher proportion of their daily calorie needs in the ad libitum buffet meal (39% in LOW versus 31% in HIGH; p=0.04). In LOW, participants reported decreased feelings of pride and powerfulness following Monopoly™ (p=0.05) and after their lunch meal (p=0.08). Relative to HIGH, participants in LOW demonstrated higher heart rates following Monopoly™ (p=0.06), but this relationship was not significant once lunch was consumed (p=0.31). Our pilot data suggest a possible causal relationship between experimentally manipulated low social status

  15. The Prevention of Depression and Anxiety in a Sample of High-Risk Adolescents: A Randomized Controlled Trial

    Science.gov (United States)

    Dobson, Keith S.; Hopkins, Jamie Ahnberg; Fata, Ladan; Scherrer, Martin; Allan, Lauren C.

    2010-01-01

    This study investigated the efficacy of cognitive behavioural therapy (CBT) techniques in preventing depression and anxiety in a group of adolescent high school students with elevated risk for developing emotional disorders. Students were screened using a measure of depression severity and clinical interview. Following screening procedures,…

  16. Online gambling's moderators: how effective? Study protocol for a randomized controlled trial.

    Science.gov (United States)

    Caillon, Julie; Grall-Bronnec, Marie; Hardouin, Jean-Benoit; Venisse, Jean-Luc; Challet-Bouju, Gaelle

    2015-05-30

    Online gambling has been legalized in France in 2010. Licenses are issued to gambling operators who demonstrate their ability to respect the legal framework (security, taxation, consumer protection, etc.). The preventive measures to protect vulnerable gamblers include an obligation to provide online gambling moderators. These moderators should allow gamblers to limit their bets, exclude themselves from the website for 7 days, and consult the balance of the gambler's account at any time. However, there are only a few published reports of empirical research investigating the effectiveness of Internet-based protective measures implemented by French law. Moreover, no empirical research has yet studied the impact of bonuses on gambling behaviors. This research is an experimental randomized controlled trial, risk prevention targeted. The research is divided into four sub-studies depending on the studied moderator: limiting bonuses, self-exclusion, self-limitation and information. The study sample consists of 485 volunteers. For each experimental condition and the control groups, the sample is composed of gamblers equally recruited from gamblers having preferences in each of the three major forms of games (lottery and scratch tickets, sports and horserace betting, and poker). For each form of gambling, the gamblers are recruited in order to obtain as many problem gamblers as non-problem gamblers. According to the randomization, the experimental session begins. The experimental session is a gambling situation on a computer in our research center. The gambler is invited to play on his favorite gambling site as usual, with his own gambler account and his own money. Data collected comprise sociodemographic characteristics, gambling habits, an interview about enjoyment and feeling out of control during the gambling session, moderator impact on gambling practice, statement of gambling parameters and questionnaires (BMIS, GRCS, CPGI, GACS). Moderator efficiency is assessed based

  17. Double blind randomized phase II study with radiation + 5-fluorouracil ± celecoxib for resectable rectal cancer

    National Research Council Canada - National Science Library

    Debucquoy, Annelies; Roels, Sarah; Goethals, Laurence; Libbrecht, Louis; Cutsem, Eric Van; Geboes, Karel; Penninckx, Freddy; D’Hoore, André; McBride, William H; Haustermans, Karin

    2009-01-01

    To assess the feasibility and efficacy of the COX-2 inhibitor celecoxib in conjunction with preoperative chemoradiation for patients with locally advanced rectal cancer in a double blind randomized phase II study...

  18. Lifetime Prevalence of Suicide Attempts Among Sexual Minority Adults by Study Sampling Strategies: A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Hottes, Travis Salway; Bogaert, Laura; Rhodes, Anne E; Brennan, David J; Gesink, Dionne

    2016-05-01

    Previous reviews have demonstrated a higher risk of suicide attempts for lesbian, gay, and bisexual (LGB) persons (sexual minorities), compared with heterosexual groups, but these were restricted to general population studies, thereby excluding individuals sampled through LGB community venues. Each sampling strategy, however, has particular methodological strengths and limitations. For instance, general population probability studies have defined sampling frames but are prone to information bias associated with underreporting of LGB identities. By contrast, LGB community surveys may support disclosure of sexuality but overrepresent individuals with strong LGB community attachment. To reassess the burden of suicide-related behavior among LGB adults, directly comparing estimates derived from population- versus LGB community-based samples. In 2014, we searched MEDLINE, EMBASE, PsycInfo, CINAHL, and Scopus databases for articles addressing suicide-related behavior (ideation, attempts) among sexual minorities. We selected quantitative studies of sexual minority adults conducted in nonclinical settings in the United States, Canada, Europe, Australia, and New Zealand. Random effects meta-analysis and meta-regression assessed for a difference in prevalence of suicide-related behavior by sample type, adjusted for study or sample-level variables, including context (year, country), methods (medium, response rate), and subgroup characteristics (age, gender, sexual minority construct). We examined residual heterogeneity by using τ(2). We pooled 30 cross-sectional studies, including 21,201 sexual minority adults, generating the following lifetime prevalence estimates of suicide attempts: 4% (95% confidence interval [CI] = 3%, 5%) for heterosexual respondents to population surveys, 11% (95% CI = 8%, 15%) for LGB respondents to population surveys, and 20% (95% CI = 18%, 22%) for LGB respondents to community surveys (Figure 1). The difference in LGB estimates by sample

  19. Robotic Surgery Readiness (RSR): A Prospective Randomized Skills Decay Recognition and Prevention Study

    Science.gov (United States)

    2016-08-01

    AWARD NUMBER: W81XWH-15-2-0030 TITLE: Robotic Surgery Readiness (RSR): A Prospective Randomized Skills Decay Recognition and Prevention Study...20164. TITLE AND SUBTITLE Robotic Surgery Readiness (RSR): A Prospective Randomized Skills Decay 5a. CONTRACT NUMBER R ognition and Prevention Study...design and skill decay model construction. Supply purchasing and acquisition for all four sites was also completed during this period. Working with

  20. Optical Methods for Identifying Hard Clay Core Samples During Petrophysical Studies

    Science.gov (United States)

    Morev, A. V.; Solovyeva, A. V.; Morev, V. A.

    2018-01-01

    X-ray phase analysis of the general mineralogical composition of core samples from one of the West Siberian fields was performed. Electronic absorption spectra of the clay core samples with an added indicator were studied. The speed and availability of applying the two methods in petrophysical laboratories during sample preparation for standard and special studies were estimated.

  1. Grab vs. composite sampling of particulate materials with significant spatial heterogeneity--a simulation study of "correct sampling errors".

    Science.gov (United States)

    Minkkinen, Pentti O; Esbensen, Kim H

    2009-10-19

    Sampling errors can be divided into two classes, incorrect sampling and correct sampling errors. Incorrect sampling errors arise from incorrectly designed sampling equipment or procedures. Correct sampling errors are due to the heterogeneity of the material in sampling targets. Excluding the incorrect sampling errors, which can all be eliminated in practice although informed and diligent work is often needed, five factors dominate sampling variance: two factors related to material heterogeneity (analyte concentration; distributional heterogeneity) and three factors related to the sampling process itself (sample type, sample size, sampling modus). Due to highly significant interactions, a comprehensive appreciation of their combined effects is far from trivial and has in fact never been illustrated in detail. Heterogeneous materials can be well characterized by the two first factors, while all essential sampling process characteristics can be summarized by combinations of the latter three. We here present simulations based on an experimental design that varies all five factors. Within the framework of the Theory of Sampling, the empirical Total Sampling Error is a function of the fundamental sampling error and the grouping and segregation error interacting with a specific sampling process. We here illustrate absolute and relative sampling variance levels resulting from a wide array of simulated repeated samplings and express the effects by pertinent lot mean estimates and associated Root Mean Squared Errors/sampling variances, covering specific combinations of materials' heterogeneity and typical sampling procedures as used in current science, technology and industry. Factors, levels and interactions are varied within limits selected to match realistic materials and sampling situations that mimic, e.g., sampling for genetically modified organisms; sampling of geological drill cores; sampling during off-loading 3-dimensional lots (shiploads, railroad cars, truckloads

  2. Probiotics for fibromyalgia: study design for a pilot double-blind, randomized controlled trial.

    Science.gov (United States)

    Roman, Pablo; Estévez, Ángeles F; Sánchez-Labraca, Nuria; Cañadas, Fernando; Miras, Alonso; Cardona, Diana

    2017-10-24

    Fibromyalgia syndrome (FMS) is a chronic, generalized and diffuse pain disorder accompanied by other symptoms such as emotional and cognitive deficits. The FMS patients show a high prevalence of gastrointestinal symptoms. Recently it has been found that microbes in the gut may regulate brain processes through the gut-microbiota-brain axis, modulating thus affection, motivation and higher cognitive functions. Therefore, the use of probiotics might be a new treatment that could improve the physical, psychological and cognitive state in FMS; however, no evidence about this issue is available. This paper describes the design and protocol of a double-blind, placebo-controlled and randomized pilot study. We use validated questionnaires, cognitive task through E-Prime and biological measures like urine cortisol and stool fecal samples. The trial aim is to explore the effects of eight weeks of probiotics therapy in physical (pain, impact of the FMS and quality of life), emotional (depression, and anxiety) and cognitive symptoms (attention, memory, and impulsivity) in FMS patients as compared to placebo. This pilot study is the first, to our knowledge, to evaluate the effects of probiotics in FMS. The primary hypothesis was that FMS patients will show a better performance on cognitive tasks, and an improvement in emotional and physical symptoms. These results will contribute to a better understanding in the gut-brain axis. Here we present the design and protocol of the study.

  3. Sample size estimation and sampling techniques for selecting a representative sample

    Directory of Open Access Journals (Sweden)

    Aamir Omair

    2014-01-01

    Full Text Available Introduction: The purpose of this article is to provide a general understanding of the concepts of sampling as applied to health-related research. Sample Size Estimation: It is important to select a representative sample in quantitative research in order to be able to generalize the results to the target population. The sample should be of the required sample size and must be selected using an appropriate probability sampling technique. There are many hidden biases which can adversely affect the outcome of the study. Important factors to consider for estimating the sample size include the size of the study population, confidence level, expected proportion of the outcome variable (for categorical variables/standard deviation of the outcome variable (for numerical variables, and the required precision (margin of accuracy from the study. The more the precision required, the greater is the required sample size. Sampling Techniques: The probability sampling techniques applied for health related research include simple random sampling, systematic random sampling, stratified random sampling, cluster sampling, and multistage sampling. These are more recommended than the nonprobability sampling techniques, because the results of the study can be generalized to the target population.

  4. Localization in random bipartite graphs: Numerical and empirical study

    Science.gov (United States)

    Slanina, František

    2017-05-01

    We investigate adjacency matrices of bipartite graphs with a power-law degree distribution. Motivation for this study is twofold: first, vibrational states in granular matter and jammed sphere packings; second, graphs encoding social interaction, especially electronic commerce. We establish the position of the mobility edge and show that it strongly depends on the power in the degree distribution and on the ratio of the sizes of the two parts of the bipartite graph. At the jamming threshold, where the two parts have the same size, localization vanishes. We found that the multifractal spectrum is nontrivial in the delocalized phase, but still near the mobility edge. We also study an empirical bipartite graph, namely, the Amazon reviewer-item network. We found that in this specific graph the mobility edge disappears, and we draw a conclusion from this fact regarding earlier empirical studies of the Amazon network.

  5. Schoolyard upgrade in a randomized controlled study design

    DEFF Research Database (Denmark)

    Christiansen, Lars Breum Skov; Toftager, Mette; Pawlowski, Charlotte Skau

    2017-01-01

    School recess physical activity is important for adolescent s health and development, and several studies have established evidence based on cross-sectional studies that it is influenced by the environment in the schoolyard. The aim of this study was to investigate the effect and variation across...... schools of a school-based intervention on students perceived opportunities for physical activity in the schoolyard, and to evaluate if an improved collective perception of opportunities was followed by an increase in PA during recess for the 13–15 year-old students. The intervention components included...... schoolyard renovation; mandatory outdoor recess; and increased adult supervision and support. Students collective perceptions were evaluated by a newly developed Schoolyard index (SYi) with seven items, and physical activity was objectively measured with accelerometer. We found variations in the change...

  6. Care for Patients with Type 2 Diabetes in a Random Sample of Community Family Practices in Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Gina Agarwal

    2012-01-01

    Full Text Available Objective. Diabetes care is an important part of family practice. Previous work indicates that diabetes management is variable. This study aimed to examine diabetes care according to best practices in one part of Ontario. Design and Participants. A retrospective chart audit of 96 charts from 18 physicians was conducted to examine charts regarding diabetes care during a one-year period. Setting. Grimsby, Ontario. Main Outcome Measures. Glycemic screening, control and management strategies, documentation and counselling for lifestyle habits, prevalence of comorbidities, screening for hypertension, hyperlipidemia, and use of appropriate recommended preventive medications in the charts were examined. Results. Mean A1c was within target (less than or equal to 7.00 in 76% of patients (ICC = −0.02, at least 4 readings per annum were taken in 75% of patients (ICC = 0.006. Nearly 2/3 of patients had been counselled about diet, more than 1/2 on exercise, and nearly all (90% were on medication. Nearly all patients had a documented blood pressure reading and lipid profile. Over half (60% had a record of their weight and/or BMI. Conclusion. Although room for improvement exists, diabetes targets were mainly reached according to recognized best practices, in keeping with international data on attainment of diabetes targets.

  7. High dose antithrombin supplementation in early preeclampsia: A randomized, double blind, placebo-controlled study.

    Science.gov (United States)

    D'Angelo, Armando; Valsecchi, Luca

    2016-04-01

    Antithrombin levels are often reduced in preeclampsia and infusion of antithrombin concentrates has been reported to prolong gestation in severe preeclampsia. We aimed to evaluate efficacy and safety of high-dose antithrombin (ATIII) supplementation in patients with single pregnancies and preeclampsia occurring before 30 weeks of gestation. In November 2004 a double-blind, placebo-controlled trial (code KB033) was started in 13 Italian centers. The planned sample size was of 240 patients (intention-to-treat, ITT population) to detect a 30% relative risk reduction of the primary endpoint, composite perinatal morbidity. Eligible patients were randomized to high dose AT (3000 IU/daily, ATIII Kedrion S.p.A., Italy), or placebo (1% glycine) for 7 days or less until delivery, whichever came first. The per-protocol (PP) population was restricted to patients receiving at least two days of treatment. The study was terminated by the sponsor in October 2007 after the enrolment of 38 evaluable patients - 20 randomized to high dose AT and 18 to placebo, 27 treated for 2 days or more - out of 164 screened patients. Enrolment failures were mainly represented by requirement for immediate delivery and consent refusal (91 patients). The primary endpoint occurred in 15 of 38 patients (39.5%), with a relative risk in the AT arm of 0.85 (95% CI 0.42-1.75) and 0.79 (95% CI 0.30-2.11) in the ITT and PP populations, respectively. Living neonates in the two arms had similar weight at birth, Apgar scores, and duration of hospitalization in neonatal ICU. In mothers, AT supplementation was associated with reduced blood loss at delivery and with surrogate laboratory markers (LDH, d-dimer). The results of this markedly underpowered trial, albeit suggestive of a potential maternal benefit, cannot support high-dose AT supplementation to improve fetal/neonatal outcomes in early preeclampsia. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Control of postoperative pain following implantable cardioverter defibrillator placement. A randomized study.

    Science.gov (United States)

    Luque Oliveros, M

    2017-11-20

    To evaluate local anesthetic infiltration with 0.5% bupivacaine in the management of surgical wound pain during the postoperative period. A randomized controlled trial was carried out from 1 January to 1 June 2017 SCOPE: Cardiovascular Surgery Department and Heart Area. Patients scheduled for implantable cardioverter defibrillator (ICD) placement, aged ≥ 18 years and who following verbal and written explanation of the purpose of the study, accepted and signed the informed consent document. The total sample consisted of 82 patients divided into anesthetic infiltration group (n=39) and control group (n=43). Patients were randomized to the control group (conventional management) or anesthetic infiltration group (infiltration of 0.5% bupivacaine at surgical wound closure after ICD implantation). Pain intensity was rated with the Numerical Rating Scale (NRS) during the postoperative period at rest and in the course of movement. Patient gender, sex and age, type and time of surgery, intensity of pain, surgical wound complications and rescue analgesia. The control group showed the greatest pain during the postoperative period according to the NRS resting score (at 2hours NRS=6.3; P=.001, 4hours NRS=6.1; P=.002 and 12hours NRS=4.1; P=.004) and in the course of movement (at 2hours NRS=7.1; P=.001, 4hours NRS=6.9; P=.003 and 12hours NRS=5.1; P=.005). The infiltration of 0.5% bupivacaine in the surgical incision after ICD implantation reduces patient pain at rest and in the course of movement during the postoperative period. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  9. Antiaggressive effect of cyproterone versus haloperidol in Alzheimer's disease: a randomized double-blind pilot study.

    Science.gov (United States)

    Huertas, David; López-Ibor Aliño, Juan J; Molina, Juan D; Chamorro, Lorenzo; Balanza, Juana; Jiménez, María P; Hornillos, Mercedes

    2007-03-01

    Alzheimer's disease (AD) is commonly accompanied by aggressive behavior. In the elderly, effective and safe antiaggressive treatment is lacking. Risks of antipsychotics in this population demand therapeutic alternatives. This randomized, double-blind, pilot trial examined the efficacy and safety of cyproterone in the treatment of agitated AD. The subjects were 27 elderly patients referred to the University Hospital of Guadalajara Psychogeriatric Clinic diagnosed with AD and associated aggressive behavior (mean Staff Observation Aggression Scale [SOAS] score >or=2). Each patient underwent a 15-day washout for psychotropics and then was randomly assigned to receive stable doses of either cyproterone (100 mg/day) or haloperidol (2 mg/day) for 90 days. The primary outcome measure was the SOAS score. This trial was conducted between October 27, 1993, and March 24, 1998. Of the 27 patients, 19 (70.4%) were women, and the mean age was 80.7 years. The trial was completed by 24 (88.9%) of the subjects (13 in the cyproterone group and 11 in the haloperidol group for 90 days). Three patients (11.1%) dropped out, all after adverse effects in the haloperidol group. Baseline aggression level in the sample was mild (mean SOAS score of 4.48 [SD = 2.04]). Efficacy analyses for all intent-to-treat patients showed that 9 (69.2%) in the cyproterone group achieved complete elimination of aggression at endpoint, in contrast to 2 patients (14.2%) in the haloperidol group (p = .012). Ten patients (71.4%) taking haloperidol had adverse events, compared with 4 (30.7%) taking cyproterone (p = .035). Cyproterone showed significantly better efficacy and safety than haloperidol in controlling mild aggression associated with AD. Additional research is needed to confirm if these results can be ratified in a larger study and generalized to patients whose aggression is more severe.

  10. Validity of protein-osmolality versus protein-creatinine ratios in the estimation of quantitative proteinuria from random samples of urine in children.

    Science.gov (United States)

    Morgenstern, Bruce Z; Butani, Lavjay; Wollan, Peter; Wilson, David M; Larson, Timothy S

    2003-04-01

    Proteinuria is an important marker of kidney disease. Simple methods to determine the presence of proteinuria in a semiquantitative fashion require measurement of either a protein-creatinine or protein-osmolality ratio. Urine samples from 134 healthy infants and children and 150 children from the pediatric nephrology practice were analyzed to develop normative data for protein-osmolality ratios on random urine samples and compare protein-osmolality with protein-creatinine ratio as a predictor of 24-hour urine protein excretion. Children were grouped according to age. Three groups were established: infants (protein excretion was determined to be a protein-osmolality ratio of 0.15 mg x kg H2O/mOsm. L; for children between 2 and 8 years old, 0.14; and for children older than 8 years, 0.17 (P = not significant between age groups). The corresponding optimal cutoff value for protein-creatinine ratio for the entire group of children older than 2 years is 0.20. Area under the curve analysis of receiver operator characteristic curves showed protein-creatinine ratio was superior to protein-osmolality ratio for predicting abnormal amounts of proteinuria in children and adolescents (P protein-creatinine ratio in children, it would be appropriate to screen urine samples for proteinuria using protein-creatinine ratio rather than protein-osmolality ratio.

  11. The clinical and rehabilitative complexity in dementia with Lewy bodies (DLB): experience on a random sample of elderly patients dwelling in an RSA ("Residenza Sanitaria Assistita") of Catania.

    Science.gov (United States)

    Santangelo, Antonino; Testai', Manuela; Albani, Salvatore; Mamazza, Grazia; Pavano, Salvatore; Zuccaro, Carmela; Atteritano, Marco; Berretta, Massimiliano; Tomarchio, Marcello; Maugeri, Domenico

    2010-01-01

    This study was aimed at evaluating the occurrence of DLB in a population sample recovered in assisted sanitary residence (RSA=from the Italian name of "Residenza Sanitaria Assistita") in the Province of Catania. We considered 126 patients from a randomized population recovered in RSA of Viagrande (Catania) in the period from 1st March, 2005 and 31st March, 2007. Those who proved to be demented according to the DSM-III diagnostic protocols, and having a mini mental state examination (MMSE)-score <24 were divided in 2 groups: Group A, all the demented people without the DLB; and Group B, the DLB patients, according to the diagnostic criteria of McKeith. All patients underwent at admission, after 1 month, and at emission the following psychometric and functional tests: MMSE, geriatric depression scale (GDS) [Yesavage J.A., Brink T.L., Rose T.L., Adey M., 1983. The development and validation of geriatric depression screening scale: a preliminary report. J. Psych. Res. 17, 37], Barthel index (BI), activities of daily living (ADL) and instrumental ADL (IADL). Particular attention was dedicated to the presence of delirium during the last 15 days before the admission and during the recovery, the mortality and the prevalence of other complaints. The observed data confirm the prevalence of fragility of DLB patients in 20% of them, a fluctuation of the cognitive capacities, a better recovery of the affectivity, a reduced functional autonomy and autosufficiency. In addition, the DLB patients display a major presence of prevalent delirium, compared to the total population of demented patients, while in this last population only incidental delirium episodes occurred during the recovery period (31.6% vs. 16.6%; p<0.001). In the DLB population decubital lesions occurred more frequently, and were of more severe staging, compared to the controls (45% vs. 27%; p<0.001). Also, the mortality of the DLB patients was higher (about 30% vs. 17% in 12 months). These data confirm the

  12. Pediatric Basic Life Support Self-training is Comparable to Instructor-led Training: A randomized manikin study

    DEFF Research Database (Denmark)

    Vestergaard, L. D.; Løfgren, Bo; Jessen, C.

    2011-01-01

    Pediatric Basic Life Support Self-training is comparable to Instructor-led Training: A randomized manikin study.......Pediatric Basic Life Support Self-training is comparable to Instructor-led Training: A randomized manikin study....

  13. Mouth-to-mouth ventilation reduces interruptions in chest compressions during lifeguard CPR: A randomized manikin study,

    DEFF Research Database (Denmark)

    Løfgren, Bo; Adelborg, Kasper; Dalgas, Christian

    Mouth-to-mouth ventilation reduces interruptions in chest compressions during lifeguard CPR: A randomized manikin study.......Mouth-to-mouth ventilation reduces interruptions in chest compressions during lifeguard CPR: A randomized manikin study....

  14. Transcutaneus electrical nerve stimulation for overactive bladder increases rectal motor activity in children: a randomized controlled study

    DEFF Research Database (Denmark)

    Jønsson, Iben; Hagstrøm, Søren; Siggaard, Charlotte

    Transcutaneus electrical nerve stimulation for overactive bladder increases rectal motor activity in children: a randomized controlled study......Transcutaneus electrical nerve stimulation for overactive bladder increases rectal motor activity in children: a randomized controlled study...

  15. A Prospective, Randomized Study Comparing 7-day and 14-day ...

    African Journals Online (AJOL)

    Objective: Standard triple therapy for Helicobacter pylori has a low eradication rate in Turkey. The aim of this study was to evaluate and compare the effectiveness of 7-day and 14-day lansoprazole, amoxicillin, clarithromycin, and bismuth subsalicylate (LACB) treatment regimens as first-line H. pylori eradication therapies.

  16. Mendelian randomization studies of biomarkers and type 2 diabetes

    NARCIS (Netherlands)

    Abbasi, Ali

    2015-01-01

    Many biomarkers are associated with type 2 diabetes (T2D) risk in epidemiological observations. The aim of this study was to identify and summarize current evidence for causal effects of biomarkers on T2D. A systematic literature search in PubMed and EMBASE (until April 2015) was done to identify

  17. A study of serial ranks via random graphs

    OpenAIRE

    Haeusler, Erich; Mason, David M.; Turova, Tatyana S.

    2000-01-01

    Serial ranks have long been used as the basis for nonparametric tests of independence in time series analysis. We shall study the underlying graph structure of serial ranks. This will lead us to a basic martingale which will allow us to construct a weighted approximation to a serial rank process. To show the applicability of this approximation, we will use it to prove two very general central limit theorems for Wald-Wolfowitz-type serial rank statistics.

  18. Localization of optical excitations on random surfaces: SNOM studies

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Localization of optical excitations on nanostructured metal surfaces and fractal colloid silver aggregates are studied by using a scanning near-field optical microscope (SNOM). The SNOM images obtained in both configurations exhibit spatially localized (within 150 to 250 nm) light intensity...... enhancement by up to two orders of magnitude. The observed phenomena are related to strong (Anderson) localization of quasi-two-dimensional light waves....

  19. In vivo photoacoustic mouse eye imaging of healing after chemical injury and automated eyeball surface estimation based on a random sample consensus algorithm

    Science.gov (United States)

    Jeon, Seungwan; Song, Hyun Beom; Kim, Jaewoo; Lee, Byung Joo; Kim, Jeong Hun; Kim, Chulhong

    2017-03-01

    Ocular chemical damage may induce limbal vessel ischemia and neovascularization, but the pathophysiology of the disease is not completely known. To observe changes in blood vessels after alkaline burn, we monitored the anterior segment and choroidal vasculature using a photoacoustic microscope (OR-PAM). We were able to observe not only the iris blood vessels but also the choroidal vessels under the sclera, which were difficult to be observed with conventional photographs. After alkali burning, we observed neovascularization and limbal ischemia and successfully tracked changes in vasculature during the 7-day healing process. We also used the RANdom SAmple Consensus (RANSAC) method to segment the abnormally generated blood vessels in the cornea by detecting the eyeball surface and successfully visualize the distance from each PA signal to the center of the eye. We believe that photoacoustic imaging has an important potential to reveal the pathophysiology of limb ischemia and neovascularization.

  20. Prevention of Anxiety and Depression in Swedish School Children: a Cluster-Randomized Effectiveness Study.

    Science.gov (United States)

    Ahlen, Johan; Hursti, Timo; Tanner, Lindsey; Tokay, Zelal; Ghaderi, Ata

    2017-07-20

    Our study aimed at evaluating FRIENDS for Life, an intervention to prevent anxiety and depression in Swedish school children. A total of 695 children between the ages of 8 and 11 were recruited from 17 schools in Stockholm, Sweden, and cluster-randomized to either the intervention or control group. Teachers in the intervention group received a full day of training and administered FRIENDS for Life in their classrooms. We assessed the children's anxiety and depressive symptoms, general mental health, and academic performance at pre- and post-intervention as well as at the 12-month follow-up. A multi-informant approach was used with data collected from children, parents, and teachers. Assessment was done with the Spence Children's Anxiety Scale, Children's Depression Inventory, and the Strengths and Difficulties Questionnaire. Children's baseline symptoms, gender, and age as well as their teacher's use of supervision were examined as moderators of effect. Our study found no short- or long-term effects of the intervention for any outcome with regard to the entire sample. We found an enhanced effect of the intervention regarding children with elevated depressive symptoms at baseline. We found a decrease in anxiety symptoms among children whose teachers attended a larger number of supervision sessions, compared to children whose teachers attended fewer supervised sessions or the control group. Mediation analyses showed that this effect was driven by change in the last phase of the intervention, suggesting that supervision might play an important role in enhancing teachers' ability to administer the intervention effectively.

  1. What about N? A methodological study of sample-size reporting in focus group studies

    Science.gov (United States)

    2011-01-01

    Background Focus group studies are increasingly published in health related journals, but we know little about how researchers use this method, particularly how they determine the number of focus groups to conduct. The methodological literature commonly advises researchers to follow principles of data saturation, although practical advise on how to do this is lacking. Our objectives were firstly,