WorldWideScience

Sample records for bivariate association tests

  1. Statistical Test for Bivariate Uniformity

    Directory of Open Access Journals (Sweden)

    Zhenmin Chen

    2014-01-01

    Full Text Available The purpose of the multidimension uniformity test is to check whether the underlying probability distribution of a multidimensional population differs from the multidimensional uniform distribution. The multidimensional uniformity test has applications in various fields such as biology, astronomy, and computer science. Such a test, however, has received less attention in the literature compared with the univariate case. A new test statistic for checking multidimensional uniformity is proposed in this paper. Some important properties of the proposed test statistic are discussed. As a special case, the bivariate statistic test is discussed in detail in this paper. The Monte Carlo simulation is used to compare the power of the newly proposed test with the distance-to-boundary test, which is a recently published statistical test for multidimensional uniformity. It has been shown that the test proposed in this paper is more powerful than the distance-to-boundary test in some cases.

  2. Score Tests of Normality in Bivariate Probit Models

    OpenAIRE

    Anthony Murphy

    2005-01-01

    A relatively simple and convenient score test of normality in the bivariate probit model is derived. Monte Carlo simulations show that the small sample performance of the bootstrapped test is quite good. The test may be readily extended to testing normality in related models.

  3. Univariate and Bivariate Loglinear Models for Discrete Test Score Distributions.

    Science.gov (United States)

    Holland, Paul W.; Thayer, Dorothy T.

    2000-01-01

    Applied the theory of exponential families of distributions to the problem of fitting the univariate histograms and discrete bivariate frequency distributions that often arise in the analysis of test scores. Considers efficient computation of the maximum likelihood estimates of the parameters using Newton's Method and computationally efficient…

  4. Joint association analysis of bivariate quantitative and qualitative traits.

    Science.gov (United States)

    Yuan, Mengdie; Diao, Guoqing

    2011-01-01

    Univariate genome-wide association analysis of quantitative and qualitative traits has been investigated extensively in the literature. In the presence of correlated phenotypes, it is more intuitive to analyze all phenotypes simultaneously. We describe an efficient likelihood-based approach for the joint association analysis of quantitative and qualitative traits in unrelated individuals. We assume a probit model for the qualitative trait, under which an unobserved latent variable and a prespecified threshold determine the value of the qualitative trait. To jointly model the quantitative and qualitative traits, we assume that the quantitative trait and the latent variable follow a bivariate normal distribution. The latent variable is allowed to be correlated with the quantitative phenotype. Simultaneous modeling of the quantitative and qualitative traits allows us to make more precise inference on the pleiotropic genetic effects. We derive likelihood ratio tests for the testing of genetic effects. An application to the Genetic Analysis Workshop 17 data is provided. The new method yields reasonable power and meaningful results for the joint association analysis of the quantitative trait Q1 and the qualitative trait disease status at SNPs with not too small MAF. PMID:22373162

  5. Testing normality in bivariate probit models : a simple artificial regression based LM test

    OpenAIRE

    Anthony Murphy

    1994-01-01

    A simple and convenient LM test of normality in the bivariate probit model is derived. The alternative hypothesis is based on a form of truncated Gram Charlier Type series. The LM test may be calculated as an artificial regression. However, the proposed artificial regression does not use the outer product gradient form. Thus it is likely to perform reasonably well in small samples.

  6. Conditional Moment Tests for Normality in Bivariate Limited Dependent Variable Models: a Monte Carlo Study

    OpenAIRE

    Riccardo LUCCHETTI; Pigini, Claudia

    2011-01-01

    In this paper, we run a Monte Carlo analysis of the finite-sample performance of an Information Matrix Test put forward by Smith (1985) for bivariate censored models. We use the bivariate probit model and Heckman selection model as examples.;Approximating the finite-sample distribution of this test statistic by its asymptotic distribution can lead to very misleading results: its size is severely distorted even in samples that common practice would judge to be perfectly adequate for asymptotic...

  7. Regression spline bivariate probit models: a practical approach to testing for exogeneity

    OpenAIRE

    Marra, G.; Radice, Rosalba; Filippou, P

    2015-01-01

    Bivariate probit models can deal with a problem usually known as endogeneity. This issue is likely to arise in observational studies when confounders are unobserved. We are concerned with testing the hypothesis of exogeneity (or absence of endogeneity) when using regression spline recursive and sample selection bivariate probit models. Likelihood ratio and gradient tests are discussed in this context and their empirical properties investigated and compared with those of the Lagrange multiplie...

  8. Testing normality in bivariate probit models : a simple artificial regression based LM test

    OpenAIRE

    Murphy, Anthony

    1994-01-01

    A simple and convenient LM test of normality in the bivariate probit model is derived. The alternative hypothesis is based on a form of truncated Gram Charlier Type series. The LM test may be calculated as an artificial regression. However, the proposed artificial regression does not use the outer product gradient form. Thus it is likely to perform reasonably well in small samples. non-peer-reviewed

  9. A simple LM test for zero correlation in the censored bivariate probit model

    OpenAIRE

    Murphy, Anthony

    1994-01-01

    A simple artificial regression based on Lagrange Multiplier (LM) test for zero correlation in the censored bivariate probit model is derived. The outer product gradient form of the LM test is not used so the proposed test is likely to have good small sample properties. non-peer-reviewed

  10. A simple LM test for zero correlation in the censored bivariate probit model

    OpenAIRE

    Murphy, Anthony

    1994-01-01

    A simple artificial regression based on Lagrange Multiplier (LM) test for zero correlation in the censored bivariate probit model is derived. The outer product gradient form of the LM test is not used so the proposed test is likely to have good small sample properties.

  11. Testing for a Single-Factor Stochastic Volatility in Bivariate Series

    Directory of Open Access Journals (Sweden)

    Masaru Chiba

    2013-12-01

    Full Text Available This paper proposes the Lagrange multiplier test for the null hypothesis thatthe bivariate time series has only a single common stochastic volatility factor and noidiosyncratic volatility factor. The test statistic is derived by representing the model in alinear state-space form under the assumption that the log of squared measurement error isnormally distributed. The empirical size and power of the test are examined in Monte Carloexperiments. We apply the test to the Asian stock market indices.

  12. Joint association analysis of bivariate quantitative and qualitative traits

    OpenAIRE

    2011-01-01

    Univariate genome-wide association analysis of quantitative and qualitative traits has been investigated extensively in the literature. In the presence of correlated phenotypes, it is more intuitive to analyze all phenotypes simultaneously. We describe an efficient likelihood-based approach for the joint association analysis of quantitative and qualitative traits in unrelated individuals. We assume a probit model for the qualitative trait, under which an unobserved latent variable and a presp...

  13. Testing the hypothesis of absence of unobserved confounding in semiparametric bivariate probit models

    OpenAIRE

    Marra, G.; R. Radice; Missiroli, S

    2014-01-01

    Lagrange multiplier and Wald tests for the hypothesis of absence of unobserved confounding are extended to the context of semiparametric recursive and sample selection bivariate probit models. The finite sample size properties of the tests are examined through a Monte Carlo study using several scenarios: correct model specification, distributional and functional misspecification, with and without an exclusion restriction. The simulation results provide some guidelines which may be important f...

  14. Estimation of the Parameters of the Bivariate Generalized Exponential Distribution using Accelerated Life Testing with Censoring Data

    Directory of Open Access Journals (Sweden)

    Salwa Asser

    2014-06-01

    Full Text Available In this paper, the estimation for the bivariate generalized exponential (BVGE distribution under type-I censored with constant stress accelerated life testing (CSALT are discussed. The scale parameter of the lifetime distribution at constant stress levels is assumed to be an inverse power law function of the stress level. The unknown parameters are estimated by the maximum likelihood approach and their approximate variance-covariance matrix is obtained. Then, the numerical studies are introduced to illustrate the approach study using samples which have been generated from the bivariate generalized exponential distribution. Keywords: Accelerated life testing, Bivariate generalized exponential distribution, Constant stress, Type-I censoring, Maximum likelihood estimation.

  15. A goodness-of-fit test for bivariate extreme-value copulas

    CERN Document Server

    Genest, Christian; Nešlehová, Johanna; Yan, Jun; 10.3150/10-BEJ279

    2011-01-01

    It is often reasonable to assume that the dependence structure of a bivariate continuous distribution belongs to the class of extreme-value copulas. The latter are characterized by their Pickands dependence function. In this paper, a procedure is proposed for testing whether this function belongs to a given parametric family. The test is based on a Cram\\'{e}r--von Mises statistic measuring the distance between an estimate of the parametric Pickands dependence function and either one of two nonparametric estimators thereof studied by Genest and Segers [Ann. Statist. 37 (2009) 2990--3022]. As the limiting distribution of the test statistic depends on unknown parameters, it must be estimated via a parametric bootstrap procedure, the validity of which is established. Monte Carlo simulations are used to assess the power of the test and an extension to dependence structures that are left-tail decreasing in both variables is considered.

  16. Bayesian estimation of the parameters of the bivariate generalized exponential distribution using accelerated life testing under censoring data

    Directory of Open Access Journals (Sweden)

    Abd El-Maseh, M. P

    2015-11-01

    Full Text Available In this paper, the Bayesian estimation for the unknown parameters for the bivariate generalized exponential (BVGE distribution under Bivariate censoring type-I samples with constant stress accelerated life testing (CSALT are discussed. The scale parameter of the lifetime distribution at constant stress levels is assumed to be an inverse power law function of the stress level. The parameters are estimated by Bayesian approach using Markov Chain Monte Carlo (MCMC method based on Gibbs sampling. Then, the numerical studies are introduced to illustrate the approach study using samples which have been generated from the BVGE distribution.

  17. On bivariate geometric distribution

    OpenAIRE

    Jayakumar, K.; Davis Antony Mundassery

    2013-01-01

    Characterizations of bivariate geometric distribution using univariate and bivariate geometric compounding are obtained. Autoregressive models with marginals as bivariate geometric distribution are developed. Various bivariate geometric distributions analogous to important bivariate exponential distributions like, Marshall-Olkin’s bivariate exponential, Downton’s bivariate exponential and Hawkes’ bivariate exponential are presented.

  18. Association of smoking and drinking with socioeconomic factors: A comparative study based on bivariate probit model analysis

    OpenAIRE

    OSHIO, Takashi; Kobayashi, Miki

    2010-01-01

    In this study, we examined the differences between smoking and drinking in regard to their associations with socioeconomic factors among about 7,000 Japanese workers. Using microdata from nationwide surveys in Japan, we estimated bivariate probit models to jointly explore how smoking and drinking are related to a wide variety of socioeconomic factors. We found that only educational attainment is consistently and negatively associated with both smoking and drinking for both genders. The associ...

  19. Modified Signed Log-Likelihood Ratio Test for Comparing the Correlation Coefficients of Two Independent Bivariate Normal Distributions

    OpenAIRE

    Kazemi, M. R.; Jafari, A A

    2016-01-01

    In this paper, we use the method of modified signed log-likelihood ratio test for the problem of testing the equality of correlation coefficients in two independent bivariate normal distributions. We compare this method with two other %competing approaches, Fisher's Z-transform and generalized test variable, using a Monte Carlo simulation. It indicates that the proposed method is better than the other approaches, in terms of the actual sizes and powers especially when the sample sizes are une...

  20. Powerful bivariate genome-wide association analyses suggest the SOX6 gene influencing both obesity and osteoporosis phenotypes in males.

    Directory of Open Access Journals (Sweden)

    Yao-Zhong Liu

    Full Text Available BACKGROUND: Current genome-wide association studies (GWAS are normally implemented in a univariate framework and analyze different phenotypes in isolation. This univariate approach ignores the potential genetic correlation between important disease traits. Hence this approach is difficult to detect pleiotropic genes, which may exist for obesity and osteoporosis, two common diseases of major public health importance that are closely correlated genetically. PRINCIPAL FINDINGS: To identify such pleiotropic genes and the key mechanistic links between the two diseases, we here performed the first bivariate GWAS of obesity and osteoporosis. We searched for genes underlying co-variation of the obesity phenotype, body mass index (BMI, with the osteoporosis risk phenotype, hip bone mineral density (BMD, scanning approximately 380,000 SNPs in 1,000 unrelated homogeneous Caucasians, including 499 males and 501 females. We identified in the male subjects two SNPs in intron 1 of the SOX6 (SRY-box 6 gene, rs297325 and rs4756846, which were bivariately associated with both BMI and hip BMD, achieving p values of 6.82x10(-7 and 1.47x10(-6, respectively. The two SNPs ranked at the top in significance for bivariate association with BMI and hip BMD in the male subjects among all the approximately 380,000 SNPs examined genome-wide. The two SNPs were replicated in a Framingham Heart Study (FHS cohort containing 3,355 Caucasians (1,370 males and 1,985 females from 975 families. In the FHS male subjects, the two SNPs achieved p values of 0.03 and 0.02, respectively, for bivariate association with BMI and femoral neck BMD. Interestingly, SOX6 was previously found to be essential to both cartilage formation/chondrogenesis and obesity-related insulin resistance, suggesting the gene's dual role in both bone and fat. CONCLUSIONS: Our findings, together with the prior biological evidence, suggest the SOX6 gene's importance in co-regulation of obesity and osteoporosis.

  1. ON GENERALIZED SARMANOV BIVARIATE DISTRIBUTIONS

    OpenAIRE

    , G. Jay Kerns

    2011-01-01

    A class of bivariate distributions which generalizes the Sarmanov class is introduced. This class possesses a simple analytical form and desirable dependence properties. The admissible range for association parameter for given bivariate distributions are derived and the range for correlation coefficients are also presented.

  2. Generalized bivariate Fibonacci polynomials

    OpenAIRE

    Catalani, Mario

    2002-01-01

    We define generalized bivariate polynomials, from which upon specification of initial conditions the bivariate Fibonacci and Lucas polynomials are obtained. Using essentially a matrix approach we derive identities and inequalities that in most cases generalize known results.

  3. Bivariate discrete Linnik distribution

    Directory of Open Access Journals (Sweden)

    Davis Antony Mundassery

    2014-10-01

    Full Text Available Christoph and Schreiber (1998a studied the discrete analogue of positive Linnik distribution and obtained its characterizations using survival function. In this paper, we introduce a bivariate form of the discrete Linnik distribution and study its distributional properties. Characterizations of the bivariate distribution are obtained using compounding schemes. Autoregressive processes are developed with marginals follow the bivariate discrete Linnik distribution.

  4. Bivariate discrete Linnik distribution

    OpenAIRE

    Davis Antony Mundassery; Jayakumar, K.

    2014-01-01

    Christoph and Schreiber (1998a) studied the discrete analogue of positive Linnik distribution and obtained its characterizations using survival function. In this paper, we introduce a bivariate form of the discrete Linnik distribution and study its distributional properties. Characterizations of the bivariate distribution are obtained using compounding schemes. Autoregressive processes are developed with marginals follow the bivariate discrete Linnik distribution.

  5. Bivariate Uniform Deconvolution

    OpenAIRE

    Benešová, Martina; van Es, Bert; Tegelaar, Peter

    2011-01-01

    We construct a density estimator in the bivariate uniform deconvolution model. For this model we derive four inversion formulas to express the bivariate density that we want to estimate in terms of the bivariate density of the observations. By substituting a kernel density estimator of the density of the observations we then get four different estimators. Next we construct an asymptotically optimal convex combination of these four estimators. Expansions for the bias, variance, as well as asym...

  6. The Bivariate Normal Copula

    OpenAIRE

    Christian Meyer

    2009-01-01

    We collect well known and less known facts about the bivariate normal distribution and translate them into copula language. In addition, we prove a very general formula for the bivariate normal copula, we compute Gini's gamma, and we provide improved bounds and approximations on the diagonal.

  7. CopulaDTA: An R Package for Copula Based Bivariate Beta-Binomial Models for Diagnostic Test Accuracy Studies in a Bayesian Framework

    OpenAIRE

    Nyaga, Victoria N; Arbyn, Marc; Aerts, Marc

    2016-01-01

    The current statistical procedures implemented in statistical software packages for pooling of diagnostic test accuracy data include hSROC regression and the bivariate random-effects meta-analysis model (BRMA). However, these models do not report the overall mean but rather the mean for a central study with random-effect equal to zero and have difficulties estimating the correlation between sensitivity and specificity when the number of studies in the meta-analysis is small and/or when the be...

  8. Bivariate extreme value distributions

    Science.gov (United States)

    Elshamy, M.

    1992-01-01

    In certain engineering applications, such as those occurring in the analyses of ascent structural loads for the Space Transportation System (STS), some of the load variables have a lower bound of zero. Thus, the need for practical models of bivariate extreme value probability distribution functions with lower limits was identified. We discuss the Gumbel models and present practical forms of bivariate extreme probability distributions of Weibull and Frechet types with two parameters. Bivariate extreme value probability distribution functions can be expressed in terms of the marginal extremel distributions and a 'dependence' function subject to certain analytical conditions. Properties of such bivariate extreme distributions, sums and differences of paired extremals, as well as the corresponding forms of conditional distributions, are discussed. Practical estimation techniques are also given.

  9. A new bivariate negative binomial regression model

    Science.gov (United States)

    Faroughi, Pouya; Ismail, Noriszura

    2014-12-01

    This paper introduces a new form of bivariate negative binomial (BNB-1) regression which can be fitted to bivariate and correlated count data with covariates. The BNB regression discussed in this study can be fitted to bivariate and overdispersed count data with positive, zero or negative correlations. The joint p.m.f. of the BNB1 distribution is derived from the product of two negative binomial marginals with a multiplicative factor parameter. Several testing methods were used to check overdispersion and goodness-of-fit of the model. Application of BNB-1 regression is illustrated on Malaysian motor insurance dataset. The results indicated that BNB-1 regression has better fit than bivariate Poisson and BNB-2 models with regards to Akaike information criterion.

  10. Ordinal bivariate inequality

    DEFF Research Database (Denmark)

    Sonne-Schmidt, Christoffer Scavenius; Tarp, Finn; Østerdal, Lars Peter Raahave

    This paper introduces a concept of inequality comparisons with ordinal bivariate categorical data. In our model, one population is more unequal than another when they have common arithmetic median outcomes and the first can be obtained from the second by correlationincreasing switches and/or median...

  11. On positive bivariate quartic forms

    OpenAIRE

    Sharipov, Ruslan

    2015-01-01

    A bivariate quartic form is a homogeneous bivariate polynomial of degree four. A criterion of positivity for such a form is known. In the present paper this criterion is reformulated in terms of pseudotensorial invariants of the form.

  12. Ordinal Bivariate Inequality

    DEFF Research Database (Denmark)

    Sonne-Schmidt, Christoffer Scavenius; Tarp, Finn; Østerdal, Lars Peter Raahave

    2016-01-01

    This paper introduces a concept of inequality comparisons with ordinal bivariate categorical data. In our model, one population is more unequal than another when they have common arithmetic median outcomes and the first can be obtained from the second by correlation-increasing switches and....../or median-preserving spreads. For the canonical 2 × 2 case (with two binary indicators), we derive a simple operational procedure for checking ordinal inequality relations in practice. As an illustration, we apply the model to childhood deprivation in Mozambique....

  13. Bivariate Exponentiated Modified Weibull Extension

    OpenAIRE

    El-Gohary, A.; El-Morshedy, M.

    2015-01-01

    In this paper, we introduce a new bivariate distribution we called it bivariate expo- nentiated modified Weibull extension distribution (BEMWE). The model introduced here is of Marshall-Olkin type. The marginals of the new bivariate distribution have exponentiated modified Weibull extension distribution which proposed by Sarhan et al.(2013). The joint probability density function and the joint cumulative distribu- tion function are in closed forms. Several properties of this distribution have...

  14. Sequential Temporal Dependencies in Associations between Symptoms of Depression and Posttraumatic Stress Disorder: An Application of Bivariate Latent Difference Score Structural Equation Modeling

    Science.gov (United States)

    King, Daniel W.; King, Lynda A.; McArdle, John J.; Shalev, Arieh Y.; Doron-LaMarca, Susan

    2009-01-01

    Depression and posttraumatic stress disorder (PTSD) are highly comorbid conditions that may arise following exposure to psychological trauma. This study examined their temporal sequencing and mutual influence using bivariate latent difference score structural equation modeling. Longitudinal data from 182 emergency room patients revealed level of…

  15. Morgenstern type bivariate Lindley Distribution

    OpenAIRE

    V S Vaidyanathan; Sharon Varghese, A

    2016-01-01

    In this paper, a bivariate Lindley distribution using Morgenstern approach is proposed which can be used for modeling bivariate life time data. Some characteristics of the distribution like moment generating function, joint moments, Pearson correlation coefficient, survival function, hazard rate function, mean residual life function, vitality function and stress-strength parameter R=Pr(Y

  16. Analysis of Bivariate Extreme Values

    OpenAIRE

    Egeland Busuttil, Chris

    2015-01-01

    Results show that there is high agreement between the distribution of the bivariate ACER functions and the distribution of the copula models with ACER marginals for all time series. The distribution of the copula models with Gumbel marginals display great discrepancies to the distribution of the bivariate ACER functions. These disagreements are greatest for short time series, and decrease as the time series become longer.

  17. Stability of Bivariate GWAS Biomarker Detection

    OpenAIRE

    Bedő, Justin; Rawlinson, David; Goudey, Benjamin; Ong, Cheng Soon

    2014-01-01

    Given the difficulty and effort required to confirm candidate causal SNPs detected in genome-wide association studies (GWAS), there is no practical way to definitively filter false positives. Recent advances in algorithmics and statistics have enabled repeated exhaustive search for bivariate features in a practical amount of time using standard computational resources, allowing us to use cross-validation to evaluate the stability. We performed 10 trials of 2-fold cross-validation of exhaustiv...

  18. Bivariate copula in fitting rainfall data

    Science.gov (United States)

    Yee, Kong Ching; Suhaila, Jamaludin; Yusof, Fadhilah; Mean, Foo Hui

    2014-07-01

    The usage of copula to determine the joint distribution between two variables is widely used in various areas. The joint distribution of rainfall characteristic obtained using the copula model is more ideal than the standard bivariate modelling where copula is belief to have overcome some limitation. Six copula models will be applied to obtain the most suitable bivariate distribution between two rain gauge stations. The copula models are Ali-Mikhail-Haq (AMH), Clayton, Frank, Galambos, Gumbel-Hoogaurd (GH) and Plackett. The rainfall data used in the study is selected from rain gauge stations which are located in the southern part of Peninsular Malaysia, during the period from 1980 to 2011. The goodness-of-fit test in this study is based on the Akaike information criterion (AIC).

  19. Covariate analysis of bivariate survival data

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, L.E.

    1992-01-01

    The methods developed are used to analyze the effects of covariates on bivariate survival data when censoring and ties are present. The proposed method provides models for bivariate survival data that include differential covariate effects and censored observations. The proposed models are based on an extension of the univariate Buckley-James estimators which replace censored data points by their expected values, conditional on the censoring time and the covariates. For the bivariate situation, it is necessary to determine the expectation of the failure times for one component conditional on the failure or censoring time of the other component. Two different methods have been developed to estimate these expectations. In the semiparametric approach these expectations are determined from a modification of Burke's estimate of the bivariate empirical survival function. In the parametric approach censored data points are also replaced by their conditional expected values where the expected values are determined from a specified parametric distribution. The model estimation will be based on the revised data set, comprised of uncensored components and expected values for the censored components. The variance-covariance matrix for the estimated covariate parameters has also been derived for both the semiparametric and parametric methods. Data from the Demographic and Health Survey was analyzed by these methods. The two outcome variables are post-partum amenorrhea and breastfeeding; education and parity were used as the covariates. Both the covariate parameter estimates and the variance-covariance estimates for the semiparametric and parametric models will be compared. In addition, a multivariate test statistic was used in the semiparametric model to examine contrasts. The significance of the statistic was determined from a bootstrap distribution of the test statistic.

  20. Morgenstern type bivariate Lindley Distribution

    Directory of Open Access Journals (Sweden)

    V S Vaidyanathan

    2016-06-01

    Full Text Available In this paper, a bivariate Lindley distribution using Morgenstern approach is proposed which can be used for modeling bivariate life time data. Some characteristics of the distribution like moment generating function, joint moments, Pearson correlation coefficient, survival function, hazard rate function, mean residual life function, vitality function and stress-strength parameter R=Pr(Y

  1. The bivariate current status model

    OpenAIRE

    Groeneboom, P.

    2013-01-01

    For the univariate current status and, more generally, the interval censoring model, distribution theory has been developed for the maximum likelihood estimator (MLE) and smoothed maximum likelihood estimator (SMLE) of the unknown distribution function, see, e.g., [12], [7], [4], [5], [6], [10], [11] and [8]. For the bivariate current status and interval censoring models distribution theory of this type is still absent and even the rate at which we can expect reasonable estimators to converge...

  2. THE BIVARIATE ANALYSIS BETWEEN THE VARIABLES THAT DEFINE THE INVESTIGATED TOURIST POPULATION IN THE CENTER DEVELOPMENT REGION AND THE OTHER IMPORTANT TOURIST VARIABLES

    OpenAIRE

    Assist. Ph.D Kulcsár Erika

    2010-01-01

    In the marketing research the instances when we need to examine the relationship between two variables are frequent. Knowing the relationship between the two variables involves the use of tests that can be parametric and nonparametric. This paper includes the non-parametric tests used in the bivariate analysis. The used tests are: chi square test, the Mann-Whitney test, the Kolmogorov-Smirnov test. Besides these tests, this paper also includes measuring the association between nominal variabl...

  3. The Statistical Relationship between Bivariate and Multinomial Choice Models

    OpenAIRE

    Weeks, Melvyn; Orne, Chris

    1999-01-01

    The authors demonstrate the conditions under which the bivariate probit model can be considered a special case of the more general multinomial probit model. Since the attendant parameter restrictions produce a singular covariance matrix, the subsequent problems of testing on the boundary of the parameter space are circumvented by the construction of a score test.

  4. Bivariate value-at-risk

    Directory of Open Access Journals (Sweden)

    Giuseppe Arbia

    2007-10-01

    Full Text Available In this paper we extend the concept of Value-at-risk (VaR to bivariate return distributions in order to obtain measures of the market risk of an asset taking into account additional features linked to downside risk exposure. We first present a general definition of risk as the probability of an adverse event over a random distribution and we then introduce a measure of market risk (b-VaR that admits the traditional b of an asset in portfolio management as a special case when asset returns are normally distributed. Empirical evidences are provided by using Italian stock market data.

  5. Bivariate control chart with copula

    Science.gov (United States)

    Lestari, Tika; Syuhada, Khreshna; Mukhaiyar, Utriweni

    2015-12-01

    Control chart is the main and powerful tool in statistical process control in order to detect and classify data, either in control or out of control. Its concept, basically, refers to the theory of prediction interval. Accordingly, in this paper, we aim at constructing of what so called predictive bivariate control charts, both classical and Copula-based ones. We argue that appropriate joint distribution function may be well estimated by employing Copula. A numerical analysis is carried out to illustrate that a Copula-based control chart outperforms than other.

  6. Nonlinear analysis of bivariate data with cross recurrence plots

    CERN Document Server

    Marwan, N

    2002-01-01

    We extend the method of recurrence plots to cross recurrence plots (CRP) which enables a nonlinear analysis of bivariate data. To quantify CRPs, we introduce three measures of complexity mainly basing on diagonal structures in CRPs. The CRP analysis of prototypical model systems with nonlinear interactions demonstrates that this technique enables to find these nonlinear interelations from bivariate time series, whereas linear correlation tests do not. Applying the CRP analysis to climatological data, we find a complex relationship between rainfall and El Nino data.

  7. A Simulation Analysis of Bivariate Availability Models

    OpenAIRE

    Caruso, Elise M.

    2000-01-01

    Equipment behavior is often discussed in terms of age and use. For example, an automobile is frequently referred to 3 years old with 30,000 miles. Bivariate failure modeling provides a framework for studying system behavior as a function of two variables. This is meaningful when studying the reliability/availability of systems and equipment. This thesis extends work done in the area of bivariate failure modeling. Four bivariate failure models are selected for analysis. The study in...

  8. Some R graphics for bivariate distributions

    OpenAIRE

    Klein, Ingo

    2008-01-01

    There is no package in R to plot bivariate distributions for discrete variables or variables given by classes. Therefore, with the help of the already implemented R routine persp R functions will be proposed for 3-D plots of the bivariate distribution of discrete variables, the so-called stereogram that generalizes the well-known histogram for cross-classified data and the approximative bivariate distribution function for cross-classified data.

  9. A simple bivariate count data regression model

    OpenAIRE

    Shiferaw Gurmu; John Elder

    2007-01-01

    This paper develops a simple bivariate count data regression model in which dependence between count variables is introduced by means of stochastically related unobserved heterogeneity components. Unlike existing commonly used bivariate models, we obtain a computationally simple closed form of the model with an unrestricted correlation pattern.

  10. Extreme behavior of bivariate elliptical distributions

    OpenAIRE

    Asimit, A. V.; Jones, B

    2007-01-01

    This paper exploits a stochastic representation of bivariate elliptical distributions in order to obtain asymptotic results which are determined by the tail behavior of the generator. Under certain specified assumptions, we present the limiting distribution of componentwise maxima, the limiting upper copula, and a bivariate version of the classical peaks over threshold result.

  11. Stochastic ordering of bivariate elliptical distributions

    OpenAIRE

    Landsman, Z; Tsanakas, A.

    2006-01-01

    It is shown that for elliptically distributed bivariate random vectors, the riskiness and dependence strength of random portfolios, in the sense of the univariate convex and bivariate concordance stochastic orders respectively, can be simply characterised in terms of the vector's Σ-matrix.

  12. The bivariate Power-Normal and the bivariate Johnson’s System bounded distribution in forestry, including height curves

    OpenAIRE

    Mønness, Erik Neslein

    2015-01-01

    bivariate diameter and height distribution yields a unified model of a forest stand. The bivariate Johnson’s System bounded distribution and the bivariate power-normal distribution are explored. The power-normal originates from the well-known Box-Cox transformation. As evaluated by the bivariate Kolmogorov-Smirnov distance, the bivariate power-normal distribution seems to be superior to the bivariate Johnson’s System bounded distribution. The conditional median height given the diameter is...

  13. Constructions for a bivariate beta distribution

    OpenAIRE

    Olkin, Ingram; Trikalinos, Thomas A.

    2014-01-01

    The beta distribution is a basic distribution serving several purposes. It is used to model data, and also, as a more flexible version of the uniform distribution, it serves as a prior distribution for a binomial probability. The bivariate beta distribution plays a similar role for two probabilities that have a bivariate binomial distribution. We provide a new multivariate distribution with beta marginal distributions, positive probability over the unit square, and correlations over the full ...

  14. Stationarity of Bivariate Dynamic Contagion Processes

    OpenAIRE

    Angelos Dassios; Xin Dong

    2014-01-01

    The Bivariate Dynamic Contagion Processes (BDCP) are a broad class of bivariate point processes characterized by the intensities as a general class of piecewise deterministic Markov processes. The BDCP describes a rich dynamic structure where the system is under the influence of both external and internal factors modelled by a shot-noise Cox process and a generalized Hawkes process respectively. In this paper we mainly address the stationarity issue for the BDCP, which is important in applica...

  15. Bivariate Interpolation by Splines and Approximation Order

    OpenAIRE

    Nürnberger, Günther

    1996-01-01

    We construct Hermite interpolation sets for bivariate spline spaces of arbitrary degree and smoothness one on non-rectangular domains with uniform type triangulations. This is done by applying a general method for constructing Lagrange interpolation sets for bivariate spline spaecs of arbitrary degree and smoothness. It is shown that Hermite interpolation yields (nearly) optimal approximation order. Applications to data fitting problems and numerical examples are given.

  16. Dependence Measures in Bivariate Gamma Frailty Models

    OpenAIRE

    van den Berg, Gerard J.; Effraimidis, Georgios

    2014-01-01

    Bivariate duration data frequently arise in economics, biostatistics and other areas. In "bivariate frailty models", dependence between the frailties (i.e., unobserved determinants) induces dependence between the durations. Using notions of quadrant dependence, we study restrictions that this imposes on the implied dependence of the durations, if the frailty terms act multiplicatively on the corresponding hazard rates. Marginal frailty distributions are often taken to be gamma distributions. ...

  17. Some theory of bivariate risk attitude

    OpenAIRE

    Marta Cardin; Paola Ferretti

    2004-01-01

    In past years the study of the impact of risk attitude among risks has become a major topic, in particular in Decision Sciences. Subsequently the attention was devoted to the more general case of bivariate random variables. The first approach to multivariate risk aversion was proposed by de Finetti (1952) and Richard (1975) and it is related to the bivariate case. More recently, multivariate risk aversion has been studied by Scarsini (1985, 1988, 1999). Nevertheless even if decision problems ...

  18. Bivariate Random Effects Meta-analysis of Diagnostic Studies Using Generalized Linear Mixed Models

    OpenAIRE

    Chu, Haitao; Guo, Hongfei; Zhou, Yijie

    2009-01-01

    Bivariate random effect models are currently one of the main methods recommended to synthesize diagnostic test accuracy studies. However, only the logit-transformation on sensitivity and specificity has been previously considered in the literature. In this paper, we consider a bivariate generalized linear mixed model to jointly model the sensitivities and specificities, and discuss the estimation of the summary receiver operating characteristic curve (ROC) and the area under the ROC curve (AU...

  19. Incomplete Bivariate Fibonacci and Lucas -Polynomials

    Directory of Open Access Journals (Sweden)

    Dursun Tasci

    2012-01-01

    Full Text Available We define the incomplete bivariate Fibonacci and Lucas -polynomials. In the case =1, =1, we obtain the incomplete Fibonacci and Lucas -numbers. If =2, =1, we have the incomplete Pell and Pell-Lucas -numbers. On choosing =1, =2, we get the incomplete generalized Jacobsthal number and besides for =1 the incomplete generalized Jacobsthal-Lucas numbers. In the case =1, =1, =1, we have the incomplete Fibonacci and Lucas numbers. If =1, =1, =1, =⌊(−1/(+1⌋, we obtain the Fibonacci and Lucas numbers. Also generating function and properties of the incomplete bivariate Fibonacci and Lucas -polynomials are given.

  20. Bivariate empirical mode decomposition applied to the estimation of out-of-phase oscillations in BWR

    International Nuclear Information System (INIS)

    Highlights: • Bivariate empirical mode decomposition (BEMD) in BWR’s instabilities is studied. • The phase determines out-of-phase oscillations in the BWR instability. • The method based in BEMD does not represent a high computational complexity. • The methodology was validated with Nuclear Power Plants stability benchmarks. • The results show that the method contributes to detect out-of-phase oscillations. - Abstract: In this paper a new method based on the bivariate empirical mode decomposition to estimate the phase of regional (out-of-phase) or global (in-phase) modes associated with instabilities in boiling water reactors (BWR), is explored. The proposed method allows decomposing the analyzed signal (constructed from two different Local Power Range Monitors, LPRMs) in different levels or intrinsic mode functions (IMF). The estimation of the phase between these LPRM signals can be achieved by tracking the modes associated to the instability of the BWR and obtaining the cross-correlation function of their corresponding IMF. This phase determines possible out-of-phase oscillations, which play an important role in the BWR instability. The method is relatively simple to implement and it does not represent a high computational complexity. The methodology was tested with simulated signals and validated with two events reported in the Forsmark and Ringhals stability benchmarks. The results of the cases studied show that the proposed method clearly contributes on the fact to detect possible cases of out-of-phase oscillations

  1. Bivariate dynamic probit models for panel data

    OpenAIRE

    Alfonso Miranda

    2010-01-01

    In this talk, I will discuss the main methodological features of the bivariate dynamic probit model for panel data. I will present an example using simulated data, giving special emphasis to the initial conditions problem in dynamic models and the difference between true and spurious state dependence. The model is fit by maximum simulated likelihood.

  2. A truncated bivariate inverted Dirichlet distribution

    Directory of Open Access Journals (Sweden)

    Saralees Nadarajah

    2013-05-01

    Full Text Available A truncated version of the bivariate inverted dirichlet distribution is introduced. Unlike the inverted dirichlet distribution, this possesses finite moments of all orders and could therefore be a better model for certain practical situations. One such situation is discussed. The moments, maximum likelihood estimators and the Fisher information matrix for the truncated distribution are derived.

  3. The Resultant of an Unmixed Bivariate System

    OpenAIRE

    Khetan, Amit

    2002-01-01

    This paper gives an explicit method for computing the resultant of any sparse unmixed bivariate system with given support. We construct square matrices whose determinant is exactly the resultant. The matrices constructed are of hybrid Sylvester and B\\'ezout type. We make use of the exterior algebra techniques of Eisenbud, Fl{\\o}ystad, and Schreyer.

  4. Five-Parameter Bivariate Probability Distribution

    Science.gov (United States)

    Tubbs, J.; Brewer, D.; Smith, O. W.

    1986-01-01

    NASA technical memorandum presents four papers about five-parameter bivariate gamma class of probability distributions. With some overlap of subject matter, papers address different aspects of theories of these distributions and use in forming statistical models of such phenomena as wind gusts. Provides acceptable results for defining constraints in problems designing aircraft and spacecraft to withstand large wind-gust loads.

  5. BIVARIATE REAL-VALUED ORTHOGONAL PERIODIC WAVELETS

    Institute of Scientific and Technical Information of China (English)

    Qiang Li; Xuezhang Liang

    2005-01-01

    In this paper, we construct a kind of bivariate real-valued orthogonal periodic wavelets. The corresponding decomposition and reconstruction algorithms involve only 8 terms respectively which are very simple in practical computation. Moreover, the relation between periodic wavelets and Fourier series is also discussed.

  6. Bivariate Poisson and Diagonal Inflated Bivariate Poisson Regression Models in R

    OpenAIRE

    Dimitris Karlis; Ioannis Ntzoufras

    2005-01-01

    In this paper we present an R package called bivpois for maximum likelihood estimation of the parameters of bivariate and diagonal inflated bivariate Poisson regression models. An Expectation-Maximization (EM) algorithm is implemented. Inflated models allow for modelling both over-dispersion (or under-dispersion) and negative correlation and thus they are appropriate for a wide range of applications. Extensions of the algorithms for several other models are also discussed. Detailed guidance a...

  7. The Minkowski dimension of the bivariate fractal interpolation surfaces

    International Nuclear Information System (INIS)

    We present a new construction of continuous bivariate fractal interpolation surface for every set of data. Furthermore, we generalize this construction to higher dimensions. Exact values for the Minkowski dimension of the bivariate fractal interpolation surfaces are obtained

  8. On some properties on bivariate Fibonacci and Lucas polynomials

    OpenAIRE

    Belbachir, Hacéne; Bencherif, Farid

    2007-01-01

    In this paper we generalize to bivariate polynomials of Fibonacci and Lucas, properties obtained for Chebyshev polynomials. We prove that the coordinates of the bivariate polynomials over appropriate basis are families of integers satisfying remarkable recurrence relations.

  9. On Bivariate Generalized Exponential-Power Series Class of Distributions

    OpenAIRE

    Jafari, Ali Akbar; Roozegar, Rasool

    2015-01-01

    In this paper, we introduce a new class of bivariate distributions by compounding the bivariate generalized exponential and power-series distributions. This new class contains some new sub-models such as the bivariate generalized exponential distribution, the bivariate generalized exponential-poisson, -logarithmic, -binomial and -negative binomial distributions. We derive different properties of the new class of distributions. The EM algorithm is used to determine the maximum likelihood estim...

  10. Characterizations of some bivariate models using reciprocal coordinate subtangents

    OpenAIRE

    Sreenarayanapurath Madhavan Sunoj; Sreejith Thoppil Bhargavan; Jorge Navarro

    2014-01-01

    In the present paper, we consider the bivariate version of reciprocal coordinate subtangent (RCST) and study its usefulness in characterizing some important bivariate models.  In particular, characterization results are proved for a general bivariate model whose conditional distributions are proportional hazard rate models (see Navarro and Sarabia, 2011), Sarmanov family and Ali-Mikhail-Haq family of bivariate distributions.  We also study the relationship between local dependence function an...

  11. On Bivariate Exponentiated Extended Weibull Family of Distributions

    OpenAIRE

    Roozegar, Rasool; Jafari, Ali Akbar

    2015-01-01

    In this paper, we introduce a new class of bivariate distributions called the bivariate exponentiated extended Weibull distributions. The model introduced here is of Marshall-Olkin type. This new class of bivariate distributions contains several bivariate lifetime models. Some mathematical properties of the new class of distributions are studied. We provide the joint and conditional density functions, the joint cumulative distribution function and the joint survival function. Special bivariat...

  12. Bounds for Trivariate Copulas with Given Bivariate Marginals

    OpenAIRE

    Quesada-Molina JoséJuan; Durante Fabrizio; Klement ErichPeter

    2008-01-01

    Abstract We determine two constructions that, starting with two bivariate copulas, give rise to new bivariate and trivariate copulas, respectively. These constructions are used to determine pointwise upper and lower bounds for the class of all trivariate copulas with given bivariate marginals.

  13. Reliability for some bivariate beta distributions

    Directory of Open Access Journals (Sweden)

    Nadarajah Saralees

    2005-01-01

    Full Text Available In the area of stress-strength models there has been a large amount of work as regards estimation of the reliability R=Pr( Xbivariate distribution with dependence between X and Y . In particular, we derive explicit expressions for R when the joint distribution is bivariate beta. The calculations involve the use of special functions.

  14. The Effects of Selection Strategies for Bivariate Loglinear Smoothing Models on NEAT Equating Functions

    Science.gov (United States)

    Moses, Tim; Holland, Paul W.

    2010-01-01

    In this study, eight statistical strategies were evaluated for selecting the parameterizations of loglinear models for smoothing the bivariate test score distributions used in nonequivalent groups with anchor test (NEAT) equating. Four of the strategies were based on significance tests of chi-square statistics (Likelihood Ratio, Pearson,…

  15. Copula-based bivariate binary response models

    OpenAIRE

    Winkelmann, Rainer

    2009-01-01

    The bivariate probit model is frequently used for estimating the effect of an endogenous binary regressor on a binary outcome variable. This paper discusses simple modifications that maintain the probit assumption for the marginal distributions while introducing non-normal dependence among the two variables using copulas. Simulation results and evidence from two applications, one on the effect of insurance status on ambulatory expenditure and one on the effect of completing high school on sub...

  16. Objective priors for the bivariate normal model

    OpenAIRE

    Berger, James O.; Sun, Dongchu

    2008-01-01

    Study of the bivariate normal distribution raises the full range of issues involving objective Bayesian inference, including the different types of objective priors (e.g., Jeffreys, invariant, reference, matching), the different modes of inference (e.g., Bayesian, frequentist, fiducial) and the criteria involved in deciding on optimal objective priors (e.g., ease of computation, frequentist performance, marginalization paradoxes). Summary recommendations as to optimal objective priors are mad...

  17. Quantitative texton sequences for legible bivariate maps.

    Science.gov (United States)

    Ware, Colin

    2009-01-01

    Representing bivariate scalar maps is a common but difficult visualization problem. One solution has been to use two dimensional color schemes, but the results are often hard to interpret and inaccurately read. An alternative is to use a color sequence for one variable and a texture sequence for another. This has been used, for example, in geology, but much less studied than the two dimensional color scheme, although theory suggests that it should lead to easier perceptual separation of information relating to the two variables. To make a texture sequence more clearly readable the concept of the quantitative texton sequence (QTonS) is introduced. A QTonS is defined a sequence of small graphical elements, called textons, where each texton represents a different numerical value and sets of textons can be densely displayed to produce visually differentiable textures. An experiment was carried out to compare two bivariate color coding schemes with two schemes using QTonS for one bivariate map component and a color sequence for the other. Two different key designs were investigated (a key being a sequence of colors or textures used in obtaining quantitative values from a map). The first design used two separate keys, one for each dimension, in order to measure how accurately subjects could independently estimate the underlying scalar variables. The second key design was two dimensional and intended to measure the overall integral accuracy that could be obtained. The results show that the accuracy is substantially higher for the QTonS/color sequence schemes. A hypothesis that texture/color sequence combinations are better for independent judgments of mapped quantities was supported. A second experiment probed the limits of spatial resolution for QTonSs. PMID:19834229

  18. Multiple imputation methods for bivariate outcomes in cluster randomised trials.

    Science.gov (United States)

    DiazOrdaz, K; Kenward, M G; Gomes, M; Grieve, R

    2016-09-10

    Missing observations are common in cluster randomised trials. The problem is exacerbated when modelling bivariate outcomes jointly, as the proportion of complete cases is often considerably smaller than the proportion having either of the outcomes fully observed. Approaches taken to handling such missing data include the following: complete case analysis, single-level multiple imputation that ignores the clustering, multiple imputation with a fixed effect for each cluster and multilevel multiple imputation. We contrasted the alternative approaches to handling missing data in a cost-effectiveness analysis that uses data from a cluster randomised trial to evaluate an exercise intervention for care home residents. We then conducted a simulation study to assess the performance of these approaches on bivariate continuous outcomes, in terms of confidence interval coverage and empirical bias in the estimated treatment effects. Missing-at-random clustered data scenarios were simulated following a full-factorial design. Across all the missing data mechanisms considered, the multiple imputation methods provided estimators with negligible bias, while complete case analysis resulted in biased treatment effect estimates in scenarios where the randomised treatment arm was associated with missingness. Confidence interval coverage was generally in excess of nominal levels (up to 99.8%) following fixed-effects multiple imputation and too low following single-level multiple imputation. Multilevel multiple imputation led to coverage levels of approximately 95% throughout. © 2016 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd. PMID:26990655

  19. Reliability for some bivariate beta distributions

    OpenAIRE

    Nadarajah Saralees

    2005-01-01

    In the area of stress-strength models there has been a large amount of work as regards estimation of the reliability R=Pr( Xbivariate distribution with dependence between X and ...

  20. On colorings of bivariate random sequences

    Czech Academy of Sciences Publication Activity Database

    Matúš, František; Kupsa, Michal

    Piscataway: IEEE, 2010, s. 1272-1276. ISBN 978-1-4244-7892-7. [IEEE International Symposium on Information Theory 2010. Austin (US), 13.06.2010-18.06.2010] R&D Projects: GA AV ČR IAA100750603; GA AV ČR KJB100750901; GA ČR GA201/08/0539 Institutional research plan: CEZ:AV0Z10750506 Keywords : colorings * ergodic sequences * entropy rate * asymptotic equipartition property Subject RIV: BD - Theory of Information http://library.utia.cas.cz/separaty/2010/MTR/matus-on colorings of bivariate random sequences.pdf

  1. Estimation of the average correlation coefficient for stratified bivariate data.

    Science.gov (United States)

    Rubenstein, L M; Davis, C S

    1999-03-15

    If the relationship between two ordered categorical variables X and Y is influenced by a third categorical variable with K levels, the Cochran-Mantel-Haenszel (CMH) correlation statistic QC is a useful stratum-adjusted summary statistic for testing the null hypothesis of no association between X and Y. Although motivated by and developed for the case of K I x J contingency tables, the correlation statistic QC is also applicable when X and Y are continuous variables. In this paper we derive a corresponding estimator of the average correlation coefficient for K I x J tables. We also study two estimates of the variance of the average correlation coefficient. The first is a restricted variance based on the variances of the observed cell frequencies under the null hypothesis of no association. The second is an unrestricted variance based on an asymptotic variance derived by Brown and Benedetti. The estimator of the average correlation coefficient works well in tables with balanced and unbalanced margins, for equal and unequal stratum-specific sample sizes, when correlation coefficients are constant over strata, and when correlation coefficients vary across strata. When the correlation coefficients are zero, close to zero, or the cell frequencies are small, the confidence intervals based on the restricted variance are preferred. For larger correlations and larger cell frequencies, the unrestricted confidence intervals give superior performance. We also apply the CMH statistic and proposed estimators to continuous non-normal data sampled from bivariate gamma distributions. We compare our methods to statistics for data sampled from normal distributions. The size and power of the CMH and normal theory statistics are comparable. When the stratum-specific sample sizes are small and the distributions are skewed, the proposed estimator is superior to the normal theory estimator. When the correlation coefficient is zero or close to zero, the restricted confidence intervals

  2. MODELING HETEROGENEITY FOR BIVARIATE SURVIVAL DATA BY POWER VARIANCE FUNCTION DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    David D. Hanagal

    2009-01-01

    Full Text Available We propose a bivariate Weibull regression model with frailty which is generated bypower variance function distribution. We assume that the bivariate survival data follow bivariateWeibull of Hanagal (2005a and distribution of censoring variable is independent of the two lifetimes. There are some interesting situations like survival times in genetic epidemiology, survivaltimes of dental implants of patients and survival times of twin births (both monozygotic anddizygotic where genetic behavior (which is unknown and random of patients follows a powervariance function frailty distribution. These are the situations which motivate to study thisparticular model. We propose two stage maximum likelihood estimation procedure for theparameters and develop large sample tests for no frailty and the significance of regressionparameters in the proposed model.

  3. Causal networks clarify productivity-richness interrelations, bivariate plots do not

    Science.gov (United States)

    Grace, James B.; Adler, Peter B.; Harpole, W. Stanley; Borer, Elizabeth T.; Seabloom, Eric W.

    2014-01-01

    Perhaps no other pair of variables in ecology has generated as much discussion as species richness and ecosystem productivity, as illustrated by the reactions by Pierce (2013) and others to Adler et al.'s (2011) report that empirical patterns are weak and inconsistent. Adler et al. (2011) argued we need to move beyond a focus on simplistic bivariate relationships and test mechanistic, multivariate causal hypotheses. We feel the continuing debate over productivity–richness relationships (PRRs) provides a focused context for illustrating the fundamental difficulties of using bivariate relationships to gain scientific understanding.

  4. On the analysis of bivariate point patterns in R using the Ripley's K(T) function

    International Nuclear Information System (INIS)

    DOSS (1989, The Annals of Statistics; 17, 749-763) provided asymptotic confidence intervals for the Ripley's K(t) function using an uncorrected estimator, K0-circumflex(t) of K(t). These asymptotic confidence intervals are used for testing whether the observed bivariate point patterns are independent. However, DOSS procedure cannot be applied to sparse bivariate point patterns, largely due to the bias inherent in K0-circumflex(t). An alternative procedure is proposed for these patterns, based on Monte Carlo confidence bands. (author). 14 refs, 4 figs

  5. A new family of bivariate discrete distributions on Z^2

    OpenAIRE

    Chesneau, Christophe; Kachour, Maher

    2015-01-01

    In this paper we introduce a new family of bivariate discrete distributions on Z 2 , called the Rademacher(α 1 , α 2) − N 2 class. Its main feature is to generate bivariate random variables with possible negative or positive values for the covariance. This new family can also be considered as an extension (on Z^2) of some standard bivariate discrete (non negative valued) distribution.

  6. Bivariate Count Data Regression Using Series Expansions: With Applications

    OpenAIRE

    A. Colin Cameron; Per Johansson

    2004-01-01

    Most research on count data regression models, i.e. models for there the dependent variable takes only non-negative integer values or count values, has focused on the univariate case. Very little attention has been given to joint modeling of two or more counts. We propose parametric regression models for bivariate counts based on squared polynomial expansions around a baseline density. The models are more flexible than the current leading bivariate count model, the bivariate Poisson. The mode...

  7. Minimum-Energy Bivariate Wavelet Frame with Arbitrary Dilation Matrix

    Directory of Open Access Journals (Sweden)

    Fengjuan Zhu

    2013-01-01

    Full Text Available In order to characterize the bivariate signals, minimum-energy bivariate wavelet frames with arbitrary dilation matrix are studied, which are based on superiority of the minimum-energy frame and the significant properties of bivariate wavelet. Firstly, the concept of minimum-energy bivariate wavelet frame is defined, and its equivalent characterizations and a necessary condition are presented. Secondly, based on polyphase form of symbol functions of scaling function and wavelet function, two sufficient conditions and an explicit constructed method are given. Finally, the decomposition algorithm, reconstruction algorithm, and numerical examples are designed.

  8. The asymptotic distribution of maxima in bivariate samples

    Science.gov (United States)

    Campbell, J. W.; Tsokos, C. P.

    1973-01-01

    The joint distribution (as n tends to infinity) of the maxima of a sample of n independent observations of a bivariate random variable (X,Y) is studied. A method is developed for deriving the asymptotic distribution of the maxima, assuming that X and Y possess asymptotic extreme-value distributions and that the probability element dF(x,y) can be expanded in a canonical series. Applied both to the bivariate normal distribution and to the bivariate gamma and compound correlated bivariate Poisson distributions, the method shows that maxima from all these distributions are asymptotically uncorrelated.

  9. A Proposed New "What if Reliability" Analysis for Assessing the Statistical Significance of Bivariate Relationships

    Science.gov (United States)

    Onwuegbuzie, Anthony J.; Roberts, J. Kyle; Daniel, Larry G.

    2005-01-01

    In this article, the authors (a) illustrate how displaying disattenuated correlation coefficients alongside their unadjusted counterparts will allow researchers to assess the impact of unreliability on bivariate relationships and (b) demonstrate how a proposed new "what if reliability" analysis can complement null hypothesis significance tests of…

  10. A Method for Determining If Unequal Shape Parameters are Necessary in a Bivariate Gamma Distribution

    Science.gov (United States)

    Tubbs, J. D.

    1983-01-01

    A procedure to aid in the deciding between four and five parameters in a Jensen's type bivariate gamma distribution is presented. It is based upon the CDF of the ratio of correlated gamma distributed variates. The criteria are posed in a test of hypothesis setting and results are presented.

  11. Height curves based on the bivariate Power-Normal and the bivariate Johnson’s System bounded distribution

    OpenAIRE

    Mønness, Erik Neslein

    2013-01-01

    English: Often, a forest stand is modeled with a diameter distribution and a height curve as somehow separate tasks. A bivariate height and diameter distribution yield a unified model of a forest stand. The conditional median height given the diameter is a possible height curve. Here the bivariate Johnson’s System bounded distribution and the bivariate power-normal distribution are evaluated and compared with a simple hyperbolic height curve. Evaluated by the deviance, the hyperbo...

  12. A bivariate process model for maintenance and inspection planning

    International Nuclear Information System (INIS)

    The paper describes decision making about monitoring and maintenance of systems described by a general stochastic process. The system is monitored and preventive and corrective maintenance actions are carried out in response to the observed system state. The decision process is simplified by using an associated process as well as the underlying state as decision variables. The bivariate approach allows a wide class of models to be considered including long term memory within a simple probability structure. Both average cost and life-cycle cost models are used as the basis for decision making. The models generalize age replacement and other simple maintenance strategies. The approach can deal with failures that prevent the system functioning further, failures defined by regulation, or by economic considerations. The unified framework developed allows the inclusion of covariates and imperfect inspection or repair

  13. An adaptive association test for microbiome data

    OpenAIRE

    Wu, Chong; Chen, Jun; Kim, Junghi; Pan, Wei

    2016-01-01

    There is increasing interest in investigating how the compositions of microbial communities are associated with human health and disease. Although existing methods have identified many associations, a proper choice of a phylogenetic distance is critical for the power of these methods. To assess an overall association between the composition of a microbial community and an outcome of interest, we present a novel multivariate testing method called aMiSPU, that is joint and highly adaptive over ...

  14. Solving Bivariate Polynomial Systems on a GPU

    International Nuclear Information System (INIS)

    We present a CUDA implementation of dense multivariate polynomial arithmetic based on Fast Fourier Transforms over finite fields. Our core routine computes on the device (GPU) the subresultant chain of two polynomials with respect to a given variable. This subresultant chain is encoded by values on a FFT grid and is manipulated from the host (CPU) in higher-level procedures. We have realized a bivariate polynomial system solver supported by our GPU code. Our experimental results (including detailed profiling information and benchmarks against a serial polynomial system solver implementing the same algorithm) demonstrate that our strategy is well suited for GPU implementation and provides large speedup factors with respect to pure CPU code.

  15. Bivariate Rayleigh Distribution and its Properties

    Directory of Open Access Journals (Sweden)

    Ahmad Saeed Akhter

    2007-01-01

    Full Text Available Rayleigh (1880 observed that the sea waves follow no law because of the complexities of the sea, but it has been seen that the probability distributions of wave heights, wave length, wave induce pitch, wave and heave motions of the ships follow the Rayleigh distribution. At present, several different quantities are in use for describing the state of the sea; for example, the mean height of the waves, the root mean square height, the height of the “significant waves” (the mean height of the highest one-third of all the waves the maximum height over a given interval of the time, and so on. At present, the ship building industry knows less than any other construction industry about the service conditions under which it must operate. Only small efforts have been made to establish the stresses and motions and to incorporate the result of such studies in to design. This is due to the complexity of the problem caused by the extensive variability of the sea and the corresponding response of the ships. Although the problem appears feasible, yet it is possible to predict service conditions for ships in an orderly and relatively simple manner Rayleigh (1980 derived it from the amplitude of sound resulting from many independent sources. This distribution is also connected with one or two dimensions and is sometimes referred to as “random walk” frequency distribution. The Rayleigh distribution can be derived from the bivariate normal distribution when the variate are independent and random with equal variances. We try to construct bivariate Rayleigh distribution with marginal Rayleigh distribution function and discuss its fundamental properties.

  16. A nonparametric copula density estimator incorporating information on bivariate marginals

    OpenAIRE

    Cheng, Yu-Hsiang; Huang, Tzee-Ming

    2016-01-01

    We propose a copula density estimator that can include information on bivariate marginals when the information is available. We use B-splines for copula density approximation and include information on bivariate marginals via a penalty term. Our estimator satisfies the constraints for a copula density. Under mild conditions, the proposed estimator is consistent.

  17. Estimation of limiting availability for a stationary bivariate process

    OpenAIRE

    Abraham, B.; Balakrishna, N

    2000-01-01

    We estimate the limiting availability of a system when the operating and repair times form a stationary bivariate sequence. These estimators are shown to be consistent and asymptotically normal under certain conditions. In particular, we estimate the limiting availability for a bivariate exponential autoregressive process.

  18. Efficient Simulation of a Bivariate Exponential Conditionals Distribution

    OpenAIRE

    Yu, Yaming

    2009-01-01

    The bivariate distribution with exponential conditionals (BEC) is introduced by Arnold and Strauss [Bivariate distributions with exponential conditionals, J. Amer. Statist. Assoc. 83 (1988) 522--527]. This work presents a simple and fast algorithm for simulating random variates from this density.

  19. Remote Associates Test and Alpha Brain Waves

    OpenAIRE

    Haarmann, Henk J.; George, Timothy; Smaliy, Alexei; Dien, Joseph

    2012-01-01

    Previous studies found that performance on the remote associates test (RAT) improves after a period of incubation and that increased alpha brain waves over the right posterior brain predict the emergence of RAT insight solutions. We report an experiment that tested whether increased alpha brain waves during incubation improve RAT performance. Participants received two blocks of RAT items (RAT1 and RAT2), with the second block consisting of items that were not solved during the first block. Pa...

  20. Nonparametric Estimation of a Bivariate Survival Function in the Presence of Censoring

    OpenAIRE

    Tsai, Wei-Yann; Leurgans, Sue; Crowley, John

    1986-01-01

    A new family of estimators of a bivariate survival function based on censored vectors is obtained from a decomposition of the bivariate survival function. These estimators are uniformly consistent under bivariate censoring and are self-consistent under univariate censoring.

  1. Dyadic Bivariate Wavelet Multipliers in L2(R2)

    Institute of Scientific and Technical Information of China (English)

    Zhong Yan LI; Xian Liang SHI

    2011-01-01

    The single 2 dilation wavelet multipliers in one-dimensional case and single A-dilation (where A is any expansive matrix with integer entries and |detA|=2)wavelet multipliers in twodimensional case were completely characterized by Wutam Consortium(1998)and Li Z.,et al.(2010).But there exist no results on multivariate wavelet multipliers corresponding to integer expansive dilation.matrix with the absolute value of determinant not 2 in L2(R2).In this paper,we choose 2I2=(0202)as the dilation matrix and consider the 2I2-dilation multivariate wavelet Ψ={ψ1,ψ2,ψ3}(which is called a dyadic bivariate wavelet)multipliers.Here we call a measurable function family f={f1,f2,f3}a dyadic bivariate wavelet multiplier if Ψ1={F-1(f1ψ1),F-1(f2ψ2),F-1(f3ψ3)} is a dyadic bivariate wavelet for any dyadic bivariate wavelet Ψ={ψ1,ψ2,ψ3},where(f)and,F-1 denote the Fourier transform and the inverse transform of function f respectively.We study dyadic bivariate wavelet multipliers,and give some conditions for dyadic bivariate wavelet multipliers.We also give concrete forms of linear phases of dyadic MRA bivariate wavelets.

  2. TREAT (TREe-based Association Test)

    Science.gov (United States)

    TREAT is an R package for detecting complex joint effects in case-control studies. The test statistic is derived from a tree-structure model by recursive partitioning the data. Ultra-fast algorithm is designed to evaluate the significance of association be

  3. The bivariate Rogers-Szegoe polynomials

    International Nuclear Information System (INIS)

    We present an operator approach to deriving Mehler's formula and the Rogers formula for the bivariate Rogers-Szegoe polynomials hn(x, y vertical bar q). The proof of Mehler's formula can be considered as a new approach to the nonsymmetric Poisson kernel formula for the continuous big q-Hermite polynomials Hn(x; a vertical bar q) due to Askey, Rahman and Suslov. Mehler's formula for hn(x, y vertical bar q) involves a 3Φ2 sum and the Rogers formula involves a 2Φ1 sum. The proofs of these results are based on parameter augmentation with respect to the q-exponential operator and the homogeneous q-shift operator in two variables. By extending recent results on the Rogers-Szegoe polynomials hn(x vertical bar q) due to Hou, Lascoux and Mu, we obtain another Rogers-type formula for hn(x, y vertical bar q). Finally, we give a change of base formula for Hn(x; a vertical bar q) which can be used to evaluate some integrals by using the Askey-Wilson integral

  4. An adaptive association test for microbiome data.

    Science.gov (United States)

    Wu, Chong; Chen, Jun; Kim, Junghi; Pan, Wei

    2016-01-01

    There is increasing interest in investigating how the compositions of microbial communities are associated with human health and disease. Although existing methods have identified many associations, a proper choice of a phylogenetic distance is critical for the power of these methods. To assess an overall association between the composition of a microbial community and an outcome of interest, we present a novel multivariate testing method called aMiSPU, that is joint and highly adaptive over all observed taxa and thus high powered across various scenarios, alleviating the issue with the choice of a phylogenetic distance. Our simulations and real-data analyses demonstrated that the aMiSPU test was often more powerful than several competing methods while correctly controlling type I error rates. The R package MiSPU is available at https://github.com/ChongWu-Biostat/MiSPU and CRAN. PMID:27198579

  5. Copula bivariate probit models: with an application to medical expenditures.

    Science.gov (United States)

    Winkelmann, Rainer

    2012-12-01

    The bivariate probit model is frequently used for estimating the effect of an endogenous binary regressor (the 'treatment') on a binary health outcome variable. This paper discusses simple modifications that maintain the probit assumption for the marginal distributions while introducing non-normal dependence using copulas. In an application of the copula bivariate probit model to the effect of insurance status on the absence of ambulatory health care expenditure, a model based on the Frank copula outperforms the standard bivariate probit model. PMID:22025413

  6. A Bivariate Analogue to the Composed Product of Polynomials

    Institute of Scientific and Technical Information of China (English)

    Donald Mills; Kent M. Neuerburg

    2003-01-01

    The concept of a composed product for univariate polynomials has been explored extensively by Brawley, Brown, Carlitz, Gao,Mills, et al. Starting with these fundamental ideas andutilizing fractional power series representation(in particular, the Puiseux expansion) of bivariate polynomials, we generalize the univariate results. We define a bivariate composed sum,composed multiplication,and composed product (based on function composition). Further, we investigate the algebraic structure of certain classes of bivariate polynomials under these operations. We also generalize a result of Brawley and Carlitz concerningthe decomposition of polynomials into irreducibles.

  7. Increasing Power of Groupwise Association Test with Likelihood Ratio Test

    Science.gov (United States)

    Sul, Jae Hoon; Han, Buhm; Eskin, Eleazar

    Sequencing studies have been discovering a numerous number of rare variants, allowing the identification of the effects of rare variants on disease susceptibility. As a method to increase the statistical power of studies on rare variants, several groupwise association tests that group rare variants in genes and detect associations between groups and diseases have been proposed. One major challenge in these methods is to determine which variants are causal in a group, and to overcome this challenge, previous methods used prior information that specifies how likely each variant is causal. Another source of information that can be used to determine causal variants is observation data because case individuals are likely to have more causal variants than control individuals. In this paper, we introduce a likelihood ratio test (LRT) that uses both data and prior information to infer which variants are causal and uses this finding to determine whether a group of variants is involved in a disease. We demonstrate through simulations that LRT achieves higher power than previous methods. We also evaluate our method on mutation screening data of the susceptibility gene for ataxia telangiectasia, and show that LRT can detect an association in real data. To increase the computational speed of our method, we show how we can decompose the computation of LRT, and propose an efficient permutation test. With this optimization, we can efficiently compute an LRT statistic and its significance at a genome-wide level. The software for our method is publicly available at http://genetics.cs.ucla.edu/rarevariants.

  8. Recursive Numerical Evaluation of the Cumulative Bivariate Normal Distribution

    OpenAIRE

    Christian Meyer

    2013-01-01

    We propose an algorithm for evaluation of the cumulative bivariate normal distribution, building upon Marsaglia's ideas for evaluation of the cumulative univariate normal distribution. The algorithm is mathematically transparent, delivers competitive performance and can easily be extended to arbitrary precision.

  9. Copula bivariate probit models: with an application to medical expenditures

    OpenAIRE

    Winkelmann, Rainer

    2011-01-01

    The bivariate probit model is frequently used for estimating the eff*ect of an endogenous binary regressor (the "treatment") on a binary health outcome variable. This paper discusses simple modifi*cations that maintain the probit assumption for the marginal distributions while introducing non-normal dependence using copulas. In an application of the copula bivariate probit model to the effect of insurance status on the absence of ambulatory health care expenditure, a model based on the Frank ...

  10. Robustness of the sample correlation - the bivariate lognormal case

    OpenAIRE

    J. C. W. Rayner; C. D. Lai; Hutchinson, T P

    1999-01-01

    The sample correlation coefficient R is almost universally used to estimate the population correlation coefficient ρ. If the pair (X,Y) has a bivariate normal distribution, this would not cause any trouble. However, if the marginals are nonnormal, particularly if they have high skewness and kurtosis, the estimated value from a sample may be quite different from the population correlation coefficient ρ.The bivariate lognormal is chosen as our case study for this robustness study. Two approache...

  11. Family-based association tests for genomewide association scans.

    Science.gov (United States)

    Chen, Wei-Min; Abecasis, Goncalo R

    2007-11-01

    With millions of single-nucleotide polymorphisms (SNPs) identified and characterized, genomewide association studies have begun to identify susceptibility genes for complex traits and diseases. These studies involve the characterization and analysis of very-high-resolution SNP genotype data for hundreds or thousands of individuals. We describe a computationally efficient approach to testing association between SNPs and quantitative phenotypes, which can be applied to whole-genome association scans. In addition to observed genotypes, our approach allows estimation of missing genotypes, resulting in substantial increases in power when genotyping resources are limited. We estimate missing genotypes probabilistically using the Lander-Green or Elston-Stewart algorithms and combine high-resolution SNP genotypes for a subset of individuals in each pedigree with sparser marker data for the remaining individuals. We show that power is increased whenever phenotype information for ungenotyped individuals is included in analyses and that high-density genotyping of just three carefully selected individuals in a nuclear family can recover >90% of the information available if every individual were genotyped, for a fraction of the cost and experimental effort. To aid in study design, we evaluate the power of strategies that genotype different subsets of individuals in each pedigree and make recommendations about which individuals should be genotyped at a high density. To illustrate our method, we performed genomewide association analysis for 27 gene-expression phenotypes in 3-generation families (Centre d'Etude du Polymorphisme Humain pedigrees), in which genotypes for ~860,000 SNPs in 90 grandparents and parents are complemented by genotypes for ~6,700 SNPs in a total of 168 individuals. In addition to increasing the evidence of association at 15 previously identified cis-acting associated alleles, our genotype-inference algorithm allowed us to identify associated alleles at 4

  12. Dissecting the correlation structure of a bivariate phenotype: common genes or shared environment?

    Indian Academy of Sciences (India)

    Saurabh Ghosh

    2005-08-01

    High correlations between two quantitative traits may be either due to common genetic factors or common environmental factors or a combination of both. In this study, we develop statistical methods to extract the genetic contribution to the total correlation between the components of a bivariate phenotype. Using data on bivariate phenotypes and marker genotypes for sib-pairs, we propose a test for linkage between a common QTL and a marker locus based on the conditional cross-sib trait correlations (trait 1 of sib 1 – trait 2 of sib 2 and conversely) given the identity-by-descent (i.b.d.) sharing at the marker locus. We use Monte-Carlo simulations to evaluate the performance of the proposed test under different trait parameters and quantitative trait distributions. An application of the method is illustrated using data on two alcohol-related phenotypes from a project on the collaborative study on the genetics of alcoholism.

  13. A Semiparametric Bivariate Probit Model for Joint Modeling of Outcomes in STEMI Patients

    OpenAIRE

    Francesca Ieva; Giampiero Marra; Anna Maria Paganoni; Rosalba Radice

    2014-01-01

    In this work we analyse the relationship among in-hospital mortality and a treatment effectiveness outcome in patients affected by ST-Elevation myocardial infarction. The main idea is to carry out a joint modeling of the two outcomes applying a Semiparametric Bivariate Probit Model to data arising from a clinical registry called STEMI Archive. A realistic quantification of the relationship between outcomes can be problematic for several reasons. First, latent factors associated with hospit...

  14. Bipolar and bivariate models in multi-criteria decision analysis: descriptive and constructive approaches

    OpenAIRE

    GRABISCH, Michel; Greco, Salvatore; Pirlot, Marc

    2008-01-01

    International audience Multi-criteria decision analysis studies decision problems in which the alternatives are evaluated on several dimensions or viewpoints. In the problems we consider in this paper, the scales used for assessing the alternatives with respect to a viewpoint are bipolar and univariate or unipolar and bivariate. In the former case, the scale is divided in two zones by a neutral point; a positive feeling is associated to the zone above the neutral point and a negative feeli...

  15. A Semiparametric Bivariate Probit Model for Joint Modeling of Outcomes in STEMI Patients

    OpenAIRE

    2014-01-01

    In this work we analyse the relationship among in-hospital mortality and a treatment effectiveness outcome in patients affected by ST-Elevation myocardial infarction. The main idea is to carry out a joint modeling of the two outcomes applying a Semiparametric Bivariate Probit Model to data arising from a clinical registry called STEMI Archive. A realistic quantification of the relationship between outcomes can be problematic for several reasons. First, latent factors associated with hospitals...

  16. Determinantal and permanental representation of generalized bivariate Fibonacci p-polynomials

    OpenAIRE

    Kaygisiz, Kenan; Sahin, Adem

    2011-01-01

    In this paper, we give some determinantal and permanental representations of generalized bivariate Fibonacci p-polynomials by using various Hessenberg matrices. The results that we obtained are important since generalized bivariate Fibonacci p-polynomials are general form of, for example, bivariate Fibonacci and Pell p-polynomials, second kind Chebyshev polynomials, bivariate Jacobsthal polynomials etc.

  17. Approximation of bivariate copulas by patched bivariate Fréchet copulas

    KAUST Repository

    Zheng, Yanting

    2011-03-01

    Bivariate Fréchet (BF) copulas characterize dependence as a mixture of three simple structures: comonotonicity, independence and countermonotonicity. They are easily interpretable but have limitations when used as approximations to general dependence structures. To improve the approximation property of the BF copulas and keep the advantage of easy interpretation, we develop a new copula approximation scheme by using BF copulas locally and patching the local pieces together. Error bounds and a probabilistic interpretation of this approximation scheme are developed. The new approximation scheme is compared with several existing copula approximations, including shuffle of min, checkmin, checkerboard and Bernstein approximations and exhibits better performance, especially in characterizing the local dependence. The utility of the new approximation scheme in insurance and finance is illustrated in the computation of the rainbow option prices and stop-loss premiums. © 2010 Elsevier B.V.

  18. Simultaneous estimation of parameters in the bivariate Emax model.

    Science.gov (United States)

    Magnusdottir, Bergrun T; Nyquist, Hans

    2015-12-10

    In this paper, we explore inference in multi-response, nonlinear models. By multi-response, we mean models with m > 1 response variables and accordingly m relations. Each parameter/explanatory variable may appear in one or more of the relations. We study a system estimation approach for simultaneous computation and inference of the model and (co)variance parameters. For illustration, we fit a bivariate Emax model to diabetes dose-response data. Further, the bivariate Emax model is used in a simulation study that compares the system estimation approach to equation-by-equation estimation. We conclude that overall, the system estimation approach performs better for the bivariate Emax model when there are dependencies among relations. The stronger the dependencies, the more we gain in precision by using system estimation rather than equation-by-equation estimation. PMID:26190048

  19. BIVARIATE LAGRANGE-TYPE VECTOR VALUED RATIONAL INTERPOLANTS

    Institute of Scientific and Technical Information of China (English)

    Chuan-qing Gu; Gong-qing Zhu

    2002-01-01

    An axiomatic definition to bivariate vector valued rational interpolation on distinct plane interpolation points is at first presented in this paper. A two-variable vector valued rational interpolation formula is explicitly constructed in the following form: the determinantal formulas for denominator scalar polynomials and for numerator vector polynomials,which possess Lagrange-type basic function expressions. A practical criterion of existence and uniqueness for interpolation is obtained. In contrast to the underlying method, the method of bivariate Thiele-type vector valued rational interpolation is reviewed.

  20. Barriers to HIV testing and characteristics associated with never testing among gay and bisexual men attending sexual health clinics in Sydney

    Directory of Open Access Journals (Sweden)

    Damian P Conway

    2015-08-01

    Full Text Available Introduction: HIV diagnoses among gay and bisexual men have increased over the past decade in Australia. HIV point-of-care testing (POCT was introduced in Australia in 2011 as a strategy to increase HIV testing by making the testing process more convenient. We surveyed gay and bisexual men undergoing POCT to assess barriers to HIV testing and characteristics associated with not having previously tested for HIV (never testing. Methods: During 2011 and 2012, gay and bisexual men who were undergoing POCT at four Sydney sexual health clinics self-completed questionnaires assessing testing history and psychological and structural barriers to HIV testing. Bivariate and multivariate logistic regression was used to assess associations between patient characteristics and never testing. Results: Of 1093 participants, 981 (89.9% reported ever testing for HIV and 110 (10.1% never testing. At least one barrier to testing was reported by 1046 men (95.7%, with only 47 men (4.3% not reporting any barrier to testing. The most commonly reported barriers to testing were annoyance at having to return for results (30.2%, not having done anything risky (29.6%, stress in waiting for results (28.4%, being afraid of testing positive (27.5% and having tested recently (23.2%. Never testing was independently associated with being non-gay-identified (adjusted odds ratio [AOR]: 1.9; 95% confidence interval [CI]: 1.1–3.2, being aged less than 25 years (AOR: 2.4; 95% CI: 1.6–3.8, living in a suburb with few gay couples (AOR: 1.9; 95% CI: 1.2–3.0, being afraid of testing HIV-positive (AOR: 1.6; 95% CI: 1.0–2.4, not knowing where to test (AOR: 3.8; 95% CI: 1.3–11.2 and reporting one or no sexual partners in the last six months (AOR: 2.7; 95% CI: 1.2–6.2. Conclusions: Barriers to HIV testing were commonly reported among the clinic-based gay and bisexual men in this study. Our findings suggest further health promotion and prevention strategies are needed to address the

  1. Barriers to HIV testing and characteristics associated with never testing among gay and bisexual men attending sexual health clinics in Sydney

    Science.gov (United States)

    Conway, Damian P; Holt, Martin; Couldwell, Deborah L; Smith, Don E; Davies, Stephen C; McNulty, Anna; Keen, Phillip; Cunningham, Philip; Guy, Rebecca

    2015-01-01

    Introduction HIV diagnoses among gay and bisexual men have increased over the past decade in Australia. HIV point-of-care testing (POCT) was introduced in Australia in 2011 as a strategy to increase HIV testing by making the testing process more convenient. We surveyed gay and bisexual men undergoing POCT to assess barriers to HIV testing and characteristics associated with not having previously tested for HIV (never testing). Methods During 2011 and 2012, gay and bisexual men who were undergoing POCT at four Sydney sexual health clinics self-completed questionnaires assessing testing history and psychological and structural barriers to HIV testing. Bivariate and multivariate logistic regression was used to assess associations between patient characteristics and never testing. Results Of 1093 participants, 981 (89.9%) reported ever testing for HIV and 110 (10.1%) never testing. At least one barrier to testing was reported by 1046 men (95.7%), with only 47 men (4.3%) not reporting any barrier to testing. The most commonly reported barriers to testing were annoyance at having to return for results (30.2%), not having done anything risky (29.6%), stress in waiting for results (28.4%), being afraid of testing positive (27.5%) and having tested recently (23.2%). Never testing was independently associated with being non-gay-identified (adjusted odds ratio [AOR]: 1.9; 95% confidence interval [CI]: 1.1–3.2), being aged less than 25 years (AOR: 2.4; 95% CI: 1.6–3.8), living in a suburb with few gay couples (AOR: 1.9; 95% CI: 1.2–3.0), being afraid of testing HIV-positive (AOR: 1.6; 95% CI: 1.0–2.4), not knowing where to test (AOR: 3.8; 95% CI: 1.3–11.2) and reporting one or no sexual partners in the last six months (AOR: 2.7; 95% CI: 1.2–6.2). Conclusions Barriers to HIV testing were commonly reported among the clinic-based gay and bisexual men in this study. Our findings suggest further health promotion and prevention strategies are needed to address the

  2. On limit relations between some families of bivariate hypergeometric orthogonal polynomials

    International Nuclear Information System (INIS)

    In this paper we deal with limit relations between bivariate hypergeometric polynomials. We analyze the limit relation from trinomial distribution to bivariate Gaussian distribution, obtaining the limit transition from the second-order partial difference equation satisfied by bivariate hypergeometric Kravchuk polynomials to the second-order partial differential equation verified by bivariate hypergeometric Hermite polynomials. As a consequence the limit relation between both families of orthogonal polynomials is established. A similar analysis between bivariate Hahn and bivariate Appell orthogonal polynomials is also presented. (paper)

  3. Bivariate luminosity function of E and SO galaxies

    International Nuclear Information System (INIS)

    A function which describes the joint distribution of luminosity and radius of galaxies - the bivariate luminosity function (BLF) is defined. A simple analytical formula for the shape of BLF is proposed and fitted to the data for E and SO galaxies from the sample of a previous author. (author)

  4. Application of Peano Kernels Theorem to Bivariate Product Cubature

    International Nuclear Information System (INIS)

    We fully utilize Peano kernels theorem to the error estimates of bivariate self-validating integration based on product cubature rules. This application enable adaptive local error estimates. We demonstrate the characteristics and effectiveness of our methods by comparing it with a conventional integrator

  5. A New Measure Of Bivariate Asymmetry And Its Evaluation

    International Nuclear Information System (INIS)

    In this paper we propose a new measure of bivariate asymmetry, based on conditional correlation coefficients. A decomposition of the Pearson correlation coefficient in terms of its conditional versions is studied and an example of application of the proposed measure is given.

  6. A Bivariate Extension to Traditional Empirical Orthogonal Function Analysis

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Hilger, Klaus Baggesen; Andersen, Ole Baltazar;

    2002-01-01

    with 24 variables. This type of analysis can be considered as an extension of traditional empirical orthogonal function (EOF) analysis which provides a marginal analysis of one variable over time. The motivation for using a bivariate extention stems from the fact that the two fields are interrelated as...

  7. A conditional bivariate reference curve with an application to human growth

    DEFF Research Database (Denmark)

    Petersen, Jørgen Holm

    conditional bivariate distribution; reference curves; percentile; non-parametric; quantile regression; non-parametric estimation......conditional bivariate distribution; reference curves; percentile; non-parametric; quantile regression; non-parametric estimation...

  8. Modeling Elicitation effects in contingent valuation studies: a Monte Carlo Analysis of the bivariate approach

    OpenAIRE

    Genius, Margarita; Strazzera, Elisabetta

    2005-01-01

    A Monte Carlo analysis is conducted to assess the validity of the bivariate modeling approach for detection and correction of different forms of elicitation effects in Double Bound Contingent Valuation data. Alternative univariate and bivariate models are applied to several simulated data sets, each one characterized by a specific elicitation effect, and their performance is assessed using standard selection criteria. The bivariate models include the standard Bivariate Probit model, and an al...

  9. Sample size and power calculations for correlations between bivariate longitudinal data

    OpenAIRE

    Comulada, W. Scott; Weiss, Robert E.

    2010-01-01

    The analysis of a baseline predictor with a longitudinally measured outcome is well established and sample size calculations are reasonably well understood. Analysis of bivariate longitudinally measured outcomes is gaining in popularity and methods to address design issues are required. The focus in a random effects model for bivariate longitudinal outcomes is on the correlations that arise between the random effects and between the bivariate residuals. In the bivariate random effects model, ...

  10. A statistical perspective on the dynamics of bivariate chaotic maps for communications modelling

    OpenAIRE

    Hilliam, Rachel; Lawrance, Anthony

    2001-01-01

    Statistical and dynamical properties of bivariate (two-dimensional) maps, are less understood than their univariate counterparts. This paper will give a synthesis of extended results with exemplifications by the contrasting bivariate logistic and Arnold cat maps. The use of synchronization from bivariate maps in communication modelling is also described.

  11. On errors of a unified family of approximation forms of bivariate continuous functions

    OpenAIRE

    Chung-Siung Kao

    2003-01-01

    Approximation forms for a regular bivariate functions $f(x,y)$ were obtained by putting expectation on a convergent bivariate stochastic sequence for which some proper error bounds are herein derived to evaluate the applicability of the approximation forms when actually applied to be approximates of regular bivariate functions.

  12. The Noval Properties and Construction of Multi-scale Matrix-valued Bivariate Wavelet wraps

    Science.gov (United States)

    Zhang, Hai-mo

    In this paper, we introduce matrix-valued multi-resolution structure and matrix-valued bivariate wavelet wraps. A constructive method of semi-orthogonal matrix-valued bivari-ate wavelet wraps is presented. Their properties have been characterized by using time-frequency analysis method, unitary extension principle and operator theory. The direct decom-position relation is obtained.

  13. On the construction of bivariate exponential distributions with an arbitrary correlation coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    In this paper we use a concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... coefficient (also negative). Secondly, the class satisfies that any linear combination (projection) of the marginal random variables is a phase {type distributions, The latter property is potentially important for the development hypothesis testing in linear models. Thirdly, it is very easy to simulate the...

  14. On the Construction of Bivariate Exponential Distributions with an Arbitrary Correlation Coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    2010-01-01

    In this article we use the concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... coefficient (also negative). Secondly, the class satisfies that any linear combination (projection) of the marginal random variables is a phase-type distribution. The latter property is partially important for the development of hypothesis testing in linear models. Finally, it is easy to simulate the...

  15. Bivariate description of offshore wave conditions with physics-based extreme value statistics

    International Nuclear Information System (INIS)

    This paper aims to find a model for the bivariate description of extreme wave heights and wave periods representing relatively deep-water sea states. To achieve this, four statistical models taken from literature and a model based on the physical behaviour of waves have been tested on wave data at two sites. The models have been compared with regard to their ability to correctly describe the data, their behaviour when used for extrapolation to extreme events, and the transparency of the methods. (author)

  16. Covariance Association Test (CVAT) Identifies Genetic Markers Associated with Schizophrenia in Functionally Associated Biological Processes

    DEFF Research Database (Denmark)

    Rohde, Palle Duun; Demontis, Ditte; Castro Dias Cuyabano, Beatriz;

    2016-01-01

    Schizophrenia is a psychiatric disorder with large personal and social costs, and understanding the genetic etiology is important. Such knowledge can be obtained by testing the association between a disease phenotype and individual genetic markers; however, such single-marker methods have limited...... power to detect genetic markers with small effects. Instead, aggregating genetic markers based on biological information might increase the power to identify sets of genetic markers of etiological significance. Several set test methods have been proposed: Here we propose a new set test derived from...... among the top performers. When extending CVAT to utilize a mixture of SNP effects, we found an increase in power to detect the causal sets. Applying the methods to a Danish schizophrenia case–control data set, we found genomic evidence for association of schizophrenia with vitamin A metabolism and...

  17. A bivariate ordered probit estimator with mixed effects

    OpenAIRE

    Buscha, Franz; Conte, Anna

    2010-01-01

    In this paper, we discuss the derivation and application of a bivariate ordered probit model with mixed effects. Our approach allows one to estimate the distribution of the effect (gamma) of an endogenous ordered variable on an ordered explanatory variable. By allowing gamma to vary over the population, our estimator offers a more flexible parametric setting to recover the causal effect of an endogenous variable in an ordered choice setting. We use Monte Carlo simulations to examine the perfo...

  18. Estimation of Multivariate Probit Models via Bivariate Probit

    OpenAIRE

    John Mullahy

    2015-01-01

    Models having multivariate probit and related structures arise often in applied health economics. When the outcome dimensions of such models are large, however, estimation can be challenging owing to numerical computation constraints and/or speed. This paper suggests the utility of estimating multivariate probit (MVP) models using a chain of bivariate probit estimators. The proposed approach offers two potential advantages over standard multivariate probit estimation procedures: significant r...

  19. Innovation Performance of Chilean SMEs: A Bivariate Probit Analysis

    OpenAIRE

    Rehman, Naqeeb Ur

    2016-01-01

    The purpose of this paper is to investigate the innovation activities of Chilean firms’ by using micro level data. Previous studies showed research gap related to micro level analysis of the Chilean SMEs. For the first time, multiple proxies have been used as dependent variables (product/process innovations and patent application/spending), which is neglected by the past studies. A micro level data has been obtained from the World Bank, Enterprise Survey on 696 Chilean SMEs. Bivariate probit...

  20. Non-parametric causal inference for bivariate time series

    CERN Document Server

    McCracken, James M

    2015-01-01

    We introduce new quantities for exploratory causal inference between bivariate time series. The quantities, called penchants and leanings, are computationally straightforward to apply, follow directly from assumptions of probabilistic causality, do not depend on any assumed models for the time series generating process, and do not rely on any embedding procedures; these features may provide a clearer interpretation of the results than those from existing time series causality tools. The penchant and leaning are computed based on a structured method for computing probabilities.

  1. Chromosome heteromorphism quantified by high-resolution bivariate flow karyotyping.

    OpenAIRE

    Trask, B; van den Engh, G; Mayall, B; Gray, J. W.

    1989-01-01

    Maternal and paternal homologues of many chromosome types can be differentiated on the basis of their peak position in Hoechst 33258 versus chromomycin A3 bivariate flow karyotypes. We demonstrate here the magnitude of DNA content differences among normal chromosomes of the same type. Significant peak-position differences between homologues were observed for an average of four chromosome types in each of the karyotypes of 98 different individuals. The frequency of individuals with differences...

  2. Exact Bivariate Polynomial Factorization in Q by Approximation of Roots

    OpenAIRE

    Feng, Yong; Wu, Wenyuan; Zhang, Jingzhong

    2010-01-01

    Factorization of polynomials is one of the foundations of symbolic computation. Its applications arise in numerous branches of mathematics and other sciences. However, the present advanced programming languages such as C++ and J++, do not support symbolic computation directly. Hence, it leads to difficulties in applying factorization in engineering fields. In this paper, we present an algorithm which use numerical method to obtain exact factors of a bivariate polynomial with rational coeffici...

  3. Spectrum-based estimators of the bivariate Hurst exponent

    Czech Academy of Sciences Publication Activity Database

    Krištoufek, Ladislav

    2014-01-01

    Roč. 90, č. 6 (2014), art. 062802. ISSN 1539-3755 R&D Projects: GA ČR(CZ) GP14-11402P Institutional support: RVO:67985556 Keywords : bivariate Hurst exponent * power-law cross-correlations * estimation Subject RIV: AH - Economics Impact factor: 2.288, year: 2014 http://library.utia.cas.cz/separaty/2014/E/kristoufek-0436818.pdf

  4. Bivariate Kumaraswamy distribution with an application on earthquake data

    Energy Technology Data Exchange (ETDEWEB)

    Özel, Gamze

    2015-03-10

    Bivariate Kumaraswamy (BK) distribution whose marginals are Kumaraswamy distributions has been recently introduced. However, its statistical properties are not studied in detail. In this study, statistical properties of the BK distribution are investigated. We suggest that the BK could provide suitable description for the earthquakes characteristics of Turkey. We support this argument using earthquakesoccurred in Turkey between 1900 and 2009. We also find that the BK distribution simulates earthquakes well.

  5. Bivariate distributions in statistical spectroscopy studies. Pt. 2

    International Nuclear Information System (INIS)

    Orthogonal polynomials in two variables, defined by a bivariate density function, are used to derive series expansions for expectation values with respect to the two variables. The convergence of the resulting polynomial expansion is due to the action of a central limit theorem. The shell model results for fixed E, J occupancies in (ds)sup(m=5T=1/2) space are compared with the polynomial expansion results and the agreement is good. (orig.)

  6. Bivariate Kumaraswamy distribution with an application on earthquake data

    International Nuclear Information System (INIS)

    Bivariate Kumaraswamy (BK) distribution whose marginals are Kumaraswamy distributions has been recently introduced. However, its statistical properties are not studied in detail. In this study, statistical properties of the BK distribution are investigated. We suggest that the BK could provide suitable description for the earthquakes characteristics of Turkey. We support this argument using earthquakesoccurred in Turkey between 1900 and 2009. We also find that the BK distribution simulates earthquakes well

  7. Probabilistic floodplain hazard mapping: managing uncertainty by using a bivariate approach for flood frequency analysis

    Science.gov (United States)

    Candela, Angela; Tito Aronica, Giuseppe

    2014-05-01

    Floods are a global problem and are considered the most frequent natural disaster world-wide. Many studies show that the severity and frequency of floods have increased in recent years and underline the difficulty to separate the effects of natural climatic changes and human influences as land management practices, urbanization etc. Flood risk analysis and assessment is required to provide information on current or future flood hazard and risks in order to accomplish flood risk mitigation, to propose, evaluate and select measures to reduce it. Both components of risk can be mapped individually and are affected by multiple uncertainties as well as the joint estimate of flood risk. Major sources of uncertainty include statistical analysis of extremes events, definition of hydrological input, channel and floodplain topography representation, the choice of effective hydraulic roughness coefficients. The classical procedure to estimate flood discharge for a chosen probability of exceedance is to deal with a rainfall-runoff model associating to risk the same return period of original rainfall, in accordance with the iso-frequency criterion. Alternatively, a flood frequency analysis to a given record of discharge data is applied, but again the same probability is associated to flood discharges and respective risk. Moreover, since flood peaks and corresponding flood volumes are variables of the same phenomenon, they should be, directly, correlated and, consequently, multivariate statistical analyses must be applied. This study presents an innovative approach to obtain flood hazard maps where hydrological input (synthetic flood design event) to a 2D hydraulic model has been defined by generating flood peak discharges and volumes from: a) a classical univariate approach, b) a bivariate statistical analysis, through the use of copulas. The univariate approach considers flood hydrographs generation by an indirect approach (rainfall-runoff transformation using input rainfall

  8. Liver function tests: Association with cardiovascular outcomes

    OpenAIRE

    2010-01-01

    An association between nonalcoholic fatty liver disease and cardiovascular disease has been repeatedly reported. Several studies have focused on levels of gamma-glutamyltransferase (GGT) and alanine aminotransferase (ALT) in relation to cardiovascular outcomes. Evidence indicates that GGT may have a potential role for cardiovascular risk stratification while the role of ALT for cardiac prognosis remains controversial. A conceptual framework that includes not only GGT and ALT but also markers ...

  9. Group association test using a hidden Markov model.

    Science.gov (United States)

    Cheng, Yichen; Dai, James Y; Kooperberg, Charles

    2016-04-01

    In the genomic era, group association tests are of great interest. Due to the overwhelming number of individual genomic features, the power of testing for association of a single genomic feature at a time is often very small, as are the effect sizes for most features. Many methods have been proposed to test association of a trait with a group of features within a functional unit as a whole, e.g. all SNPs in a gene, yet few of these methods account for the fact that generally a substantial proportion of the features are not associated with the trait. In this paper, we propose to model the association for each feature in the group as a mixture of features with no association and features with non-zero associations to explicitly account for the possibility that a fraction of features may not be associated with the trait while other features in the group are. The feature-level associations are first estimated by generalized linear models; the sequence of these estimated associations is then modeled by a hidden Markov chain. To test for global association, we develop a modified likelihood ratio test based on a log-likelihood function that ignores higher order dependency plus a penalty term. We derive the asymptotic distribution of the likelihood ratio test under the null hypothesis. Furthermore, we obtain the posterior probability of association for each feature, which provides evidence of feature-level association and is useful for potential follow-up studies. In simulations and data application, we show that our proposed method performs well when compared with existing group association tests especially when there are only few features associated with the outcome. PMID:26420797

  10. Semantic Search in the Remote Associates Test.

    Science.gov (United States)

    Davelaar, Eddy J

    2015-07-01

    Searching through semantic memory may involve the use of several retrieval cues. In a verbal fluency task, the set of available cues is limited and every candidate word is a target. Individuals exhibit clustering behavior as predicted by optimal foraging theory. In another semantic search task, the remote associates task (RAT), three cues are presented and a single target word has to be found. Whereas the task has been widely studied as a task of creativity or insight problem solving, in this article, the RAT is treated as a semantic retrieval task and assessed from the perspective of information foraging theory. Experiments are presented that address the superadditive combination of cues and the anti-clustering behavior in the recall sequence. A new type of search behavior in the RAT is put forward that involves maximizing the difference in activation between target and distractors. This type of search is advantageous when the target is weak and cue patches are contaminated with strong competitors. PMID:25982148

  11. Comparison of Tests for Association and Linkage in Incomplete Families

    OpenAIRE

    Cervino, A. C. L.; Hill, A V S

    2000-01-01

    To analyze incomplete families, the following statistical tests can be used: LRAT—a simple likelihood-based association test, TRANSMIT, SIBASSOC/STDT, and RCTDT. We compared these four tests, for the diallelic case, on simulated data sets. The comparisons focused on the power to detect linkage and association when different familial structures, resistance to population stratification, resistance to misclassification of the disease status of the healthy sib, and the effect of nonpaternity were...

  12. Interactive analysis of gappy bivariate time series using AGSS

    OpenAIRE

    Lewis, Peter A.W.; Ray, Bonnie K.

    1992-01-01

    Bivariate time series which display nonstationary behavior, such as cycles or long-term trends, are common in fields such as oceanography and meteorology. These are usually very large-scale data sets and often may contain long gaps of missing values in one or both series, with the gaps perhaps occurring at different time periods in the two series. We present a simplified but effective method of interactively examining and filling in the missing values in such series using extensions of the me...

  13. Asymptotic formulas for the gamma function constructed by bivariate means

    OpenAIRE

    Yang, Zhen-Hang

    2014-01-01

    Let $K,M,N$ denote three bivariate means. In the paper, the author prove the asymptotic formulas for the gamma function have the form of% \\begin{equation*} \\Gamma \\left( x+1\\right) \\thicksim \\sqrt{2\\pi }M\\left( x+\\theta,x+1-\\theta \\right) ^{K\\left( x+\\epsilon ,x+1-\\epsilon \\right) }e^{-N\\left( x+\\sigma ,x+1-\\sigma \\right) } \\end{equation*}% or% \\begin{equation*} \\Gamma \\left( x+1\\right) \\thicksim \\sqrt{2\\pi }M\\left( x+\\theta ,x+\\sigma \\right) ^{K\\left( x+\\epsilon ,x+1-\\epsilon \\right) }e^{-M\\...

  14. Exact Bivariate Polynomial Factorization in Q by Approximation of Roots

    CERN Document Server

    Feng, Yong; Zhang, Jingzhong

    2010-01-01

    Factorization of polynomials is one of the foundations of symbolic computation. Its applications arise in numerous branches of mathematics and other sciences. However, the present advanced programming languages such as C++ and J++, do not support symbolic computation directly. Hence, it leads to difficulties in applying factorization in engineering fields. In this paper, we present an algorithm which use numerical method to obtain exact factors of a bivariate polynomial with rational coefficients. Our method can be directly implemented in efficient programming language such C++ together with the GNU Multiple-Precision Library. In addition, the numerical computation part often only requires double precision and is easily parallelizable.

  15. Bivariate-t distribution for transition matrix elements in Breit-Wigner to Gaussian domains of interacting particle systems

    International Nuclear Information System (INIS)

    Interacting many-particle systems with a mean-field one-body part plus a chaos generating random two-body interaction having strength λ exhibit Poisson to Gaussian orthogonal ensemble and Breit-Wigner (BW) to Gaussian transitions in level fluctuations and strength functions with transition points marked by λ=λc and λ=λF, respectively; λF>>λc. For these systems a theory for the matrix elements of one-body transition operators is available, as valid in the Gaussian domain, with λ>λF, in terms of orbital occupation numbers, level densities, and an integral involving a bivariate Gaussian in the initial and final energies. Here we show that, using a bivariate-t distribution, the theory extends below from the Gaussian regime to the BW regime up to λ=λc. This is well tested in numerical calculations for 6 spinless fermions in 12 single-particle states

  16. Household Poverty Dynamics in Malawi: A Bivariate Probit Analysis

    Science.gov (United States)

    Kenala Bokosi, Fanwell

    The aim of this study is to identify the sources of expenditure and poverty dynamics among Malawian households between 1998 and 2002 and to model poverty transitions in Malawi using a bivariate probit model with endogenous selection to address the initial conditions' problem. The exogeneity of the initial state is strongly rejected and could result in considerable overstatement of the effects of the explanatory factors. The results of the bivariate probit model do indicate that education of the household head, per capita acreage cultivated and changes in household size are significantly related to the probability of being poor in 2002 irrespective of the poverty status in 1998. For those households who were poor in 1998, the probability of being poor in 2002 was significantly influenced by household size, value of livestock owned and mean time to services, while residence in the Northern region was a significant variable in determining the probability of being poor in 2002 for households that were not poor in 1998.

  17. A bivariate luminosity model for GRB pulses and flares

    International Nuclear Information System (INIS)

    We have fitted the complete Swift BAT and XRT light curves of 88 GRBs for which we have a redshift with a total of 331 pulses. For each GRB we also include an afterglow component to fit the plateau phase and the late decay seen in the XRT data. The combination of pulses and afterglow model all the emission detected, prompt plus afterglow, including late X-ray flares detected only in the XRT. Each pulse is described by a simple physical model which includes the spectrum at peak and the temporal characteristics of the pulse. We find that the pulse peak luminosity is correlated with both the mean photon energy in the bolometric band of the pulse spectrum at the peak, referred to as Ezbol, and the temporal parameter Tzf which is a measure of the pulse width. An empirical bivariate luminosity model set up with these parameters provides a good fit to the pulse luminosity. The analysis indicates that prompt pulses and X-ray flares are one and the same and arise from the same physical process and this physical process is responsible for the bivariate nature of the luminosity.

  18. A Bayesian semiparametric model for bivariate sparse longitudinal data.

    Science.gov (United States)

    Das, Kiranmoy; Li, Runze; Sengupta, Subhajit; Wu, Rongling

    2013-09-30

    Mixed-effects models have recently become popular for analyzing sparse longitudinal data that arise naturally in biological, agricultural and biomedical studies. Traditional approaches assume independent residuals over time and explain the longitudinal dependence by random effects. However, when bivariate or multivariate traits are measured longitudinally, this fundamental assumption is likely to be violated because of intertrait dependence over time. We provide a more general framework where the dependence of the observations from the same subject over time is not assumed to be explained completely by the random effects of the model. We propose a novel, mixed model-based approach and estimate the error-covariance structure nonparametrically under a generalized linear model framework. We use penalized splines to model the general effect of time, and we consider a Dirichlet process mixture of normal prior for the random-effects distribution. We analyze blood pressure data from the Framingham Heart Study where body mass index, gender and time are treated as covariates. We compare our method with traditional methods including parametric modeling of the random effects and independent residual errors over time. We conduct extensive simulation studies to investigate the practical usefulness of the proposed method. The current approach is very helpful in analyzing bivariate irregular longitudinal traits. PMID:23553747

  19. THE INSTABILITY DEGREE IN THE DIEMNSION OF SPACES OF BIVARIATE SPLINE

    Institute of Scientific and Technical Information of China (English)

    Zhiqiang Xu; Renhong Wang

    2002-01-01

    In this paper, the dimension of the spaces of bivariate spline with degree less that 2r and smoothness order r on the Morgan-Scott triangulation is considered. The concept of the instability degree in the dimension of spaces of bivariate spline is presented. The results in the paper make us conjecture the instability degree in the dimension of spaces of bivariate spline is infinity.

  20. Characterization of Bivariate Distributions Using Concomitants of Generalized (k) Record Values

    OpenAIRE

    Poruthiyudian Yageen Thomas; Philip Anne; Thankachan Geetha Veena

    2014-01-01

    In this paper we have derived some properties of concomitants of generalized (k) record values which characterize the generalized Morgenstern family of bivariate distributions.  The role of concomitants of generalized (k) record values in the unique determination of the parent bivariate distribution has been established.  We have also illustrated how the concomitants of generalized (k) record values characterize the Morgenstern family of bivariate distributions.

  1. Bivariate gamma-geometric law and its induced L\\'evy process

    OpenAIRE

    Barreto-Souza, Wagner

    2013-01-01

    In this article we introduce a three-parameter extension of the bivariate exponential-geometric (BEG) law (Kozubowski and Panorska, 2005). We refer to this new distribution as bivariate gamma-geometric (BGG) law. A bivariate random vector $(X,N)$ follows BGG law if $N$ has geometric distribution and $X$ may be represented (in law) as a sum of $N$ independent and identically distributed gamma variables, where these variables are independent of $N$. Statistical properties such as moment generat...

  2. A Bivariate Markov Regime Switching GARCH Approach to Estimate Time Varying Minimum Variance Hedge Ratios

    OpenAIRE

    Hsiang-Tai Lee; Jonathan Yoder

    2005-01-01

    This paper develops a new bivariate Markov regime switching BEKK-GARCH (RS-BEKK-GARCH) model. The model is a state-dependent bivariate BEKK- GARCH model, and an extension of Gray’s univariate generalized regime- switching (GRS) model to the bivariate case. To solve the path- dependency problem inherent in the bivariate regime switching BEKK-GARCH model, we propose a recombining method for the covariance term in the conditional variance-covariance matrix. The model is applied to estimate time-...

  3. Sequence Kernel Association Test of Multiple Continuous Phenotypes.

    Science.gov (United States)

    Wu, Baolin; Pankow, James S

    2016-02-01

    Genetic studies often collect multiple correlated traits, which could be analyzed jointly to increase power by aggregating multiple weak effects and provide additional insights into the etiology of complex human diseases. Existing methods for multiple trait association tests have primarily focused on common variants. There is a surprising dearth of published methods for testing the association of rare variants with multiple correlated traits. In this paper, we extend the commonly used sequence kernel association test (SKAT) for single-trait analysis to test for the joint association of rare variant sets with multiple traits. We investigate the performance of the proposed method through extensive simulation studies. We further illustrate its usefulness with application to the analysis of diabetes-related traits in the Atherosclerosis Risk in Communities (ARIC) Study. We identified an exome-wide significant rare variant set in the gene YAP1 worthy of further investigations. PMID:26782911

  4. Gunite and Associated Tanks Treatability Study Equipment Testing at the Tanks Technology Cold Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Burks, BL

    2001-02-27

    This report provides a summary of the cold tests performed on the equipment to be used in the Gunite and Associated Tanks Treatability Study. The testing was performed from June 1996 to May 1997 at the Tanks Technology Cold Test Facility located at the 7600 complex at Oak Ridge National Laboratory. Testing of specific equipment grouped into the following sections: (1) Modified Light-Duty Utility Arm Testing, (2) Remotely Operated Vehicle Testing, (3) Waste Dislodging and Conveyance System and Balance of Plant Equipment Testing, (4) Camera and Lighting System Testing, and (5) Characterization End-Effector Testing. Each section contains descriptions of a series of tests that summarize the test objectives, testing performed, and test results. General conclusions from the testing are also provided.

  5. Comparing Johnson’s SBB, Weibull and Logit-Logistic bivariate distributions for modeling tree diameters and heights using copulas

    Directory of Open Access Journals (Sweden)

    Jose Javier Gorgoso-Varela

    2016-04-01

    Full Text Available Aim of study: In this study we compare the accuracy of three bivariate distributions: Johnson’s SBB, Weibull-2P and LL-2P functions for characterizing the joint distribution of tree diameters and heights.Area of study: North-West of Spain.Material and methods: Diameter and height measurements of 128 plots of pure and even-aged Tasmanian blue gum (Eucalyptus globulus Labill. stands located in the North-west of Spain were considered in the present study. The SBB bivariate distribution was obtained from SB marginal distributions using a Normal Copula based on a four-parameter logistic transformation. The Plackett Copula was used to obtain the bivariate models from the Weibull and Logit-logistic univariate marginal distributions. The negative logarithm of the maximum likelihood function was used to compare the results and the Wilcoxon signed-rank test was used to compare the related samples of these logarithms calculated for each sample plot and each distribution.Main results: The best results were obtained by using the Plackett copula and the best marginal distribution was the Logit-logistic.Research highlights: The copulas used in this study have shown a good performance for modeling the joint distribution of tree diameters and heights. They could be easily extended for modelling multivariate distributions involving other tree variables, such as tree volume or biomass.

  6. Patch testing for food-associated allergies in orofacial granulomatosis.

    LENUS (Irish Health Repository)

    Fitzpatrick, Laura

    2011-01-01

    Food-associated allergies, especially to benzoates and cinnamon-related compounds, have been associated with orofacial granulomatosis and both standard and urticarial patch testing have been used to detect such allergies. Elimination diets have also been shown to be effective in some patients.

  7. Selection effects in the bivariate brightness distribution for spiral galaxies

    International Nuclear Information System (INIS)

    The joint distribution of total luminosity and characteristic surface brightness (the bivariate brightness distribution) is investigated for a complete sample of spiral galaxies in the Virgo cluster. The influence of selection and physical limits of various kinds on the apparent distribution are detailed. While the distribution of surface brightness for bright galaxies may be genuinely fairly narrow, faint galaxies exist right across the (quite small) range of accessible surface brightnesses so no statement can be made about the true extent of the distribution. The lack of high surface brightness bright galaxies in the Virgo sample relative to an overall RC2 sample (mostly field galaxies) supports the contention that the star-formation rate is reduced in the inner region of the cluster for environmental reasons. (author)

  8. Efficient estimation of semiparametric copula models for bivariate survival data

    KAUST Repository

    Cheng, Guang

    2014-01-01

    A semiparametric copula model for bivariate survival data is characterized by a parametric copula model of dependence and nonparametric models of two marginal survival functions. Efficient estimation for the semiparametric copula model has been recently studied for the complete data case. When the survival data are censored, semiparametric efficient estimation has only been considered for some specific copula models such as the Gaussian copulas. In this paper, we obtain the semiparametric efficiency bound and efficient estimation for general semiparametric copula models for possibly censored data. We construct an approximate maximum likelihood estimator by approximating the log baseline hazard functions with spline functions. We show that our estimates of the copula dependence parameter and the survival functions are asymptotically normal and efficient. Simple consistent covariance estimators are also provided. Numerical results are used to illustrate the finite sample performance of the proposed estimators. © 2013 Elsevier Inc.

  9. Functional imaging of implicit marijuana associations during performance on an Implicit Association Test (IAT)

    NARCIS (Netherlands)

    S.L. Ames; J.L. Grenard; A.W. Stacy; L. Xiao; Q. He; S.W Wong; G. Xue; R.W. Wiers; A. Bechara

    2013-01-01

    This research evaluated the neural correlates of implicit associative memory processes (habit-based processes) through the imaging (fMRI) of a marijuana Implicit Association Test. Drug-related associative memory effects have been shown to consistently predict level of drug use. To observe difference

  10. Bi-variable damage model for fatigue life prediction of metal components

    Institute of Scientific and Technical Information of China (English)

    Miao Zhang; Qing-Chun Meng; Xing Zhang; Wei-Ping Hu

    2011-01-01

    Based on the theory of continuum damage mechanics, a bi-variable damage mechanics model is developed, which, according to thermodynamics, is accessible to derivation of damage driving force, damage evolution equation and damage evolution criteria. Furthermore, damage evolution equations of time rate are established by the generalized Drucker's postulate. The damage evolution equation of cycle rate is obtained by integrating the time damage evolution equations, and the fatigue life prediction method for smooth specimens under repeated loading with constant strain amplitude is constructed. Likewise, for notched specimens under the repeated loading with constant strain amplitude, the fatigue life prediction method is obtained on the ground of the theory of conservative integral in damage mechanics. Thus, the material parameters in the damage evolution equation can be obtained by reference to the fatigue test results of standard specimens with stress concentration factor equal to 1, 2 and 3.

  11. The bivariate combined model for spatial data analysis.

    Science.gov (United States)

    Neyens, Thomas; Lawson, Andrew B; Kirby, Russell S; Faes, Christel

    2016-08-15

    To describe the spatial distribution of diseases, a number of methods have been proposed to model relative risks within areas. Most models use Bayesian hierarchical methods, in which one models both spatially structured and unstructured extra-Poisson variance present in the data. For modelling a single disease, the conditional autoregressive (CAR) convolution model has been very popular. More recently, a combined model was proposed that 'combines' ideas from the CAR convolution model and the well-known Poisson-gamma model. The combined model was shown to be a good alternative to the CAR convolution model when there was a large amount of uncorrelated extra-variance in the data. Less solutions exist for modelling two diseases simultaneously or modelling a disease in two sub-populations simultaneously. Furthermore, existing models are typically based on the CAR convolution model. In this paper, a bivariate version of the combined model is proposed in which the unstructured heterogeneity term is split up into terms that are shared and terms that are specific to the disease or subpopulation, while spatial dependency is introduced via a univariate or multivariate Markov random field. The proposed method is illustrated by analysis of disease data in Georgia (USA) and Limburg (Belgium) and in a simulation study. We conclude that the bivariate combined model constitutes an interesting model when two diseases are possibly correlated. As the choice of the preferred model differs between data sets, we suggest to use the new and existing modelling approaches together and to choose the best model via goodness-of-fit statistics. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26928309

  12. Small Sample Kernel Association Tests for Human Genetic and Microbiome Association Studies.

    Science.gov (United States)

    Chen, Jun; Chen, Wenan; Zhao, Ni; Wu, Michael C; Schaid, Daniel J

    2016-01-01

    Kernel machine based association tests (KAT) have been increasingly used in testing the association between an outcome and a set of biological measurements due to its power to combine multiple weak signals of complex relationship with the outcome through the specification of a relevant kernel. Human genetic and microbiome association studies are two important applications of KAT. However, the classic KAT framework relies on large sample theory, and conservativeness has been observed for small sample studies, especially for microbiome association studies. The common approach for addressing the small sample problem relies on computationally intensive resampling methods. Here, we derive an exact test for KAT with continuous traits, which resolve the small sample conservatism of KAT without the need for resampling. The exact test has significantly improved power to detect association for microbiome studies. For binary traits, we propose a similar approximate test, and we show that the approximate test is very powerful for a wide range of kernels including common variant- and microbiome-based kernels, and the approximate test controls the type I error well for these kernels. In contrast, the sequence kernel association tests have slightly inflated genomic inflation factors after small sample adjustment. Extensive simulations and application to a real microbiome association study are used to demonstrate the utility of our method. PMID:26643881

  13. On the construction of bivariate linear exponential distribution with FGM family

    OpenAIRE

    El-Damcese, M. A.; Ramadan, Dina. A.

    2015-01-01

    In this paper we propose a Farlie-Gumbel-Morgenstern (FGM) family of bivariate linear exponential distributions generated from given marginal's. Therefore, properties of FGM are analogous to properties of bivariate distributions. We study some important statistical properties and results for the new distribution.

  14. A Practical Comparison of the Bivariate Probit and Linear IV Estimators

    OpenAIRE

    Chiburis, Richard C.; Das, Jishnu; Lokshin, Michael

    2011-01-01

    This paper presents asymptotic theory and Monte-Carlo simulations comparing maximum-likelihood bivariate probit and linear instrumental variables estimators of treatment effects in models with a binary endogenous treatment and binary outcome. The three main contributions of the paper are (a) clarifying the relationship between the Average Treatment Effect obtained in the bivariate probit m...

  15. Generalized Wigner Operator and Bivariate Normal Distribution in p-q Phase Space

    International Nuclear Information System (INIS)

    We introduce a kind of generalized Wigner operator, whose normally ordered form can lead to the bivariate normal distribution in p-q phase space. While this bivariate normal distribution corresponds to the pure vacuum state in the generalized Wigner function phase space, it corresponds to a mixed state in the usual Wigner function phase space

  16. A semi-explicit density function for Kulkarni's bivariate phase-type distribution

    OpenAIRE

    Breuer, Lothar

    2014-01-01

    For a bivariate random variable $(Z_1,Z_2)$ having Kulkarni's bivariate phase-type distribution (see \\cite{Ku89}), we derive a simple expression for the semi-explicit density function $E (e^{-sZ_2} 1_{ \\{ Z_1 \\in dy \\} })$. Some immediate consequences are presented as concluding remarks.

  17. Behavior of bivariate interpolation operators at points of discontinuity of the first kind

    OpenAIRE

    Campiti, Michele; Mazzone, Giusy; Tacelli, Cristian

    2011-01-01

    We introduce an index of convergence for double sequences of real numbers. This index is used to describe the behaviour of some bivariate interpolation sequences at points of discontinuity of the first kind. We consider in particular the case of bivariate Lagrange and Shepard operators.

  18. Bayesian neural networks for bivariate binary data: an application to prostate cancer study.

    Science.gov (United States)

    Chakraborty, Sounak; Ghosh, Malay; Maiti, Tapabrata; Tewari, Ashutosh

    2005-12-15

    Prostate cancer is one of the most common cancers in American men. The cancer could either be locally confined, or it could spread outside the organ. When locally confined, there are several options for treating and curing this disease. Otherwise, surgery is the only option, and in extreme cases of outside spread, it could very easily recur within a short time even after surgery and subsequent radiation therapy. Hence, it is important to know, based on pre-surgery biopsy results how likely the cancer is organ-confined or not. The paper considers a hierarchical Bayesian neural network approach for posterior prediction probabilities of certain features indicative of non-organ confined prostate cancer. In particular, we find such probabilities for margin positivity (MP) and seminal vesicle (SV) positivity jointly. The available training set consists of bivariate binary outcomes indicating the presence or absence of the two. In addition, we have certain covariates such as prostate specific antigen (PSA), gleason score and the indicator for the cancer to be unilateral or bilateral (i.e. spread on one or both sides) in one data set and gene expression microarrays in another data set. We take a hierarchical Bayesian neural network approach to find the posterior prediction probabilities for a test and validation set, and compare these with the actual outcomes for the first data set. In case of the microarray data we use leave one out cross-validation to access the accuracy of our method. We also demonstrate the superiority of our method to the other competing methods through a simulation study. The Bayesian procedure is implemented by an application of the Markov chain Monte Carlo numerical integration technique. For the problem at hand, our Bayesian bivariate neural network procedure is shown to be superior to the classical neural network, Radford Neal's Bayesian neural network as well as bivariate logistic models to predict jointly the MP and SV in a patient in both the

  19. Association tests and software for copy number variant data

    Directory of Open Access Journals (Sweden)

    Plagnol Vincent

    2009-01-01

    Full Text Available Abstract Recent studies have suggested that copy number variation (CNV significantly contributes to genetic predisposition to several common disorders. These findings, combined with the imperfect tagging of CNVs by single nucleotide polymorphisms (SNPs, have motivated the development of association studies directly targeting CNVs. Several assays, including comparative genomic hybridisation arrays, SNP genotyping arrays, or DNA quantification through real-time polymerase chain reaction analysis, allow direct assessment of CNV status in cohorts sufficiently large to provide adequate statistical power for association studies. When analysing data provided by these assays, association tests for CNV data are not fundamentally different from SNP-based association tests. The main difference arises when the quality of the CNV assay is not sufficient to convert unequivocally the raw measurement into discrete calls -- a common issue, given the technological limitations of current CNV assays. When this is the case, association tests are more appropriately based on the raw continuous measurement provided by the CNV assay, instead of potentially inaccurate discrete calls, thus motivating the development of new statistical methods. Here, the programs available for CNV association testing for case control or family data are reviewed, using either discrete calls or raw continuous data.

  20. Comparison of Model Reliabilities from Single-Step and Bivariate Blending Methods

    DEFF Research Database (Denmark)

    Taskinen, Matti; Mäntysaari, Esa; Lidauer, Martin;

    2013-01-01

    Model based reliabilities in genetic evaluation are compared between three methods: animal model BLUP, single-step BLUP, and bivariate blending after genomic BLUP. The original bivariate blending is revised in this work to better account animal models. The study data is extracted from...... be calculated. Model reliabilities by the single-step and the bivariate blending methods were higher than by animal model due to genomic information. Compared to the single-step method, the bivariate blending method reliability estimates were, in general, lower. Computationally bivariate blending method was...... the production trait evaluation of Nordic Red dairy cattle. Genotyped bulls with daughters are used as training animals, and genotyped bulls and producing cows as candidate animals. For simplicity, size of the data is chosen so that the full inverses of the mixed model equation coefficient matrices can...

  1. Factors Associated with Hepatitis B Testing Among Vietnamese Americans

    OpenAIRE

    Tung T Nguyen; McPhee, Stephen J.; Stewart, Susan; Gildengorin, Ginny; Zhang, Lena; Wong, Ching; Maxwell, Annette E.; Bastani, Roshan; Taylor, Vicky M.; Chen, Moon S.

    2010-01-01

    BACKGROUND Chronic hepatitis B and hepatitis B-associated liver cancer is a major health disparity among Vietnamese Americans, who have a chronic hepatitis B prevalence rate of 7–14% and an incidence rate for liver cancer six times that of non-Latino whites. OBJECTIVE Describe factors associated with hepatitis B testing among Vietnamese Americans. DESIGN A population-based telephone survey conducted in 2007–2008. PARTICIPANTS Vietnamese Americans age 18–64 and living in the Northern Californi...

  2. Trait anxiety among undergraduates according to the Implicit Association Test.

    Science.gov (United States)

    Huang, Peng; Yang, Zhibing; Miao, Danmin; Lu, Huijie; Zhu, Xia

    2012-08-01

    Trait anxiety, which includes stress and anxiety, affects mental health. However, early studies using the Implicit Association Test-Anxiety (IAT-Anxiety) did not consider the participants' trait anxiety. In the present study, the hypothesis that trait anxiety would influence the results of the IAT-Anxiety was tested. A total of 148 healthy undergraduates were assessed with the Profile of Mood State (POMS) test and the State-Trait Anxiety Inventory (STAI) to test explicit anxiety; they were then assessed for implicit anxiety with the IAT-Anxiety. High trait anxiety was positively correlated with negative mood; low trait anxiety tended to be associated with greater vigor and higher self-esteem. Significant main effects were found for both critical block and group among participants who received the IAT-Anxiety. Future studies of the IAT-Anxiety should consider trait anxiety as a within-subject factor for group matching to enhance the persuasiveness of the results. PMID:23045843

  3. Detecting flood event trends assigned to changes in urbanisation levels using a bivariate copula model

    Science.gov (United States)

    Requena, Ana; Prosdocimi, Ilaria; Kjeldsen, Thomas R.; Mediero, Luis

    2014-05-01

    Flood frequency analyses based on stationary assumptions are usually employed for estimating design floods. However, more complex non-stationarity approaches are trying to be incorporated with the aim of improving such estimates. In this study, the effect of changing urbanisation on maximum flood peak (Q) and volume (V) series is analysed. The potential changes in an urbanised catchment and in a nearby hydrologically similar rural catchment in northwest England are investigated. The urbanised catchment is characterised by a noticeable increase of the urbanisation level in time, while the rural catchment has not been altered by anthropogenic actions. Winter, summer and annual maximum flood events are studied. With the aim of analysing changes in time, two non-superimposed time-windows are defined covering the periods 1976-1992 and 1993-2008, respectively. A preliminary analysis of temporal trends in Q, V and Kendall's tau is visually done, being formal tested by a resampling procedure. Differences were found among winter, summer and annual maximum flood events. As annual maximum flood events are commonly used for designing purposes, the corresponding bivariate distribution (margins and copula) was obtained for the different time-windows. Trends regarding both time-windows were analysed by comparing bivariate return period curves in the Q-V space. Different behaviours were found depending on the catchment. As a result, the application of the proposed methodology provides useful information in describing changes in flood events, regarding different flood variables and their relationship. In addition, the methodology can inform practitioners on the potential changes connected with urbanisation for appropriate design flood estimation.

  4. INLAND DISSOLVED SALT CHEMISTRY: STATISTICAL EVALUATION OF BIVARIATE AND TERNARY DIAGRAM MODELS FOR SURFACE AND SUBSURFACE WATERS

    Science.gov (United States)

    We compared the use of ternary and bivariate diagrams to distinguish the effects of atmospheric precipitation, rock weathering, and evaporation on inland surface and subsurface water chemistry. The three processes could not be statistically differentiated using bivariate models e...

  5. Multiply-Constrained Semantic Search in the Remote Associates Test

    Science.gov (United States)

    Smith, Kevin A.; Huber, David E.; Vul, Edward

    2013-01-01

    Many important problems require consideration of multiple constraints, such as choosing a job based on salary, location, and responsibilities. We used the Remote Associates Test to study how people solve such multiply-constrained problems by asking participants to make guesses as they came to mind. We evaluated how people generated these guesses…

  6. ML-PAT. Mohawk Language Picture Association Test.

    Science.gov (United States)

    Cole, Glory; And Others

    This picture association test booklet for the Mohawk language has two parts. Part One contains 10 questions and Part Two contains 40 questions. Each item consists of a word in Mohawk and a number of drawing from which the learner is to choose the correct one that represents the word. (AMH)

  7. Associative symmetry of the memory for object-location associations as revealed by the testing effect.

    Science.gov (United States)

    Sommer, Tobias; Schoell, Eszter; Büchel, Christian

    2008-06-01

    The nature of episodic associations has been subject to a long standing debate, where the two opposing positions postulate associations as either a holistic representation of the constituent elements or as independently modifiable pointers between them. In spite of a history of inconsistent findings, evidence in favour of the theory of symmetric associations has accumulated, yet only for verbal memory [Caplan, J. B., Glaholt, M. G., & McIntosh, A. R. (2006). Linking associative and serial list memory: Pairs versus triples. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32(6), 1244-1265; Kahana, M. J. (2002). Associative symmetry and memory theory. Memory and Cognition, 30(6), 823-840]. Although object-location associations differ in several fundamental characteristics from verbal paired-associates, we recently found associative symmetry in the memory for this class of associations as well [Sommer, T., Rose, M., & Büchel, C. (2007). Associative symmetry vs. independent associations in the memory for object-location associations. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33(1), 90-106]. Due to the inconsistencies in the verbal literature, we felt it to be pertinent to confirm this finding using another experimental approach. Based on recent advances in understanding the effects of successive testing, we were able to make use of this knowledge and introduce this effect as an experimental manipulation in the study of associative symmetry. In particular, we investigated whether the influence of a prior memory test on a subsequent memory test differs when the same or opposite constituent element of an object-location paired-associate cues the retrieval on each test. We observed an identical testing effect for both conditions, which was exclusively driven by reminiscence, the recovery of previously inaccessible information. This finding lends strong support in favour of holistically or symmetrically represented object

  8. Bivariate ensemble model output statistics approach for joint forecasting of wind speed and temperature

    Science.gov (United States)

    Baran, Sándor; Möller, Annette

    2016-06-01

    Forecast ensembles are typically employed to account for prediction uncertainties in numerical weather prediction models. However, ensembles often exhibit biases and dispersion errors, thus they require statistical post-processing to improve their predictive performance. Two popular univariate post-processing models are the Bayesian model averaging (BMA) and the ensemble model output statistics (EMOS). In the last few years, increased interest has emerged in developing multivariate post-processing models, incorporating dependencies between weather quantities, such as for example a bivariate distribution for wind vectors or even a more general setting allowing to combine any types of weather variables. In line with a recently proposed approach to model temperature and wind speed jointly by a bivariate BMA model, this paper introduces an EMOS model for these weather quantities based on a bivariate truncated normal distribution. The bivariate EMOS model is applied to temperature and wind speed forecasts of the 8-member University of Washington mesoscale ensemble and the 11-member ALADIN-HUNEPS ensemble of the Hungarian Meteorological Service and its predictive performance is compared to the performance of the bivariate BMA model and a multivariate Gaussian copula approach, post-processing the margins with univariate EMOS. While the predictive skills of the compared methods are similar, the bivariate EMOS model requires considerably lower computation times than the bivariate BMA method.

  9. Chromosome heteromorphism quantified by high-resolution bivariate flow karyotyping.

    Science.gov (United States)

    Trask, B; van den Engh, G; Mayall, B; Gray, J W

    1989-11-01

    Maternal and paternal homologues of many chromosome types can be differentiated on the basis of their peak position in Hoechst 33258 versus chromomycin A3 bivariate flow karyotypes. We demonstrate here the magnitude of DNA content differences among normal chromosomes of the same type. Significant peak-position differences between homologues were observed for an average of four chromosome types in each of the karyotypes of 98 different individuals. The frequency of individuals with differences in homologue peak positions varied among chromosome types: e.g., chromosome 15, 61%; chromosome 3, 4%. Flow karyotypes of 33 unrelated individuals were compared to determine the range of peak position among normal chromosomes. Chromosomes Y, 21, 22, 15, 16, 13, 14, and 19 were most heteromorphic, and chromosomes 2-8 and X were least heteromorphic. The largest chromosome 21 was 45% larger than the smallest 21 chromosome observed. The base composition of the variable regions differed among chromosome types. DNA contents of chromosome variants determined from flow karyotypes were closely correlated to measurements of DNA content made of gallocyanin chrome alum-stained metaphase chromosomes on slides. Fluorescence in situ hybridization with chromosome-specific repetitive sequences indicated that variability in their copy number is partly responsible for peak-position variability in some chromosomes. Heteromorphic chromosomes are identified for which parental flow karyotype information will be essential if de novo rearrangements resulting in small DNA content changes are to be detected with flow karyotyping. PMID:2479266

  10. A bivariate optimal replacement policy for a multistate repairable system

    International Nuclear Information System (INIS)

    In this paper, a deteriorating simple repairable system with k+1 states, including k failure states and one working state, is studied. It is assumed that the system after repair is not 'as good as new' and the deterioration of the system is stochastic. We consider a bivariate replacement policy, denoted by (T,N), in which the system is replaced when its working age has reached T or the number of failures it has experienced has reached N, whichever occurs first. The objective is to determine the optimal replacement policy (T,N)* such that the long-run expected profit per unit time is maximized. The explicit expression of the long-run expected profit per unit time is derived and the corresponding optimal replacement policy can be determined analytically or numerically. We prove that the optimal policy (T,N)* is better than the optimal policy N* for a multistate simple repairable system. We also show that a general monotone process model for a multistate simple repairable system is equivalent to a geometric process model for a two-state simple repairable system in the sense that they have the same structure for the long-run expected profit (or cost) per unit time and the same optimal policy. Finally, a numerical example is given to illustrate the theoretical results

  11. Bivariate log-convexity of the more extended means and its applications

    OpenAIRE

    Yang, Zhen-Hang

    2014-01-01

    In this paper, the bivariate log-convexity of the two-parameter homogeneous function in parameter pair is vestigated. From this the bivariate log-convexity of the more extended means with respect to a parameter pair is solved. It follows that Stolarsky means, Gini means, two-parameter identric (exponential) means and two-parameter Heronian means are all bivariate log-concave on $\\mathbb{[}0\\mathbb{,\\infty )}^{2}$ and log-convex on $% \\mathbb{(-\\infty ,}0\\mathbb{]}^{2}$ with respect to paramet...

  12. Testing for spatial association of qualitative data using symbolic dynamics

    Science.gov (United States)

    Ruiz, Manuel; López, Fernando; Páez, Antonio

    2010-09-01

    Qualitative spatial variables are important in many fields of research. However, unlike the decades-worth of research devoted to the spatial association of quantitative variables, the exploratory analysis of spatial qualitative variables is relatively less developed. The objective of the present paper is to propose a new test ( Q) for spatial independence. This is a simple, consistent, and powerful statistic for qualitative spatial independence that we develop using concepts from symbolic dynamics and symbolic entropy. The Q test can be used to detect, given a spatial distribution of events, patterns of spatial association of qualitative variables in a wide variety of settings. In order to enable hypothesis testing, we give a standard asymptotic distribution of an affine transformation of the symbolic entropy under the null hypothesis of independence in the spatial qualitative process. We include numerical experiments to demonstrate the finite sample behaviour of the test, and show its application by means of an empirical example that explores the spatial association of fast food establishments in the Greater Toronto Area in Canada.

  13. Factors Associated with Hepatitis B Testing Among Vietnamese Americans

    OpenAIRE

    Tung T Nguyen; McPhee, Stephen J.; Stewart, Susan; Gildengorin, Ginny; Zhang, Lena; Wong, Ching; Maxwell, Annette E.; Bastani, Roshan; Taylor, Vicky M.; Chen, Moon S.

    2010-01-01

    Chronic hepatitis B and hepatitis B-associated liver cancer is a major health disparity among Vietnamese Americans, who have a chronic hepatitis B prevalence rate of 7–14% and an incidence rate for liver cancer six times that of non-Latino whites. Describe factors associated with hepatitis B testing among Vietnamese Americans. A population-based telephone survey conducted in 2007–2008. Vietnamese Americans age 18–64 and living in the Northern California and Washington, DC areas (N = ...

  14. Assessing acute stress with the Implicit Association Test.

    Science.gov (United States)

    Sato, Hirotsune; Kawahara, Jun-ichiro

    2012-01-01

    Assessments of acute stress using self-report questionnaires can be biased by various factors, including social desirability. The present study used a bias-free method, the Implicit Association Test (IAT), to assess stress. Unlike a previous study (Schmukle & Egloff, 2004) in which acute stress was not detected with the IAT, this study manipulated stress by generating test anxiety and threatening self-esteem. The results revealed that the IAT effect was greater in the high-stress group than in the low-stress group. Participants in the high-stress group associated their concept of self with the concept of anxiety more strongly than did those in the low-stress group. This result suggests that the IAT is a sensitive measure for detecting group differences in acute stress. PMID:21432650

  15. Implicit measure for yoga research: Yoga implicit association test

    OpenAIRE

    Ilavarasu, Judu V; Sasidharan K Rajesh; Alex Hankey

    2014-01-01

    Context: The implicit association test (IAT), a new tool for yoga research is presented. Implicit measures could be used in those situations where (1) The construct is difficult to self-report, (2) there is a threat of social desirability. Clinically, we can assess cognitive dissonance by evaluating incongruence between implicit and explicit measures. Explicit preferences are self-reported. Implicit preferences are what we inherently believe, often without our conscious awareness. Aims: T...

  16. Univariate description and bivariate statistical inference: the first step delving into data.

    Science.gov (United States)

    Zhang, Zhongheng

    2016-03-01

    In observational studies, the first step is usually to explore data distribution and the baseline differences between groups. Data description includes their central tendency (e.g., mean, median, and mode) and dispersion (e.g., standard deviation, range, interquartile range). There are varieties of bivariate statistical inference methods such as Student's t-test, Mann-Whitney U test and Chi-square test, for normal, skews and categorical data, respectively. The article shows how to perform these analyses with R codes. Furthermore, I believe that the automation of the whole workflow is of paramount importance in that (I) it allows for others to repeat your results; (II) you can easily find out how you performed analysis during revision; (III) it spares data input by hand and is less error-prone; and (IV) when you correct your original dataset, the final result can be automatically corrected by executing the codes. Therefore, the process of making a publication quality table incorporating all abovementioned statistics and P values is provided, allowing readers to customize these codes to their own needs. PMID:27047950

  17. Baker- Lin-Huang type Bivariate distributions based on order statistics

    CERN Document Server

    Bairamov, I

    2011-01-01

    Baker (2008) introduced a new class of bivariate distributions based on distributions of order statistics from two independent samples of size n. Lin-Huang (2010) discovered an important property of Baker's distribution and showed that the Pearson's correlation coefficient for this distribution converges to maximum attainable value, i.e. the correlation coefficient of the Frech\\'et upper bound, as n increases to infinity. Bairamov and Bayramoglu (2011) investigated a new class of bivariate distributions constructed by using Baker's model and distributions of order statistics from dependent random variables, allowing high correlation than that of Baker's distribution. In this paper a new class of Baker's type bivariate distributions with high correlation are constructed on the base of distributions of order statistics by using an arbitrary continuous copula instead of the product copula. Keywords: Bivariate distribution function, FGM distributions, copula, positive quadrant dependent, negative quadrant depende...

  18. Local Lagrange Interpolations Using Bivariate Splines of Degree Seven on Triangulated Quadrangulations

    OpenAIRE

    Xuqiong Luo; Qikui Du

    2013-01-01

    A local Lagrange interpolation scheme using bivariate C2 splines of degree seven over a checkerboard triangulated quadrangulation is constructed. The method provides optimal order approximation of smooth functions.

  19. Baker- Lin-Huang type Bivariate distributions based on order statistics

    OpenAIRE

    Bairamov, I.; Bayramoglu, K.

    2011-01-01

    Baker (2008) introduced a new class of bivariate distributions based on distributions of order statistics from two independent samples of size n. Lin-Huang (2010) discovered an important property of Baker's distribution and showed that the Pearson's correlation coefficient for this distribution converges to maximum attainable value, i.e. the correlation coefficient of the Frech\\'et upper bound, as n increases to infinity. Bairamov and Bayramoglu (2011) investigated a new class of bivariate di...

  20. Issues concerning Landowner Management Plan Adoption Decisions: A Recursive Bivariate Probit Approach

    OpenAIRE

    Omkar Joshi; Grebner, Donald L.; Munn, Ian A.; Robert K. Grala

    2015-01-01

    Despite the likely benefits of having a written forest management plan, a small number of landowners in the United States have the one. A recursive bivariate probit model was used to identify the possible relationship between landowners’ decision to obtain a management plan and their interest in future timber harvesting. Our study results based on recursive bivariate model suggest that landowners having larger land ownerships, longer forest ownership tenure, and higher education were more lik...

  1. The Impact of Truancy on Educational Attainment : A Bivariate Ordered Probit Estimator with Mixed Effects

    OpenAIRE

    Buscha, Franz; Conte, Anna

    2010-01-01

    This paper investigates the relationship between educational attainment and truancy. Using data from the Youth Cohort Study of England and Wales, we estimate the causal impact that truancy has on educational attainment at age 16. Problematic is that both truancy and attainment are measured as ordered responses requiring a bivariate ordered probit model to account for the potential endogeneity of truancy. Furthermore, we extent the 'naïve' bivariate ordered probit estimator to include mixed ef...

  2. Bivariate raising and lowering differential operators for eigenfunctions of a 2D Fourier transform

    International Nuclear Information System (INIS)

    We define a two-dimensional (2D) Fourier transform that self-reproduces a one-parameter family of bivariate Hermite functions; these are eigenfunctions of a Hamiltonian differential operator of second order, whose exponential is that transform. We find explicit forms of the bivariate raising and lowering partial differential operators of first degree for the eigenfunctions of this 2D Fourier transform. (paper)

  3. Bivariate frequency analysis of flood characteristics at Glomma and Gudbrandsdalslågen

    OpenAIRE

    2004-01-01

    The spring flood is a multivariate event that can be characterized by the floodcharacteristics peak discharge, duration and volume. Traditionally these flood characteristics have been modelled separately, but by modelling the spring flood as a multivariate event, information about the joint probabilistic behaviour is obtained. In this thesis the bivariate logistic extreme value distribution with GEV margins are used to model asymptotically dependent flood characteristics, and the bivariate...

  4. On the approximation properties of bivariate $(p, q)-$Bernstein operators

    OpenAIRE

    Karaisa, Ali

    2016-01-01

    In the present study, we have given a corrigendum to our paper on the approximation properties of bivariate $(p, q)-$Bernstein operators. Recently, we \\cite{kar} have defined the bivariate $(p, q)-$Bernstein operators. Later, we have aware of Acar et. al \\cite{acar} already have given some moments. In this case, we have revised \\cite[Lemma 2.3]{kar}.

  5. Analysis of meteorological droughts for the Saskatchewan River Basin using univariate and bivariate approaches

    Science.gov (United States)

    Masud, M. B.; Khaliq, M. N.; Wheater, H. S.

    2015-03-01

    This study is focused on the Saskatchewan River Basin (SRB) that spans southern parts of Alberta, Saskatchewan and Manitoba, the three Prairie Provinces of Canada, where most of the country's agricultural activities are concentrated. The SRB is confronted with immense water-related challenges and is now one of the ten GEWEX (Global Energy and Water Exchanges) Regional Hydroclimate Projects in the world. In the past, various multi-year droughts have been observed in this part of Canada that impacted agriculture, energy and socio-economic sectors. Therefore, proper understanding of the spatial and temporal characteristics of historical droughts is important for many water resources planning and management related activities across the basin. In the study, observed gridded data of daily precipitation and temperature and conventional univariate and copula-based bivariate frequency analyses are used to characterize drought events in terms of drought severity and duration on the basis of two drought indices, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). Within the framework of univariate and bivariate analyses, drought risk indicators are developed and mapped across the SRB to delineate the most vulnerable parts of the basin. Based on the results obtained, southern parts of the SRB (i.e., western part of the South Saskatchewan River, Seven Persons Creek and Bigstick Lake watersheds) are associated with a higher drought risk, while moderate risk is noted for the North Saskatchewan River (except its eastern parts), Red Deer River, Oldman River, Bow River, Sounding Creek, Carrot River and Battle River watersheds. Lower drought risk is found for the areas surrounding the Saskatchewan-Manitoba border (particularly, the Saskatchewan River watershed). It is also found that the areas characterized with higher drought severity are also associated with higher drought duration. A comparison of SPI- and SPEI

  6. Bivariate wavelet-based clustering of sea-level and atmospheric pressure time series

    Science.gov (United States)

    Barbosa, Susana; Gouveia, Sonia; Scotto, Manuel; Alonso, Andres

    2015-04-01

    The atmospheric pressure is responsible for a downward force acting on the sea surface which is compensated, to some extent, by corresponding sea-level variations. The static response of the sea surface can be linearly modelled, a decrease (increase) in atmospheric pressure of 1 mb raising (depressing) sea level by 1 cm. However, the dynamic sea surface response to atmospheric pressure loading, associated with ocean dynamics and wind effects, is scale-dependent and difficult to establish. The present study addresses the co-variability of sea-level and pressure time series in the Baltic Sea from the bivariate analysis of tide gauge and reanalysis records. The time series are normalised by the corresponding standard deviation and the wavelet covariance is computed as a measure of the association between sea-level and pressure across scales. A clustering procedure using a dissimilarity matrix based on the wavelet covariance is then implemented. Different classical clustering techniques, including average, single and complete linkage criteria are applied and the group linkage is selected in order to maximise the dendrogram's goodness-of-fit.

  7. Dyadic Bivariate Fourier Multipliers for Multi-Wavelets in L2(R2)

    Institute of Scientific and Technical Information of China (English)

    Zhongyan Li∗; Xiaodi Xu

    2015-01-01

    The single 2 dilation orthogonal wavelet multipliers in one dimensional case and single A-dilation (where A is any expansive matrix with integer entries and|detA|=2) wavelet multipliers in high dimensional case were completely characterized by the Wutam Consortium (1998) and Z. Y. Li, et al. (2010). But there exist no more results on orthogonal multivariate wavelet matrix multipliers corresponding integer expansive dilation matrix with the absolute value of determinant not 2 in L2(R2). In this paper, we choose as the dilation matrix and consider the 2I2-dilation orthogonal multivariate wavelet Y={y1,y2,y3}, (which is called a dyadic bivariate wavelet) multipliers. We call the 3×3 matrix-valued function A(s)=[ fi,j(s)]3×3, where fi,j are measurable functions, a dyadic bivariate matrix Fourier wavelet multiplier if the inverse Fourier transform of A(s)(cy1(s),cy2(s),cy3(s))⊤ = ( b g1(s), b g2(s), b g3(s))⊤ is a dyadic bivariate wavelet whenever (y1,y2,y3) is any dyadic bivariate wavelet. We give some conditions for dyadic matrix bivariate wavelet multipliers. The results extended that of Z. Y. Li and X. L. Shi (2011). As an application, we construct some useful dyadic bivariate wavelets by using dyadic Fourier matrix wavelet multipliers and use them to image denoising.

  8. General Framework for Meta-Analysis of Haplotype Association Tests.

    Science.gov (United States)

    Wang, Shuai; Zhao, Jing Hua; An, Ping; Guo, Xiuqing; Jensen, Richard A; Marten, Jonathan; Huffman, Jennifer E; Meidtner, Karina; Boeing, Heiner; Campbell, Archie; Rice, Kenneth M; Scott, Robert A; Yao, Jie; Schulze, Matthias B; Wareham, Nicholas J; Borecki, Ingrid B; Province, Michael A; Rotter, Jerome I; Hayward, Caroline; Goodarzi, Mark O; Meigs, James B; Dupuis, Josée

    2016-04-01

    For complex traits, most associated single nucleotide variants (SNV) discovered to date have a small effect, and detection of association is only possible with large sample sizes. Because of patient confidentiality concerns, it is often not possible to pool genetic data from multiple cohorts, and meta-analysis has emerged as the method of choice to combine results from multiple studies. Many meta-analysis methods are available for single SNV analyses. As new approaches allow the capture of low frequency and rare genetic variation, it is of interest to jointly consider multiple variants to improve power. However, for the analysis of haplotypes formed by multiple SNVs, meta-analysis remains a challenge, because different haplotypes may be observed across studies. We propose a two-stage meta-analysis approach to combine haplotype analysis results. In the first stage, each cohort estimate haplotype effect sizes in a regression framework, accounting for relatedness among observations if appropriate. For the second stage, we use a multivariate generalized least square meta-analysis approach to combine haplotype effect estimates from multiple cohorts. Haplotype-specific association tests and a global test of independence between haplotypes and traits are obtained within our framework. We demonstrate through simulation studies that we control the type-I error rate, and our approach is more powerful than inverse variance weighted meta-analysis of single SNV analysis when haplotype effects are present. We replicate a published haplotype association between fasting glucose-associated locus (G6PC2) and fasting glucose in seven studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium and we provide more precise haplotype effect estimates. PMID:27027517

  9. Cryogenic testing and analysis associated with Tevatron lower temperature operation

    International Nuclear Information System (INIS)

    An upgrade of the Tevatron cryogenic system was installed and commissioned in 1993 to allow lower temperature operation. As a result, higher energy operation is possible. Following the installation and initial commissioning, it was decided to continue the current colliding beam physics at the previous energy of 900 GeV. This has allowed us to perform parasitic lower temperature tests in the Tevatron over the last year and a half. This paper presents the results of operational experiences and thermal and hydraulic testing which has taken place. The primary goal of the testing is to better understand the operation of the cold compressor system, associated instrumentation, and the performance of the existing magnet system during lower temperature operation. This will lead to a tentatively scheduled higher energy test run in the fall of 1995. The test results have shown that more elaborate controlling methods are necessary in order to achieve reliable system operation. Fortunately, our new satellite refrigerator controls system is capable of the expansion necessary to reach our goal. New features are being added to the control system which will allow for more intelligent control and better diagnostics for component monitoring and trending

  10. An evolutionary framework for association testing in resequencing studies.

    Directory of Open Access Journals (Sweden)

    C Ryan King

    2010-11-01

    Full Text Available Sequencing technologies are becoming cheap enough to apply to large numbers of study participants and promise to provide new insights into human phenotypes by bringing to light rare and previously unknown genetic variants. We develop a new framework for the analysis of sequence data that incorporates all of the major features of previously proposed approaches, including those focused on allele counts and allele burden, but is both more general and more powerful. We harness population genetic theory to provide prior information on effect sizes and to create a pooling strategy for information from rare variants. Our method, EMMPAT (Evolutionary Mixed Model for Pooled Association Testing, generates a single test per gene (substantially reducing multiple testing concerns, facilitates graphical summaries, and improves the interpretation of results by allowing calculation of attributable variance. Simulations show that, relative to previously used approaches, our method increases the power to detect genes that affect phenotype when natural selection has kept alleles with large effect sizes rare. We demonstrate our approach on a population-based re-sequencing study of association between serum triglycerides and variation in ANGPTL4.

  11. Bootstrapped Permutation Test for Multiresponse Inference on Brain Behavior Associations.

    Science.gov (United States)

    Ng, Bernard; Poline, Jean Baptiste; Thirion, Bertrand; Greicius, Michael

    2015-01-01

    Despite that diagnosis of neurological disorders commonly involves a collection of behavioral assessments, most neuroimaging studies investigating the associations between brain and behavior largely analyze each behavioral measure in isolation. To jointly model multiple behavioral scores, sparse multiresponse regression (SMR) is often used. However, directly applying SMR without statistically controlling for false positives could result in many spurious findings. For models, such as SMR, where the distribution of the model parameters is unknown, permutation test and stability selection are typically used to control for false positives. In this paper, we present another technique for inferring statistically significant features from models with unknown parameter distribution. We refer to this technique as bootstrapped permutation test (BPT), which uses Studentized statistics to exploit the intuition that the variability in parameter estimates associated with relevant features would likely be higher with responses permuted. On synthetic data, we show that BPT provides higher sensitivity in identifying relevant features from the SMR model than permutation test and stability selection, while retaining strong control on the false positive rate. We further apply BPT to study the associations between brain connectivity estimated from pseudo-rest fMRI data of 1139 fourteen year olds and behavioral measures related to ADHD. Significant connections are found between brain networks known to be implicated in the behavioral tasks involved. Moreover, we validate the identified connections by fitting a regression model on pseudo-rest data with only those connections and applying this model on resting state fMRI data of 337 left out subjects to predict their behavioral scores. The predicted scores significantly correlate with the actual scores, hence verifying the behavioral relevance of the found connections. PMID:26221670

  12. Completing the implicit association test reduces positive intergroup interaction behavior.

    Science.gov (United States)

    Vorauer, Jacquie D

    2012-10-01

    It is frequently suggested that increasing awareness of intergroup bias and limited control over biased responses can improve intergroup interaction behavior. Some uses of the Implicit Association Test (IAT) epitomize this approach to improving intergroup relations. However, if completing the IAT enhances caution and inhibition, reduces self-efficacy, or primes categorical thinking, the test may instead have negative effects. Two experiments demonstrated that when White individuals completed a race-relevant IAT prior to an intergroup interaction (as compared with when they did not), their interaction partner left the exchange feeling less positively regarded. No such effect was evident when White individuals completed a race-irrelevant IAT (Study 1) or an explicit prejudice measure (Study 2) before the exchange, or when their interaction partner was White (Study 1). Mediation analyses (Study 2) suggested that White participants who completed the IAT communicated less positive regard because they adopted a cautious approach to the interaction, limiting their self-disclosure. PMID:22894938

  13. Non-Linear Wavelet Regression and Branch & Bound Optimization for the Full Identification of Bivariate Operator Fractional Brownian Motion

    Science.gov (United States)

    Frecon, Jordan; Didier, Gustavo; Pustelnik, Nelly; Abry, Patrice

    2016-08-01

    Self-similarity is widely considered the reference framework for modeling the scaling properties of real-world data. However, most theoretical studies and their practical use have remained univariate. Operator Fractional Brownian Motion (OfBm) was recently proposed as a multivariate model for self-similarity. Yet it has remained seldom used in applications because of serious issues that appear in the joint estimation of its numerous parameters. While the univariate fractional Brownian motion requires the estimation of two parameters only, its mere bivariate extension already involves 7 parameters which are very different in nature. The present contribution proposes a method for the full identification of bivariate OfBm (i.e., the joint estimation of all parameters) through an original formulation as a non-linear wavelet regression coupled with a custom-made Branch & Bound numerical scheme. The estimation performance (consistency and asymptotic normality) is mathematically established and numerically assessed by means of Monte Carlo experiments. The impact of the parameters defining OfBm on the estimation performance as well as the associated computational costs are also thoroughly investigated.

  14. Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission

    CERN Document Server

    Takeuchi, Tsutomu T; Yuan, Fang-Ting; Buat, Veronique; Burgarella, Denis

    2012-01-01

    Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of galaxies show a strong evolution from $z = 0$ to $z = 1$, but the FIR LF evolves much stronger than the FUV one. The FUV is dominantly radiated from newly formed short-lived OB stars, while the FIR is emitted by dust grains heated by the FUV radiation field. It is known that dust is always associated with star formation activity. Thus, both FUV and FIR are tightly related to the star formation in galaxies, but in a very complicated manner. In order to disentangle the relation between FUV and FIR emissions, we estimate the UV-IR bivariate LF (BLF) of galaxies with {\\sl GALEX} and {\\sl AKARI} All-Sky Survey datasets. Recently we invented a new mathematical method to construct the BLF with given marginals and prescribed correlation coefficient. This method makes use of a tool from mathematical statistics, so called "copula". The copula enables us to construct a bivariate distribution function from given marginal distributions with prescri...

  15. A semiparametric bivariate probit model for joint modeling of outcomes in STEMI patients.

    Science.gov (United States)

    Ieva, Francesca; Marra, Giampiero; Paganoni, Anna Maria; Radice, Rosalba

    2014-01-01

    In this work we analyse the relationship among in-hospital mortality and a treatment effectiveness outcome in patients affected by ST-Elevation myocardial infarction. The main idea is to carry out a joint modeling of the two outcomes applying a Semiparametric Bivariate Probit Model to data arising from a clinical registry called STEMI Archive. A realistic quantification of the relationship between outcomes can be problematic for several reasons. First, latent factors associated with hospitals organization can affect the treatment efficacy and/or interact with patient's condition at admission time. Moreover, they can also directly influence the mortality outcome. Such factors can be hardly measurable. Thus, the use of classical estimation methods will clearly result in inconsistent or biased parameter estimates. Secondly, covariate-outcomes relationships can exhibit nonlinear patterns. Provided that proper statistical methods for model fitting in such framework are available, it is possible to employ a simultaneous estimation approach to account for unobservable confounders. Such a framework can also provide flexible covariate structures and model the whole conditional distribution of the response. PMID:24799953

  16. A Basic Bivariate Structure of Personality Attributes Evident Across Nine Languages.

    Science.gov (United States)

    Saucier, Gerard; Thalmayer, Amber Gayle; Payne, Doris L; Carlson, Robert; Sanogo, Lamine; Ole-Kotikash, Leonard; Church, A Timothy; Katigbak, Marcia S; Somer, Oya; Szarota, Piotr; Szirmák, Zsofia; Zhou, Xinyue

    2013-01-01

    Here, two studies seek to characterize a parsimonious common-denominator personality structure with optimal cross-cultural replicability. Personality differences are observed in all human populations and cultures, but lexicons for personality attributes contain so many distinctions that parsimony is lacking. Models stipulating the most important attributes have been formulated by experts or by empirical studies drawing on experience in a very limited range of cultures. Factor analyses of personality lexicons of nine languages of diverse provenance (Chinese, Korean, Filipino, Turkish, Greek, Polish, Hungarian, Maasai, and Senoufo) were examined, and their common structure was compared to that of several prominent models in psychology. A parsimonious bivariate model showed evidence of substantial convergence and ubiquity across cultures. Analyses involving key markers of these dimensions in English indicate that they are broad dimensions involving the overlapping content of the interpersonal circumplex, models of communion and agency, and morality/warmth and competence. These "Big Two" dimensions-Social Self-Regulation and Dynamism-provide a common-denominator model involving the two most crucial axes of personality variation, ubiquitous across cultures. The Big Two might serve as an umbrella model serving to link diverse theoretical models and associated research literatures. PMID:23301793

  17. Semiparametric bivariate zero-inflated Poisson models with application to studies of abundance for multiple species

    Science.gov (United States)

    Arab, Ali; Holan, Scott H.; Wikle, Christopher K.; Wildhaber, Mark L.

    2012-01-01

    Ecological studies involving counts of abundance, presence–absence or occupancy rates often produce data having a substantial proportion of zeros. Furthermore, these types of processes are typically multivariate and only adequately described by complex nonlinear relationships involving externally measured covariates. Ignoring these aspects of the data and implementing standard approaches can lead to models that fail to provide adequate scientific understanding of the underlying ecological processes, possibly resulting in a loss of inferential power. One method of dealing with data having excess zeros is to consider the class of univariate zero-inflated generalized linear models. However, this class of models fails to address the multivariate and nonlinear aspects associated with the data usually encountered in practice. Therefore, we propose a semiparametric bivariate zero-inflated Poisson model that takes into account both of these data attributes. The general modeling framework is hierarchical Bayes and is suitable for a broad range of applications. We demonstrate the effectiveness of our model through a motivating example on modeling catch per unit area for multiple species using data from the Missouri River Benthic Fishes Study, implemented by the United States Geological Survey.

  18. Disentangling recoding processes and evaluative associations in a gender attitude implicit association test among adult males.

    Science.gov (United States)

    Jin, Zheng

    2016-11-01

    The course of male development of implicit gender attitudes between young age (N = 30, age 17-26 years) and old age (N = 34, age 56-78 years) was investigated. The findings demonstrated that younger males had a stronger implicit preference for females relative to males than did older participants, shedding light on the nature of age differences in gender attitudes in regard to implicit measures. Although younger and older participants demonstrated different levels of gender bias on an implicit association test (IAT), the application of the ReAL model [Meissner, F., & Rothermund, K. (2013). Estimating the contributions of associations and recoding in the implicit association test: The ReAL model for the IAT. Journal of Personality and Social Psychology, 104(1), 45-69.] showed that evaluative associations of both female and male were activated at equivalent levels among both the young and old age groups, but younger males were more able to recode the female gender and a positive evaluation into common categories. Thus, the differences in attitudinal responses between younger and older males exaggerated the differences in the underlying evaluative associations with respect to gender and concealed the differences in recoding processes. These findings have important implications for the measurement and interpretation of implicit gender attitudes. PMID:26933754

  19. Diagnostic performance of des-γ-carboxy prothrombin (DCP) for hepatocellular carcinoma: a bivariate meta-analysis.

    Science.gov (United States)

    Gao, P; Li, M; Tian, Q B; Liu, Dian-Wu

    2012-01-01

    Serum markers are needed to be developed to specifically diagnose Hepatocellular carcinoma (HCC). Des-γ-carboxy prothrombin (DCP) is a promising tool with limited expense and widely accessibility, but the reported results have been controversial. In order to review the performance of DCP for the diagnosis of HCC, the meta-analysis was performed. After a systematic review of relevant studies, the sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR, respectively) were pooled using a bivariate meta-analysis. Potential between-study heterogeneity was explored by meta-regression model. The post-test probability and the likelihood ratio scattergram to evaluate clinical usefulness were calculated. Based on literature review of 20 publications, the overall sensitivity, specificity, PLR and NLR of DCP for the detection of HCC were 67% (95%CI, 58%-74%), 92% (95%CI, 88%-94%), 7.9 (95%CI, 5.6-11.2) and 0.36 (95%CI, 0.29-0.46), respectively. The area under the bivariate summary receiving operating characteristics curve was 0.89 (95%CI, 0.85-0.92). Significant heterogeneity was present. In conclusion, the major role of DCP is the moderate confirmation of HCC. More prospective studies of DCP are needed in future. PMID:22248272

  20. On a bivariate spectral relaxation method for unsteady magneto-hydrodynamic flow in porous media.

    Science.gov (United States)

    Magagula, Vusi M; Motsa, Sandile S; Sibanda, Precious; Dlamini, Phumlani G

    2016-01-01

    The paper presents a significant improvement to the implementation of the spectral relaxation method (SRM) for solving nonlinear partial differential equations that arise in the modelling of fluid flow problems. Previously the SRM utilized the spectral method to discretize derivatives in space and finite differences to discretize in time. In this work we seek to improve the performance of the SRM by applying the spectral method to discretize derivatives in both space and time variables. The new approach combines the relaxation scheme of the SRM, bivariate Lagrange interpolation as well as the Chebyshev spectral collocation method. The technique is tested on a system of four nonlinear partial differential equations that model unsteady three-dimensional magneto-hydrodynamic flow and mass transfer in a porous medium. Computed solutions are compared with previously published results obtained using the SRM, the spectral quasilinearization method and the Keller-box method. There is clear evidence that the new approach produces results that as good as, if not better than published results determined using the other methods. The main advantage of the new approach is that it offers better accuracy on coarser grids which significantly improves the computational speed of the method. The technique also leads to faster convergence to the required solution. PMID:27119059

  1. IDF relationships using bivariate copula for storm events in Peninsular Malaysia

    Science.gov (United States)

    Ariff, N. M.; Jemain, A. A.; Ibrahim, K.; Wan Zin, W. Z.

    2012-11-01

    SummaryIntensity-duration-frequency (IDF) curves are used in many hydrologic designs for the purpose of water managements and flood preventions. The IDF curves available in Malaysia are those obtained from univariate analysis approach which only considers the intensity of rainfalls at fixed time intervals. As several rainfall variables are correlated with each other such as intensity and duration, this paper aims to derive IDF points for storm events in Peninsular Malaysia by means of bivariate frequency analysis. This is achieved through utilizing the relationship between storm intensities and durations using the copula method. Four types of copulas; namely the Ali-Mikhail-Haq (AMH), Frank, Gaussian and Farlie-Gumbel-Morgenstern (FGM) copulas are considered because the correlation between storm intensity, I, and duration, D, are negative and these copulas are appropriate when the relationship between the variables are negative. The correlations are attained by means of Kendall's τ estimation. The analysis was performed on twenty rainfall stations with hourly data across Peninsular Malaysia. Using Akaike's Information Criteria (AIC) for testing goodness-of-fit, both Frank and Gaussian copulas are found to be suitable to represent the relationship between I and D. The IDF points found by the copula method are compared to the IDF curves yielded based on the typical IDF empirical formula of the univariate approach. This study indicates that storm intensities obtained from both methods are in agreement with each other for any given storm duration and for various return periods.

  2. Implicit associations in cybersex addiction: Adaption of an Implicit Association Test with pornographic pictures.

    Science.gov (United States)

    Snagowski, Jan; Wegmann, Elisa; Pekal, Jaro; Laier, Christian; Brand, Matthias

    2015-10-01

    Recent studies show similarities between cybersex addiction and substance dependencies and argue to classify cybersex addiction as a behavioral addiction. In substance dependency, implicit associations are known to play a crucial role, and such implicit associations have not been studied in cybersex addiction, so far. In this experimental study, 128 heterosexual male participants completed an Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) modified with pornographic pictures. Further, problematic sexual behavior, sensitivity towards sexual excitation, tendencies towards cybersex addiction, and subjective craving due to watching pornographic pictures were assessed. Results show positive relationships between implicit associations of pornographic pictures with positive emotions and tendencies towards cybersex addiction, problematic sexual behavior, sensitivity towards sexual excitation as well as subjective craving. Moreover, a moderated regression analysis revealed that individuals who reported high subjective craving and showed positive implicit associations of pornographic pictures with positive emotions, particularly tended towards cybersex addiction. The findings suggest a potential role of positive implicit associations with pornographic pictures in the development and maintenance of cybersex addiction. Moreover, the results of the current study are comparable to findings from substance dependency research and emphasize analogies between cybersex addiction and substance dependencies or other behavioral addictions. PMID:26026385

  3. Construct validity of the Big Five Implicit Association Test

    Directory of Open Access Journals (Sweden)

    Gaja Zager Kocjan

    2014-02-01

    Full Text Available Psychology has recently seen a noticeable increase in interest for implicit measures of attitudes and personality characteristics. The far most known implicit measure is the Implicit Association Test – IAT. We adapted this test in order to assess the Big Five personality dimensions (B5 IAT. We examined B5 IAT measurement characteristics on two samples. Based on the findings of the first sample (N = 62, improvements were made in the B5 IAT, to be tested again on another sample (N = 75. The two studies have shown similar results. The reliabilities of the personality dimensions measured with the B5 IAT failed to achieve a satisfactory level in most cases. The reason probably lies in a lower adequacy of certain stimuli and in the considerable length of the test procedure. The convergent validity of the B5 IAT with explicit measures of personality was low, which may be due to different structures underlying implicit and explicit measures. Results obtained on the first sample have shown that the correlations between IAT adjectives are adequately explained by five latent dimensions. However, these results should be interpreted with caution due to B5 IAT low reliabilities and small sample sizes. The second sample proved to be very unstable, thus the confirmatory factor analysis could not be conducted. Since this is the first attempt to adapt B5 IAT to Slovene language, it is hardly surprising that the results are not entirely consistent with the expectations. As implicit measures currently fail to meet relevant psychometric characteristics, they are not yet applicable in psychological practice. Nevertheless, they have great potential in exploring personality and individual differences, as they overcome many limitations of existing explicit measures.

  4. Reducing uncertainty in the selection of bi-variate distributions of flood peaks and volumes using copulas and hydrological process-based model selection

    Science.gov (United States)

    Szolgay, Jan; Gaál, Ladislav; Bacigál, Tomáš; Kohnová, Silvia; Blöschl, Günter

    2016-04-01

    Bi-variate distributions of flood peaks and flood event volumes are needed for a range of practical purposes including e.g. retention basin design and identifying extent and duration of flooding in flood hazard zones. However, the selection of the types of bi-variate distributions and estimating their parameters from observed peak-volume pairs are associated with far larger uncertainties compared to uni-variate distributions, since observed flood records of required length are rarely available. This poses a serious problem to reliable flood risk estimation in bi-variate design cases. The aim of this contribution was to shed light on the possibility of reducing uncertainties in the estimation of the dependence models/parameters from a regional perspective. The peak-volume relationships were modeled in terms of copulas. Flood events were classified according to their origin. In order to reduce the uncertainty in estimating flood risk, pooling and analyzing catchments of similar behavior according to flood process types was attempted. Most of the work reported in the literature so far did not direct the multivariate analysis toward discriminating certain types of models regionally according to specific runoff generation processes. Specifically, the contribution addresses these problems: - Are the peak-volume relationships of different flood types for a given catchment similar? - Are the peak-volume dependence structures between catchments in a larger region for given flood types similar? - Are some copula types more suitable for given flood process types and does this have consequences for reliable risk estimation? The target region is located in the northern parts of Austria, and consists of 72 small and mid-sized catchments. Instead of the traditional approach that deals with annual maximum floods, the current analysis includes all independent flood events in the region. 24 872 flood events from the period 1976-2007 were identified, and classified as synoptic, flash

  5. Applying the Implicit Association Test to Measure Intolerance of Uncertainty.

    Science.gov (United States)

    Mosca, Oriana; Dentale, Francesco; Lauriola, Marco; Leone, Luigi

    2016-08-01

    Intolerance of Uncertainty (IU) is a key trans-diagnostic personality construct strongly associated with anxiety symptoms. Traditionally, IU is measured through self-report measures that are prone to bias effects due to impression management concerns and introspective difficulties. Moreover, self-report scales are not able to intercept the automatic associations that are assumed to be main determinants of several spontaneous responses (e.g., emotional reactions). In order to overcome these limitations, the Implicit Association Test (IAT) was applied to measure IU, with a particular focus on reliability and criterion validity issues. The IU-IAT and the Intolerance of Uncertainty Inventory (IUI) were administered to an undergraduate student sample (54 females and 10 males) with a mean age of 23 years (SD = 1.7). Successively, participants were asked to provide an individually chosen uncertain event from their own lives that may occur in the future and were requested to identify a number of potential negative consequences of it. Participants' responses in terms of cognitive thoughts (i.e., cognitive appraisal) and worry reactions toward these events were assessed using the two subscales of the Worry and Intolerance of Uncertainty Beliefs Questionnaire. The IU-IAT showed an adequate level of internal consistency and a not significant correlation with the IUI. A path analysis model, accounting for 35% of event-related worry, revealed that IUI had a significant indirect effect on the dependent variable through event-related IU thoughts. By contrast, as expected, IU-IAT predicted event-related worry independently from IU thoughts. In accordance with dual models of social cognition, these findings suggest that IU can influence event-related worry through two different processing pathways (automatic vs. deliberative), supporting the criterion and construct validity of the IU-IAT. The potential role of the IU-IAT for clinical applications was discussed. PMID:27451266

  6. Minimizing the influence of recoding in the Implicit Association Test: the Recoding-Free Implicit Association Test (IAT-RF).

    Science.gov (United States)

    Rothermund, Klaus; Teige-Mocigemba, Sarah; Gast, Anne; Wentura, Dirk

    2009-01-01

    Recoding processes can influence the Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) in a way that impedes an unequivocal interpretation of the resulting compatibility effects. We present a modified version of the IAT that aims to eliminate recoding, the IAT-RF (short for "IAT-recoding free"). In the IAT-RF, compatible and incompatible assignments of categories to responses switch randomly between trials within a single experimental block. Abandoning an extended sequence of consistent category-response mappings undermines recoding processes in the IAT-RF. Two experiments reveal that the IAT-RF is capable of assessing compatibility effects between the nominally defined categories of the task and effectively prevents recoding. By enforcing a processing of the stimuli in terms of their task-relevant category membership, the IAT-RF eliminates the confounding of compatibility effects with task switch costs and becomes immune against biased selections of stimuli. PMID:18609400

  7. Mutual nonlinear prediction as a tool to evaluate coupling strength and directionality in bivariate time series: Comparison among different strategies based on k nearest neighbors

    Science.gov (United States)

    Faes, Luca; Porta, Alberto; Nollo, Giandomenico

    2008-08-01

    We compare the different existing strategies of mutual nonlinear prediction regarding their ability to assess the coupling strength and directionality of the interactions in bivariate time series. Under the common framework of k -nearest neighbor local linear prediction, we test three approaches based on cross prediction, mixed prediction, and predictability improvement. The measures of interdependence provided by these approaches are first evaluated on short realizations of bivariate time series generated by coupled Henon models, investigating also the effects of noise. The usefulness of the three mutual nonlinear prediction schemes is then assessed in a common physiological application during known conditions of interaction—i.e., the analysis of the interdependence between heart rate and arterial pressure variability in healthy humans during supine resting and passive head-up tilting. Based on both simulation results and physiological interpretability of cardiovascular results, we conclude that cross prediction is valuable to quantify the coupling strength and predictability improvement to elicit directionality of the interactions in short and noisy bivariate time series.

  8. A note on finding peakedness in bivariate normal distribution using Mathematica

    Directory of Open Access Journals (Sweden)

    Anwer Khurshid

    2007-07-01

    Full Text Available Peakedness measures the concentration around the central value. A classical standard measure of peakedness is kurtosis which is the degree of peakedness of a probability distribution. In view of inconsistency of kurtosis in measuring of the peakedness of a distribution, Horn (1983 proposed a measure of peakedness for symmetrically unimodal distributions. The objective of this paper is two-fold. First, Horn’s method has been extended for bivariate normal distribution. Secondly, to show that computer algebra system Mathematica can be extremely useful tool for all sorts of computation related to bivariate normal distribution. Mathematica programs are also provided.

  9. Interbasis expansions for the isotropic 3D harmonic oscillator and bivariate Krawtchouk polynomials

    International Nuclear Information System (INIS)

    An explicit expression for the general bivariate Krawtchouk polynomials is obtained in terms of the standard Krawtchouk and dual Hahn polynomials. The bivariate Krawtchouk polynomials occur as matrix elements of the unitary reducible representations of SO(3) on the energy eigenspaces of the three-dimensional isotropic harmonic oscillator and the explicit formula is obtained from the decomposition of these representations into their irreducible components. The decomposition entails expanding the Cartesian basis states in the spherical bases that span irreducible SO(3) representations. The overlap coefficients are obtained from the Clebsch–Gordan problem for the su(1,1) Lie algebra. (paper)

  10. The Pattern of Variation between Diarrhea and Malaria Coexistence with Corresponding Risk Factors in, Chikhwawa, Malawi: A Bivariate Multilevel Analysis

    Directory of Open Access Journals (Sweden)

    Salule Masangwi

    2015-07-01

    Full Text Available Developing countries face a huge burden of infectious diseases, a number of which co-exist. This paper estimates the pattern and variation of malaria and diarrhea coexistence in Chikhwawa, a district in Southern Malawi using bivariate multilevel modelling with Bayesian estimation. A probit link was employed to examine hierarchically built data from a survey of individuals (n = 6,727 nested within households (n = 1,380 nested within communities (n = 33. Results show significant malaria [ ] and diarrhea [ ] variations with a strong correlation between them [ ] at household level. There are significant malaria [ ] and diarrhea [   ] variations at community level but with a small correlation [ ] between them. There is also significant correlation between malaria and diarrhea at individual level [ 0.241]. These results suggest a close association between reported malaria-like illness and diarrheal illness especially at household and individual levels in Southern Malawi.

  11. Improving the modelling of redshift-space distortions: I. A bivariate Gaussian description for the galaxy pairwise velocity distributions

    CERN Document Server

    Bianchi, Davide; Guzzo, Luigi

    2014-01-01

    As a step towards a more accurate modelling of redshift-space distortions in galaxy surveys, we develop a general description of the probability distribution function of galaxy pairwise velocities within the framework of the so-called streaming model. For a given galaxy separation $\\vec{r}$, such function can be described as a superposition of virtually infinite local distributions. We characterize these in terms of their moments and then consider the specific case in which they are Gaussian functions, each with its own mean $\\mu$ and dispersion $\\sigma$. Based on physical considerations, we make the further crucial assumption that these two parameters are in turn distributed according to a bivariate Gaussian, with its own mean and covariance matrix. Tests using numerical simulations explicitly show that with this compact description one can correctly model redshift-space distorsions on all scales, fully capturing the overall linear and nonlinear dynamics of the galaxy flow at different separations. In partic...

  12. CONSTRUCTION OF COMPACTLY SUPPORTED BIVARIATE ORTHOGONAL WAVELETS BY UNIVARIATE ORTHOGONAL WAVELETS

    Institute of Scientific and Technical Information of China (English)

    Yang Jianwei; Li Luoqing; Tang Yuanyan

    2005-01-01

    After some permutation of conjugate quadrature filter, new conjugate quadrature filters can be derived. In terms of this permutation, an approach is developed for constructing compactly supported bivariate orthogonal wavelets from univariate orthogonal wavelets. Non-separable orthogonal wavelets can be achieved. To demonstrate this method, an example is given.

  13. A Change of Heart? A Bivariate Probit Model of International Students' Change of Return Intention

    OpenAIRE

    Jan-Jan Soon

    2010-01-01

    Using a bivariate probit model on a sample of 623 international students studying at tertiary-level courses in New Zealand universities, this paper identifies the factors that affect the change in the students' intention of whether or not to return to their home countries after completing their studies.

  14. A simple approximation to the bivariate normal distribution with large correlation coefficient

    OpenAIRE

    Albers, Willem; Kallenberg, Wilbert C.M.

    1994-01-01

    The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the error terms.

  15. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    OpenAIRE

    Takeuchi, Tsutomu T.

    2010-01-01

    We show an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient $|\\rho|

  16. Carbon and oxygen isotopic ratio bi-variate distribution for marble artifacts quarry assignment

    International Nuclear Information System (INIS)

    Statistical description, by a Gaussian bi-variate probability distribution of 13 C/12 C and 18 O/16 O isotopic ratios in the ancient marble quarries has been done and the new method for obtaining the confidence level quarry assignment for marble artifacts has been presented. (author) 8 figs., 3 tabs., 4 refs

  17. BIVARIATE MODELLING OF CLUSTERED CONTINUOUS AND ORDERED CATEGORICAL OUTCOMES. (R824757)

    Science.gov (United States)

    Simultaneous observation of continuous and ordered categorical outcomes for each subject is common in biomedical research but multivariate analysis of the data is complicated by the multiple data types. Here we construct a model for the joint distribution of bivariate continuous ...

  18. Contributions to the Underlying Bivariate Normal Method for Factor Analyzing Ordinal Data

    Science.gov (United States)

    Xi, Nuo; Browne, Michael W.

    2014-01-01

    A promising "underlying bivariate normal" approach was proposed by Jöreskog and Moustaki for use in the factor analysis of ordinal data. This was a limited information approach that involved the maximization of a composite likelihood function. Its advantage over full-information maximum likelihood was that very much less computation was…

  19. Bivariate normal, conditional and rectangular probabilities: A computer program with applications

    Science.gov (United States)

    Swaroop, R.; Brownlow, J. D.; Ashwworth, G. R.; Winter, W. R.

    1980-01-01

    Some results for the bivariate normal distribution analysis are presented. Computer programs for conditional normal probabilities, marginal probabilities, as well as joint probabilities for rectangular regions are given: routines for computing fractile points and distribution functions are also presented. Some examples from a closed circuit television experiment are included.

  20. A comparison of bivariate and univariate QTL mapping in livestock populations

    Directory of Open Access Journals (Sweden)

    Sorensen Daniel

    2003-11-01

    Full Text Available Abstract This study presents a multivariate, variance component-based QTL mapping model implemented via restricted maximum likelihood (REML. The method was applied to investigate bivariate and univariate QTL mapping analyses, using simulated data. Specifically, we report results on the statistical power to detect a QTL and on the precision of parameter estimates using univariate and bivariate approaches. The model and methodology were also applied to study the effectiveness of partitioning the overall genetic correlation between two traits into a component due to many genes of small effect, and one due to the QTL. It is shown that when the QTL has a pleiotropic effect on two traits, a bivariate analysis leads to a higher statistical power of detecting the QTL and to a more precise estimate of the QTL's map position, in particular in the case when the QTL has a small effect on the trait. The increase in power is most marked in cases where the contributions of the QTL and of the polygenic components to the genetic correlation have opposite signs. The bivariate REML analysis can successfully partition the two components contributing to the genetic correlation between traits.

  1. THE GALEX ARECIBO SDSS SURVEY. VII. THE BIVARIATE NEUTRAL HYDROGEN-STELLAR MASS FUNCTION FOR MASSIVE GALAXIES

    International Nuclear Information System (INIS)

    We present the bivariate neutral atomic hydrogen (H I)-stellar mass function (HISMF) φ(MHI, M*) for massive (log M*/M☉ \\gt 10) galaxies derived from a sample of 480 local (0.025 HI,M*>1010 and find that massive galaxies contribute 41% of the H I density in the local universe. In addition to the binned HISMF, we derive a continuous bivariate fit, which reveals that the Schechter parameters only vary weakly with stellar mass: MHI*, the characteristic H I mass, scales as M*0.39; α, the slope of the HISMF at moderate H I masses, scales as M*0.07; and f, the fraction of galaxies with H I gas fraction greater than 1%, scales as M*-0.24. The variation of f with stellar mass should be a strong constraint for numerical simulations. To understand the physical mechanisms that produce the shape of the HISMF, we redefine the parameters of the Schechter function as explicit functions of stellar mass and star formation rate (SFR) to produce a trivariate fit. This analysis reveals strong trends with SFR. While MHI* varies weakly with stellar mass and SFR (MHI* ∝ M*0.22, MHI* ∝ SFR–0.03), α is a stronger function of both stellar mass and especially SFR (α ∝ M*0.47, α ∝ SFR0.95). The HISMF is a crucial tool that can be used to constrain cosmological galaxy simulations, test observational predictions of the H I content of populations of galaxies, and identify galaxies whose properties deviate from average trends

  2. A Gene Score Test for Disease Association with Multiple Genes

    OpenAIRE

    Changchun Xie

    2011-01-01

    The traditional method for creating a gene score to predict a given outcome is to use the most statistically significant single nucleotide polymorphisms (SNPs) from all SNPs which were tested. There are several disadvantages of this approach such as excluding SNPs that do not have strong single effects when tested on their own but do have strong joint effects when tested together with other SNPs. The interpretation of results from the traditional gene score may lack biological insight since t...

  3. Testing of a paper-and-pencil Personalized Single Category Implicit Association Test (SC-IAT-P)

    OpenAIRE

    Bardin, Brigitte; Perrissol, Stéphane; Py, Jacques; Fos, Yoann; Souchon, Nicolas

    2016-01-01

    The purpose of this series of studies is to test a paper-and-pencil procedure adapted from a computerized Implicit Association Test: the SC-IAT-P (Personalized Single Category Implicit Association Test, Bardin, et al. 2014). This adaptation combines the advantages of SC-IAT (Karpinski & Steinman, 2006), IAT-P (Olson & Fazio, 2004) and paper-and-pencil IAT (Lemm, Lane, Sattler, Khan & Nosek, 2008). It is capable of measuring implicit attitude toward a single object, limits the infl...

  4. Semiparametric inference for surrogate endpoints with bivariate censored data.

    Science.gov (United States)

    Ghosh, Debashis

    2008-03-01

    Considerable attention has been recently paid to the use of surrogate endpoints in clinical research. We deal with the situation where the two endpoints are both right censored. While proportional hazards analyses are typically used for this setting, their use leads to several complications. In this article, we propose the use of the accelerated failure time model for analysis of surrogate endpoints. Based on the model, we then describe estimation and inference procedures for several measures of surrogacy. A complication is that potentially both the independent and dependent variable are subject to censoring. We adapt the Theil-Sen estimator to this problem, develop the associated asymptotic results, and propose a novel resampling-based technique for calculating the variances of the proposed estimators. The finite-sample properties of the estimation methodology are assessed using simulation studies, and the proposed procedures are applied to data from an acute myelogenous leukemia clinical trial. PMID:17651457

  5. Estimating twin concordance for bivariate competing risks twin data

    DEFF Research Database (Denmark)

    Scheike, Thomas; Holst, Klaus K.; Hjelmborg, Jacob B.

    2014-01-01

    For twin time-to-event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experienced...... the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair...... dependence over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer...

  6. [Test anxiety: associations with personal and family variables].

    Science.gov (United States)

    Rosário, Pedro; Núñez, José Carlos; Salgado, Ana; González-Pienda, Julio A; Valle, Antonio; Joly, Cristina; Bernardo, Ana

    2008-11-01

    Test anxiety is a common behavior among students facing social pressure centered on mastery. Only a few studies have analyzed the relations between test anxiety, academic procrastination, personal and family variables and math grades. This work focus on the analysis of the impact of students' social-personal variables such as parents' education level, number of siblings and under-achievement by performing ANOVAs in two samples of 533 and 796 students from junior high-school. Corroborating the findings in other studies, the data stress that test anxiety is higher in girls and decreases when students' parents have higher educational levels, with the number of courses flunked, and when students' math grades were lower. Test anxiety and procrastination correlate positive and significantly. Findings are discussed and compared with those of previous researches. The implications for teaching practice are also analyzed. PMID:18940051

  7. MAVL wastes containers functional demonstration and associated tests program

    International Nuclear Information System (INIS)

    In the framework of studies on the MAVL wastes, the CEA develops containers for middle time wastes storage. This program aims to realize a ''B wastes containers'' demonstrator. A demonstrator is a container, parts of a container or samples which must validate the tests. This document presents the state of the study in the following three chapters: functions description, base data and design choices; presentation of the functional demonstrators; demonstration tests description. (A.L.B.)

  8. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    CERN Document Server

    Takeuchi, Tsutomu T

    2010-01-01

    We show an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient $|\\rho| <1/3 $), the Farlie-Gumbel-Morgenstern (FGM) copula provides an intuitive and natural way for constructing such a bivariate DF. When the linear correlation is stronger, the FGM copula cannot work anymore. In this case, we propose to use a Gaussian copula, which connects two given marginals and directly related to the linear correlation coefficient between two variables. Using the copulas, we constructed the BLFs and discuss its statistical properties. Especially, we focused on the FUV--FIR BLF, since these two luminosities are related to the star formation (SF) activity. Though both the FUV and FIR are related to the SF activity, the univariate LFs have a very ...

  9. A spatial bivariate probit model for correlated binary data with application to adverse birth outcomes.

    Science.gov (United States)

    Neelon, Brian; Anthopolos, Rebecca; Miranda, Marie Lynn

    2014-04-01

    Motivated by a study examining geographic variation in birth outcomes, we develop a spatial bivariate probit model for the joint analysis of preterm birth and low birth weight. The model uses a hierarchical structure to incorporate individual and areal-level information, as well as spatially dependent random effects for each spatial unit. Because rates of preterm birth and low birth weight are likely to be correlated within geographic regions, we model the spatial random effects via a bivariate conditionally autoregressive prior, which induces regional dependence between the outcomes and provides spatial smoothing and sharing of information across neighboring areas. Under this general framework, one can obtain region-specific joint, conditional, and marginal inferences of interest. We adopt a Bayesian modeling approach and develop a practical Markov chain Monte Carlo computational algorithm that relies primarily on easily sampled Gibbs steps. We illustrate the model using data from the 2007-2008 North Carolina Detailed Birth Record. PMID:22599322

  10. Modeling two-vehicle crash severity by a bivariate generalized ordered probit approach.

    Science.gov (United States)

    Chiou, Yu-Chiun; Hwang, Cherng-Chwan; Chang, Chih-Chin; Fu, Chiang

    2013-03-01

    This study simultaneously models crash severity of both parties in two-vehicle accidents at signalized intersections in Taipei City, Taiwan, using a novel bivariate generalized ordered probit (BGOP) model. Estimation results show that the BGOP model performs better than the conventional bivariate ordered probit (BOP) model in terms of goodness-of-fit indices and prediction accuracy and provides a better approach to identify the factors contributing to different severity levels. According to estimated parameters in latent propensity functions and elasticity effects, several key risk factors are identified-driver type (age>65), vehicle type (motorcycle), violation type (alcohol use), intersection type (three-leg and multiple-leg), collision type (rear ended), and lighting conditions (night and night without illumination). Corresponding countermeasures for these risk factors are proposed. PMID:23246710

  11. Reprint of "Modeling two-vehicle crash severity by a bivariate generalized ordered probit approach".

    Science.gov (United States)

    Chiou, Yu-Chiun; Hwang, Cherng-Chwan; Chang, Chih-Chin; Fu, Chiang

    2013-12-01

    This study simultaneously models crash severity of both parties in two-vehicle accidents at signalized intersections in Taipei City, Taiwan, using a novel bivariate generalized ordered probit (BGOP) model. Estimation results show that the BGOP model performs better than the conventional bivariate ordered probit (BOP) model in terms of goodness-of-fit indices and prediction accuracy and provides a better approach to identify the factors contributing to different severity levels. According to estimated parameters in latent propensity functions and elasticity effects, several key risk factors are identified-driver type (age>65), vehicle type (motorcycle), violation type (alcohol use), intersection type (three-leg and multiple-leg), collision type (rear ended), and lighting conditions (night and night without illumination). Corresponding countermeasures for these risk factors are proposed. PMID:23915470

  12. Random Walks with Bivariate Levy-Stable Jumps in Comparison with Levy Flights

    International Nuclear Information System (INIS)

    In this paper we compare the Levy flight model on a plane with the random walk resulting from bivariate Levy-stable random jumps with the uniform spectral measure. We show that, in general, both processes exhibit similar properties, i.e. they are characterized by the presence of the jumps with extremely large lengths and uniformly distributed directions (reflecting the same heavy-tail behavior and the spherical symmetry of the jump distributions), connecting characteristic clusters of short steps. The bivariate Levy-stable random walks, belonging to the class of the well investigated stable processes, can enlarge the class of random-walk models for transport phenomena if other than uniform spectral measures are considered. (author)

  13. Obtaining DDF Curves of Extreme Rainfall Data Using Bivariate Copula and Frequency Analysis

    DEFF Research Database (Denmark)

    Sadri, Sara; Madsen, Henrik; Mikkelsen, Peter Steen; Burn, D H

    2009-01-01

    copulas can give a more accurate IDF curve. We study IDF curves using a copula in a bivariate frequency analysis of extreme rainfall. To be able to choose the most suitable copula among candidate copulas (i.e., Gumbel, Clayton, and Frank) we demonstrated IDF curves based on variation of depth with...... distribution and the duration was fit with a Pearson type III distribution for rainfall extracted using method 3. The Clayton copula was found to be appropriate for bivariate analysis of rainfall depth and duration for both methods 2 and 3. DDF curves derived using the Clayton copula for depth and duration of...... duration. If rainfall series are extracted by storage volume and duration (method 3), the difference between DDF curves derived from the Clayton copula and the empirical DDF curves are more appreciable and in general, DDF curves derived from method 3 show a smaller depth for the same duration for any...

  14. Bivariate Drought Analysis Using Streamflow Reconstruction with Tree Ring Indices in the Sacramento Basin, California, USA

    OpenAIRE

    Jaewon Kwak; Soojun Kim; Gilho Kim; Singh, Vijay P; Jungsool Park; Hung Soo Kim

    2016-01-01

    Long-term streamflow data are vital for analysis of hydrological droughts. Using an artificial neural network (ANN) model and nine tree-ring indices, this study reconstructed the annual streamflow of the Sacramento River for the period from 1560 to 1871. Using the reconstructed streamflow data, the copula method was used for bivariate drought analysis, deriving a hydrological drought return period plot for the Sacramento River basin. Results showed strong correlation among drought characteris...

  15. The bivariate probit model of uncomplicated control of tumor: a heuristic exposition of the methodology

    International Nuclear Information System (INIS)

    Purpose: To describe the concept, models, and methods for the construction of estimates of joint probability of uncomplicated control of tumors in radiation oncology. Interpolations using this model can lead to the identification of more efficient treatment regimens for an individual patient. The requirement to find the treatment regimen that will maximize the joint probability of uncomplicated control of tumors suggests a new class of evolutionary experimental designs--Response Surface Methods--for clinical trials in radiation oncology. Methods and Materials: The software developed by Lesaffre and Molenberghs is used to construct bivariate probit models of the joint probability of uncomplicated control of cancer of the oropharynx from a set of 45 patients for each of whom the presence/absence of recurrent tumor (the binary event E-bar1/E1) and the presence/absence of necrosis (the binary event E2/E-bar2) of the normal tissues of the target volume is recorded, together with the treatment variables dose, time, and fractionation. Results: The bivariate probit model can be used to select a treatment regime that will give a specified probability, say P(S) = 0.60, of uncomplicated control of tumor by interpolation within a set of treatment regimes with known outcomes of recurrence and necrosis. The bivariate probit model can be used to guide a sequence of clinical trials to find the maximum probability of uncomplicated control of tumor for patients in a given prognostic stratum using Response Surface methods by extrapolation from an initial set of treatment regimens. Conclusions: The design of treatments for individual patients and the design of clinical trials might be improved by use of a bivariate probit model and Response Surface Methods

  16. Risk management activities of a non-industrial private forest owner with a bivariate utility function

    OpenAIRE

    Brunette, Marielle; Couture, Stéphane

    2014-01-01

    In this paper, we propose to analyse the choice of risk management activity made by a nonindustrial private forest owner who derives utility from consumption and from the sentimental value of the forest that bears a risk of disaster. We consider a bivariate utility function depending on consumption and sentimental value of forest. In this context, we analyse insurance and/or self-insurance decisions. We show that, under fair premium, full insurance is optimal only if the cross derivative of t...

  17. Monotonicity properties of the asymptotic relative efficiency between common correlation statistics in the bivariate normal model

    OpenAIRE

    Molzon, Raymond; Pinelis, Iosif

    2009-01-01

    Pearson's is the most common correlation statistic, used mainly in parametric settings. Most common among nonparametric correlation statistics are Spearman's and Kendall's. We show that for bivariate normal i.i.d. samples the pairwise asymptotic relative efficiency between these three statistics depends monotonically on the population correlation coefficient. This monotonicity is a corollary to a stronger result. The proofs rely on the use of l'Hospital-type rules for monotonicity patterns.

  18. The Assessment of Performance of Correlation Estimates in Discrete Bivariate Distributions Using Bootstrap Methodology

    OpenAIRE

    Tsagris, Michael; Elmatzoglou, Ioannis; Christos C. Frangos

    2015-01-01

    Little attention has been given to the correlation coefficient when data come from discrete or continuous non-normal populations. In this article, we consider the efficiency of two correlation coefficients which are from the same family, Pearson's and Spearman's estimators. Two discrete bivariate distributions were examined: the Poisson and the Negative Binomial. The comparison between these two estimators took place using classical and bootstrap techniques for the construction of confidence ...

  19. Assessment of Performance of Correlation Estimates in Discrete Bivariate Distributions using Bootstrap Methodology

    OpenAIRE

    Tsagris, Michail; Elmatzoglou, Ioannis; C. Frangos, Christos

    2012-01-01

    Little attention has been given to the correlation coefficient when data come from discrete or continuous non-normal populations. In this article, we consider the efficiency of two correlation coefficients which are from the same family, Pearson's and Spearman's estimators. Two discrete bivariate distributions were examined: the Poisson and the Negative Binomial. The comparison between these two estimators took place using classical and bootstrap techniques for the construction of confidence ...

  20. Tourists intra-destination visits and transportation mode: a bivariate model

    OpenAIRE

    Lorenzo Masiero; Judit Zoltan

    2012-01-01

    This paper investigates tourists’ profile in relation to both intra-destination movement patterns and transportation mode choices at the destination through the use of bivariate probit models. The analysis is based on a field survey conducted among tourists visiting the Canton of Ticino, Switzerland. The results show a positive correlation between visiting more than one region and the use of private transportation at the destination. In particular, the two variables are explained by a m...

  1. The Role of Wealth and Health in Insurance Choice: Bivariate Probit Analysis in China

    OpenAIRE

    Yiding Yue; Jinyou Zou

    2014-01-01

    This paper captures the correlation between the choices of health insurance and pension insurance using the bivariate probit model and then studies the effect of wealth and health on insurance choice. Our empirical evidence shows that people who participate in a health care program are more likely to participate in a pension plan at the same time, while wealth and health have different effects on the choices of the health care program and the pension program. Generally, the higher an individu...

  2. FIML Estimation of a Bivariate Probit Selection Rule – An Application on Firm Growth and Subsidisation

    OpenAIRE

    Reize, Frank

    2001-01-01

    This study applies a full information maximum likelihood (FIML) estimator of the sample selection model with bivariate selection rule for the investigation of the impact of subsidised firm foundation from unemployment on employment growth of the firm. The empirical analysis is based on the ZEW Firm Start-up Panel using a cohort of firms founded in 15 labour market districts during 1993 and 1995. Estimation results show that the use of the FIML estimator is clearly warranted, compared to a two...

  3. On the dynamics of product and process innovations: A bivariate random effects probit model

    OpenAIRE

    Flaig, Gebhard; Stadler, Manfred

    1996-01-01

    Based on a stochastic dynamic model of a firm's optimal innovative behavior we derive a simultaneous equation system for product and process innovations with intertemporal spillover effects. We estimate various versions of the model with dichotomous Innovation data at the firm level by using a bivariate dynamic random effects probit model. The data set, provided by the Ifo-Institute, covers the period between 1981 and 1989 and includes 586 firms of the West German manufacturing sector. It tur...

  4. Identification in a Generalization of Bivariate Probit Models with Endogenous Regressors

    OpenAIRE

    Sukjin Han; Edward J. Vytlacil

    2013-01-01

    This paper provides identification results for a class of models specified by a triangular system of two equations with binary endogenous variables. The joint distribution of the latent error terms is specified through a parametric copula structure, including the normal copula as a special case, while the marginal distributions of the latent error terms are allowed to be arbitrary but known. This class of models includes bivariate probit models as a special case. The paper demonstrates that a...

  5. Determinants of Crop Choices by Bangladeshi Farmers: A Bivariate Probit Analysis

    OpenAIRE

    Rahman, Sanzidur

    2008-01-01

    Using a bivariate probit model, the study jointly determines the factors underlying the probability of Bangladeshi farmers adopting a diversified cropping system and/or modern rice technology. Results reveal that the availability of irrigation is the single most important determinant of the decision to adopt modern rice technology, and adoption is higher among the tenant farmers. The exact opposite is true for the likelihood of adopting a diversified cropping system, which is significantly hi...

  6. Estimation of a semiparametric recursive bivariate probit model with nonparametric mixing

    OpenAIRE

    Marra, G.; Papageorgiou, G.; R. Radice

    2013-01-01

    We consider an extension of the recursive bivariate probit model for estimating the effect of a binary variable on a binary outcome in the presence of unobserved confounders, nonlinear covariate effects and overdispersion. Specifically, the model consists of a system of two binary outcomes with a binary endogenous regressor which includes smooth functions of covariates, hence allowing for flexible functional dependence of the responses on the continuous regressors, and arbitrary random interc...

  7. Non-Linear Integral Equations to Construct Bivariate Densities with Given Marginals and Dependence Function

    OpenAIRE

    Molenberghs, Geert; Lesaffre, Emmanuel

    1997-01-01

    The local dependence function, introduced by Holland and Wang (1987) and studied by Wang (1993) as a continuous version of the local cross-ratio, describes the local relation between two random variables. Three explicit numerical algorithms are proposed to approximate bivariate densities given the marginal densities and the local dependence function. This approach is suited for simulation purposes, to provide illustrative examples of densities with given marginals, and for e...

  8. Technical note: Towards a continuous classification of climate using bivariate colour mapping

    Directory of Open Access Journals (Sweden)

    A. J. Teuling

    2011-06-01

    Full Text Available Climate is often defined in terms of discrete classes. Here I use bivariate colour mapping to show that the global distribution of Köppen-Geiger climate classes can largely be reproduced by combining the simple means of two key states of the climate system (i.e., air temperature and relative humidity. This allows for a classification that is not only continuous in space, but can be applied at and transferred between timescales ranging from minutes to decades.

  9. Efficient estimation in the bivariate normal copula model: normal margins are least favourable

    OpenAIRE

    Klaassen, Chris A. J.; Wellner, Jon A.

    1997-01-01

    Consider semi-parametric bivariate copula models in which the family of copula functions is parametrized by a Euclidean parameter θ of interest and in which the two unknown marginal distributios are the (infinite-dimensional) nuisance parameters. The efficient score for θ can be characterized in terms of the solutions of two coupled Sturm-Liouville equations. Where the family of copula functions corresponds to the normal distributios with mean 0, variance 1 and correlation θ, the solution of ...

  10. Asymptotic mean and variance of gini correlation for bivariate normal samples

    OpenAIRE

    Xu, W.; Hung, YS; Niranjan, M.; Shen, M

    2010-01-01

    This paper derives the asymptotic analytical forms of the mean and variance of the Gini correlation (GC) with respect to samples drawn from bivariate normal populations. The asymptotic relative efficiency (ARE) of the Gini correlation to Pearson's product moment correlation coefficient (PPMCC) is investigated under the normal assumptions. To gain further insight into GC, we also compare the Gini correlation to other two closely related correlation coefficients, namely, the order statistics co...

  11. Coordinate-Momentum Intermediate Representation and Marginal Distributions of Quantum Mechanical Bivariate Normal Distribution

    International Nuclear Information System (INIS)

    We introduce bivariate normal distribution operator for state vector |ψ> and find that its marginal distribution leads to one-dimensional normal distribution corresponding to the measurement probability |λ,ν|2, where |x>λ,ν is the coordinate-momentum intermediate representation. As a by-product, the one-dimensional normal distribution in statistics can be explained as a Radon transform of two-dimensional Gaussian function.

  12. On minimum divergence adaptation of discrete bivariate distributions to given marginals

    Czech Academy of Sciences Publication Activity Database

    Vajda, Igor; van der Meulen, E. C.

    2005-01-01

    Roč. 51, č. 1 (2005), s. 313-320. ISSN 0018-9448 R&D Projects: GA ČR GA201/02/1391; GA MŠk 1M0572 Institutional research plan: CEZ:AV0Z10750506 Keywords : approximation of contingency tables * bivariate discrete distributions * minimization of divergences Subject RIV: BD - Theory of Information Impact factor: 2.183, year: 2005

  13. Natural convection test in Phenix reactor and associated CATHARE calculation

    International Nuclear Information System (INIS)

    The Phenix sodium cooled fast reactor started operation in 1973 and was stopped in 2009. Before the reactor was definitively stopped, final tests were performed, including a natural convection test in the primary circuit. One objective of this natural convection test in Phenix reactor is the qualification of plant dynamic codes as CATHARE code for future safety studies. The paper firstly describes the Phenix reactor primary circuit. The initial test conditions and the detailed transient scenario are presented. Then, the CATHARE modelling of the Phenix primary circuit is described. The whole transient scenario is calculated, including the nominal state, the steam generators dry out, the scram, the onset of natural convection in the primary circuit and the natural convection phases. The CATHARE calculations are compared to the Phenix measurements. A particular attention is paid to the significant decrease of the core power before the scram. Then, the evolution of main components inlet and outlet temperatures is compared. The need of coupling a system code with a CFD code to model the 3D behaviour of large pools is pointed out. This work is in progress. (author)

  14. Galaxy And Mass Assembly (GAMA): Bivariate functions of H$\\alpha$ star forming galaxies

    CERN Document Server

    Gunawardhana, M L P; Taylor, E N; Bland-Hawthorn, J; Norberg, P; Baldry, I K; Loveday, J; Owers, M S; Wilkins, S M; Colless, M; Brown, M J I; Driver, S P; Alpaslan, M; Brough, S; Cluver, M; Croom, S; Kelvin, L; Lara-López, M A; Liske, J; López-Sánchez, A R; Robotham, A S G

    2014-01-01

    We present bivariate luminosity and stellar mass functions of H$\\alpha$ star forming galaxies drawn from the Galaxy And Mass Assembly (GAMA) survey. While optically deep spectroscopic observations of GAMA over a wide sky area enable the detection of a large number of $0.001<{SFR}_{H\\alpha}$ (M$_{\\odot}$ yr$^{-1}$)$<100$ galaxies, the requirement for an H$\\alpha$ detection in targets selected from an $r$-band magnitude limited survey leads to an incompleteness due to missing optically faint star forming galaxies. Using $z<0.1$ bivariate distributions as a reference we model the higher-$z$ distributions, thereby approximating a correction for the missing optically faint star forming galaxies to the local SFR and stellar mass densities. Furthermore, we obtain the $r$-band LFs and stellar mass functions of H$\\alpha$ star forming galaxies from the bivariate LFs. As our sample is selected on the basis of detected H$\\alpha$ emission, a direct tracer of on-going star formation, this sample represents a true ...

  15. Image Segmentation Method Based On Finite Doubly Truncated Bivariate Gaussian Mixture Model with Hierarchical Clustering

    Directory of Open Access Journals (Sweden)

    G V S Rajkumar

    2011-07-01

    Full Text Available Image segmentation is one of the most important area of image retrieval. In colour image segmentation the feature vector of each image region is 'n' dimension different from grey level image. In this paper a new image segmentation algorithm is developed and analyzed using the finite mixture of doubly truncated bivariate Gaussian distribution by integrating with the hierarchical clustering. The number of image regions in the whole image is determined using the hierarchical clustering algorithm. Assuming that a bivariate feature vector (consisting of Hue angle and Saturation of each pixel in the image region follows a doubly truncated bivariate Gaussian distribution, the segmentation algorithm is developed. The model parameters are estimated using EM-Algorithm, the updated equations of EM-Algorithm for a finite mixture of doubly truncated Gaussian distribution are derived. A segmentation algorithm for colour images is proposed by using component maximum likelihood. The performance of the developed algorithm is evaluated by carrying out experimentation with five images taken form Berkeley image dataset and computing the image segmentation metrics like, Global Consistency Error (GCE, Variation of Information (VOI, and Probability Rand Index (PRI. The experimentation results show that this algorithm outperforms the existing image segmentation algorithms.

  16. Simultaneous determination of Nifuroxazide and Drotaverine hydrochloride in pharmaceutical preparations by bivariate and multivariate spectral analysis

    Science.gov (United States)

    Metwally, Fadia H.

    2008-02-01

    The quantitative predictive abilities of the new and simple bivariate spectrophotometric method are compared with the results obtained by the use of multivariate calibration methods [the classical least squares (CLS), principle component regression (PCR) and partial least squares (PLS)], using the information contained in the absorption spectra of the appropriate solutions. Mixtures of the two drugs Nifuroxazide (NIF) and Drotaverine hydrochloride (DRO) were resolved by application of the bivariate method. The different chemometric approaches were applied also with previous optimization of the calibration matrix, as they are useful in simultaneous inclusion of many spectral wavelengths. The results found by application of the bivariate, CLS, PCR and PLS methods for the simultaneous determinations of mixtures of both components containing 2-12 μg ml -1 of NIF and 2-8 μg ml -1 of DRO are reported. Both approaches were satisfactorily applied to the simultaneous determination of NIF and DRO in pure form and in pharmaceutical formulation. The results were in accordance with those given by the EVA Pharma reference spectrophotometric method.

  17. Hypothesis testing using pairwise distances and associated kernels

    CERN Document Server

    Sejdinovic, Dino; Sriperumbudur, Bharath; Fukumizu, Kenji

    2012-01-01

    We provide a unifying framework linking two classes of statistics used in two-sample and independence testing: on the one hand, the energy distances and distance covariances from the statistics literature; on the other, distances between embeddings of distributions to reproducing kernel Hilbert spaces (RKHS), as established in machine learning. The equivalence holds when energy distances are computed with semimetrics of negative type, in which case a kernel may be defined such that the RKHS distance between distributions corresponds exactly to the energy distance. We determine the class of probability distributions for which kernels induced by semimetrics are characteristic (that is, for which embeddings of the distributions to an RKHS are injective). Finally, we investigate the performance of this family of kernels in two-sample and independence tests: we show in particular that the energy distance most commonly employed in statistics is just one member of a parametric family of kernels, and that other choic...

  18. Biosynthesis of glycosaminoglycans: associated disorders and biochemical tests.

    Science.gov (United States)

    Sasarman, Florin; Maftei, Catalina; Campeau, Philippe M; Brunel-Guitton, Catherine; Mitchell, Grant A; Allard, Pierre

    2016-03-01

    Glycosaminoglycans (GAG) are long, unbranched heteropolymers with repeating disaccharide units that make up the carbohydrate moiety of proteoglycans. Six distinct classes of GAGs are recognized. Their synthesis follows one of three biosynthetic pathways, depending on the type of oligosaccharide linker they contain. Chondroitin sulfate, dermatan sulfate, heparan sulfate, and heparin sulfate contain a common tetrasaccharide linker that is O-linked to specific serine residues in core proteins. Keratan sulfate can contain three different linkers, either N-linked to asparagine or O-linked to serine/threonine residues in core proteins. Finally, hyaluronic acid does not contain a linker and is not covalently attached to a core protein. Most inborn errors of GAG biosynthesis are reported in small numbers of patients. To date, in 20 diseases, convincing evidence for pathogenicity has been presented for mutations in a total of 16 genes encoding glycosyltransferases, sulfotransferases, epimerases or transporters. GAG synthesis defects should be suspected in patients with a combination of characteristic clinical features in more than one connective tissue compartment: bone and cartilage (short long bones with or without scoliosis), ligaments (joint laxity/dislocations), and subepithelial (skin, sclerae). Some produce distinct clinical syndromes. The commonest laboratory tests used for this group of diseases are analysis of GAGs, enzyme assays, and molecular testing. In principle, GAG analysis has potential as a general first-line diagnostic test for GAG biosynthesis disorders. PMID:26689402

  19. An inquisition into bivariate threshold effects in the inflation-growth correlation: Evaluating South Africa’s macroeconomic objectives

    OpenAIRE

    Andrew Phiri

    2013-01-01

    Is the SARB’s inflation target of 3-6% compatible with the 6% economic growth objective set by ASGISA? Estimations of inflation-growth bivariate Threshold Vector Autoregressive with corresponding bivariate Threshold Vector Error Correction (BTVEC-BTVAR) econometric models for sub-periods coupled with the South African inflation-growth experience between 1960 and 2010; suggest on optimal inflation-growth combinations for South African data presenting a two-fold proposition. Firstly, for the pe...

  20. Bayesian Approach to Zero-Inflated Bivariate Ordered Probit Regression Model, with an Application to Tobacco Use

    OpenAIRE

    Shiferaw Gurmu; Dagne, Getachew A.

    2012-01-01

    This paper presents a Bayesian analysis of bivariate ordered probit regression model with excess of zeros. Specifically, in the context of joint modeling of two ordered outcomes, we develop zero-inflated bivariate ordered probit model and carry out estimation using Markov Chain Monte Carlo techniques. Using household tobacco survey data with substantial proportion of zeros, we analyze the socioeconomic determinants of individual problem of smoking and chewing tobacco. In our illustration, we ...

  1. Simultaneous determination of uranium(VI) and thorium(IV) ions with carminic acid by bivariate calibration

    International Nuclear Information System (INIS)

    A bivariate calibration method, has been applied to the simultaneous determination of U(VI) and Th(IV) ions as complexes with carminic acid by visible absorption spectrophotometry. The bivariate calibration method was applied satisfactorily to the determination of these ions in synthetic solutions simulating sulfuric acid leach solution obtained from uranium-thorium ores and the results were compared with those given by first derivative spectrophotometry. No significant advantages of any method were found. (author)

  2. Opt-Out HIV Testing of Inmates in North Carolina Prisons: Factors Associated with not Wanting a Test and not Knowing They Were Tested.

    Science.gov (United States)

    Grodensky, Catherine A; Rosen, David L; Hino, Sayaka; Golin, Carol E; Wohl, David A

    2016-04-01

    Opt-out HIV testing is recommended for correctional settings but may occur without inmates' knowledge or against their wishes. Through surveying inmates receiving opt-out testing in a large prison system, we estimated the proportion unaware of being tested or not wanting a test, and associations [prevalence ratios (PRs)] with inmate characteristics. Of 871 tested, 11.8 % were unknowingly tested and 10.8 % had unwanted tests. Not attending an educational HIV course [PR = 2.34, 95 % confidence interval (CI) 1.47-3.74], lower HIV knowledge (PR = 0.95, 95 % CI 0.91-0.98), and thinking testing is not mandatory (PR = 9.84, 95 % CI 4.93-19.67) were associated with unawareness of testing. No prior incarcerations (PR = 1.59, 95 % CI 1.03-2.46) and not using crack/cocaine recently (PR = 2.37, 95 % CI 1.21-4.64) were associated with unwanted testing. Residence at specific facilities was associated with both outcomes. Increased assessment of inmate understanding and enhanced implementation are needed to ensure inmates receive full benefits of opt-out testing: being informed and tested according to their wishes. PMID:26386591

  3. Bivariate distributions in statistical spectroscopy studies. Pt. 3. Non interacting particle strength densities for one-body transition operators

    International Nuclear Information System (INIS)

    In statistical spectroscopy, it was shown by French et al. (Ann. Phys., N.Y. 181, 235 (1988)) that the bivariate strength densities take a convolution form with the non interacting particle (NIP) strength density being convoluted with a spreading bivariate Gaussian due to interactions. Leaving aside the question of determining the parameters of the spreading bivariate Gaussian, one needs good methods for constructing the NIP bivariate strength densities IhO(E, E') (h is a one-body hamiltonian and O is a transition operator) in large shell model spaces. A formalism for constructing IhO is developed for one-body transition operators by using spherical orbits and spherical configurations. For rapid construction and also for applying the statistical theory in large shell model spaces IhO is decomposed into partial densities defined by unitary orbit configurations (unitary orbit is a set of spherical orbits). Trace propagation formulas for the bivariate moments Mrs with r + s ≤ 2 of the partial NIP strength densities, which will determine the Gaussian representation, are derived. In a large space numerical example with Gamow-Teller β- transition operator, the superposition of unitary orbit partial bivariate Gaussian densities is shown to give a good representation of the exact NIP strength densities. Trace propagation formulas for Mrs with r + s ≤ 4 are also derived in m-particle scalar spaces which are useful for many purposes. (orig.)

  4. Bivariate and Multivariate Associations between Trait Listening Goals and Trait Communicator Preferences

    Science.gov (United States)

    Keaton, Shaughan A.; Keteyian, Robert V.; Bodie, Graham D.

    2014-01-01

    This article provides validity evidence for a measure of listening goals by showing theoretically consistent relationships with an existing communication preference questionnaire. Participants (N = 257) were administered trait measures for listening goals and communicator preferences. The four listening goals--relational, task-oriented,…

  5. Which global stock indices trigger stronger contagion risk in the Vietnamese stock market? Evidence using a bivariate analysis

    Directory of Open Access Journals (Sweden)

    Wang Kuan-Min

    2013-01-01

    Full Text Available This paper extends recent investigations into risk contagion effects on stock markets to the Vietnamese stock market. Daily data spanning October 9, 2006 to May 3, 2012 are sourced to empirically validate the contagion effects between stock markets in Vietnam, and China, Japan, Singapore, and the US. To facilitate the validation of contagion effects with market-related coefficients, this paper constructs a bivariate EGARCH model of dynamic conditional correlation coefficients. Using the correlation contagion test and Dungey et al.’s (2005 contagion test, we find contagion effects between the Vietnamese and four other stock markets, namely Japan, Singapore, China, and the US. Second, we show that the Japanese stock market causes stronger contagion risk in the Vietnamese stock market compared to the stock markets of China, Singapore, and the US. Finally, we show that the Chinese and US stock markets cause weaker contagion effects in the Vietnamese stock market because of stronger interdependence effects between the former two markets.

  6. Testing exogeneity in the bivariate probit model: Monte Carlo evidence and an application to health economics

    OpenAIRE

    D. Fabbri; C. Monfardini; R. Radice

    2004-01-01

    Many economic applications involve the modeling of a binary variable as simultaneously determined with one of its dycotomous regressors. In this paper we deal with a prominent health economics case study, that of cesarean section delivery utilization across public and private hospitals. Estimating the probability of cesarean section in a univariate framework neglecting the potential endogeneity of the hospital type dummy might lead to invalid inference. Since little is known...

  7. Psychometric Characteristics Associated with Changes on the Passage Comprehension Test of the Woodcock Reading Mastery Tests.

    Science.gov (United States)

    Halpin, Gerald; Simpson, Robert

    Forty adolescent subjects with behavior problems at home or at school were administered the Woodcock Reading Mastery Tests. Subjects ranged in age from 12 to 18, and included 25 males and 15 females. The Passage Comprehension Test for each subject was rescored using three different ceiling criteria: (1) five errors in six consecutive responses,…

  8. Testing Alternative Hypotheses Regarding the Association between Behavioral Inhibition and Language Development in Toddlerhood

    Science.gov (United States)

    Watts, Ashley K. Smith; Patel, Deepika; Corley, Robin P.; Friedman, Naomi P.; Hewitt, John K.; Robinson, JoAnn L.; Rhee, Soo H.

    2014-01-01

    Studies have reported an inverse association between language development and behavioral inhibition or shyness across childhood, but the direction of this association remains unclear. This study tested alternative hypotheses regarding this association in a large sample of toddlers. Data on behavioral inhibition and expressive and receptive…

  9. A General Framework for Association Tests With Multivariate Traits in Large-Scale Genomics Studies

    OpenAIRE

    He, Qianchuan; Avery, Christy L; Lin, Dan-Yu

    2013-01-01

    Genetic association studies often collect data on multiple traits that are correlated. Discovery of genetic variants influencing multiple traits can lead to better understanding of the etiology of complex human diseases. Conventional univariate association tests may miss variants that have weak or moderate effects on individual traits. We propose several multivariate test statistics to complement univariate tests. Our framework covers both studies of unrelated individuals and family studies a...

  10. Factors Associated with Delayed Tuberculosis Test-seeking Behavior in the Peruvian Amazon

    OpenAIRE

    Ford, Carolyn M.; Bayer, Angela M; Gilman, Robert H.; Onifade, Dami; Acosta, Colleen; Cabrera, Lilia; Vidal, Carlos; Evans, Carlton A.

    2009-01-01

    This study aimed to determine the psychosocial factors associated with delayed test-seeking among tuberculosis patients. The duration of symptoms before seeking medical care was assessed by interview for 108 newly diagnosed pulmonary tuberculosis patients in the city of Iquitos in the Peruvian Amazon, which has high tuberculosis incidence. Beliefs associated with test-seeking behavior and delay was assessed in these patients. The median delay from symptom onset to seeking diagnostic testing w...

  11. THE GALEX ARECIBO SDSS SURVEY. VII. THE BIVARIATE NEUTRAL HYDROGEN-STELLAR MASS FUNCTION FOR MASSIVE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Lemonias, Jenna J.; Schiminovich, David [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Catinella, Barbara [Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85741 Garching (Germany); Heckman, Timothy M. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Moran, Sean M., E-mail: jenna@astro.columbia.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-10-20

    We present the bivariate neutral atomic hydrogen (H I)-stellar mass function (HISMF) φ(M{sub H{sub I}}, M{sub *}) for massive (log M{sub *}/M{sub ☉} \\gt 10) galaxies derived from a sample of 480 local (0.025 < z < 0.050) galaxies observed in H I at Arecibo as part of the GALEX Arecibo SDSS Survey. We fit six different models to the HISMF and find that a Schechter function that extends down to a 1% H I gas fraction, with an additional fractional contribution below that limit, is the best parameterization of the HISMF. We calculate Ω{sub H{sub I,{sub M{sub *>10{sup 1}{sup 0}}}}} and find that massive galaxies contribute 41% of the H I density in the local universe. In addition to the binned HISMF, we derive a continuous bivariate fit, which reveals that the Schechter parameters only vary weakly with stellar mass: M{sub H{sub I}{sup *}}, the characteristic H I mass, scales as M{sub *}{sup 0.39}; α, the slope of the HISMF at moderate H I masses, scales as M{sub *}{sup 0.07}; and f, the fraction of galaxies with H I gas fraction greater than 1%, scales as M{sub *}{sup -0.24}. The variation of f with stellar mass should be a strong constraint for numerical simulations. To understand the physical mechanisms that produce the shape of the HISMF, we redefine the parameters of the Schechter function as explicit functions of stellar mass and star formation rate (SFR) to produce a trivariate fit. This analysis reveals strong trends with SFR. While M{sub H{sub I}{sup *}} varies weakly with stellar mass and SFR (M{sub H{sub I}{sup *}} ∝ M{sub *}{sup 0.22}, M{sub H{sub I}{sup *}} ∝ SFR{sup –0.03}), α is a stronger function of both stellar mass and especially SFR (α ∝ M{sub *}{sup 0.47}, α ∝ SFR{sup 0.95}). The HISMF is a crucial tool that can be used to constrain cosmological galaxy simulations, test observational predictions of the H I content of populations of galaxies, and identify galaxies whose properties deviate from average trends.

  12. Testing in Microbiome-Profiling Studies with MiRKAT, the Microbiome Regression-Based Kernel Association Test

    OpenAIRE

    Zhao, Ni; Chen, Jun; Carroll, Ian M.; Ringel-Kulka, Tamar; Epstein, Michael P.; Zhou, Hua; Zhou, Jin J.; Ringel, Yehuda; Li, Hongzhe; Wu, Michael C.

    2015-01-01

    High-throughput sequencing technology has enabled population-based studies of the role of the human microbiome in disease etiology and exposure response. Distance-based analysis is a popular strategy for evaluating the overall association between microbiome diversity and outcome, wherein the phylogenetic distance between individuals’ microbiome profiles is computed and tested for association via permutation. Despite their practical popularity, distance-based approaches suffer from important c...

  13. The Pattern of Variation between Diarrhea and Malaria Coexistence with Corresponding Risk Factors in, Chikhwawa, Malawi: A Bivariate Multilevel Analysis.

    Science.gov (United States)

    Masangwi, Salule; Ferguson, Neil; Grimason, Anthony; Morse, Tracy; Kazembe, Lawrence

    2015-07-01

    Developing countries face a huge burden of infectious diseases, a number of which co-exist. This paper estimates the pattern and variation of malaria and diarrhea coexistence in Chikhwawa, a district in Southern Malawi using bivariate multilevel modelling with Bayesian estimation. A probit link was employed to examine hierarchically built data from a survey of individuals (n = 6,727) nested within households (n = 1,380) nested within communities (n = 33). Results show significant malaria [σ²μ₁=0.901 (95% CI:0.746,1.056)] and diarrhea [σ²μ₂=1.009 (95% CI:0.860,1.158)] variations with a strong correlation between them [r(¹,²)μ=0.565] at household level. There are significant malaria [σ²ν₁=0.053 (95% CI: 0.018,0.088)] and diarrhea [σ²ν₂=0.099(95% CI : 0.030,0.168) ] variations at community level but with a small correlation [r(¹,²) ν=0.124] between them. There is also significant correlation between malaria and diarrhea at individual level [ r(¹,²) e=0.241]. These results suggest a close association between reported malaria-like illness and diarrheal illness especially at household and individual levels in Southern Malawi. PMID:26197332

  14. Bivariate Drought Analysis Using Streamflow Reconstruction with Tree Ring Indices in the Sacramento Basin, California, USA

    Directory of Open Access Journals (Sweden)

    Jaewon Kwak

    2016-03-01

    Full Text Available Long-term streamflow data are vital for analysis of hydrological droughts. Using an artificial neural network (ANN model and nine tree-ring indices, this study reconstructed the annual streamflow of the Sacramento River for the period from 1560 to 1871. Using the reconstructed streamflow data, the copula method was used for bivariate drought analysis, deriving a hydrological drought return period plot for the Sacramento River basin. Results showed strong correlation among drought characteristics, and the drought with a 20-year return period (17.2 million acre-feet (MAF per year in the Sacramento River basin could be considered a critical level of drought for water shortages.

  15. THEOREMS OF PEANO'S TYPE FOR BIVARIATE FUNCTIONS AND OPTIMAL RECOVERY OF LINEAR FUNCTIONALS

    Institute of Scientific and Technical Information of China (English)

    N.K. Dicheva

    2001-01-01

    The best recovery of a linear functional Lf , f =f (x,y), on thebasis of given linear functionals Ljf ,j=1,2, … ,N in a sense of Sard has been investigated, using analogy of Peano's theorem. The best recovery of a bivariate function by given scattered data has been obtained in a simple analytical form as a special case.CLC Number:O17 Document ID:AAuthor Resume:Natasha K. Dicheva ,e-mail: dichevan_fgs@uacg, acad. bg References:[1]Rudin,W. ,Principles of Mathematical Analysis,2ed. ,McGraw-Hill Book Co. ,New York,1964.[2]Rudin,W. ,Real and Complex Analysis,McGraw-Hill publishing Co. ,New York,1976.[3]Hewitt,E. and Stromberg,K. ,Real and Abstract Analysis,Springer-Verlag,New York,Berlin,1965.[4]Lusternik,L. and Sobolev,V. ,Elements of the Functional Analysis,Izd. Nauka,Moskva,1965 (in Russian).[5]Sard,A.,Integral Representation of Remainders Duke Math. J.,15(1948),333-345.[6]Sard,A. ,Linear Approximation,Amer. Math. Soc. ,Math. Surverys,9,1963.[7]Smolyak,S.A. ,On the optimal reconvery of Functions and Functionals of Them,Ph. D. Thesis,Moscow State University,1965.[8]Nielson,G.,Bivariate Spline Functions and the Approximation of Linear Functionals,Numer.Math.,21(1973),138-160.[9]Mansfield,L.E. ,Optimal Approximations and Error Bounds in Spaces of Bivariate Functions,J. Approx. Theory 5(1972),77-96.[10]Mansfield,L.E. ,On the Optimal Approximation of Linear Functionals in Spaces of Bivariate Functions,SIAM J. Numer. Anal ,8(1971),115-126.[11]Ritter,D. ,Two Dimensional Spline Functions and best Approximation of Linear Functionals,J. Approx. Theory,3(1970),352-368.[12]Laurent,P.J. ,Approximation et optimisation,Hermann,Paris,1972.[13]Bojanov,B. ,Hakopian,H.A. and Sahakian,A.A. ,Spline Functions and Multivariate Interpolations,Kluwer Academic Publishers,Dordrecht,1993.[14]Dicheve,N.K.,On the best Recovery of Linear Functional and its Applications,Boundary Elements XXI,eds. C.A. Brebbia and H. Power,WIT Press,Southampton,Boston,(1999),739-747.Manuscript Received

  16. An efficient algorithm for generating random number pairs drawn from a bivariate normal distribution

    Science.gov (United States)

    Campbell, C. W.

    1983-01-01

    An efficient algorithm for generating random number pairs from a bivariate normal distribution was developed. Any desired value of the two means, two standard deviations, and correlation coefficient can be selected. Theoretically the technique is exact and in practice its accuracy is limited only by the quality of the uniform distribution random number generator, inaccuracies in computer function evaluation, and arithmetic. A FORTRAN routine was written to check the algorithm and good accuracy was obtained. Some small errors in the correlation coefficient were observed to vary in a surprisingly regular manner. A simple model was developed which explained the qualities aspects of the errors.

  17. Normally Ordered Bivariate-Normal-Distribution Forms of Two-Mode Mixed States with Entanglement Involved

    International Nuclear Information System (INIS)

    Based on the technique of integration within an ordered product of operators we have demonstrated that single-mode mixed states' density matrices can be recast into the normally ordered Gaussian forms [Chin. Phys. Lett. 24 (2007) 3322]. Here we employ the Weyl ordering invariance under similar transformations to show that some two-mode mixed states with entanglement involved can be put into normally ordered form in the bivariate normal distribution too and its marginal distributions can be analysed. In this way, density operators of quantum statistics can be analogous to mathematical statistics, and calculation of variances can be simplified

  18. A Family of Generalized Wigner Operators and Their Physical Meaning as Bivariate Normal Distribution

    International Nuclear Information System (INIS)

    By extending the usual Wigner operator to the s-parameterized one, we find that in the process of the generalized Weyl quantization the s parameter plays the role of correlation between two quadratures Q and P. This can be exposed by comparing the normally ordered form of Ωs with the standard form of the Gaussian bivariate normal distribution of random variables in statistics. Three different expressions of Ωs and the quantization scheme with use of it are presented. (fundamental areas of phenomenology (including applications))

  19. Bivariate multicanonical Monte Carlo of the 3D±J spin glass

    International Nuclear Information System (INIS)

    The low-temperature behavior of spin glasses in three dimensions has been the subject of a long-standing, unresolved controversy between the mean-field picture, (which maintains the existence of an infinite number of free-energy minima due to replica symmetry breaking) and the droplet pincture (which claims that only two minima exist). In hope of resolving the controversy, the authors have carried out a new simulation of the 3D±J model, using a bivariate multicanonical Monte Carlo method. It is expected that the multicanonical method will be useful in overcoming the slow dynamics of spin-glass simulation

  20. A Bivariate Whole Genome Linkage Study Identified Genomic Regions Influencing Both BMD and Bone Structure

    OpenAIRE

    Liu, Xiao-Gang; Liu, Yong-Jun; Liu, Jianfeng; Pei, Yufang; Xiong, Dong-Hai; Shen, Hui; Deng, Hong-Yi; Papasian, Christopher J.; Drees, Betty M.; Hamilton, James J.; Recker, Robert R.; Deng, Hong-Wen

    2008-01-01

    Areal BMD (aBMD) and areal bone size (ABS) are biologically correlated traits and are each important determinants of bone strength and risk of fractures. Studies showed that aBMD and ABS are genetically correlated, indicating that they may share some common genetic factors, which, however, are largely unknown. To study the genetic factors influencing both aBMD and ABS, bivariate whole genome linkage analyses were conducted for aBMD-ABS at the femoral neck (FN), lumbar spine (LS), and ultradis...

  1. A BIVARIATE PROBABILITY MODEL TO IDENTIFY “HONESTY” VERSUS “CHEATING” IN ECONOMIC SURVEYS: XENOPHOBIA IS ILLUSTRATED

    Directory of Open Access Journals (Sweden)

    Ramalingam Shanmugam

    2014-01-01

    Full Text Available Making successful policies for manufacturing or globalized business sectors require “honest” answers by the respondents in the surveys. When some respondents cheat in their answers to the questions in a survey for a variety of reasons, the survey results become useless. Currently, there is no appropriate probability model to address this phenomenon “cheating” in a survey. An efficient methodology is needed to estimate the proportion of “cheaters” in a survey and assess the statistical significance of the estimate. Such a methodology does not exist now in the literature. This article fulfils the need. In a pioneering manner, this article has formulated a bivariate probability model to explain the “cheating” in surveys. Several statistical properties of this new model are identified and explained. For illustration of the new probability model, the responses from 259 less and 217 more educated Germans about xenophobia are considered. The xenophobia is a stumbling block to a successful business operation in this globalized economy. Two psychometric reasons: “Insecurity level” and “social pressure” behind the xenophobia are captured with the help of the probability model and they are explained. The model of this article helps to predict “honesty” versus “cheating” levels in a survey. A statistical testing procedure is prepared to check whether an estimated “social pressure” level is significant.

  2. Microquake activity associated with underground nuclear testing at the Nevada Test Site

    International Nuclear Information System (INIS)

    In the fall of 1976, the Los Alamos Close-In Seismic Network was added to the existing strong motion net deployed around each nuclear test conducted by Los Alamos. Six to ten stations, including both accelerometers and seismometers, are installed within a two-DOB (depth of burial) circle around SGZ (surface ground zero) and operated until the major portion of the microquake activity ceases, usually within 48 hours. Epicentral locations are determined and local magnitudes are calculated from event durations. Four primary conclusions have been reached on the basis of the data analyzed to date: (1) major faults bounding the immediate site of a nuclear test confine the observed microquake activity to the structural block in which the test is conducted; (2) microquake epicenters are generally distributed around the cavity created by the nuclear test with the peak occurrence generally occurring about three cavity radii away from the working point; (3) magnitudes of locatable microquakes apparently distribute randomly over the entire region of activity; and (4) the microquake activity as a function of time appears to be controlled by the collapse phenomenology

  3. Adaptive robust genetic association tests using case-parents triad families.

    Science.gov (United States)

    Wang, Jiun-Yi; Tai, John Jen

    2015-05-01

    Using the conditional likelihood, a model-specific score test can be derived under a given genetic model to test genetic association for case-parents triad family data. When the underlying genetic model is correctly specified, the score test is most powerful. However, it can lose substantial power when the model is misspecified. Several robust tests have been proposed to deal with the problem, such as the maximum test statistic, the maximin efficiency robust test, and the constrained likelihood ratio test. These tests have been shown to be robust against model misspecification compared with those model-specific score tests, but they are either time-consuming in computation or not sufficiently high in power robustness under some situations. In this study, a data-driven procedure is proposed to construct two adaptive robust genetic association tests WMERT and WMAX . The WMERT is simple in calculation and has fairly high power robustness. The empirical power of WMAX is quite stable and close to those of the model-specific score tests. The two proposed tests should be beneficial to practical genetic association studies. A real dataset consisting of neural tube defect triad families is used for illustration of the methods. R-scripts are also provided for numerical calculation of the proposed methods in practical studies. PMID:25764170

  4. Issues concerning Landowner Management Plan Adoption Decisions: A Recursive Bivariate Probit Approach

    Directory of Open Access Journals (Sweden)

    Omkar Joshi

    2015-01-01

    Full Text Available Despite the likely benefits of having a written forest management plan, a small number of landowners in the United States have the one. A recursive bivariate probit model was used to identify the possible relationship between landowners’ decision to obtain a management plan and their interest in future timber harvesting. Our study results based on recursive bivariate model suggest that landowners having larger land ownerships, longer forest ownership tenure, and higher education were more likely to have a forest management plan and future timber harvesting interest. While the landowners having interest for wildlife management were also interested to have a written management plan, they did not prefer to harvest in future. Study results indicate that written management plan means more than a timber harvesting strategy to landowners in general. Many elderly landowners with a low level of income and less formal education and those having small or medium sized tracts of forestland are less likely to own a written management plan. Therefore, this group requires special attention in various government sponsored forest management related extension activities. Future research on understanding landowner perception behind written management plan is recommended.

  5. Awareness and acceptability of human papillomavirus vaccine: an application of the instrumental variables bivariate probit model

    Directory of Open Access Journals (Sweden)

    Do Young Kyung

    2012-01-01

    Full Text Available Abstract Background Although lower uptake rates of the human papillomavirus (HPV vaccine among socioeconomically disadvantaged populations have been documented, less is known about the relationships between awareness and acceptability, and other factors affecting HPV vaccine uptake. The current study aimed to estimate the potential effectiveness of increased HPV vaccine awareness on the acceptability of HPV vaccination in a nationally representative sample of women, using a methodology that controlled for potential non-random selection. Methods This study used a population-based sample from the 2007 Health Information National Trends Survey, a cross-sectional study of the US population aged 18 years or older, and focused on the subsample of 742 women who have any female children under the age of 18 years in the household. An instrumental variables bivariate probit model was used to jointly estimate HPV vaccine awareness and acceptability. Results The proportion of HPV vaccine acceptability among the previously aware and non-aware groups was 58% and 47%, respectively. Results from the instrumental variables bivariate probit model showed that the estimated marginal effect of awareness on acceptability was 46 percentage points, an effect that was even greater than observed. Conclusions Among populations who are not currently aware of the HPV vaccine, the potential impact of raising awareness on acceptability of HPV vaccination is substantial. This finding provides additional support to strengthening public health programs that increase awareness and policy efforts that address barriers to HPV vaccination.

  6. Bivariate cumulative probit model for the comparison of neuronal encoding hypotheses.

    Science.gov (United States)

    Hillmann, Julia; Kneib, Thomas; Koepcke, Lena; Juárez Paz, León M; Kretzberg, Jutta

    2014-01-01

    Understanding the way stimulus properties are encoded in the nerve cell responses of sensory organs is one of the fundamental scientific questions in neurosciences. Different neuronal coding hypotheses can be compared by use of an inverse procedure called stimulus reconstruction. Here, based on different attributes of experimentally recorded neuronal responses, the values of certain stimulus properties are estimated by statistical classification methods. Comparison of stimulus reconstruction results then allows to draw conclusions about relative importance of covariate features. Since many stimulus properties have a natural order and can therefore be considered as ordinal, we introduce a bivariate ordinal probit model to obtain classifications for the combination of light intensity and velocity of a visual dot pattern based on different covariates extracted from recorded spike trains. For parameter estimation, we develop a Bayesian Gibbs sampler and incorporate penalized splines to model nonlinear effects. We compare the classification performance of different individual cell covariates and simple features of groups of neurons and find that the combination of at least two covariates increases the classification performance significantly. Furthermore, we obtain a non-linear effect for the first spike latency. The model is compared to a naïve Bayesian stimulus estimation method where it yields comparable misclassification rates for the given dataset. Hence, the bivariate ordinal probit model is shown to be a helpful tool for stimulus reconstruction particularly thanks to its flexibility with respect to the number of covariates as well as their scale and effect type. PMID:24186131

  7. A bivariate optimal replacement policy with cumulative repair cost limit under cumulative damage model

    Indian Academy of Sciences (India)

    MIN-T SAI LAI; SHIH-CHIH CHEN

    2016-05-01

    In this paper, a bivariate replacement policy (n, T) for a cumulative shock damage process is presented that included the concept of cumulative repair cost limit. The arrival shocks can be divided into two kinds of shocks. Each type-I shock causes a random amount of damage and these damages are additive. When the total damage exceeds a failure level, the system goes into serious failure. Type-II shock causes the system into minor failure and such a failure can be corrected by minimal repair. When a minor failure occurs, the repaircost will be evaluated and minimal repair is executed if the accumulated repair cost is less than a predetermined limit L. The system is replaced at scheduled time T, at n-th minor failure, or at serious failure. The long-term expected cost per unit time is derived using the expected costs as the optimality criterion. The minimum-cost policy is derived, and existence and uniqueness of the optimal n* and T* are proved. This bivariate optimal replacement policy (n, T) is showed to be better than the optimal T* and the optimal n* policy.

  8. Exploiting Bivariate Dependencies to Speedup Structure Learning in Bayesian Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    Amin Nikanjam; Adel Rahmani

    2012-01-01

    Bayesian optimization algorithm (BOA) is one of the successful and widely used estimation of distribution algorithms (EDAs) which have been employed to solve different optimization problems.In EDAs,a model is learned from the selected population that encodes interactions among problem variables.New individuals are generated by sampling the model and incorporated into the population.Different probabilistic models have been used in EDAs to learn interactions.Bayesian network (BN) is a well-known graphical model which is used in BOA.Learning a proper model in EDAs and particularly in BOA is distinguished as a computationally expensive task.Different methods have been proposed in the literature to improve the complexity of model building in EDAs.This paper employs bivariate dependencies to learn accurate BNs in BOA efficiently.The proposed approach extracts the bivariate dependencies using an appropriate pairwise interaction-detection metric.Due to the static structure of the underlying problems,these dependencies are used in each generation of BOA to learn an accurate network.By using this approach,the computational cost of model building is reduced dramatically.Various optimization problems are selected to be solved by the algorithm.The experimental results show that the proposed approach successfully finds the optimum in problems with different types of interactions efficiently.Significant speedups are observed in the model building procedure as well.

  9. A method of moments to estimate bivariate survival functions: the copula approach

    Directory of Open Access Journals (Sweden)

    Silvia Angela Osmetti

    2013-05-01

    Full Text Available In this paper we discuss the problem on parametric and non parametric estimation of the distributions generated by the Marshall-Olkin copula. This copula comes from the Marshall-Olkin bivariate exponential distribution used in reliability analysis. We generalize this model by the copula and different marginal distributions to construct several bivariate survival functions. The cumulative distribution functions are not absolutely continuous and they unknown parameters are often not be obtained in explicit form. In order to estimate the parameters we propose an easy procedure based on the moments. This method consist in two steps: in the first step we estimate only the parameters of marginal distributions and in the second step we estimate only the copula parameter. This procedure can be used to estimate the parameters of complex survival functions in which it is difficult to find an explicit expression of the mixed moments. Moreover it is preferred to the maximum likelihood one for its simplex mathematic form; in particular for distributions whose maximum likelihood parameters estimators can not be obtained in explicit form.

  10. A semiparametric approach to simultaneous covariance estimation for bivariate sparse longitudinal data.

    Science.gov (United States)

    Das, Kiranmoy; Daniels, Michael J

    2014-03-01

    Estimation of the covariance structure for irregular sparse longitudinal data has been studied by many authors in recent years but typically using fully parametric specifications. In addition, when data are collected from several groups over time, it is known that assuming the same or completely different covariance matrices over groups can lead to loss of efficiency and/or bias. Nonparametric approaches have been proposed for estimating the covariance matrix for regular univariate longitudinal data by sharing information across the groups under study. For the irregular case, with longitudinal measurements that are bivariate or multivariate, modeling becomes more difficult. In this article, to model bivariate sparse longitudinal data from several groups, we propose a flexible covariance structure via a novel matrix stick-breaking process for the residual covariance structure and a Dirichlet process mixture of normals for the random effects. Simulation studies are performed to investigate the effectiveness of the proposed approach over more traditional approaches. We also analyze a subset of Framingham Heart Study data to examine how the blood pressure trajectories and covariance structures differ for the patients from different BMI groups (high, medium, and low) at baseline. PMID:24400941

  11. Test of Association Between 10 SNPs in the Oxytocin Receptor Gene and Conduct Disorder

    OpenAIRE

    Sakai, Joseph T.; Crowley, Thomas J.; Stallings, Michael C.; McQueen, Matthew; Hewitt, John K.; Hopfer, Christian; Hoft, Nicole R.; Ehringer, Marissa A.

    2012-01-01

    Animal and human studies have implicated oxytocin (OXT) in affiliative and prosocial behaviors. We tested whether genetic variation in the OXT receptor (OXTR) gene is associated with conduct disorder (CD).

  12. A Simple Test of Class-Level Genetic Association Can Reveal Novel Cardiometabolic Trait Loci

    OpenAIRE

    Qian, Jing; Nunez, Sara; Reed, Eric; Reilly, Muredach P.; Foulkes, Andrea S.

    2016-01-01

    Background Characterizing the genetic determinants of complex diseases can be further augmented by incorporating knowledge of underlying structure or classifications of the genome, such as newly developed mappings of protein-coding genes, epigenetic marks, enhancer elements and non-coding RNAs. Methods We apply a simple class-level testing framework, termed Genetic Class Association Testing (GenCAT), to identify protein-coding gene association with 14 cardiometabolic (CMD) related traits acro...

  13. British Nuclear Test Veterans' Association. Radiation exposure and subsequent health history of veterans and their children

    International Nuclear Information System (INIS)

    The present study of veterans' health carried out in association with Tyne Tees Television presents new and disturbing evidence of significant health effects in both veterans and their children, based on the health records of 1,454 members of the British Nuclear Test Veterans' Association, of whom 1,147 were fathers. (orig./MG)

  14. Comparison of a commercial bovine pregnancy-associated glycoprotein ELISA test and a pregnancy-associated glycoprotein radiomimmunoassay test for early pregnancy diagnosis in dairy cattle.

    Science.gov (United States)

    Karen, Aly; Sousa, Noelita Melo De; Beckers, Jean-François; Bajcsy, Árpád Csaba; Tibold, János; Mádl, István; Szenci, Ottó

    2015-08-01

    The present study aimed to compare the accuracy of a commercial PAG-ELISA test (Bovine Preg Test 29) and bovine pregnancy-associated glycoprotein radioimmunoassay (PAG-RIA) for diagnosing pregnancy at Day 28 after insemination in dairy cows. Transrectal ultrasonography (TRUS) was performed in 100 Holstein-Friesian cows at Day 28 after artificial insemination (AI; Day 0) to diagnose pregnancy. After TRUS examination, blood sample was collected from the coccygeal vessels of each cow to measure the concentrations of bPAGs by PAG-RIA test and Bovine Preg Test 29. Milk samples were collected at Days 0, 21 and 28 for measurement of progesterone (P4) by ELISA test. The cows were re-examined by TRUS at Day 42 to confirm the pregnancy diagnoses. The actual gold standard was based on TRUS outcomes at Day 28 that agreed with the outcomes of PAG-RIA test or PAG-ELISA test. If the outcomes of TRUS at Day 28 and PAG-RIA test and PAG-ELISA test did not agree, the gold standard was based on the outcome of TRUS at Day 42. Out of 100 inseminated cows, 41 were confirmed pregnant at Day 28 after AI. Based on the actual gold standard, the sensitivity of TRUS, PAG-ELISA and PAG-RIA tests for diagnosing pregnant cows at Day 28 were 92.7%, 90.2% and 100%, while the specificity of the three tests for diagnosing non-pregnant cows were 91.5%, 98.3% and 94.4%, respectively. The overall accuracy of the three tests were 92%, 95% and 97%, respectively. The degree of agreement (Kappa±S.E.) between PAG-RIA and PAG-ELISA test was 0.90 ±0.04. The degrees of agreement between PAG-RIA and PAG-ELISA and TRUS at Day 28 were 0.80±0.05 and 0.76±0.06, respectively. In conclusion, the commercial PAG-ELISA test is a highly accurate method for diagnosing early pregnancy in dairy cows on Day 28 after AI and may be used as an alternative method to the TRUS and the PAG-RIA test. PMID:26059776

  15. Lactulose Hydrogen Breath Test Result Is Associated with Age and Gender

    OpenAIRE

    Newberry, Carolyn; Tierney, Ann; Pickett-Blakely, Octavia

    2016-01-01

    Small intestinal bacterial overgrowth (SIBO) is associated with chronic gastrointestinal diseases and structural/functional abnormalities of the gastrointestinal tract. SIBO’s association with clinical characteristics is unclear. This study investigates the association between clinical factors and SIBO according to lactulose hydrogen breath test (LHBT) result. Methods. A cross-sectional study in a university-based gastroenterology practice was performed. Data was abstracted from the medical r...

  16. A robust statistical method for case-control association testing with copy number variation

    OpenAIRE

    Barnes, Chris; Plagnol, Vincent; Fitzgerald, Tomas; Redon, Richard; Marchini, Jonathan; Clayton, David; Hurles, Matthew E.

    2008-01-01

    Copy number variation (CNV) is pervasive in the human genome and can play a causal role in genetic diseases. The functional impact of CNV cannot be fully captured through linkage disequilibrium with SNPs. These observations motivate the development of statistical methods for performing direct CNV association studies. We show through simulation that current tests for CNV association are prone to false-positive associations in the presence of differential errors between cases and controls, espe...

  17. An enhanced version of Cochran-Armitage trend test for genome-wide association studies.

    Science.gov (United States)

    Ghodsi, Mansi; Amiri, Saeid; Hassani, Hossein; Ghodsi, Zara

    2016-09-01

    Genome-wide association studies the evaluation of association between candidate gene and disease status is widely carried out using Cochran-Armitage trend test. However, only a small number of research papers have evaluated the distribution of p-values for the Cochran-Armitage trend test. In this paper, an enhanced version of Cochran-Armitage trend test based on bootstrap approach is introduced. The achieved results confirm that the distribution of p-values of the proposed approach fits better to the uniform distribution, and it is thus concluded that the proposed method, which needs less assumptions in comparison with the conventional method, can be successfully used to test the genetic association. PMID:27617223

  18. Testing for direct genetic effects using a screening step in family-based association studies

    Directory of Open Access Journals (Sweden)

    Sharon M Lutz

    2013-11-01

    Full Text Available In genome wide association studies (GWAS, families based studies tend to have less power to detect genetic associations than population based studies, such as case-control studies. This can be an issue when testing if genes in a family based GWAS have a direct effect on the phenotype of interest or if the genes act indirectly through a secondary phenotype. When multiple SNPs are tested for a direct effect in the family based study, a screening step can be used to minimize the burden of multiple comparisons in the causal analysis. We propose a 2-stage screening step that can be incorporated into the family based association test (FBAT approach similar to the conditional mean model approach in the VanSteen-algorithm [1]. Simulations demonstrate that the type 1 error is preserved and this method is advantageous when multiple markers are tested. This method is illustrated by an application to the Framingham Heart Study.

  19. Pulmonary function tests in patients with amyotrophic lateral sclerosis and the association between these tests and survival

    OpenAIRE

    Seyed-Ali Javad Mousavi; Babak Zamani; Shahab Shahabi Shahmiri; Mohammad Rohani; Gholam Ali Shahidi; Elyas Mostafapour; Helia Hemasian; Hanieh Raji

    2014-01-01

    Background: The rapidity of progression of amyotrophic lateral sclerosis (ALS) to death or respiratory failure impacts patients, clinicians, and clinical investigators. The aim of this study is to evaluate of the pulmonary function tests (PFTs) in patients with ALS and the association between these PFTs and survival Methods: A total of 36 ALS patients who PFTs, including vital capacity (VC), maximum mid-expiratory flow rate (MMEFR), forced vital capacity (FVC), and forced expiratory volume in...

  20. Noise Removal From Microarray Images Using Maximum a Posteriori Based Bivariate Estimator

    Directory of Open Access Journals (Sweden)

    A.Sharmila Agnal

    2013-01-01

    Full Text Available Microarray Image contains information about thousands of genes in an organism and these images are affected by several types of noises. They affect the circular edges of spots and thus degrade the image quality. Hence noise removal is the first step of cDNA microarray image analysis for obtaining gene expression level and identifying the infected cells. The Dual Tree Complex Wavelet Transform (DT-CWT is preferred for denoising microarray images due to its properties like improved directional selectivity and near shift-invariance. In this paper, bivariate estimators namely Linear Minimum Mean Squared Error (LMMSE and Maximum A Posteriori (MAP derived by applying DT-CWT are used for denoising microarray images. Experimental results show that MAP based denoising method outperforms existing denoising techniques for microarray images.

  1. Long-term availability of uranium resources: a bivariate statistical approach

    International Nuclear Information System (INIS)

    This poster describes the bivariate supply model that is based on deposit cost and Uranium content, both being functions of grade and tonnage. This model is applied to the case of the United States taking into account known and unknown US deposits,a bias has been applied due to the discovery of bigger and richer deposits. In a next step the supply model will be used in the price formation mechanism which will allow long-term resource depletion to be included in the mid-term dynamics of the price mechanism. Today conventional price formation mechanisms are generally limited to short/mid-term with limited production rates but with no resource depletion

  2. On the joint spectral density of bivariate random sequences. Thesis Technical Report No. 21

    Science.gov (United States)

    Aalfs, David D.

    1995-01-01

    For univariate random sequences, the power spectral density acts like a probability density function of the frequencies present in the sequence. This dissertation extends that concept to bivariate random sequences. For this purpose, a function called the joint spectral density is defined that represents a joint probability weighing of the frequency content of pairs of random sequences. Given a pair of random sequences, the joint spectral density is not uniquely determined in the absence of any constraints. Two approaches to constraining the sequences are suggested: (1) assume the sequences are the margins of some stationary random field, (2) assume the sequences conform to a particular model that is linked to the joint spectral density. For both approaches, the properties of the resulting sequences are investigated in some detail, and simulation is used to corroborate theoretical results. It is concluded that under either of these two constraints, the joint spectral density can be computed from the non-stationary cross-correlation.

  3. Analysis of the Bivariate Parameter Wind Differences Between Jimsphere and Windsonde

    Science.gov (United States)

    Susko, Michael

    1987-01-01

    An analysis is presented for the bivariate parameter differences between the FPS-16 Radar/Jimsphere and the Meteorological Sounding System (MSS) Windsonde. The Jimsphere is used as the standard to measure the ascent wind during the Space Shuttle launches at Kennedy Space Center, Florida, and the Windsonde is the backup system. In addition, a discussion of the terrestrial environment (below 20 km) and a description of the Jimsphere and Windsonde wind sensors are given. Computation of the wind statistics from 64 paired Jimsphere and Windsonde balloon releases in support of 14 Space Shuttle launches shows a good agreement between the two wind sensors. From the analysis of buildup and back-off data for various scales of distance and the comparison of the cumulative percent frequency (CPF) versus wind speed change, it is shown that the wind speed change for various scales of distances for the Jimsphere and Windsonde compare favorably.

  4. Statistical Evaluation of Bivariate, Ternary and Discriminant Function Tectonomagmatic Discrimination Diagrams

    OpenAIRE

    VERMA, Surendra P.

    2010-01-01

    This work applies a statistical methodology involving the calculation of success rates to evaluate a total of 28 tectonomagmatic discrimination diagrams: four bivariate (Ti/Y-Zr/Y; Zr-Zr/Y; Ti/1000-V; and Nb/Y-Ti/Y); six ternary (Zr-3Y-Ti/1000; MgO-Al2O3-FeOt, Th-Ta-Hf/3; 10MnO-15P2O5-TiO2; Zr/4-Y-2Nb; and La/10-Nb/8-Y/15); and three old (Score1-Score2; F1-F2; and F2-F3) and three sets of new discriminant function diagrams (each set consisting of five DF1-DF2 type diagrams proposed during 200...

  5. Constructing a bivariate distribution function with given marginals and correlation: application to the galaxy luminosity function

    Science.gov (United States)

    Takeuchi, Tsutomu T.

    2010-08-01

    We provide an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient |ρ| correlation is stronger, the FGM copula cannot work anymore. In this case, we propose using a Gaussian copula, which connects two given marginals and is directly related to the linear correlation coefficient between two variables. Using the copulas, we construct the bivariate luminosity function (BLF) and discuss its statistical properties. We focus especially on the far-infrared-far-ulatraviolet (FUV-FIR) BLF, since these two wavelength regions are related to star-formation (SF) activity. Though both the FUV and FIR are related to SF activity, the univariate LFs have a very different functional form: the former is well described by the Schechter function whilst the latter has a much more extended power-law-like luminous end. We construct the FUV-FIR BLFs using the FGM and Gaussian copulas with different strengths of correlation, and examine their statistical properties. We then discuss some further possible applications of the BLF: the problem of a multiband flux-limited sample selection, the construction of the star-formation rate (SFR) function, and the construction of the stellar mass of galaxies (M*)-specific SFR (SFR/M*) relation. The copulas turn out to be a very useful tool to investigate all these issues, especially for including complicated selection effects.

  6. A continuous bivariate model for wind power density and wind turbine energy output estimations

    International Nuclear Information System (INIS)

    The wind power probability density function is useful in both the design process of a wind turbine and in the evaluation process of the wind resource available at a potential site. The continuous probability models used in the scientific literature to estimate the wind power density distribution function and wind turbine energy output assume that air density is independent of the wind speed. A constant annual value for air density of 1.225 kg m-3, corresponding to standard conditions (sea level, 15 oC), is generally used. A bivariate probability model (BPM) is presented in this paper for wind power density and wind turbine energy output estimations. This model takes into account the time variability of air density and wind speed, as well as the correlation existing between both variables. Contingency type bivariate distributions with specified marginal distributions have been used for this purpose. The proposed model is applied in this paper to meteorological data (temperature, pressure, relative humidity, wind speed) recorded over a one year period at a weather station located at the facilities of the Technological Institute of the Canary Islands (Spain). The conclusion reached is that the BPM presented in this paper is more realistic than the univariate probability models (UPMs) normally used in the scientific literature. In the particular case under study, and for all the situations analysed, the BPM has provided values for the annual mean wind power density and annual energy output of a wind turbine that fit the sample data better than the UPMs. However, as a result of the climatological characteristics of the area where the analysis was performed, the results do not differ notably from those obtained through the use of a UPM and the mean air density of the area

  7. A bivariate mixture model analysis of body weight and ascites traits in broilers.

    Science.gov (United States)

    Zerehdaran, S; van Grevehof, E M; van der Waaij, E H; Bovenhuis, H

    2006-01-01

    The objective of the present study was to use bivariate mixture models to study the relationships between body weight (BW) and ascites indicator traits. Existing data were used from an experiment in which birds were housed in 2 groups under different climate conditions. In the first group, BW, the ratio of right ventricular weight to total ventricular weight (RV:TV), and hematocrit value (HCT) were measured in 4,202 broilers under cold conditions; in the second group, the same traits were measured in 795 birds under normal temperature conditions. Cold-stress conditions were applied to identify individuals that were susceptible to ascites. The RV:TV and HCT were approximately normally distributed under normal temperature conditions, whereas the distributions of these traits were skewed under cold temperature conditions, suggesting different underlying distributions. Fitting a bivariate mixture model to the observations showed that there was only one homogeneous population for ascites traits under normal temperature conditions, whereas there was a mixture of (2) distributions under cold conditions. One distribution contained nonascitic birds and the other distribution contained ascitic birds. In the distribution of nonascitic birds, the inferred phenotypic correlations (phenotypic correlations with 2 distinguishing underlying distributions) of BW with RV:TV and HCT were close to zero (0.10 and -0.07, respectively), whereas in the distribution of ascitic birds, the inferred phenotypic correlations of BW with RV:TV and HCT were negative (-0.39 and -0.4, respectively). The negative inferred correlations of BW with RV:TV and HCT in the distribution of ascitic birds resulted in negative overall correlations (correlations without 2 distinguishing distributions) of BW with RV:TV (-0.30) and HCT (-0.37) under cold conditions. The present results indicate that the overall correlations between BW and ascites traits are dependent on the relative frequency of ascitic and

  8. A fast multilocus test with adaptive SNP selection for large-scale genetic-association studies

    KAUST Repository

    Zhang, Han

    2013-09-11

    As increasing evidence suggests that multiple correlated genetic variants could jointly influence the outcome, a multilocus test that aggregates association evidence across multiple genetic markers in a considered gene or a genomic region may be more powerful than a single-marker test for detecting susceptibility loci. We propose a multilocus test, AdaJoint, which adopts a variable selection procedure to identify a subset of genetic markers that jointly show the strongest association signal, and defines the test statistic based on the selected genetic markers. The P-value from the AdaJoint test is evaluated by a computationally efficient algorithm that effectively adjusts for multiple-comparison, and is hundreds of times faster than the standard permutation method. Simulation studies demonstrate that AdaJoint has the most robust performance among several commonly used multilocus tests. We perform multilocus analysis of over 26,000 genes/regions on two genome-wide association studies of pancreatic cancer. Compared with its competitors, AdaJoint identifies a much stronger association between the gene CLPTM1L and pancreatic cancer risk (6.0 × 10(-8)), with the signal optimally captured by two correlated single-nucleotide polymorphisms (SNPs). Finally, we show AdaJoint as a powerful tool for mapping cis-regulating methylation quantitative trait loci on normal breast tissues, and find many CpG sites whose methylation levels are jointly regulated by multiple SNPs nearby.

  9. The association between methacholine challenge test and respiratory symptoms: a study on 146 patients

    Directory of Open Access Journals (Sweden)

    Paknejad O

    2011-02-01

    Full Text Available "nBackground: Asthma is a life-threatening disease that can cause death due to bronchospasm. In addition to clinical symptoms such as wheezing, acute paroxysmal dyspnea, chronic cough after exposure to cold air or cough after exercise, spirometry is also necessary for the diagnosis of asthma. The association between respiratory symptoms and a positive methacholine challenge test (MCT is still controversial. The aim of this study was to determine the association between methacholine test results and respiratory symptoms and allergy."n "nMethods: One hundred and forty-six patients with respiratory symptoms and normal baseline pulmonary function tests were enrolled in this cross-sectional study. The participants were divided into two groups according to their positive or negative response to MCT. The association between MCT and the clinical symptoms and allergy was later evaluated statistically."n "nResults: Out of 146 participants of the study 59 (40.4% were female and 87 (59.6% were male. The mean age of the participants was 33.8±13.8 years. Sixty-one patients (41.8% had positive results for the test. There was an association between a history of allergy, wheezing and age with positive MCT results. The other clinical signs had no association with the test."n "nConclusion: Methacholine challenge test is the best diagnostic test for ruling out asthma in patients with normal pulmonary function tests in whom we cannot definitely rule out asthma based solely on clinical symptoms. Nevertheless, in adults with a history of allergy, wheezing and also in patients below 30, the probability for a positive MCT is high.

  10. On the Relationship between Pearson Correlation Coefficient and Kendall’s Tau under Bivariate Homogeneous Shock Model

    OpenAIRE

    Jiantian Wang

    2012-01-01

    This paper studies the relationship between Kendall's tau and Pearson correlation coefficient under the so-called bivariate homogeneous shock (BHS) model. We find Capéraà-Genest-type inequality may not hold for general BHS model. Computational simulations suggest that the Denials' inequality is likely to be true.

  11. Case-Control Association Testing in the Presence of Unknown Relationships

    OpenAIRE

    Choi, Yoonha; Wijsman, Ellen M; Weir, Bruce S.

    2009-01-01

    Genome-wide association studies result in inflated false positive results when unrecognized cryptic relatedness exists. A number of methods have been proposed for testing association between markers and disease with a correction for known pedigree-based relationships. However, in most case-control studies, relationships are generally unknown, yet the design is predicated on the assumption of at least ancestral relatedness among cases. Here, we focus on adjusting cryptic relatedness when the g...

  12. Bayesian Genetic Association Test when Secondary Phenotypes Are Available Only in the Case Group

    OpenAIRE

    Yongku Kim; Minjung Kwak

    2016-01-01

    In many case-control genetic association studies, a secondary phenotype that may have common genetic factors with disease status can be identified. When information on the secondary phenotype is available only for the case group due to cost and different data sources, a fitting linear regression model ignoring supplementary phenotype data may provide limited knowledge regarding genetic association. We set up a joint model and use a Bayesian framework to estimate and test the effect of genetic...

  13. Characterizing switching and congruency effects in the Implicit Association Test as reactive and proactive cognitive control

    OpenAIRE

    Hilgard, Joseph; Bartholow, Bruce D.; Dickter, Cheryl L.; Blanton, Hart

    2014-01-01

    Recent research has identified an important role for task switching, a cognitive control process often associated with executive functioning, in the Implicit Association Test (IAT). However, switching does not fully account for IAT effects, particularly when performance is scored using more recent d-score formulations. The current study sought to characterize multiple control processes involved in IAT performance through the use of event-related brain potentials (ERPs). Participants performed...

  14. Test Methods and Protocols for Environmental and Safety Hazards Associated with Home Energy Retrofits

    Energy Technology Data Exchange (ETDEWEB)

    Cautley, D. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Viner, J. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Lord, M. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Pearce, M. [NorthernSTAR Building America Partnership, St. Paul, MN (United States)

    2012-12-01

    A number of health hazards and hazards to the durability of homes may be associated with energy retrofitting and home renovation projects. Among the hazards associated with energy retrofit work, exposure to radon is thought to cause more than 15,000 deaths per year in the U.S., while carbon monoxide poisoning results in about 20,000 injuries and 450 deaths per year. Testing procedures have been developed for identifying and quantifying hazards during retrofitting. These procedures commonly include a battery of tests to screen combustion appliances for safe operation, including worst case depressurization measurement, backdrafting (spillage) under depressurized or normal conditions, and carbon monoxide production.

  15. The association between late-life cognitive test scores and retrospective informant interview data

    OpenAIRE

    Marioni, Riccardo E; Matthews, Fiona E; Brayne, Carol; MRC Cognitive Function & Ageing St

    2011-01-01

    Background: Cognitive assessment of older persons, particularly those with impairment, is hampered by measurement error and the ethical issues of testing people with dementia. A potential source of valuable information about end-of-life cognitive status can be gained from those who knew the respondent well mostly relatives or friends. This study tested the association benveen last cognitive assessment before death and a retrospective informant assessment of cognition.Methods: Data were analyz...

  16. Social Determinants of Health Associated with Self-Reported HIV Testing among Women

    Directory of Open Access Journals (Sweden)

    Shahab Rezaeian

    2013-04-01

    Full Text Available Background: There currently is lack of knowledge about HIV testing practices in Iran. The purpose of this pilot study was to evaluate the prevalence of self-reported HIV testing and its associated factors among women.Methods: This cross-sectional study was conducted in Sanandaj City, located in the west of Iran, in 2012. Data were collected using self-administered questionnaire including demographics characteristics and the main outcome variable was self-reported HIV testing. The univariate and multivariate logistic regression models using STATA software was used for data analysis.Results: A total of 1200 women were interviewed during the study (Response rate=87.5%. The mean age was 29.67 years (SD: 7.01 years, 49% were aged 28 years or younger, 39.2% were single, 16.9% were pregnant and 60% did not have academic education. The proportion of women that were HIV-tested was, 32.1% (CI 95%: 29.2%, 35.0%. HIV testing was associated with younger age, knowledge of HIV/AIDS, household wealth, pregnancy, academic education, occupation and duration time of occupation, rating of quality of health services and substance use history in her husband.Conclusion: The self-reported HIV testing rate among our sample women is 32.1%, lower than the HIV testing rate in other studies. Therefore, interventions to expand HIV testing and increase awareness of HIV risk are urgently needed in Iran.

  17. Flood hazard in the Mekong Delta - a probabilistic, bivariate, and non-stationary analysis with a short-termed future perspective

    Science.gov (United States)

    Dung, N. V.; Merz, B.; Bárdossy, A.; Apel, H.

    2013-02-01

    In this paper we present a novel approach for flood hazard analysis of the whole Mekong Delta with a particular focus on the Vietnamese part. Based on previous studies identifying the flood regime in the Mekong delta as non-stationary (Delgado et al., 2010), we develop a non-stationary approach for flood hazard analysis. Moreover, the approach is also bi-variate, as the flood severity in the Mekong Delta is determined by both maximum discharge and flood volume, which determines the flood duration. Probabilities of occurrences of peak discharge and flood volume are estimated by a copula. The flood discharges and volumes are used to derive synthetic hydrographs, which in turn constitute the upper boundary condition for a large-scale hydrodynamic model covering the whole Mekong Delta. The hydrodynamic model transforms the hydrographs into hazard maps. In addition, we extrapolate the observed trends in flood peak and volume and their associated non-stationary extreme value distributions to the year 2030 in order to give a flood hazard estimate for the near future. The uncertainty of extreme flood events in terms of different possible combinations of peak discharge and flood volume given by the copula is considered. Also, the uncertainty in flood hydrograph shape is combined with parameter uncertainty of the hydrodynamic model in a Monte Carlo framework yielding uncertainty estimates in terms of quantile flood maps. The proposed methodology sets the frame for the development of probabilistic flood hazard maps for the entire Mekong Delta. The combination of bi-variate, non-stationary extreme value statistics with large-scale flood inundation modeling and uncertainty quantification is novel in itself. Moreover, it is in particular novel for the Mekong Delta: a region where not even a standard hazard analysis based on a univariate, stationary extreme value statistic exists.

  18. Estimated of the associated uncertaintes with the linearity test of activimeters

    International Nuclear Information System (INIS)

    Activimeters determine the activity of radioactive samples and are validated by performance tests. This research determined the expanded uncertainties associated with the linearity test. We used two activimeters and a source of 99Tcm for testing recommended by the IAEA protocol, which consider the decay of radioactive samples. The expanded uncertainties evaluated were not correlated with each other and our analysis considered a rectangular probability distribution. The results are also presented in graphical form by the function of normalized activity measured in terms of conventional true value

  19. Fatigue testing of a carbon fibre composite wind turbine blade with associated material characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, G.A.; Richardson, D.J. [Univ. of the West of England, Faculty of Engineering, Bristol (United Kingdom)

    1996-09-01

    Within the EC project JOULE 2, the University of the West of England (UWE) tested a carbon fibre reinforced epoxy (CFRE) full scale wind turbine blade together with an associated material test coupon programme. All the work was closely linked with the manufacturer Polymarine BV of the Netherlands, who designed and manufactured the blade and provided test specimens, the UWE carried out the research into the validation of the design calculations together with a check of the strength and fatigue life of the blade. (au)

  20. Impairment of Self-control and its manifestations in Continuous Word Association Test

    Directory of Open Access Journals (Sweden)

    Gabriela Marhevská

    2013-01-01

    Full Text Available The aim of work is to find out how self–control influences word associations. The research presented herein provides new insight into manifestations of self–control. Experimental study is based on the Strength model (Baumeister, Bratslavsky, Muraven, & Tice, 1998, which assumes that self–control relies on limited resources of ego which become depleted with increased exercising of self–control (Ego depletion. The aim of this experiment was to verify in an empirical manner that the impairment of self–control can be manifested in word association tests. Continuous word association test (Kondáš, 1979 was used in this experiment. Distinct indicators of continuous word associations were divided into the following 4 categories; verbal dynamics, abnormalities in association, errors in the reproduction of association reactions and the overall number of mistakes. Parallel task and “e letter” crossing out exercises were used in order to impair ego resource.One–Way ANOVA was used in the analysis. The results of the study indicate that impaired self–control, induced by the “e letter” crossing out task, increased verbal dynamics. According to the obtained results, Continuous word association test provoke automatic processes. Further important indicators of impaired self–control were increased perseverations of potentially conflicting word ′control′, erroneous reproductions of potentially conflicting word ′explosions′ and the overall indicator of mistakes in conflict word‚ explosions and control‘. The experiment results show an increase in the number of mistakes of word association production when self–control is impaired.

  1. Using the Implicit Association Test as an Unconsciousness Raising Tool in Psychology

    Science.gov (United States)

    Casad, Bettina J.; Flores, Abdiel J.; Didway, Jessica D.

    2013-01-01

    People are reluctant to admit they harbor implicit biases. Students (N = 68) from four social psychology courses completed an assignment designed to raise awareness about implicit biases. After completing an Implicit Association Test (IAT), students answered six essay questions, read two articles on the IAT, and answered five additional essay…

  2. 2015 Groundwater Radiological Monitoring Results Associated with the Advanced Test Reactor Complex Cold Waste Ponds

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Michael George [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-02-01

    This report summarizes radiological monitoring results from groundwater wells associated with the Idaho National Laboratory Site’s Advanced Test Reactor Complex Cold Waste Ponds Reuse Permit (I-161-02). All radiological monitoring is performed to fulfill Department of Energy requirements under the Atomic Energy Act.

  3. Assessing Associative Distance among Ideas Elicited by Tests of Divergent Thinking

    Science.gov (United States)

    Acar, Selcuk; Runco, Mark A.

    2014-01-01

    Tests of divergent thinking represent the most commonly used assessment of creative potential. Typically they are scored for total ideational output (fluency), ideational originality, and, sometimes, ideational flexibility. That scoring system provides little information about the underlying process and about the associations among ideas. It also…

  4. Reactions to the Implicit Association Test as an Educational Tool: A Mixed Methods Study

    Science.gov (United States)

    Hillard, Amy L.; Ryan, Carey S.; Gervais, Sarah J.

    2013-01-01

    We examined reactions to the Race Implicit Association Test (IAT), which has been widely used but rarely examined as an educational tool to raise awareness about racial bias. College students (N = 172) were assigned to read that the IAT reflected either personal beliefs or both personal and extrapersonal factors (single vs. multiple explanation…

  5. Analysis of Secondary School Students' Perceptions about Information Technologies through a Word Association Test

    Science.gov (United States)

    Eren, Fetah; Sahin, Ismail; Celik, Ismail; Akturk, Ahmet Oguz

    2014-01-01

    The aim of this study is to discover secondary school students' perceptions related to information technologies and the connections between concepts in their cognitive structures. A word association test consisting of six concepts related to information technologies is used to collect data from 244 secondary school students. Concept maps that…

  6. The Implicit Association Test as a Class Assignment: Student Affective and Attitudinal Reactions

    Science.gov (United States)

    Morris, Kathryn A.; Ashburn-Nardo, Leslie

    2010-01-01

    The Implicit Association Test (IAT) is a popular means of examining "hidden" biases. However, some express concerns about classroom use of the IAT, citing students' potentially negative affective reactions to taking the IAT and discovering their implicit biases. To investigate the validity of this criticism, 35 social psychology students completed…

  7. Factors associated with HIV testing and condom use in Mozambique: implications for programs

    Directory of Open Access Journals (Sweden)

    Agha Sohail

    2012-09-01

    Full Text Available Abstract Background To identify predictors of HIV testing and condom use in Mozambique. Methods Nationally representative survey data collected in Mozambique in 2009 was analyzed. Logistic regression analysis was used for two outcomes: HIV testing and condom use. Results Women at a higher risk of HIV were less likely to be tested for HIV than women at a lower risk: compared to married women, HIV testing was lower among never married women (OR = 0.37, CI: 0.25-0.54; compared to women with one lifetime partner, HIV testing was lower among women with four or more lifetime partners (OR = 0.62, CI: 0.47-0.83. Large wealth differentials were observed: compared to the poorest women, HIV testing was higher among the wealthiest women (OR = 3.03, CI: 1.96-4.68. Perceived quality of health services was an important predictor of HIV testing: HIV testing was higher among women who rated health services as being of very good quality (OR = 2.12, CI: 1.49-3.00. Type of sexual partner was the strongest predictor of condom use: condom use was higher among men who reported last sex with a girlfriend (OR = 9.75, CI: 6.81-13.97 or a casual partner (OR = 11.05, CI: 7.21-16.94. Being tested for HIV during the last two years was the only programmatic variable that predicted condom use. Interestingly, being tested for HIV more than two years ago was not associated with condom use. Frequent mass media exposure was neither associated with HIV testing nor with condom use. Conclusions The focus of HIV testing should shift from married women (routinely tested during antenatal care visits to unmarried women and women with multiple sexual partners. Financial barriers to HIV testing appear to be substantial. Since HIV testing is done without a fee being charged, these barriers are presumably related to the cost of transportation to static health facilities. Mechanisms should be developed to cover the cost of transportation to health facilities

  8. Associations Between Functional Movement Screening, the Y Balance Test, and Injuries in Coast Guard Training.

    Science.gov (United States)

    Cosio-Lima, Ludmila; Knapik, Joseph J; Shumway, Richard; Reynolds, Katy; Lee, Youngil; Greska, Eric; Hampton, Michael

    2016-07-01

    Tests that have the ability to predict injuries in various military and athletic populations are important because of the role they could play in primary prevention. Functional Movement Screen (FMS) and Y Balance Tests (YBT) may provide this prognostic ability. This study examined the association between injuries and age, physical characteristics, FMS, and upper and lower body YBTs among Coast Guard Maritime Security Response Team (MSRT) candidates. Thirty-one male Coast Guard Maritime Security Response Team candidates were administered the 7 FMS tests and lower- and upper-body YBTs before their intense 2-month training course. Age, height, weight, and body mass index were also obtained. Physical training-related injuries were recorded during the course. Injury incidence was 41%. Older age and lower scores on either FMS or the upper-body YBT were associated with higher injury risk. Performance of the lower-body YBT was not associated with injury risk. This is the first investigation showing that lower scores on the upper-body YBT were associated with higher injury risk and is in consonance with previous investigations demonstrating associations between lower FMS scores and higher injury risk. Certain limitations need to be addressed. Future studies should determine if FMS and the YBTs have prognostic ability in other populations. PMID:27391617

  9. Clinical audit of genetic testing and referral patterns for fragile X and associated conditions.

    Science.gov (United States)

    Cotter, Megan; Archibald, Alison D; McClaren, Belinda J; Burgess, Trent; Francis, David; Hills, Louise; Martyn, Melissa; Oertel, Ralph; Slater, Howard; Cohen, Jonathan; Metcalfe, Sylvia A

    2016-06-01

    An audit was conducted of laboratory/clinical databases of genetic tests performed between January 2003 and December 2009, and for 2014, as well as referrals to the clinical service and a specialist multidisciplinary clinic, to determine genetic testing request patterns for fragile X syndrome and associated conditions and referrals for genetic counseling/multidisciplinary management in Victoria, Australia. An expanded allele (full mutation, premutation or intermediate) was found in 3.7% of tests. Pediatricians requested ∼70% of test samples, although fewer general practitioners and more obstetricians/gynecologists ordered tests in 2014. Median age at testing for individuals with a full mutation seeking a diagnosis without a fragile X family history was 4.3 years (males) and 9.4 years (females); these ages were lower when pediatricians ordered the tests (2.1 years and 6.1 years, respectively). Individuals with a premutation were generally tested at a later age (median age: males, 33.2 years; females, 36.4 years). Logistic regression showed that a family history of ID (OR 3.28 P = 0.005, CI 1.77-5.98) was the only indication to independently increase the likelihood of a test-positive (FM or PM) result. Following testing, ∼25% of full mutation or premutation individuals may not have attended clinical services providing genetic counseling or multidisciplinary management for these families. The apparent delay in fragile X syndrome diagnosis and lack of appropriate referrals for some may result in less than optimal management for these families. These findings suggest continued need for awareness and education of health professionals around diagnosis and familial implications of fragile X syndrome and associated conditions. © 2016 Wiley Periodicals, Inc. PMID:26892444

  10. Meta-Analysis of Rare Variant Association Tests in Multiethnic Populations.

    Science.gov (United States)

    Mensah-Ablorh, Akweley; Lindstrom, Sara; Haiman, Christopher A; Henderson, Brian E; Marchand, Loic Le; Lee, Seunngeun; Stram, Daniel O; Eliassen, A Heather; Price, Alkes; Kraft, Peter

    2016-01-01

    Several methods have been proposed to increase power in rare variant association testing by aggregating information from individual rare variants (MAF tests had greater power when all causal rare variants were deleterious, and variance component-based tests had greater power when some causal rare variants were deleterious and some were protective. Multiethnic studies had greater power than single-ethnicity studies at many loci, with inclusion of African Americans providing the largest impact. On average, studies including African Americans had as much as 20% greater power than equivalently sized studies without African Americans. This suggests that association studies between rare variants and complex disease should consider including subjects from multiple ethnicities, with preference given to genetically diverse groups. PMID:26639010

  11. Testing Pairwise Association between Spatially Autocorrelated Variables: A New Approach Using Surrogate Lattice Data

    Science.gov (United States)

    Deblauwe, Vincent; Kennel, Pol; Couteron, Pierre

    2012-01-01

    Background Independence between observations is a standard prerequisite of traditional statistical tests of association. This condition is, however, violated when autocorrelation is present within the data. In the case of variables that are regularly sampled in space (i.e. lattice data or images), such as those provided by remote-sensing or geographical databases, this problem is particularly acute. Because analytic derivation of the null probability distribution of the test statistic (e.g. Pearson's r) is not always possible when autocorrelation is present, we propose instead the use of a Monte Carlo simulation with surrogate data. Methodology/Principal Findings The null hypothesis that two observed mapped variables are the result of independent pattern generating processes is tested here by generating sets of random image data while preserving the autocorrelation function of the original images. Surrogates are generated by matching the dual-tree complex wavelet spectra (and hence the autocorrelation functions) of white noise images with the spectra of the original images. The generated images can then be used to build the probability distribution function of any statistic of association under the null hypothesis. We demonstrate the validity of a statistical test of association based on these surrogates with both actual and synthetic data and compare it with a corrected parametric test and three existing methods that generate surrogates (randomization, random rotations and shifts, and iterative amplitude adjusted Fourier transform). Type I error control was excellent, even with strong and long-range autocorrelation, which is not the case for alternative methods. Conclusions/Significance The wavelet-based surrogates are particularly appropriate in cases where autocorrelation appears at all scales or is direction-dependent (anisotropy). We explore the potential of the method for association tests involving a lattice of binary data and discuss its potential for

  12. Pulmonary function tests in patients with amyotrophic lateral sclerosis and the association between these tests and survival.

    Directory of Open Access Journals (Sweden)

    Seyed-Ali Javad Mousavi

    2014-09-01

    Full Text Available The rapidity of progression of amyotrophic lateral sclerosis (ALS to death or respiratory failure impacts patients, clinicians, and clinical investigators. The aim of this study is to evaluate of the pulmonary function tests (PFTs in patients with ALS and the association between these PFTs and survival Methods: A total of 36 ALS patients who PFTs, including vital capacity (VC, maximum mid-expiratory flow rate (MMEFR, forced vital capacity (FVC, and forced expiratory volume in 1 s (FEV1, were available from the time of diagnosis were included in this study. Non-pulmonary characteristics assessed at the time of PFTs. Data were analyzed using chi-square, Student's independent t-test, Kaplan-Meier, correlation, and receiver operating characteristic (ROC curve.The mean age of subjects was 55.36 (SD = 12.24 year, and the male to female ratio was 2.6. Twenty-five (69.4% were died in 5 years period of our study. The mean and median survival time (In months was calculated as 42.51 (95% confidence interval [CI] 33.64-51.39 and 38 (95% CI 27.23-48.77 months, respectively. The rate of ALS survival was 74% at 1(st year, 41% at 3(rd year and 10% at 5(th year of starting symptoms. The results of Kaplan-Meier test showed survival was significantly longer in the group with PFTs closer to normal. In addition, ROC analysis showed that FVC < 50% could potentially be a predictor of death in ALS patients(P = 0.003, area under curve = 0.649.We found single measures of upright FVC, FEV1 to be significantly associated with survival, even after controlling for relevant non-pulmonary patient characteristics. Our study demonstrated that upright FVC, FEV1, VC, and MMEFR are useful non-invasive measures in the prediction of survival in ALS.

  13. Association between physiological falls risk and physical performance tests among community-dwelling older adults

    Directory of Open Access Journals (Sweden)

    Singh DK

    2015-08-01

    Full Text Available Devinder KA Singh,1 Sharmila GK Pillai,1 Sin Thien Tan,1 Chu Chiau Tai,1 Suzana Shahar2 1Physiotherapy Programme, School of Rehabilitation Sciences, 2Nutrition and Dietetics Programme, School of Healthcare Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia Background: Physical performance and balance declines with aging and may lead to increased risk of falls. Physical performance tests may be useful for initial fall-risk screening test among community-dwelling older adults. Physiological profile assessment (PPA, a composite falls risk assessment tool is reported to have 75% accuracy to screen for physiological falls risk. PPA correlates with Timed Up and Go (TUG test. However, the association between many other commonly used physical performance tests and PPA is not known. The aim of the present study was to examine the association between physiological falls risk measured using PPA and a battery of physical performance tests.Methods: One hundred and forty older adults from a senior citizens club in Kuala Lumpur, Malaysia (94 females, 46 males, aged 60 years and above (65.77±4.61, participated in this cross-sectional study. Participants were screened for falls risk using PPA. A battery of physical performance tests that include ten-step test (TST, short physical performance battery (SPPB, functional reach test (FRT, static balance test (SBT, TUG, dominant hand-grip strength (DHGS, and gait speed test (GST were also performed. Spearman’s rank correlation and binomial logistic regression were performed to examine the significantly associated independent variables (physical performance tests with falls risk (dependent variable.Results: Approximately 13% older adults were at high risk of falls categorized using PPA. Significant differences (P<0.05 were demonstrated for age, TST, SPPB, FRT, SBT, TUG between high and low falls risk group. A significant (P<0.01 weak correlation

  14. Cognitive factors associated with the willingness for HIV testing among pregnant women in China

    Institute of Scientific and Technical Information of China (English)

    Li Chunrong; Yang Liu; Kong Jinwang

    2014-01-01

    Background The spread of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic in the worldwide trend is not contained effectively.The pregnant women infected HIV seriously in the high HIV epidemic areas in China.The transmission of HIV to child may be cut off if HIV positive mother was found early by HIV testing.Pregnant women mandatorily received the HIV counseling and testing services.Most of them did not know the knowledge about HIV prevention and were not willing to receive HIV testing actively.Willingness for HIV testing among pregnant women was investigated,which can help to promote them to take up HIV testing actively.This study assessed the prevalence of the willingness for HIV testing and cognitive factors associated with it.Methods A cross-sectional survey was conducted to 500 pregnant women via face-to-face interviews with anonymous structured questionnaire guided by the Health Belief Model (HBM).Results The prevalence of the willingness for HIV testing was 58.60%.Perceived higher susceptibility to HIV (multivariateadjusted odds ratio (ORm)=2.02,95% confidence interval (CI):1.40-5.06),more knowledge for HIV (ORm=1.92,95% CI:1.11-3.87) and perceived less social stigma (ORm=0.80,95% CI:0.34-0.91) were associated with higher willingness for HIV testing among pregnant women.Conclusion To prevent HIV mother to children transmission,it is necessary to enhance knowledge for HIV,change cognitive factors and increase willingness for HIV testing among pregnant women.

  15. Complications associated with the apnea test in the determination of the brain death

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-liang; FANG Qiang; LI Li; QIU Yun-qing; LUO Ben-yan

    2008-01-01

    Background An apnea test is essentialin the clinical determination of brain death.This study was conducted to analyse complications associated with the apnea test in the determination of the brain death.Methods On 93 adult patients In coma in Zhejiang Province of China from January 2003 to December 2006,179 apnea tests were performed as a part of the determination of brain death.Potential risk conditions and complications were analysed during apnea tests.Results During apnea,sedous cardiac arrhythmia did not occur in all patients.Complications occurred in 37 of 179 (21%)apnea tests.Hypotension occurred in 30 patients(17%)and it was obsewed in 8/94(9%)tests with baseline value of systolic arterial blood pressure not less than 120 mmHg,and 22/85(26%)lass than 120 mmHg(P<0.05).Severe hypoxaemia occurred in 10 patients(6%)of which 3/138(2%)tests with baseline value of arterial oxygen pressure not less than 200 mmHg,and 7/41(17%)less than 200 mmHg(P<0.05).Conclusions This study demonstrated that complications occurred mostly in patients with inadequate baseline systolic arterial blood pressure and preoxygenation.Adequate precautions during the apnea tests may reduce the risk of cardiovascular and oxygenation complication.

  16. Effects of three heavy metals on the bacteria growth kinetics. A bivariate model for toxicological assessment

    Energy Technology Data Exchange (ETDEWEB)

    Rial, Diego; Vazquez, Jose Antonio; Murado, Miguel Anxo [Instituto de Investigacions Marinas (CSIC), Vigo (ES). Grupo de Reciclado y Valorizacion de Materiales Residuales (REVAL)

    2011-05-15

    The effects of three heavy metals (Co, Ni and Cd) on the growth kinetics of five bacterial strains with different characteristics (Pseudomonas sp., Phaeobacter sp. strain 27-4, Listonella anguillarum, Carnobacterium piscicola and Leuconostoc mesenteroides subsp. lysis) were studied in a batch system. A bivariate model, function of time and dose, is proposed to describe simultaneously all the kinetic profiles obtained by incubating a microorganism at increasing concentrations of individual metals. This model combines the logistic equation for describing growth, with a modification of the cumulative Weibull's function for describing the dose-dependent variations of growth parameters. The comprehensive model thus obtained - which minimizes the effects of the experimental error - was statistically significant in all the studied cases, and it raises doubts about toxicological evaluations that are based on a single growth parameter, especially if it is not obtained from a kinetic equation. In lactic acid bacteria cultures (C. piscicola and L. mesenteroides), Cd induced remarkable differences in yield and time course of characteristic metabolites. A global parameter is defined (ED{sub 50,{tau}}: dose of toxic chemical that reduces the biomass of a culture by 50% compared to that produced by the control at the time corresponding to its semi maximum biomass) that allows comparing toxic effects on growth kinetics using a single value. (orig.)

  17. The Role of Wealth and Health in Insurance Choice: Bivariate Probit Analysis in China

    Directory of Open Access Journals (Sweden)

    Yiding Yue

    2014-01-01

    Full Text Available This paper captures the correlation between the choices of health insurance and pension insurance using the bivariate probit model and then studies the effect of wealth and health on insurance choice. Our empirical evidence shows that people who participate in a health care program are more likely to participate in a pension plan at the same time, while wealth and health have different effects on the choices of the health care program and the pension program. Generally, the higher an individual’s wealth level is, the more likelihood he will participate in a health care program; but wealth has no effect on the participation of pension. Health status has opposite effects on choices of health care programs and pension plans; the poorer an individual’s health is, the more likely he is to participate in health care programs, while the better health he enjoys, the more likely he is to participate in pension plans. When the investigation scope narrows down to commercial insurance, there is only a significant effect of health status on commercial health insurance. The commercial insurance choice and the insurance choice of the agricultural population are more complicated.

  18. Improving risk estimates of runoff producing areas: formulating variable source areas as a bivariate process.

    Science.gov (United States)

    Cheng, Xiaoya; Shaw, Stephen B; Marjerison, Rebecca D; Yearick, Christopher D; DeGloria, Stephen D; Walter, M Todd

    2014-05-01

    Predicting runoff producing areas and their corresponding risks of generating storm runoff is important for developing watershed management strategies to mitigate non-point source pollution. However, few methods for making these predictions have been proposed, especially operational approaches that would be useful in areas where variable source area (VSA) hydrology dominates storm runoff. The objective of this study is to develop a simple approach to estimate spatially-distributed risks of runoff production. By considering the development of overland flow as a bivariate process, we incorporated both rainfall and antecedent soil moisture conditions into a method for predicting VSAs based on the Natural Resource Conservation Service-Curve Number equation. We used base-flow immediately preceding storm events as an index of antecedent soil wetness status. Using nine sub-basins of the Upper Susquehanna River Basin, we demonstrated that our estimated runoff volumes and extent of VSAs agreed with observations. We further demonstrated a method for mapping these areas in a Geographic Information System using a Soil Topographic Index. The proposed methodology provides a new tool for watershed planners for quantifying runoff risks across watersheds, which can be used to target water quality protection strategies. PMID:24632403

  19. Uncertain Characterization of Flood Hazard Using Bivariate Analysis Based on Copulas

    Science.gov (United States)

    Candela, Angela; Tito Aronica, Giuseppe

    2015-04-01

    This study presents a methodology to derive probabilistic flood hazard map in flood prone areas taking into account uncertainties in the definition of design-hydrographs. Particularly, we present an innovative approach to obtain probabilistic inundation and flood hazard maps where hydrological input (synthetic flood design event) to a 2D hydraulic model has been defined by generating flood peak discharges and volumes from a bivariate statistical analysis, through the use of copulas. This study also aims to quantify the contribution of boundary conditions uncertainty in order to explore the impact of this uncertainty on probabilistic flood hazard mapping. The uncertainty of extreme flood events is considered in terms of different possible combinations of peak discharge and flood volume given by the copula. Further, we analyzed the role of a multivariate probability hydrological analysis on inundation and flood hazard maps highlighting the differences between deterministic and probabilistic approaches. The methodology has been applied to a study area located in Sicily that was subject to several flooding events in the past.

  20. The Bivariate Size-luminosity Relations for Lyman Break Galaxies at z ~ 4 - 5

    CERN Document Server

    Huang, Kuang-Han; Ravindranath, Swara; Su, Jian

    2013-01-01

    We study the bivariate size-luminosity distribution of Lyman Break Galaxies (LBGs) selected at redshifts around 4 and 5 in GOODS and the HUDF fields. We model the size-luminosity distribution as a combination of log-normal distribution (in size) and Schechter function (in luminosity), therefore it enables a more detailed study of the selection effects. We perform extensive simulations to quantify the dropout-selection completenesses and measurement biases and uncertainties in two-dimensional size and magnitude bins, and transform the theoretical size-luminosity distribution to the expected distribution for the observed data. Using maximum-likelihood estimator (MLE), we find that the Schechter function parameters for B-dropouts are \\alpha=-1.68^{+0.068}_{-0.095}, M*=-20.60^{+0.13}_{-0.17}, and \\phi*=1.79^{+0.32}_{-0.52} x 10^{-3} Mpc^{-3}. The log-normal size distribution is characterized by the peak R_0=1.34^{+0.099}_{-0.108} kpc at M_{1500}=-21 mag, width \\sigma_{\\lnR}=0.83^{+0.046}_{-0.044}, and the slope o...

  1. Modeling both of the number of pausibacillary and multibacillary leprosy patients by using bivariate poisson regression

    Science.gov (United States)

    Winahju, W. S.; Mukarromah, A.; Putri, S.

    2015-03-01

    Leprosy is a chronic infectious disease caused by bacteria of leprosy (Mycobacterium leprae). Leprosy has become an important thing in Indonesia because its morbidity is quite high. Based on WHO data in 2014, in 2012 Indonesia has the highest number of new leprosy patients after India and Brazil with a contribution of 18.994 people (8.7% of the world). This number makes Indonesia automatically placed as the country with the highest number of leprosy morbidity of ASEAN countries. The province that most contributes to the number of leprosy patients in Indonesia is East Java. There are two kind of leprosy. They consist of pausibacillary and multibacillary. The morbidity of multibacillary leprosy is higher than pausibacillary leprosy. This paper will discuss modeling both of the number of multibacillary and pausibacillary leprosy patients as responses variables. These responses are count variables, so modeling will be conducted by using bivariate poisson regression method. Unit experiment used is in East Java, and predictors involved are: environment, demography, and poverty. The model uses data in 2012, and the result indicates that all predictors influence significantly.

  2. THE BIVARIATE SIZE-LUMINOSITY RELATIONS FOR LYMAN BREAK GALAXIES AT z ∼ 4-5

    International Nuclear Information System (INIS)

    We study the bivariate size-luminosity distribution of Lyman break galaxies (LBGs) selected at redshifts around 4 and 5 in GOODS and the HUDF fields. We model the size-luminosity distribution as a combination of log-normal distribution (in size) and Schechter function (in luminosity), therefore it enables a more detailed study of the selection effects. We perform extensive simulations to quantify the dropout-selection completenesses and measurement biases and uncertainties in two-dimensional size and magnitude bins, and transform the theoretical size-luminosity distribution to the expected distribution for the observed data. Using maximum-likelihood estimator, we find that the Schechter function parameters for B 435-dropouts and are consistent with the values in the literature, but the size distributions are wider than expected from the angular momentum distribution of the underlying dark matter halos. The slope of the size-luminosity (RL) relation is similar to those found for local disk galaxies, but considerably shallower than local early-type galaxies.

  3. Bivariate spatial analysis of temperature and precipitation from general circulation models and observation proxies

    KAUST Repository

    Philbin, R.

    2015-05-22

    This study validates the near-surface temperature and precipitation output from decadal runs of eight atmospheric ocean general circulation models (AOGCMs) against observational proxy data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis temperatures and Global Precipitation Climatology Project (GPCP) precipitation data. We model the joint distribution of these two fields with a parsimonious bivariate Matérn spatial covariance model, accounting for the two fields\\' spatial cross-correlation as well as their own smoothnesses. We fit output from each AOGCM (30-year seasonal averages from 1981 to 2010) to a statistical model on each of 21 land regions. Both variance and smoothness values agree for both fields over all latitude bands except southern mid-latitudes. Our results imply that temperature fields have smaller smoothness coefficients than precipitation fields, while both have decreasing smoothness coefficients with increasing latitude. Models predict fields with smaller smoothness coefficients than observational proxy data for the tropics. The estimated spatial cross-correlations of these two fields, however, are quite different for most GCMs in mid-latitudes. Model correlation estimates agree well with those for observational proxy data for Australia, at high northern latitudes across North America, Europe and Asia, as well as across the Sahara, India, and Southeast Asia, but elsewhere, little consistent agreement exists.

  4. Identifying the ideal body size and shape characteristics associated with children's physical performance tests in Peru.

    Science.gov (United States)

    Bustamante Valdivia, A; Maia, J; Nevill, A

    2015-04-01

    We used allometric models to identify the optimal body size/shape characteristics associated with physical and motor performance tests in Peruvian schoolchildren. The sample consisted of 3624 subjects (1669 boys and 1955 girls) aged 11-17 years from 31 public schools belonging to four cities located in the three natural regions in central Peru. Motor performance included 12-min run, standing long jump, grip strength, curl-ups, shuttle run, and sit and reach. The reciprocal Ponderal index (RPI), a characteristic sometimes referred to as the somatotype "ectomorphy," was found to be the most suitable body shape indicator associated with 12-min run, standing long jump, curl-up, and shuttle run performance. A positive maturation offset parameter was also associated with greater standing long jump, grip strength, shuttle run, and sit-and-reach performances. With the exception of the sit-and-reach flexibility, sex differences are pervasive in all tests favoring boys. Rainforest schoolchildren are best performers in the power and flexibility tests, whereas those from high altitude were superior in the 12-min endurance test even after taking their much lighter body size characteristics into account. This latter finding suggests that living at high altitude in Peru benefits children's endurance performance both before and even after controlling for differences in the confounding variable of body size/shape. PMID:24779794

  5. Predicting alcohol use with a recoding-free variant of the Implicit Association Test.

    Science.gov (United States)

    Houben, Katrijn; Rothermund, Klaus; Wiers, Reinout W

    2009-05-01

    Recently, a modified version of the Implicit Association Test (IAT), the IAT-RF (IAT-Recoding Free) was developed which prevents recoding processes by switching response assignments randomly between trials rather than between blocks. In this study, the IAT-RF was used to measure and examine the predictive validity of recoding-free implicit alcohol associations with positive arousal. Findings with the IAT-RF demonstrated that alcohol was overall more strongly associated with negative sedation than with positive arousal. However, more importantly, the size of this compatibility effect was positively correlated with alcohol use indicating that stronger implicit alcohol associations with positive arousal are related to increased drinking. Further, implicit alcohol associations with positive arousal measured with the IAT-RF also predicted unique variance in alcohol use above the variance explained by explicit measures. Hence, the present findings suggest that implicit associations with positive arousal may play an important role in drinking behavior, and demonstrate the validity of the IAT-RF as a measure of implicit alcohol associations. PMID:19162409

  6. Identifying genetic marker sets associated with phenotypes via an efficient adaptive score test

    KAUST Repository

    Cai, T.

    2012-06-25

    In recent years, genome-wide association studies (GWAS) and gene-expression profiling have generated a large number of valuable datasets for assessing how genetic variations are related to disease outcomes. With such datasets, it is often of interest to assess the overall effect of a set of genetic markers, assembled based on biological knowledge. Genetic marker-set analyses have been advocated as more reliable and powerful approaches compared with the traditional marginal approaches (Curtis and others, 2005. Pathways to the analysis of microarray data. TRENDS in Biotechnology 23, 429-435; Efroni and others, 2007. Identification of key processes underlying cancer phenotypes using biologic pathway analysis. PLoS One 2, 425). Procedures for testing the overall effect of a marker-set have been actively studied in recent years. For example, score tests derived under an Empirical Bayes (EB) framework (Liu and others, 2007. Semiparametric regression of multidimensional genetic pathway data: least-squares kernel machines and linear mixed models. Biometrics 63, 1079-1088; Liu and others, 2008. Estimation and testing for the effect of a genetic pathway on a disease outcome using logistic kernel machine regression via logistic mixed models. BMC bioinformatics 9, 292-2; Wu and others, 2010. Powerful SNP-set analysis for case-control genome-wide association studies. American Journal of Human Genetics 86, 929) have been proposed as powerful alternatives to the standard Rao score test (Rao, 1948. Large sample tests of statistical hypotheses concerning several parameters with applications to problems of estimation. Mathematical Proceedings of the Cambridge Philosophical Society, 44, 50-57). The advantages of these EB-based tests are most apparent when the markers are correlated, due to the reduction in the degrees of freedom. In this paper, we propose an adaptive score test which up- or down-weights the contributions from each member of the marker-set based on the Z-scores of

  7. Brief implicit association test: Validity and utility in prediction of voting behavior

    Directory of Open Access Journals (Sweden)

    Pavlović Maša D.

    2013-01-01

    Full Text Available We employed the Brief Implicit Association Test (a recently developed short version of IAT to measure implicit political attitudes toward four political parties running for Serbian parliament. To test its criterion validity, we measured voting intention and actual voting behavior. In addition, we introduced political involvement as a potential moderator of the BIAT’s predictive and incremental validity. The BIAT demonstrated good internal and predictive validity, but lacked incremental validity over self-report measures. Predictive power of the BIAT was moderated by political involvement - the BIAT scores were stronger predictors of voting intention and behavior among voters highly involved in politics. [Projekat Ministarstva nauke Republike Srbije, br. 179018

  8. Radiocontrast media-associated exanthema: Identification of cross-reactivity and tolerability by allergologic testing

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, Cornelia S.; Pfeuffer, Petra; Raith, Petra; Broecker, Eva-B. [Department of Dermatology, Venereology and Allergology, University of Wuerzburg, Josef Schneider Strasse 2, 97080 Wuerzburg (Germany); Trautmann, Axel [Department of Dermatology, Venereology and Allergology, University of Wuerzburg, Josef Schneider Strasse 2, 97080 Wuerzburg (Germany)], E-mail: trautmann_a@klinik.uni-wuerzburg.de

    2009-10-15

    Background: All iodinated radiocontrast media (RCM) may cause hypersensitivity reactions, either immediate-type within 5-10 min of RCM injection or delayed-type, which become apparent more than 1 h after RCM exposure. Delayed-type hypersensitivity to RCM may pose a problem for future radiologic investigations because due to possible immunological cross-reactivity all iodinated RCM are usually avoided. Objective: The aim of this study was not only to identify the causal RCM for the exanthema but also to demonstrate that patients may receive alternative iodinated RCM despite a history of RCM-induced allergic exanthema. Methods: We evaluated 32 patients with a history of exanthema after RCM application using standardized patch, prick and intradermal skin testing. In case of positive skin tests intravenous challenges with skin-test-negative RCM were performed to identify non-ionic monomer RCM which are tolerated. Results: In 6 out of 32 patients skin tests strongly suggested a delayed-type non-IgE-mediated allergic hypersensitivity to the RCM iomeprol (3 x), iopromide (2x), and iopamidol. In 4 patients alternative non-ionic monomer RCM (2x iosarcol, iopromide, and iomeprol) were identified by controlled challenge tests. Conclusions: The evaluation of patients with RCM-associated exanthema should always include appropriate skin tests ensuring that patients with a delayed-type allergic RCM-induced exanthema are not missed. Moreover, allergologic testing may identify alternative RCM of the group of non-ionic monomers, which are tolerated in future radiologic investigations.

  9. Radiocontrast media-associated exanthema: Identification of cross-reactivity and tolerability by allergologic testing

    International Nuclear Information System (INIS)

    Background: All iodinated radiocontrast media (RCM) may cause hypersensitivity reactions, either immediate-type within 5-10 min of RCM injection or delayed-type, which become apparent more than 1 h after RCM exposure. Delayed-type hypersensitivity to RCM may pose a problem for future radiologic investigations because due to possible immunological cross-reactivity all iodinated RCM are usually avoided. Objective: The aim of this study was not only to identify the causal RCM for the exanthema but also to demonstrate that patients may receive alternative iodinated RCM despite a history of RCM-induced allergic exanthema. Methods: We evaluated 32 patients with a history of exanthema after RCM application using standardized patch, prick and intradermal skin testing. In case of positive skin tests intravenous challenges with skin-test-negative RCM were performed to identify non-ionic monomer RCM which are tolerated. Results: In 6 out of 32 patients skin tests strongly suggested a delayed-type non-IgE-mediated allergic hypersensitivity to the RCM iomeprol (3 x), iopromide (2x), and iopamidol. In 4 patients alternative non-ionic monomer RCM (2x iosarcol, iopromide, and iomeprol) were identified by controlled challenge tests. Conclusions: The evaluation of patients with RCM-associated exanthema should always include appropriate skin tests ensuring that patients with a delayed-type allergic RCM-induced exanthema are not missed. Moreover, allergologic testing may identify alternative RCM of the group of non-ionic monomers, which are tolerated in future radiologic investigations.

  10. Position Weight Matrix, Gibbs Sampler, and the Associated Significance Tests in Motif Characterization and Prediction

    Directory of Open Access Journals (Sweden)

    Xuhua Xia

    2012-01-01

    Full Text Available Position weight matrix (PWM is not only one of the most widely used bioinformatic methods, but also a key component in more advanced computational algorithms (e.g., Gibbs sampler for characterizing and discovering motifs in nucleotide or amino acid sequences. However, few generally applicable statistical tests are available for evaluating the significance of site patterns, PWM, and PWM scores (PWMS of putative motifs. Statistical significance tests of the PWM output, that is, site-specific frequencies, PWM itself, and PWMS, are in disparate sources and have never been collected in a single paper, with the consequence that many implementations of PWM do not include any significance test. Here I review PWM-based methods used in motif characterization and prediction (including a detailed illustration of the Gibbs sampler for de novo motif discovery, present statistical and probabilistic rationales behind statistical significance tests relevant to PWM, and illustrate their application with real data. The multiple comparison problem associated with the test of site-specific frequencies is best handled by false discovery rate methods. The test of PWM, due to the use of pseudocounts, is best done by resampling methods. The test of individual PWMS for each sequence segment should be based on the extreme value distribution.

  11. Association between preseason functional tests and injuries in youth football: a prospective follow-up.

    Science.gov (United States)

    Frisch, A; Urhausen, A; Seil, R; Croisier, J L; Windal, T; Theisen, D

    2011-12-01

    This prospective cohort study aimed at identifying player-related risk factors for injuries in youth football as determined by extensive preseasonal screening. All male U15-U19 players from a regional football school (season 2007-2008; n = 67) underwent preseason evaluations assessing physical fatigue, emotional stress and injury history (questionnaire), anthropometric variables, general joint laxity (Beighton score), lower limb coordination (functional hop tests), aerobic fitness (shuttle run test), strength of knee extensor and flexor muscles (isokinetic tests), static and dynamic balance (force plate tests), and explosive strength (jump tests on force plate). Football exposure and all football-related injuries (n = 163) were recorded during the entire subsequent season (44 weeks). Total injury incidence was 10.4 injuries/1000  h and was higher in competition than in training [relative risk = 3.3; CI(95%) (2.39; 4.54); P < 0.001]. Lower limb injuries were most frequent (87%). Acute contact injuries represented 37%, while intrinsic (noncontact and chronic) injuries amounted to 63%. Of all the variables tested, only physical fatigue was significantly associated with injury, as revealed by univariate and multivariate analyses. The same result was observed when considering only intrinsic injuries as outcome. A single preseason test session may be of limited interest in the framework of an injury prevention strategy. PMID:22017708

  12. On the level of skill in predicting maximum sunspot number - A comparative study of single variate and bivariate precursor techniques

    Science.gov (United States)

    Wilson, Robert M.

    1990-01-01

    The level of skill in predicting the size of the sunspot cycle is investigated for the two types of precursor techniques, single variate and bivariate fits, both applied to cycle 22. The present level of growth in solar activity is compared to the mean level of growth (cycles 10-21) and to the predictions based on the precursor techniques. It is shown that, for cycle 22, both single variate methods (based on geomagnetic data) and bivariate methods suggest a maximum amplitude smaller than that observed for cycle 19, and possibly for cycle 21. Compared to the mean cycle, cycle 22 is presently behaving as if it were a +2.6 sigma cycle (maximum amplitude of about 225), which means that either it will be the first cycle not to be reliably predicted by the combined precursor techniques or its deviation relative to the mean cycle will substantially decrease over the next 18 months.

  13. On the estimation of causality in a bivariate dynamic probit model on panel data with Stata software. A technical review

    OpenAIRE

    Eric Delattre; Richard Moussa

    2015-01-01

    In order to assess causality between binary economic outcomes, we consider the estimation of a bivariate dynamic probit model on panel data that has the particulary to account the initial conditions of the dynamic process. Due to the untractable form of the likelihood function that is a two dimensions integral, we use an approximation method: the adaptative Gauss-Hermite quadrature method as proposed by Liu and Pierce (1994). For the accuracy of the method and to reduce computing time, we der...

  14. BIVOPROB: A Computer Program for Maximum-Likelihood Estimation of Bivariate Ordered-Probit Models for Censored Data

    OpenAIRE

    Calhoun, C. A.

    1989-01-01

    Despite the large number of models devoted to the statistical analysis of censored data, relatively little attention has been given to the case of censored discrete outcomes. In this paper, the author presents a technical description and user's guide to a computer program for estimating bivariate ordered-probit models for censored and uncensored data. The model and program are currently being applied in an analysis of World Fertility Survey data for Europe and the United States, and the resul...

  15. Factors associated with car seat test failure in late preterm infants: A retrospective chart review

    Science.gov (United States)

    Smith, Ryan W; Mohamed, Adel; Young, Jennifer; Jefferies, Ann; Shah, Vibhuti

    2016-01-01

    BACKGROUND: Professional organizations recommend car seat testing of preterm infants before discharge from hospital. Late preterm infants (LPIs, 340/7 to 366/7 weeks’ gestational age) are at the greatest risk for failure, despite often being well. OBJECTIVE: To determine the incidence of car seat testing failure in LPIs and associative factors. METHODS: A retrospective chart review was performed of inborn LPIs admitted to all levels of newborn care between July 1, 2012 and June 30, 2013. Data collected included maternal demographics, labour and delivery history, and neonatal course. Data were analyzed using backward logistic regression. RESULTS: A total of 511 charts were reviewed and 367 LPIs were eligible for inclusion. Of the 313 LPIs tested (mean [± SD] gestational age 36 weeks ±6 days and birth weight 2614±405 g), 80 (26%) failed (95% CI 21% to 31%). Most failed due to desaturations (≥2) of <88% for ≥10 s (n=33 [41%]). Multiple gestation was associated with failure (adjusted OR 2.45 [95% CI 1.44 to 4.18]; P=0.001), and there was a trend toward statistical significance for the variable postnatal age (0.996 [95% CI 0.99 to 1.00]; P=0.05). Infants who passed their car seat test had higher postnatal ages than those who failed (mean difference 39.4 h [95% CI 12.7 h to 66.0 h]; P=0.004). CONCLUSION: Twenty-six percent of LPIs failed car seat testing. Ideally, infants should be tested after an appropriate transitional period. The authors identified factors that may be important in designing future, prospective studies in this area. Future research should evaluate the clinical significance of car seat testing and resource utilization. PMID:26941555

  16. The inferiority complex in paranoia readdressed. A study with the Implicit Association Test

    OpenAIRE

    von Collani, Gernot; Werner, Ronny; Moritz, Steffen

    2006-01-01

    It has been theorised that patients with persecutory delusions display a lack of covert self-esteem (formerly termed the 'inferiority complex'), while at the same time displaying normal or even heightened levels of explicit self-esteem. However, the empirical basis for this assumption is inconsistent. Methods. In view of apparent shortcomings of prior studies to assess implicit self-esteem, the Implicit Association Test was utilised to readdress this theory. The Rosenberg scale served as an i...

  17. Neighborhood Social Context and Individual Polycyclic Aromatic Hydrocarbon Exposures Associated with Child Cognitive Test Scores

    OpenAIRE

    Lovasi, Gina S.; Eldred-Skemp, Nicolia; Quinn, James W.; Chang, Hsin-Wen; Rauh, Virginia A.; Rundle, Andrew; Orjuela, Manuela A.; Perera, Frederica P.

    2014-01-01

    Childhood cognitive and test-taking abilities have long-term implications for educational achievement and health, and may be influenced by household environmental exposures and neighborhood contexts. This study evaluates whether age 5 scores on the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R, administered in English) are associated with polycyclic aromatic hydrocarbon (PAH) exposure and neighborhood context variables including poverty, low educational attainment, low...

  18. Distal Sensory Polyneuropathy is Associated with Neuropsychological Test Performance among Persons with HIV

    OpenAIRE

    Fellows, Robert P.; Byrd, Desiree A.; Elliott, Kathryn; Robinson-Papp, Jessica; Mindt, Monica Rivera; Morgello, Susan

    2012-01-01

    While distal sensory polyneuropathy (DSP) is the most common neurological condition associated with HIV, causing nerve damage in upper and lower extremities, its impact on neuropsychological test performance is unclear. In this study, we analyzed baseline data for 278 HIV-infected participants with comprehensive neurological and neurocognitive evaluations to examine the contribution of DSP and anatomic distribution of neuropathic signs (upper extremity or lower extremity) on standardized doma...

  19. Water associated zero maze: a novel rat test for long term traumatic re-experiencing

    OpenAIRE

    Ritov, Gilad; Richter-levin, Gal

    2014-01-01

    Often, freezing and startle behaviors in the context of a previously experienced stress are taken as an indication of post-traumatic stress disorder (PTSD)-like symptoms in rats. However, PTSD is characterized by large individual variations of symptoms. In order to take into consideration the complex and long term distinctive variations in effects of trauma exposure additional behavioral measures are required. The current study used a novel behavioral test, the water associated zero maze (WAZ...

  20. Perceived characteristics of the environment associated with active travel: development and testing of a new scale

    OpenAIRE

    Mutrie Nanette; Mitchell Richard; Ogilvie David; Petticrew Mark; Platt Stephen

    2008-01-01

    Abstract Background Environmental characteristics may be associated with patterns of physical activity. However, the development of instruments to measure perceived characteristics of the local environment is still at a comparatively early stage, and published instruments are not necessarily suitable for application in all settings. We therefore developed and established the test-retest reliability of a new scale for use in a study of the correlates of active travel and overall physical activ...

  1. Modelling the IAT:Implicit Association Test reflects shallow linguistic environment and not deep personal attitudes

    OpenAIRE

    Lynott, Dermot; Connell, Louise; O'Brien, Kerry S.; Kansal, Himanshu

    2012-01-01

    People often have thoughts, attitudes and biases that are not themselves consciously aware of or that they would rather not share with others. To assess such attitudes, researchers use paradigms like the Implicit Association Test (IAT) that do not rely on explicit responding to determine the level of bias a person holds towards a particular target concept (e.g., race, gender, age). Responses in the IAT are assumed to reflect deeply held beliefs and attitudes, and not shallow, superficial asso...

  2. Neighborhood Social Context and Individual Polycyclic Aromatic Hydrocarbon Exposures Associated with Child Cognitive Test Scores.

    Science.gov (United States)

    Lovasi, Gina S; Eldred-Skemp, Nicolia; Quinn, James W; Chang, Hsin-Wen; Rauh, Virginia A; Rundle, Andrew; Orjuela, Manuela A; Perera, Frederica P

    2014-07-01

    Childhood cognitive and test-taking abilities have long-term implications for educational achievement and health, and may be influenced by household environmental exposures and neighborhood contexts. This study evaluates whether age 5 scores on the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R, administered in English) are associated with polycyclic aromatic hydrocarbon (PAH) exposure and neighborhood context variables including poverty, low educational attainment, low English language proficiency, and inadequate plumbing. The Columbia Center for Children's Environmental Health enrolled African-American and Dominican-American New York City women during pregnancy, and conducted follow-up for subsequent childhood health outcomes including cognitive test scores. Individual outcomes were linked to data characterizing 1-km network buffers around prenatal addresses, home observations, interviews, and prenatal PAH exposure data from personal air monitors. Prenatal PAH exposure above the median predicted 3.5 point lower total WPPSI-R scores and 3.9 point lower verbal scores; the association was similar in magnitude across models with adjustments for neighborhood characteristics. Neighborhood-level low English proficiency was independently associated with 2.3 point lower mean total WPPSI-R score, 1.2 point lower verbal score, and 2.7 point lower performance score per standard deviation. Low neighborhood-level educational attainment was also associated with 2.0 point lower performance scores. In models examining effect modification, neighborhood associations were similar or diminished among the high PAH exposure group, as compared with the low PAH exposure group. Early life exposure to personal PAH exposure or selected neighborhood-level social contexts may predict lower cognitive test scores. However, these results may reflect limited geographic exposure variation and limited generalizability. PMID:24994947

  3. Long-lead station-scale prediction of hydrological droughts in South Korea based on bivariate pattern-based downscaling

    Science.gov (United States)

    Sohn, Soo-Jin; Tam, Chi-Yung

    2015-07-01

    Capturing climatic variations in boreal winter to spring (December-May) is essential for properly predicting droughts in South Korea. This study investigates the variability and predictability of the South Korean climate during this extended season, based on observations from 60 station locations and multi-model ensemble (MME) hindcast experiments (1983/1984-2005/2006) archived at the APEC Climate Center (APCC). Multivariate empirical orthogonal function (EOF) analysis results based on observations show that the first two leading modes of winter-to-spring precipitation and temperature variability, which together account for ~80 % of the total variance, are characterized by regional-scale anomalies covering the whole South Korean territory. These modes were also closely related to some of the recurrent large-scale circulation changes in the northern hemisphere during the same season. Consistent with the above, examination of the standardized precipitation evapotranspiration index (SPEI) indicates that drought conditions in South Korea tend to be accompanied by regional-to-continental-scale circulation anomalies over East Asia to the western north Pacific. Motivated by the aforementioned findings on the spatial-temporal coherence among station-scale precipitation and temperature anomalies, a new bivariate and pattern-based downscaling method was developed. The novelty of this method is that precipitation and temperature data were first filtered using multivariate EOFs to enhance their spatial-temporal coherence, before being linked to large-scale circulation variables using canonical correlation analysis (CCA). To test its applicability and to investigate its related potential predictability, a perfect empirical model was first constructed with observed datasets as predictors. Next, a model output statistics (MOS)-type hybrid dynamical-statistical model was developed, using products from nine one-tier climate models as inputs. It was found that, with model sea

  4. Long-lead station-scale prediction of hydrological droughts in South Korea based on bivariate pattern-based downscaling

    Science.gov (United States)

    Sohn, Soo-Jin; Tam, Chi-Yung

    2016-05-01

    Capturing climatic variations in boreal winter to spring (December-May) is essential for properly predicting droughts in South Korea. This study investigates the variability and predictability of the South Korean climate during this extended season, based on observations from 60 station locations and multi-model ensemble (MME) hindcast experiments (1983/1984-2005/2006) archived at the APEC Climate Center (APCC). Multivariate empirical orthogonal function (EOF) analysis results based on observations show that the first two leading modes of winter-to-spring precipitation and temperature variability, which together account for ~80 % of the total variance, are characterized by regional-scale anomalies covering the whole South Korean territory. These modes were also closely related to some of the recurrent large-scale circulation changes in the northern hemisphere during the same season. Consistent with the above, examination of the standardized precipitation evapotranspiration index (SPEI) indicates that drought conditions in South Korea tend to be accompanied by regional-to-continental-scale circulation anomalies over East Asia to the western north Pacific. Motivated by the aforementioned findings on the spatial-temporal coherence among station-scale precipitation and temperature anomalies, a new bivariate and pattern-based downscaling method was developed. The novelty of this method is that precipitation and temperature data were first filtered using multivariate EOFs to enhance their spatial-temporal coherence, before being linked to large-scale circulation variables using canonical correlation analysis (CCA). To test its applicability and to investigate its related potential predictability, a perfect empirical model was first constructed with observed datasets as predictors. Next, a model output statistics (MOS)-type hybrid dynamical-statistical model was developed, using products from nine one-tier climate models as inputs. It was found that, with model sea

  5. Multivariate Gene-Based Association Test on Family Data in MGAS.

    Science.gov (United States)

    Vroom, César-Reyer; Posthuma, Danielle; Li, Miao-Xin; Dolan, Conor V; van der Sluis, Sophie

    2016-09-01

    In analyses of unrelated individuals, the program multivariate gene-based association test by extended Simes (MGAS), which facilitates multivariate gene-based association testing, was shown to have correct Type I error rate and superior statistical power compared to other multivariate gene-based approaches. Here we show, through simulation, that MGAS can also be applied to data including genetically related subjects (e.g., family data), by using p value information obtained in Plink or in generalized estimating equations (with the 'exchangeable' working correlation matrix), both of which account for the family structure on a univariate single nucleotide polymorphism-based level by applying a sandwich correction of standard errors. We show that when applied to family-data, MGAS has correct Type I error rate, and given the details of the simulation setup, adequate power. Application of MGAS to seven eye measurement phenotypes showed statistically significant association with two genes that were not discovered in previous univariate analyses of a composite score. We conclude that MGAS is a useful and convenient tool for multivariate gene-based genome-wide association analysis in both unrelated and related individuals. PMID:27048268

  6. Problems associated with the apnea test in the diagnosis of brain death

    Directory of Open Access Journals (Sweden)

    Saposnik Gustavo

    2004-07-01

    Full Text Available Background: Brain death is the absence of all cortical functions, including the brainstem. The apnea test (AT is a necessary requisite to complete this diagnosis. Anecdotal reports describing hypotension and acidosis due to apnea test have been reported. However, there are few studies that evaluate complications or difficulties related to this procedure. Objective: To analyze medical problems associated with the apnea test. Methods and Patients: We analyzed clinical features, potential risk conditions, and problems in 129 brain dead patients during the apnea test. The diagnosis of brain death was made according to the American Academy of Neurology recommendations. Results: Clinical problems during the apnea test were detected in more than two thirds of patients, including: arterial hypotension (12%, acidosis (68%, and hypoxemia (23%. Four patients developed major complications, including: pneumothorax, cardiac arrest, bradycardia, atrial fibrillation and myocardial infarction. Conclusion: The apnea test is not an innocuous procedure. Complications during the AT are more common than reported and limit organ procurement for transplantation. Guidelines for performing the AT should be followed in order to avoid clinical complications.

  7. Binomial Mixture Model Based Association Testing to Account for Genetic Heterogeneity for GWAS.

    Science.gov (United States)

    Xu, Zhiyuan; Pan, Wei

    2016-04-01

    Genome-wide association studies (GWAS) have confirmed the ubiquitous existence of genetic heterogeneity for common disease: multiple common genetic variants have been identified to be associated, while many more are yet expected to be uncovered. However, the single SNP (single-nucleotide polymorphism) based trend test (or its variants) that has been dominantly used in GWAS is based on contrasting the allele frequency difference between the case and control groups, completely ignoring possible genetic heterogeneity. In spite of the widely accepted notion of genetic heterogeneity, we are not aware of any previous attempt to apply genetic heterogeneity motivated methods in GWAS. Here, to explicitly account for unknown genetic heterogeneity, we applied a mixture model based single-SNP test to the Wellcome Trust Case Control Consortium (WTCCC) GWAS data with traits of Crohn's disease, bipolar disease, coronary artery disease, and type 2 diabetes, identifying much larger numbers of significant SNPs and risk loci for each trait than those of the popular trend test, demonstrating potential power gain of the mixture model based test. PMID:26916514

  8. An Adaptive Association Test for Multiple Phenotypes with GWAS Summary Statistics.

    Science.gov (United States)

    Kim, Junghi; Bai, Yun; Pan, Wei

    2015-12-01

    We study the problem of testing for single marker-multiple phenotype associations based on genome-wide association study (GWAS) summary statistics without access to individual-level genotype and phenotype data. For most published GWASs, because obtaining summary data is substantially easier than accessing individual-level phenotype and genotype data, while often multiple correlated traits have been collected, the problem studied here has become increasingly important. We propose a powerful adaptive test and compare its performance with some existing tests. We illustrate its applications to analyses of a meta-analyzed GWAS dataset with three blood lipid traits and another with sex-stratified anthropometric traits, and further demonstrate its potential power gain over some existing methods through realistic simulation studies. We start from the situation with only one set of (possibly meta-analyzed) genome-wide summary statistics, then extend the method to meta-analysis of multiple sets of genome-wide summary statistics, each from one GWAS. We expect the proposed test to be useful in practice as more powerful than or complementary to existing methods. PMID:26493956

  9. A general framework for association tests with multivariate traits in large-scale genomics studies.

    Science.gov (United States)

    He, Qianchuan; Avery, Christy L; Lin, Dan-Yu

    2013-12-01

    Genetic association studies often collect data on multiple traits that are correlated. Discovery of genetic variants influencing multiple traits can lead to better understanding of the etiology of complex human diseases. Conventional univariate association tests may miss variants that have weak or moderate effects on individual traits. We propose several multivariate test statistics to complement univariate tests. Our framework covers both studies of unrelated individuals and family studies and allows any type/mixture of traits. We relate the marginal distributions of multivariate traits to genetic variants and covariates through generalized linear models without modeling the dependence among the traits or family members. We construct score-type statistics, which are computationally fast and numerically stable even in the presence of covariates and which can be combined efficiently across studies with different designs and arbitrary patterns of missing data. We compare the power of the test statistics both theoretically and empirically. We provide a strategy to determine genome-wide significance that properly accounts for the linkage disequilibrium (LD) of genetic variants. The application of the new methods to the meta-analysis of five major cardiovascular cohort studies identifies a new locus (HSCB) that is pleiotropic for the four traits analyzed. PMID:24227293

  10. A threat in the computer: the race implicit association test as a stereotype threat experience.

    Science.gov (United States)

    Frantz, Cynthia M; Cuddy, Amy J C; Burnett, Molly; Ray, Heidi; Hart, Allen

    2004-12-01

    Three experiments test whether the threat of appearing racist leads White participants to perform worse on the race Implicit Association Test (IAT) and whether self-affirmation can protect from this threat. Experiments 1 and 2 suggest that White participants show a stereotype threat effect when completing the race IAT, leading to stronger pro-White scores when the test is believed to be diagnostic of racism. This effect increases for domain-identified (highly motivated to control prejudice) participants (Experiment 2). In Experiment 3, self-affirmation inoculates participants against stereotype threat while taking the race IAT. These findings have methodological implications for use of the race IAT and theoretical implications concerning the malleability of automatic prejudice and the potential interpersonal effects of the fear of appearing racist. PMID:15536243

  11. A multi-marker test based on family data in genome-wide association study

    Directory of Open Access Journals (Sweden)

    Zhang Shuanglin

    2007-09-01

    Full Text Available Abstract Background Complex diseases are believed to be the results of many genes and environmental factors. Hence, multi-marker methods that can use the information of markers from different genes are appropriate for mapping complex disease genes. There already have been several multi-marker methods proposed for case-control studies. In this article, we propose a multi-marker test called a Multi-marker Pedigree Disequilibrium Test (MPDT to analyze family data from genome-wide association studies. If the parental phenotypes are available, we also propose a two-stage test in which a genomic screening test is used to select SNPs, and then the MPDT is used to test the association of the selected SNPs. Results We use simulation studies to evaluate the performance of the MPDT and the two-stage approach. The results show that the MPDT constantly outperforms the single marker transmission/disequilibrium test (TDT 1. Comparing the power of the two-stage approach with that of the one-stage approach, which approach is more powerful depends on the value of the prevalence; when the prevalence is no less than 10%, the two-stage approach may be more powerful than the one-stage approach. Otherwise, the one-stage approach is more powerful. Conclusion The proposed MPDT, is more powerful than the single marker TDT. When the parental phenotypes are available and the prevalence is no less than 10%, the proposed two-stage approach is more powerful than the one-stage approach.

  12. Factors associated with HIV testing among male motorbike taxi drivers in urban Vietnam.

    Science.gov (United States)

    Huy, Nguyen Van; Khuyen, Le Thi; Ha, Pham Nguyen

    2015-01-01

    Using the Attitude-Skills-Knowledge (ASK) model, this study examined the prevalence of, and factors associated with, human immunodeficiency virus (HIV) testing among male motorbike taxi drivers (MMTDs). In a cross-sectional design, using quantitative approaches, 291 MMTDs were recruited from 135 sites across 13 districts in Hanoi, Vietnam, for a face-to-face interview. Applying the ASK model modified as a central theory, logistic regression was used to identify determinants of HIV testing. Although many MMTDs engaged in multiple risk behaviours for HIV, only 20.6% had been tested for HIV during the past 12 months. The tested model included one factor of the ASK model, HIV prevention knowledge (adjusted odds ratio [AOR] = 4.76; 95% confidence interval [CI] = 2.12-10.7) and five additional factors: being married (AOR = 3.13; 95% CI = 1.25-4.78), preferring sex with men or with both men and women (AOR = 8.72; 95% CI = 1.48-51.5), having lower number of lifetime sex partners (AOR = 0.66; 95% CI = 0.49-0.88), higher number of past year sex partners (AOR = 2.97: 95% CI = 1.21-7.31) and discussing condom use when having sex with partners (AOR = 0.08; 95% CI = 0.01-7.31). This modified ASK model provided better fit than the ASK model, as it explained more variance in HIV testing (47 vs. 29.8%). Recognising factors associated with HIV testing among MMTDs enables us to create suitable public health intervention strategies. PMID:25415855

  13. A view on coupled cluster perturbation theory using a bivariational Lagrangian formulation.

    Science.gov (United States)

    Kristensen, Kasper; Eriksen, Janus J; Matthews, Devin A; Olsen, Jeppe; Jørgensen, Poul

    2016-02-14

    We consider two distinct coupled cluster (CC) perturbation series that both expand the difference between the energies of the CCSD (CC with single and double excitations) and CCSDT (CC with single, double, and triple excitations) models in orders of the Møller-Plesset fluctuation potential. We initially introduce the E-CCSD(T-n) series, in which the CCSD amplitude equations are satisfied at the expansion point, and compare it to the recently developed CCSD(T-n) series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)], in which not only the CCSD amplitude, but also the CCSD multiplier equations are satisfied at the expansion point. The computational scaling is similar for the two series, and both are term-wise size extensive with a formal convergence towards the CCSDT target energy. However, the two series are different, and the CCSD(T-n) series is found to exhibit a more rapid convergence up through the series, which we trace back to the fact that more information at the expansion point is utilized than for the E-CCSD(T-n) series. The present analysis can be generalized to any perturbation expansion representing the difference between a parent CC model and a higher-level target CC model. In general, we demonstrate that, whenever the parent parameters depend upon the perturbation operator, a perturbation expansion of the CC energy (where only parent amplitudes are used) differs from a perturbation expansion of the CC Lagrangian (where both parent amplitudes and parent multipliers are used). For the latter case, the bivariational Lagrangian formulation becomes more than a convenient mathematical tool, since it facilitates a different and faster convergent perturbation series than the simpler energy-based expansion. PMID:26874478

  14. Analysis of input variables of an artificial neural network using bivariate correlation and canonical correlation

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Valter Magalhaes; Pereira, Iraci Martinez, E-mail: valter.costa@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The monitoring of variables and diagnosis of sensor fault in nuclear power plants or processes industries is very important because a previous diagnosis allows the correction of the fault and, like this, to prevent the production stopped, improving operator's security and it's not provoking economics losses. The objective of this work is to build a set, using bivariate correlation and canonical correlation, which will be the set of input variables of an artificial neural network to monitor the greater number of variables. This methodology was applied to the IEA-R1 Research Reactor at IPEN. Initially, for the input set of neural network we selected the variables: nuclear power, primary circuit flow rate, control/safety rod position and difference in pressure in the core of the reactor, because almost whole of monitoring variables have relation with the variables early described or its effect can be result of the interaction of two or more. The nuclear power is related to the increasing and decreasing of temperatures as well as the amount radiation due fission of the uranium; the rods are controls of power and influence in the amount of radiation and increasing and decreasing of temperatures; the primary circuit flow rate has the function of energy transport by removing the nucleus heat. An artificial neural network was trained and the results were satisfactory since the IEA-R1 Data Acquisition System reactor monitors 64 variables and, with a set of 9 input variables resulting from the correlation analysis, it was possible to monitor 51 variables. (author)

  15. New Colors for Histology: Optimized Bivariate Color Maps Increase Perceptual Contrast in Histological Images.

    Directory of Open Access Journals (Sweden)

    Jakob Nikolas Kather

    Full Text Available Accurate evaluation of immunostained histological images is required for reproducible research in many different areas and forms the basis of many clinical decisions. The quality and efficiency of histopathological evaluation is limited by the information content of a histological image, which is primarily encoded as perceivable contrast differences between objects in the image. However, the colors of chromogen and counterstain used for histological samples are not always optimally distinguishable, even under optimal conditions.In this study, we present a method to extract the bivariate color map inherent in a given histological image and to retrospectively optimize this color map. We use a novel, unsupervised approach based on color deconvolution and principal component analysis to show that the commonly used blue and brown color hues in Hematoxylin-3,3'-Diaminobenzidine (DAB images are poorly suited for human observers. We then demonstrate that it is possible to construct improved color maps according to objective criteria and that these color maps can be used to digitally re-stain histological images.To validate whether this procedure improves distinguishability of objects and background in histological images, we re-stain phantom images and N = 596 large histological images of immunostained samples of human solid tumors. We show that perceptual contrast is improved by a factor of 2.56 in phantom images and up to a factor of 2.17 in sets of histological tumor images.Thus, we provide an objective and reliable approach to measure object distinguishability in a given histological image and to maximize visual information available to a human observer. This method could easily be incorporated in digital pathology image viewing systems to improve accuracy and efficiency in research and diagnostics.

  16. Analysis of input variables of an artificial neural network using bivariate correlation and canonical correlation

    International Nuclear Information System (INIS)

    The monitoring of variables and diagnosis of sensor fault in nuclear power plants or processes industries is very important because a previous diagnosis allows the correction of the fault and, like this, to prevent the production stopped, improving operator's security and it's not provoking economics losses. The objective of this work is to build a set, using bivariate correlation and canonical correlation, which will be the set of input variables of an artificial neural network to monitor the greater number of variables. This methodology was applied to the IEA-R1 Research Reactor at IPEN. Initially, for the input set of neural network we selected the variables: nuclear power, primary circuit flow rate, control/safety rod position and difference in pressure in the core of the reactor, because almost whole of monitoring variables have relation with the variables early described or its effect can be result of the interaction of two or more. The nuclear power is related to the increasing and decreasing of temperatures as well as the amount radiation due fission of the uranium; the rods are controls of power and influence in the amount of radiation and increasing and decreasing of temperatures; the primary circuit flow rate has the function of energy transport by removing the nucleus heat. An artificial neural network was trained and the results were satisfactory since the IEA-R1 Data Acquisition System reactor monitors 64 variables and, with a set of 9 input variables resulting from the correlation analysis, it was possible to monitor 51 variables. (author)

  17. Assessing protein conformational sampling methods based on bivariate lag-distributions of backbone angles

    KAUST Repository

    Maadooliat, Mehdi

    2012-08-27

    Despite considerable progress in the past decades, protein structure prediction remains one of the major unsolved problems in computational biology. Angular-sampling-based methods have been extensively studied recently due to their ability to capture the continuous conformational space of protein structures. The literature has focused on using a variety of parametric models of the sequential dependencies between angle pairs along the protein chains. In this article, we present a thorough review of angular-sampling-based methods by assessing three main questions: What is the best distribution type to model the protein angles? What is a reasonable number of components in a mixture model that should be considered to accurately parameterize the joint distribution of the angles? and What is the order of the local sequence-structure dependency that should be considered by a prediction method? We assess the model fits for different methods using bivariate lag-distributions of the dihedral/planar angles. Moreover, the main information across the lags can be extracted using a technique called Lag singular value decomposition (LagSVD), which considers the joint distribution of the dihedral/planar angles over different lags using a nonparametric approach and monitors the behavior of the lag-distribution of the angles using singular value decomposition. As a result, we developed graphical tools and numerical measurements to compare and evaluate the performance of different model fits. Furthermore, we developed a web-tool (http://www.stat.tamu. edu/~madoliat/LagSVD) that can be used to produce informative animations. © The Author 2012. Published by Oxford University Press.

  18. Lactulose Hydrogen Breath Test Result Is Associated with Age and Gender

    Science.gov (United States)

    Newberry, Carolyn; Tierney, Ann; Pickett-Blakely, Octavia

    2016-01-01

    Small intestinal bacterial overgrowth (SIBO) is associated with chronic gastrointestinal diseases and structural/functional abnormalities of the gastrointestinal tract. SIBO's association with clinical characteristics is unclear. This study investigates the association between clinical factors and SIBO according to lactulose hydrogen breath test (LHBT) result. Methods. A cross-sectional study in a university-based gastroenterology practice was performed. Data was abstracted from the medical records of subjects undergoing LHBT from 6/1/2009 to 6/1/2013. Logistic regression analysis was performed to determine the association between predictor variables: age, sex, body mass index (BMI), and positive LHBT, the outcome of interest. Results. LHBT was performed in 791 subjects. Fifty-four percent had a positive LHBT. There was no statistically significant difference between the LHBT results according to age or BMI. In females, the likelihood of a positive LHBT increased with age (OR 1.02; 95% CI: 1.01–1.03). In males, the likelihood of a positive LHBT result decreased with age (OR 0.98; 95% CI: 0.97–1.00). Conclusion. There was an association between age, with respect to sex, and a positive LHBT. With increased age in females, the odds of a positive LHBT increased, while, in men, the odds of a positive LHBT decreased with age. PMID:27073800

  19. Lactulose Hydrogen Breath Test Result Is Associated with Age and Gender.

    Science.gov (United States)

    Newberry, Carolyn; Tierney, Ann; Pickett-Blakely, Octavia

    2016-01-01

    Small intestinal bacterial overgrowth (SIBO) is associated with chronic gastrointestinal diseases and structural/functional abnormalities of the gastrointestinal tract. SIBO's association with clinical characteristics is unclear. This study investigates the association between clinical factors and SIBO according to lactulose hydrogen breath test (LHBT) result. Methods. A cross-sectional study in a university-based gastroenterology practice was performed. Data was abstracted from the medical records of subjects undergoing LHBT from 6/1/2009 to 6/1/2013. Logistic regression analysis was performed to determine the association between predictor variables: age, sex, body mass index (BMI), and positive LHBT, the outcome of interest. Results. LHBT was performed in 791 subjects. Fifty-four percent had a positive LHBT. There was no statistically significant difference between the LHBT results according to age or BMI. In females, the likelihood of a positive LHBT increased with age (OR 1.02; 95% CI: 1.01-1.03). In males, the likelihood of a positive LHBT result decreased with age (OR 0.98; 95% CI: 0.97-1.00). Conclusion. There was an association between age, with respect to sex, and a positive LHBT. With increased age in females, the odds of a positive LHBT increased, while, in men, the odds of a positive LHBT decreased with age. PMID:27073800

  20. A Joint Location-Scale Test Improves Power to Detect Associated SNPs, Gene Sets, and Pathways.

    Science.gov (United States)

    Soave, David; Corvol, Harriet; Panjwani, Naim; Gong, Jiafen; Li, Weili; Boëlle, Pierre-Yves; Durie, Peter R; Paterson, Andrew D; Rommens, Johanna M; Strug, Lisa J; Sun, Lei

    2015-07-01

    Gene-based, pathway, and other multivariate association methods are motivated by the possibility of GxG and GxE interactions; however, accounting for such interactions is limited by the challenges associated with adequate modeling information. Here we propose an easy-to-implement joint location-scale (JLS) association testing framework for single-variant and multivariate analysis that accounts for interactions without explicitly modeling them. We apply the JLS method to a gene-set analysis of cystic fibrosis (CF) lung disease, which is influenced by multiple environmental and genetic factors. We identify and replicate an association between the constituents of the apical plasma membrane and CF lung disease (p = 0.0099 and p = 0.0180, respectively) and highlight a role for the SLC9A3-SLC9A3R1/2-EZR complex in contributing to CF lung disease. Many association studies could benefit from re-analysis with the JLS method that leverages complex genetic architecture for SNP, gene, and pathway identification. Analytical verification, simulation, and additional proof-of-principle applications support our approach. PMID:26140448

  1. Identifying temporal and causal contributions of neural processes underlying the Implicit Association Test (IAT

    Directory of Open Access Journals (Sweden)

    Chad Edward Forbes

    2012-11-01

    Full Text Available The Implicit Association Test (IAT is a popular behavioral measure that assesses the associative strength between outgroup members and stereotypical and counterstereotypical traits. Less is known, however, about the degree to which the IAT reflects automatic processing. Two studies examined automatic processing contributions to a gender-IAT using a data driven, social neuroscience approach. Performance on congruent (e.g., categorizing male names with synonyms of strength and incongruent (e.g., categorizing female names with synonyms of strength IAT blocks were separately analyzed using EEG (event-related potentials, or ERPs, and coherence; Study 1 and lesion (Study 2 methodologies. Compared to incongruent blocks, performance on congruent IAT blocks was associated with more positive ERPs that manifested in frontal and occipital regions at automatic processing speeds, occipital regions at more controlled processing speeds and was compromised by volume loss in the anterior temporal lobe, insula and medial PFC. Performance on incongruent blocks was associated with volume loss in supplementary motor areas, cingulate gyrus and a region in medial PFC similar to that found for congruent blocks. Greater coherence was found between frontal and occipital regions to the extent individuals exhibited more bias. This suggests there are separable neural contributions to congruent and incongruent blocks of the IAT but there is also a surprising amount of overlap. Given the temporal and regional neural distinctions, these results provide converging evidence that stereotypic associative strength assessed by the IAT indexes automatic processing to a degree.

  2. FLAGS: A Flexible and Adaptive Association Test for Gene Sets Using Summary Statistics.

    Science.gov (United States)

    Huang, Jianfei; Wang, Kai; Wei, Peng; Liu, Xiangtao; Liu, Xiaoming; Tan, Kai; Boerwinkle, Eric; Potash, James B; Han, Shizhong

    2016-03-01

    Genome-wide association studies (GWAS) have been widely used for identifying common variants associated with complex diseases. Despite remarkable success in uncovering many risk variants and providing novel insights into disease biology, genetic variants identified to date fail to explain the vast majority of the heritability for most complex diseases. One explanation is that there are still a large number of common variants that remain to be discovered, but their effect sizes are generally too small to be detected individually. Accordingly, gene set analysis of GWAS, which examines a group of functionally related genes, has been proposed as a complementary approach to single-marker analysis. Here, we propose a FL: exible and A: daptive test for G: ene S: ets (FLAGS), using summary statistics. Extensive simulations showed that this method has an appropriate type I error rate and outperforms existing methods with increased power. As a proof of principle, through real data analyses of Crohn's disease GWAS data and bipolar disorder GWAS meta-analysis results, we demonstrated the superior performance of FLAGS over several state-of-the-art association tests for gene sets. Our method allows for the more powerful application of gene set analysis to complex diseases, which will have broad use given that GWAS summary results are increasingly publicly available. PMID:26773050

  3. Bivariate hydrologic risk analysis based on a coupled entropy-copula method for the Xiangxi River in the Three Gorges Reservoir area, China

    Science.gov (United States)

    Fan, Y. R.; Huang, W. W.; Huang, G. H.; Huang, K.; Li, Y. P.; Kong, X. M.

    2016-07-01

    In this study, a bivariate hydrologic risk framework is proposed based on a coupled entropy-copula method. In the proposed risk analysis framework, bivariate flood frequency would be analyzed for different flood variable pairs (i.e., flood peak-volume, flood peak-duration, flood volume-duration). The marginal distributions of flood peak, volume, and duration are quantified through both parametric (i.e., gamma, general extreme value (GEV), and lognormal distributions) and nonparametric (i.e., entropy) approaches. The joint probabilities of flood peak-volume, peak-duration, and volume-duration are established through copulas. The bivariate hydrologic risk is then derived based on the joint return period to reflect the interactive effects of flood variables on the final hydrologic risk values. The proposed method is applied to the risk analysis for the Xiangxi River in the Three Gorges Reservoir area, China. The results indicate the entropy method performs best in quantifying the distribution of flood duration. Bivariate hydrologic risk would then be generated to characterize the impacts of flood volume and duration on the occurrence of a flood. The results suggest that the bivariate risk for flood peak-volume would not decrease significantly for the flood volume less than 1000 m3/s. Moreover, a flood in the Xiangxi River may last at least 5 days without significant decrease of the bivariate risk for flood peak-duration.

  4. Association testing for next-generation sequencing data using score statistics

    DEFF Research Database (Denmark)

    Skotte, Line; Korneliussen, Thorfinn Sand; Albrechtsen, Anders

    2012-01-01

    where there is not enough data to call genotypes accurately. Ignoring the genotype classification uncertainty by basing subsequent analyses on called genotypes leads to a loss in power. Additionally, using called genotypes can lead to spurious association signals. Some methods taking the uncertainty...... to association testing for next-generation sequencing data. The joint model accounts for the genotype classification uncertainty via the posterior probabilities of the genotypes given the observed sequencing data, which gives the approach higher power than methods based on called genotypes. This strategy remains...... of genotype calls into account have been proposed; most require numerical optimization which for large-scale data is not always computationally feasible. We show that using a score statistic for the joint likelihood of observed phenotypes and observed sequencing data provides an attractive approach...

  5. Does the name-race implicit association test measure racial prejudice?

    Science.gov (United States)

    van Ravenzwaaij, Don; van der Maas, Han L J; Wagenmakers, Eric-Jan

    2011-01-01

    Research using the Implicit Association Test (IAT) has shown that names labeled as Caucasian elicit more positive associations than names labeled as non-Caucasian. One interpretation of this result is that the IAT measures latent racial prejudice. An alternative explanation is that the result is due to differences in in-group/out-group membership. In this study, we conducted three different IATs: one with same-race Dutch names versus racially charged Moroccan names; one with same-race Dutch names versus racially neutral Finnish names; and one with Moroccan names versus Finnish names. Results showed equivalent effects for the Dutch-Moroccan and Dutch-Finnish IATs, but no effect for the Finnish-Moroccan IAT. This suggests that the name-race IAT-effect is not due to racial prejudice. A diffusion model decomposition indicated that the IAT-effects were caused by changes in speed of information accumulation, response conservativeness, and non-decision time. PMID:21106475

  6. Reliability of rapid diagnostic tests in diagnosing pregnancy-associated malaria in north-eastern Tanzania

    DEFF Research Database (Denmark)

    Minja, Daniel T.; Schmiegelow, Christentze; Oesterholt, Mayke; Magistrado, Pamela A.; Boström, Stéphanie; John, Davis; Pehrson, Caroline; Andersen, Daniel; Deloron, Philippe; Salanti, Ali; Lemnge, Martha; Luty, Adrian J.; Alifrangis, Michael; Theander, Thor; Lusingu, John P.

    2012-01-01

    Background: Accurate diagnosis and prompt treatment of pregnancy-associated malaria (PAM) are key aspects in averting adverse pregnancy outcomes. Microscopy is the gold standard in malaria diagnosis, but it has limited detection and availability. When used appropriately, rapid diagnostic tests...... (RDTs) could be an ideal diagnostic complement to microscopy, due to their ease of use and adequate sensitivity in detecting even sub-microscopic infections. Polymerase chain reaction (PCR) is even more sensitive, but it is mainly used for research purposes. The accuracy and reliability of RDTs in...... microscopy, respectively, whereas nineteen (42.2% [29.0 - 56.7]) of the microscopy negative, but RDT positive, samples were positive by PCR. Three (0.05% [0.02 - 0.2]) samples were positive by microscopy but negative by RDT. 351 of the 5,461 samples negative by both RDT and microscopy were tested by PCR and...

  7. Test plan for Fauske and Associates to perform tube propagation experiments with simulated Hanford tank wastes

    International Nuclear Information System (INIS)

    This test plan, prepared at Pacific Northwest National Laboratory for Westinghouse Hanford Company, provides guidance for performing tube propagation experiments on simulated Hanford tank wastes and on actual tank waste samples. Simulant compositions are defined and an experimental logic tree is provided for Fauske and Associates (FAI) to perform the experiments. From this guidance, methods and equipment for small-scale tube propagation experiments to be performed at the Hanford Site on actual tank samples will be developed. Propagation behavior of wastes will directly support the safety analysis (SARR) for the organic tanks. Tube propagation may be the definitive tool for determining the relative reactivity of the wastes contained in the Hanford tanks. FAI have performed tube propagation studies previously on simple two- and three-component surrogate mixtures. The simulant defined in this test plan more closely represents actual tank composition. Data will be used to support preparation of criteria for determining the relative safety of the organic bearing wastes

  8. Detecting a Weak Association by Testing its Multiple Perturbations: a Data Mining Approach

    OpenAIRE

    Min-Tzu Lo; Wen-Chung Lee

    2014-01-01

    Many risk factors/interventions in epidemiologic/biomedical studies are of minuscule effects. To detect such weak associations, one needs a study with a very large sample size (the number of subjects, n). The n of a study can be increased but unfortunately only to an extent. Here, we propose a novel method which hinges on increasing sample size in a different direction–the total number of variables (p). We construct a p-based ‘multiple perturbation test', and conduct power calculations and co...

  9. Estimate of uncertainties correlated and no correlated associated to performance tests of activity meters

    International Nuclear Information System (INIS)

    Activimeters should undergo performance for verifying the functionality tests as technical recommendations. This study estimated the associated expanded uncertainties uncorrelated to the results conducted on three instruments, two detectors with ionization chamber and one with Geiger Mueller tubes. For this we used a standard reference source and screened certified by the National Institute of Technology and Standardization. The methodology of this research was based on the protocols listed in the technical document of the International Atomic Energy Agency. Later two quantities were correlated presenting real correlation and improving expanded uncertainty 3.7%. (author)

  10. Psychology data from the Race Implicit Association Test on the Project Implicit Demo website

    OpenAIRE

    Kaiyuan Xu; Brian Nosek; Greenwald, Anthony G.

    2014-01-01

    This data archive includes Race Implicit Association Test (IAT) scores of 2,355,303 Internet volunteers who completed educational/demonstration versions of the Race IAT at https://implicit.harvard.edu from 2002 to 2012. Data in this archive can be downloaded for all years, either separately by year or in a single file. Codebooks, indicating the variable labels and value labels, and changes of variables over years, are available for both individual-year data sets and the entire data set. Parti...

  11. A simple screening test for variant transthyretins associated with familial transthyretin amyloidosis using isoelectric focusing.

    Science.gov (United States)

    Connors, L H; Ericsson, T; Skare, J; Jones, L A; Lewis, W D; Skinner, M

    1998-09-30

    Variant forms of the plasma protein transthyretin (TTR) are associated with the most frequently occurring type of familial systemic amyloidosis. Organ system involvement in transthyretin type amyloidosis (ATTR) is often similar to that which occurs in light chain amyloid disease (AL). The proper diagnosis of ATTR is important since treatment (liver transplantation) differs from that in AL (chemotherapy). We present a two-step test to screen sera for variant TTRs using non-denaturing gel electrophoresis performed in 7.5% acrylamide (PAGE) followed by isoelectric focusing (IEF) between pH 4.0 and 7.0 in 2.5 M urea. Serum samples from 110 patients with amyloidosis and their relatives were tested using this IEF technique and compared to genetic mutation results. Sera from patients with ATTR who underwent liver transplantation were also examined prior to and following surgery. IEF analysis showed the presence of both wild-type and variant TTR in 74 of the 110 serum samples tested. Genomic DNA from peripheral blood was used to identify TTR gene mutations in 77 of the 110 patients. Fifteen variants including Val122Ile, preponderant in the African-American population, could be demonstrated by IEF. The sensitivity of IEF was 96% (74/77) and the specificity was 100% (33/33). The predictive values for a positive or negative result were 100% (74/74) and 92% (33/36), respectively. There were no false-positive results and 4% (3/77) false-negative results. In sera from patients with ATTR who underwent liver transplantation, variant TTR was detected by IEF before, but not after, surgery. A simple, accurate, sensitive method is presented as a useful screening test for variant transthyretins associated with ATTR. PMID:9748569

  12. Factors associated with late diagnosis of HIV infection and missed opportunities for earlier testing.

    Science.gov (United States)

    Gullón, Alejandra; Verdejo, José; de Miguel, Rosa; Gómez, Ana; Sanz, Jesús

    2016-10-01

    Late diagnosis (LD) of human immunodeficiency virus (HIV) infection continues to be a significant problem that increases disease burden both for patients and for the public health system. Guidelines have been updated in order to facilitate earlier HIV diagnosis, introducing "indicator condition-guided HIV testing". In this study, we analysed the frequency of LD and associated risk factors. We retrospectively identified those cases that could be considered missed opportunities for an earlier diagnosis. All patients newly diagnosed with HIV infection who attended Hospital La Princesa, Madrid (Spain) between 2007 and 2014 were analysed. We collected epidemiological, clinical and immunological data. We also reviewed electronic medical records from the year before the HIV diagnosis to search for medical consultations due to clinical indicators. HIV infection was diagnosed in 354 patients. The median CD4 count at presentation was 352 cells/mm(3). Overall, 158 patients (50%) met the definition of LD, and 97 (30.7%) the diagnosis of advanced disease. LD was associated with older age and was more frequent amongst immigrants. Heterosexual relations and injection drug use were more likely to be the reasons for LD than relations between men who have sex with men. During the year preceding the diagnosis, 46.6% of the patients had sought medical advice owing to the presence of clinical indicators that should have led to HIV testing. Of those, 24 cases (14.5%) were classified as missed opportunities for earlier HIV diagnosis because testing was not performed. According to these results, all health workers should pursue early HIV diagnosis through the proper implementation of HIV testing guidelines. Such an approach would prove directly beneficial to the patient and indirectly beneficial to the general population through the reduction in the risk of transmission. PMID:27144427

  13. SPS: A Simulation Tool for Calculating Power of Set-Based Genetic Association Tests.

    Science.gov (United States)

    Li, Jiang; Sham, Pak Chung; Song, Youqiang; Li, Miaoxin

    2015-07-01

    Set-based association tests, combining a set of single-nucleotide polymorphisms into a unified test, have become important approaches to identify weak-effect or low-frequency risk loci of complex diseases. However, there is no comprehensive and user-friendly tool to estimate power of set-based tests for study design. We developed a simulation tool to estimate statistical power of multiple representative set-based tests (SPS). SPS has a graphic interface to facilitate parameter settings and result visualization. Advanced functions include loading real genotypes to define genetic architecture, set-based meta-analysis for risk loci with or without heterogeneity, and parallel simulations. In proof-of-principle examples, SPS took no more than 3 sec on average to estimate the power in a conventional setting. The SPS has been integrated into a user-friendly software tool (KGG) as an independent functional module and it is freely available at http://statgenpro.psychiatry.hku.hk/limx/kgg/. PMID:25995121

  14. Factors associated with functional capacity test results in patients with non-specific chronic low back pain: A systematic review

    NARCIS (Netherlands)

    Abbema, R. van; Lakke, S.E.; Reneman, M.F.; Schans, van der; Haastert, C.J.; Geertzen, J.H.; Wittink, H.

    2011-01-01

    INTRODUCTION: Functional capacity tests are standardized instruments to evaluate patients' capacities to execute work-related activities. Functional capacity test results are associated with biopsychosocial factors, making it unclear what is being measured in capacity testing. An overview of these f

  15. Factors Associated with Functional Capacity Test Results in Patients With Non-Specific Chronic Low Back Pain : A Systematic Review

    NARCIS (Netherlands)

    van Abbema, Renske; Lakke, Sandra E.; Reneman, Michiel F.; van der Schans, Cees P.; van Haastert, Corrien J. M.; Geertzen, Jan H. B.; Wittink, Harriet

    2011-01-01

    Introduction: Functional capacity tests are standardized instruments to evaluate patients' capacities to execute work-related activities. Functional capacity test results are associated with biopsychosocial factors, making it unclear what is being measured in capacity testing. An overview of these f

  16. Water Associated Zero Maze: A novel rat test for long term traumatic re-experiencing

    Directory of Open Access Journals (Sweden)

    Gilad eRitov

    2014-01-01

    Full Text Available Often, freezing and startle behaviors in the context of a previously experienced stress are taken as an indication of posttraumatic stress disorder (PTSD-like symptoms in rats. However, PTSD is characterized by large individual variations of symptoms. In order to take into consideration the complex and long term distinctive variations in effects of trauma exposure additional behavioral measures are required.The current study used a novel behavioral test, the Water Associated Zero Maze (WAZM. This test was planned to enable a formation of an association between the context of the maze and an underwater trauma or swim stress in order to examine the impact of exposure to the context which immediately precedes a stressful or a traumatic experience on rat's complex behavior. Rats were exposed to the WAZM and immediately after to an underwater trauma or short swim. One month later rats were re-exposed to the context of the WAZM while their behavior was video recorded. Furthermore, c-Fos expression in the amygdala was measured 90 min after this exposure.The results of the current study indicate that the WAZM can be used to discern behavioral changes measured a long time after the actual traumatic or stressful events. Furthermore, the behavioral changes detected were accompanied by changes of c-Fos expression in the amygdala of exposed rats. We suggest that the WAZM can be used to model traumatic memories re-experiencing in rodent models of human stress-related pathologies such as PTSD.

  17. Joint mouse–human phenome-wide association to test gene function and disease risk

    Science.gov (United States)

    Wang, Xusheng; Pandey, Ashutosh K.; Mulligan, Megan K.; Williams, Evan G.; Mozhui, Khyobeni; Li, Zhengsheng; Jovaisaite, Virginija; Quarles, L. Darryl; Xiao, Zhousheng; Huang, Jinsong; Capra, John A.; Chen, Zugen; Taylor, William L.; Bastarache, Lisa; Niu, Xinnan; Pollard, Katherine S.; Ciobanu, Daniel C.; Reznik, Alexander O.; Tishkov, Artem V.; Zhulin, Igor B.; Peng, Junmin; Nelson, Stanley F.; Denny, Joshua C.; Auwerx, Johan; Lu, Lu; Williams, Robert W.

    2016-01-01

    Phenome-wide association is a novel reverse genetic strategy to analyze genome-to-phenome relations in human clinical cohorts. Here we test this approach using a large murine population segregating for ∼5 million sequence variants, and we compare our results to those extracted from a matched analysis of gene variants in a large human cohort. For the mouse cohort, we amassed a deep and broad open-access phenome consisting of ∼4,500 metabolic, physiological, pharmacological and behavioural traits, and more than 90 independent expression quantitative trait locus (QTL), transcriptome, proteome, metagenome and metabolome data sets—by far the largest coherent phenome for any experimental cohort (www.genenetwork.org). We tested downstream effects of subsets of variants and discovered several novel associations, including a missense mutation in fumarate hydratase that controls variation in the mitochondrial unfolded protein response in both mouse and Caenorhabditis elegans, and missense mutations in Col6a5 that underlies variation in bone mineral density in both mouse and human. PMID:26833085

  18. Radioactive waste isolation in salt: Peer review of the Golder Associates draft test plan for in situ testing in an exploratory shaft in salt

    Energy Technology Data Exchange (ETDEWEB)

    Hambley, D.F.; Mraz, D.Z.; Unterberter, R.R.; Stormont, J.C.; Neuman, S.P.; Russell, J.E.; Jacoby, C.H.; Hull, A.B.; Brady, B.H.G.; Ditmars, J.D.

    1987-01-01

    This report documents the peer review conducted by Argonne National Laboratory of a document entitled ''Draft Test Plan for In Situ Testing in an Exploratory Shaft in Salt,'' prepared for Battelle Memorial Institute's Office of Nuclear Waste Isolation by Golder Associates, Inc. In general, the peer review panelists found the test plan to be technically sound, although some deficiencies were identified. Recommendations for improving the test plan are presented in this review report. A microfiche copy of the following unpublished report is attached to the inside back cover of this report: ''Draft Test Plan for In Situ Testing in an Exploratory Shaft in Salt,'' prepared by Golder Associates, Inc., for Office of Nuclear Waste Isolation, Battelle Memorial Institute, Columbus, Ohio (March 1985).

  19. Radioactive waste isolation in salt: Peer review of the Golder Associates draft test plan for in situ testing in an exploratory shaft in salt

    International Nuclear Information System (INIS)

    This report documents the peer review conducted by Argonne National Laboratory of a document entitled ''Draft Test Plan for In Situ Testing in an Exploratory Shaft in Salt,'' prepared for Battelle Memorial Institute's Office of Nuclear Waste Isolation by Golder Associates, Inc. In general, the peer review panelists found the test plan to be technically sound, although some deficiencies were identified. Recommendations for improving the test plan are presented in this review report. A microfiche copy of the following unpublished report is attached to the inside back cover of this report: ''Draft Test Plan for In Situ Testing in an Exploratory Shaft in Salt,'' prepared by Golder Associates, Inc., for Office of Nuclear Waste Isolation, Battelle Memorial Institute, Columbus, Ohio (March 1985)

  20. Crossmatch testing in kidney transplantation: Patterns of practice and associations with rejection and graft survival

    International Nuclear Information System (INIS)

    Methods of crossmatch testing prior to kidney transplantation are not standardized and there are limited large-scale data on the use and outcomes implications of crossmatch modality. Data describing the most sensitive crossmatch modality for crossmatch-negative kidney transplants were drawn from the Organ Procurement and Transplant Network Registry. Within the cohort transplanted in 1999-2005, we identified patient and transplant characteristics predictive of each testing modality by multivariate logistic regression. We assessed associations of crossmatch modality with rejection risk by logistic regression and with graft survival by Cox's hazards analysis. Among 230,995 transplants, use of flow cytometry with T-and B-lymphocytes (T and B FC) increased progressively in 1987-2005. Among the recent transplants performed in 1999-2005 (n=64,320), negative T and B FC crossmatch was associated with 15% lower relative risk of first-year acute rejection (adjusted HR 0.85, 95% CI 0.80-0.89) compared to negative T-antihuman-globulin and B-National Institutes of Health/Wash (T AHG and B) crossmatch. Five-year graft survival after transplant with negative T and B FC (82.6%) was modestly better than after negative T AHG and B (81.4%, P0.008) or T AHG crossmatch (81.1%, P 60 years. Many subgroups for whom negative T and B FC crossmatch predicted lower rejection risk (Caucasians, deceased donor recipients, re-transplants) were not more likely to be crossmatched by this method. We conclude that current practice patterns have not aligned utilization of T and B FC crossmatch with associated benefits. Prospective evaluation of the relationship of crossmatch modality with outcomes is warranted. (author)

  1. Magnetopause shape as a bivariate function of interplanetary magnetic field B(sub z) and solar wind dynamic pressure

    Science.gov (United States)

    Roelof, Edmond C.; Sibeck, David G.

    1993-01-01

    We present a new method for determining the shape of the magnetopause as a bivariate function of the hourly averaged solar wind dynamic pressure (p) and the north-south component of the interplanetary magnetic field (IMF) B(sub z). We represent the magnetopause (for X(sub GSE) greater than -40 R(sub E)) as an ellipsoid of revolution in solar-wind-aberrated coordinates and express the (p, B(sub z)) dependence of each of the three ellipsoid parameters as a second-order (6-term) bivariate expansion in Inp and B(sub z). We define 12 overlapping bins in a normalized dimensionless (p, B(sub z)) `control space' and fit an ellipsoid to those magnetopause crossings having (p, B(sub z)) values within each bin. We also calculate the bivariate (Inp, B(sub z)) moments to second order over each bin in control space. We can then calculate the six control-space expansion coefficients for each of the three ellipsoid parameters in configuration space. From these coefficients we can derive useful diagnosis of the magnetopause shape as joint functions of p and B(sub z): the aspect ratio of the ellipsoid's minor-to-major axes; the flank distance, radius of curvature, and flaring angle (at X(sub GSE) = 0); and the subsolar distance and radius of curvature. We confirm and quantify previous results that during periods of southward B(sub z) the subsolar magnetopause moves inward, while at X(sub GSE) = 0 the flank magnetopause moves outward and the flaring angle increases.

  2. Predicting the Size of Sunspot Cycle 24 on the Basis of Single- and Bi-Variate Geomagnetic Precursor Methods

    Science.gov (United States)

    Wilson, Robert M.; Hathaway, David H.

    2009-01-01

    Examined are single- and bi-variate geomagnetic precursors for predicting the maximum amplitude (RM) of a sunspot cycle several years in advance. The best single-variate fit is one based on the average of the ap index 36 mo prior to cycle minimum occurrence (E(Rm)), having a coefficient of correlation (r) equal to 0.97 and a standard error of estimate (se) equal to 9.3. Presuming cycle 24 not to be a statistical outlier and its minimum in March 2008, the fit suggests cycle 24 s RM to be about 69 +/- 20 (the 90% prediction interval). The weighted mean prediction of 11 statistically important single-variate fits is 116 +/- 34. The best bi-variate fit is one based on the maximum and minimum values of the 12-mma of the ap index; i.e., APM# and APm*, where # means the value post-E(RM) for the preceding cycle and * means the value in the vicinity of cycle minimum, having r = 0.98 and se = 8.2. It predicts cycle 24 s RM to be about 92 +/- 27. The weighted mean prediction of 22 statistically important bi-variate fits is 112 32. Thus, cycle 24's RM is expected to lie somewhere within the range of about 82 to 144. Also examined are the late-cycle 23 behaviors of geomagnetic indices and solar wind velocity in comparison to the mean behaviors of cycles 2023 and the geomagnetic indices of cycle 14 (RM = 64.2), the weakest sunspot cycle of the modern era.

  3. A tutorial on Bayesian bivariate meta-analysis of mixed binary-continuous outcomes with missing treatment effects.

    Science.gov (United States)

    Gajic-Veljanoski, Olga; Cheung, Angela M; Bayoumi, Ahmed M; Tomlinson, George

    2016-05-30

    Bivariate random-effects meta-analysis (BVMA) is a method of data synthesis that accounts for treatment effects measured on two outcomes. BVMA gives more precise estimates of the population mean and predicted values than two univariate random-effects meta-analyses (UVMAs). BVMA also addresses bias from incomplete reporting of outcomes. A few tutorials have covered technical details of BVMA of categorical or continuous outcomes. Limited guidance is available on how to analyze datasets that include trials with mixed continuous-binary outcomes where treatment effects on one outcome or the other are not reported. Given the advantages of Bayesian BVMA for handling missing outcomes, we present a tutorial for Bayesian BVMA of incompletely reported treatment effects on mixed bivariate outcomes. This step-by-step approach can serve as a model for our intended audience, the methodologist familiar with Bayesian meta-analysis, looking for practical advice on fitting bivariate models. To facilitate application of the proposed methods, we include our WinBUGS code. As an example, we use aggregate-level data from published trials to demonstrate the estimation of the effects of vitamin K and bisphosphonates on two correlated bone outcomes, fracture, and bone mineral density. We present datasets where reporting of the pairs of treatment effects on both outcomes was 'partially' complete (i.e., pairs completely reported in some trials), and we outline steps for modeling the incompletely reported data. To assess what is gained from the additional work required by BVMA, we compare the resulting estimates to those from separate UVMAs. We discuss methodological findings and make four recommendations. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26553369

  4. An association between anxiety and neurocardiogenic syncope during head-up tilt table testing.

    Science.gov (United States)

    Cohen, T J; Thayapran, N; Ibrahim, B; Quan, C; Quan, W; von zur Muhlen, F

    2000-05-01

    To study the association between anxiety and neurocardiogenic syncope as determined by head-up tilt table testing (HUT) in men and women with presyncope or syncope, patients with unexplained syncope or presyncope undergoing HUT were asked to complete the Burns Anxiety Inventory (BAI), a validated inventory of 33 questions with responses graded from 0 to 3. HUT consisted of a 30-minute tilt to 60 degrees, which if negative, was repeated with an isoproterenol infusion. A positive HUT was defined as symptomatic hypotension and/or bradycardia. Of the 66 patients who completed the BAI and underwent HUT, 33 were men and 33 were women. The mean age was 57 +/- 18 years (17-91 years). Patients with a positive HUT had a higher BAI score than those with a negative HUT (22 +/- 12 vs 14 +/- 13, P = 0.017). This association was stronger in women with a BAI score of 24 +/- 11 in those with a positive HUT versus 13 +/- 8 in those with a negative HUT (P = 0.005). In contrast, the mean BAI score for men with a positive HUT was 19 +/- 13, as compared to 15 +/- 16 for a negative HUT (P = 0.5). In conclusion, the present study demonstrates a statistical association between anxiety (as determined by BAI) and HUT result. Gender-based analysis revealed a more statistically significant relationship between anxiety and HUT outcome for women as compared to men. PMID:10833703

  5. Regional admixture mapping and structured association testing: conceptual unification and an extensible general linear model.

    Directory of Open Access Journals (Sweden)

    David T Redden

    2006-08-01

    Full Text Available Individual genetic admixture estimates, determined both across the genome and at specific genomic regions, have been proposed for use in identifying specific genomic regions harboring loci influencing phenotypes in regional admixture mapping (RAM. Estimates of individual ancestry can be used in structured association tests (SAT to reduce confounding induced by various forms of population substructure. Although presented as two distinct approaches, we provide a conceptual framework in which both RAM and SAT are special cases of a more general linear model. We clarify which variables are sufficient to condition upon in order to prevent spurious associations and also provide a simple closed form "semiparametric" method of evaluating the reliability of individual admixture estimates. An estimate of the reliability of individual admixture estimates is required to make an inherent errors-in-variables problem tractable. Casting RAM and SAT methods as a general linear model offers enormous flexibility enabling application to a rich set of phenotypes, populations, covariates, and situations, including interaction terms and multilocus models. This approach should allow far wider use of RAM and SAT, often using standard software, in addressing admixture as either a confounder of association studies or a tool for finding loci influencing complex phenotypes in species as diverse as plants, humans, and nonhuman animals.

  6. Characterizing switching and congruency effects in the Implicit Association Test as reactive and proactive cognitive control.

    Science.gov (United States)

    Hilgard, Joseph; Bartholow, Bruce D; Dickter, Cheryl L; Blanton, Hart

    2015-03-01

    Recent research has identified an important role for task switching, a cognitive control process often associated with executive functioning, in the Implicit Association Test (IAT). However, switching does not fully account for IAT effects, particularly when performance is scored using more recent d-score formulations. The current study sought to characterize multiple control processes involved in IAT performance through the use of event-related brain potentials (ERPs). Participants performed a race-evaluative IAT while ERPs were recorded. Behaviorally, participants experienced superadditive reaction time costs of incongruency and task switching, consistent with previous studies. The ERP showed a marked medial frontal negativity (MFN) 250-450 ms post-stimulus at midline fronto-central locations that were more negative for incongruent than congruent trials but more positive for switch than for no-switch trials, suggesting separable control processes are engaged by these two factors. Greater behavioral IAT bias was associated with both greater switch-related and congruency-related ERP activity. Findings are discussed in terms of the Dual Mechanisms of Control model of reactive and proactive cognitive control. PMID:24812074

  7. Research Problems Associated with Limiting the Applied Force in Vibration Tests and Conducting Base-Drive Modal Vibration Tests

    Science.gov (United States)

    Scharton, Terry D.

    1995-01-01

    The intent of this paper is to make a case for developing and conducting vibration tests which are both realistic and practical (a question of tailoring versus standards). Tests are essential for finding things overlooked in the analyses. The best test is often the most realistic test which can be conducted within the cost and budget constraints. Some standards are essential, but the author believes more in the individual's ingenuity to solve a specific problem than in the application of standards which reduce problems (and technology) to their lowest common denominator. Force limited vibration tests and base-drive modal tests are two examples of realistic, but practical testing approaches. Since both of these approaches are relatively new, a number of interesting research problems exist, and these are emphasized herein.

  8. Implications of the Implicit Association Test D-Transformation for Psychological Assessment.

    Science.gov (United States)

    Blanton, Hart; Jaccard, James; Burrows, Christopher N

    2015-08-01

    Psychometricians strive to eliminate random error from their psychological inventories. When random error affecting tests is diminished, tests more accurately characterize people on the psychological dimension of interest. We document an unusual property of the scoring algorithm for a measure used to assess a wide range of psychological states. The "D-score" algorithm for coding the Implicit Association Test (IAT) requires the presence of random noise in order to obtain variability. Without consequential degrees of random noise, all individuals receive extreme scores. We present results from an algebraic proof, a computer simulation, and an online survey of implicit racial attitudes to show how trial error can bias IAT assessments. We argue as a result that the D-score algorithm should not be used for formal assessment purposes, and we offer an alternative to this approach based on multiple regression. Our critique focuses primarily on the IAT designed to measure unconscious racial attitudes, but it applies to any IAT developed to provide psychological assessments within clinical, organizational, and developmental branches of psychology-and in any other field where the IAT might be used. PMID:25296761

  9. Association testing of copy number variants in schizophrenia and autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Crespi Bernard J

    2012-05-01

    Full Text Available Abstract Background Autism spectrum disorders and schizophrenia have been associated with an overlapping set of copy number variant loci, but the nature and degree of overlap in copy number variants (deletions compared to duplications between these two disorders remains unclear. Methods We systematically evaluated three lines of evidence: (1 the statistical bases for associations of autism spectrum disorders and schizophrenia with a set of the primary CNVs thus far investigated, from previous studies; (2 data from case series studies on the occurrence of these CNVs in autism spectrum disorders, especially among children, and (3 data on the extent to which the CNVs were associated with intellectual disability and developmental, speech, or language delays. We also conducted new analyses of existing data on these CNVs in autism by pooling data from seven case control studies. Results Four of the CNVs considered, dup 1q21.1, dup 15q11-q13, del 16p11.2, and dup 22q11.21, showed clear statistical evidence as autism risk factors, whereas eight CNVs, del 1q21.1, del 3q29, del 15q11.2, del 15q13.3, dup 16p11.2, dup 16p13.1, del 17p12, and del 22q11.21, were strongly statistically supported as risk factors for schizophrenia. Three of the CNVs, dup 1q21.1, dup 16p11.2, and dup 16p13.1, exhibited statistical support as risk factors for both autism and schizophrenia, although for each of these CNVs statistical significance was nominal for tests involving one of the two disorders. For the CNVs that were statistically associated with schizophrenia but were not statistically associated with autism, a notable number of children with the CNVs have been diagnosed with autism or ASD; children with these CNVs also demonstrate a high incidence of intellectual disability and developmental, speech, or language delays. Conclusions These findings suggest that although CNV loci notably overlap between autism and schizophrenia, the degree of strongly statistically

  10. Factors associated with satisfaction with community-based non-medicalized counseling and testing using HIV rapid tests among MSM in France.

    Science.gov (United States)

    Préau, Marie; Lorente, Nicolas; Sagaon-Teyssier, Luis; Champenois, Karen; Gall, Jean Marie Le; Mabire, Xavier; Spire, Bruno; Mora, Marion; Yazdanpanah, Yazdan; Suzan, Marie

    2016-10-01

    The aims of the study were to determine the level of satisfaction of men who have sex with men (MSM) participating in two community-based non-medicalized counseling and testing programs (ANRS-DRAG and ANRS-COM'TEST) offering HIV rapid tests (hereafter CBOffer), and to identify factors associated with satisfaction. Between 2009 and 2011, 436 participants voluntarily benefited from a CBOffer in the two programs. They completed self-administered questionnaires before and after testing. Psychosocial scores were constructed using principal component analyses to reflect the following dimensions: post-test satisfaction, avoidance of at-risk situations as a HIV risk-reduction strategy, and attitudes towards condom use. Logarithmic regression of the post-test satisfaction score was performed on these scores and on other selected explanatory variables, including the variable "self-identification as homosexual or bisexual". Post-test satisfaction ranged between 90-99 and below 90 for 50% and 25% of the participants, respectively. Post-test satisfaction with the CBOffer was independently associated with self-defined sexuality, meeting place for sexual partners, participants' attitudes about being HIV-positive, and condom use. The very high level of satisfaction was associated with both personal and socio-behavioral factors. Vulnerable MSM could be targeted better and, accordingly, could use this offer more frequently as a combined prevention tool. PMID:27088324

  11. Understanding and using the brief Implicit Association Test: recommended scoring procedures.

    Directory of Open Access Journals (Sweden)

    Brian A Nosek

    Full Text Available A brief version of the Implicit Association Test (BIAT has been introduced. The present research identified analytical best practices for overall psychometric performance of the BIAT. In 7 studies and multiple replications, we investigated analytic practices with several evaluation criteria: sensitivity to detecting known effects and group differences, internal consistency, relations with implicit measures of the same topic, relations with explicit measures of the same topic and other criterion variables, and resistance to an extraneous influence of average response time. The data transformation algorithms D outperformed other approaches. This replicates and extends the strong prior performance of D compared to conventional analytic techniques. We conclude with recommended analytic practices for standard use of the BIAT.

  12. Does the compatibility effect in the race Implicit Association Test reflect familiarity or affect?

    Science.gov (United States)

    Kinoshita, Sachiko; Peek-O'Leary, Marie

    2005-06-01

    In the Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) involving race classification (white vs. black), an apparent compatibility effect is found between the "pleasant" attribute and the "white" category. This race IAT effect has been interpreted in terms of "implicit prejudice"--that is, more positive evaluation of whites than of blacks that is not open to consciousness. We suggested instead that the race IAT effect is better interpreted in terms of the salience asymmetry account proposed by Rothermund and Wentura (2004), whereby greater familiarity with the white category makes it more salient. Evidence that has been presented against the familiarity interpretation is considered, and alternative interpretations of findings related to the race IAT effect are discussed. PMID:16235627

  13. An assessment on the use of bivariate, multivariate and soft computing techniques for collapse susceptibility in GIS environ

    Indian Academy of Sciences (India)

    Işık Yilmaz; Marian Marschalko; Martin Bednarik

    2013-04-01

    The paper presented herein compares and discusses the use of bivariate, multivariate and soft computing techniques for collapse susceptibility modelling. Conditional probability (CP), logistic regression (LR) and artificial neural networks (ANN) models representing the bivariate, multivariate and soft computing techniques were used in GIS based collapse susceptibility mapping in an area from Sivas basin (Turkey). Collapse-related factors, directly or indirectly related to the causes of collapse occurrence, such as distance from faults, slope angle and aspect, topographical elevation, distance from drainage, topographic wetness index (TWI), stream power index (SPI), Normalized Difference Vegetation Index (NDVI) by means of vegetation cover, distance from roads and settlements were used in the collapse susceptibility analyses. In the last stage of the analyses, collapse susceptibility maps were produced from the models, and they were then compared by means of their validations. However, Area Under Curve (AUC) values obtained from all three models showed that the map obtained from soft computing (ANN) model looks like more accurate than the other models, accuracies of all three models can be evaluated relatively similar. The results also showed that the conditional probability is an essential method in preparation of collapse susceptibility map and highly compatible with GIS operating features.

  14. Bivariate mass-size relation as a function of morphology as determined by Galaxy Zoo 2 crowdsourced visual classifications

    Science.gov (United States)

    Beck, Melanie; Scarlata, Claudia; Fortson, Lucy; Willett, Kyle; Galloway, Melanie

    2016-01-01

    It is well known that the mass-size distribution evolves as a function of cosmic time and that this evolution is different between passive and star-forming galaxy populations. However, the devil is in the details and the precise evolution is still a matter of debate since this requires careful comparison between similar galaxy populations over cosmic time while simultaneously taking into account changes in image resolution, rest-frame wavelength, and surface brightness dimming in addition to properly selecting representative morphological samples.Here we present the first step in an ambitious undertaking to calculate the bivariate mass-size distribution as a function of time and morphology. We begin with a large sample (~3 x 105) of SDSS galaxies at z ~ 0.1. Morphologies for this sample have been determined by Galaxy Zoo crowdsourced visual classifications and we split the sample not only by disk- and bulge-dominated galaxies but also in finer morphology bins such as bulge strength. Bivariate distribution functions are the only way to properly account for biases and selection effects. In particular, we quantify the mass-size distribution with a version of the parametric Maximum Likelihood estimator which has been modified to account for measurement errors as well as upper limits on galaxy sizes.

  15. Collective estimation of multiple bivariate density functions with application to angular-sampling-based protein loop modeling

    KAUST Repository

    Maadooliat, Mehdi

    2015-10-21

    This paper develops a method for simultaneous estimation of density functions for a collection of populations of protein backbone angle pairs using a data-driven, shared basis that is constructed by bivariate spline functions defined on a triangulation of the bivariate domain. The circular nature of angular data is taken into account by imposing appropriate smoothness constraints across boundaries of the triangles. Maximum penalized likelihood is used to fit the model and an alternating blockwise Newton-type algorithm is developed for computation. A simulation study shows that the collective estimation approach is statistically more efficient than estimating the densities individually. The proposed method was used to estimate neighbor-dependent distributions of protein backbone dihedral angles (i.e., Ramachandran distributions). The estimated distributions were applied to protein loop modeling, one of the most challenging open problems in protein structure prediction, by feeding them into an angular-sampling-based loop structure prediction framework. Our estimated distributions compared favorably to the Ramachandran distributions estimated by fitting a hierarchical Dirichlet process model; and in particular, our distributions showed significant improvements on the hard cases where existing methods do not work well.

  16. An inquisition into bivariate threshold effects in the inflation-growth correlation: Evaluating South Africa’s macroeconomic objectives

    Directory of Open Access Journals (Sweden)

    Andrew Phiri

    2013-10-01

    Full Text Available Is the SARB’s inflation target of 3-6% compatible with the 6% economic growth objective set by ASGISA? Estimations of inflation-growth bivariate Threshold Vector Autoregressive with corresponding bivariate Threshold Vector Error Correction (BTVEC-BTVAR econometric models for sub-periods coupled with the South African inflation-growth experience between 1960 and 2010; suggest on optimal inflation-growth combinations for South African data presenting a two-fold proposition. Firstly, for the performance of economic growth to improve so it coincides with the 6% target objective as defined by ASGISA, may require the sustainment of an inflation rate of below 3.08%. Secondly, given the current economic environment with inflation averages of above 3.08% and economic growth rates of below 5.58%, lower inflation rates are to be best pursued through the attainment of higher economic growth rates. Consequentially, the overall implication of the study offers support in favour of a lower, ‘close-to-zero’ inflation target as a means of ensuring improved macroeconomic performance within the economy, while simultaneously contending that it would prove beneficial for stabilization economic policies to be devised such that these low levels of inflation are attained through higher economic growth rates.

  17. Testing for natural selection in human exonic splicing regulators associated with evolutionary rate shifts.

    Science.gov (United States)

    Ramalho, Rodrigo F; Gelfman, Sahar; de Souza, Jorge E; Ast, Gil; de Souza, Sandro J; Meyer, Diogo

    2013-04-01

    Despite evidence that at the interspecific scale, exonic splicing silencers (ESSs) are under negative selection in constitutive exons, little is known about the effects of slightly deleterious polymorphisms on these splicing regulators. Through the application of a modified version of the McDonald-Kreitman test, we compared the normalized proportions of human polymorphisms and human/rhesus substitutions affecting exonic splicing regulators (ESRs) on sequences of constitutive and alternative exons. Our results show a depletion of substitutions and an enrichment of SNPs associated with ESS gain in constitutive exons. Moreover, we show that this evolutionary pattern is also present in a set of ESRs previously involved in the transition from constitutive to skipped exons in the mammalian lineage. The similarity between these two sets of ESRs suggests that the transition from constitutive to skipped exons in mammals is more frequently associated with the inhibition than with the promotion of splicing signals. This is in accordance with the hypothesis of a constitutive origin of exon skipping and corroborates previous findings about the antagonistic role of certain exonic splicing enhancers. PMID:23529588

  18. Pemphigus vulgaris of the cervix: diagnostic difficulties associated with the Pap test.

    Science.gov (United States)

    Munhoz de Paula Alves Coelho, Karina; Stall, Jaqueline; Henrique Condeixa de França, Paulo; Cristina de Carvalho Tavares, Lara; Stefanello Bublitz, Giuliano; Loos, Beliza; Carvalho Costa, Luciana; Fronza Júnior, Hercílio

    2015-08-01

    Pemphigus vulgaris (PV) is a rare mucocutaneous disease caused by the abnormal production of antibodies against epithelial cell surface glycoproteins, resulting in loss of cell adhesion and intraepithelial blister formation. Cervical involvement in PV has been poorly reported, and there is little information regarding the criteria about consequential cytological changes identified in a Papanicolaou-stained cervicovaginal smear (Pap smear). Here, we report a case of PV manifesting in the cervix as well as the difficulty associated with the cytomorphological identification and interpretation of acantholytic cells. This case involved a 40-year-old patient with no history of Pap test abnormalities and no prior diagnosis of PV. In the cytological assessment, cells were identified both in isolation and in clusters that exhibited round nuclei of increased volume, inconspicuous nucleoli, and perinuclear halos. The patient underwent a cervical biopsy that revealed vesiculobullous lesions and morphological pattern consistent with PV. A skin biopsy confirmed this diagnosis. We concluded that knowledge of PV cytomorphology is important because difficulties associated with the identification and interpretation of acantholytic cells might be responsible for false positive diagnoses of cervical neoplasia. However, a suspected diagnosis of PV is possible if the cytological findings are carefully correlated with the clinical data. PMID:25728997

  19. Psychology data from the Race Implicit Association Test on the Project Implicit Demo website

    Directory of Open Access Journals (Sweden)

    Kaiyuan Xu

    2014-03-01

    Full Text Available This data archive includes Race Implicit Association Test (IAT scores of 2,355,303 Internet volunteers who completed educational/demonstration versions of the Race IAT at https://implicit.harvard.edu from 2002 to 2012. Data in this archive can be downloaded for all years, either separately by year or in a single file. Codebooks, indicating the variable labels and value labels, and changes of variables over years, are available for both individual-year data sets and the entire data set. Participation in the (still on-going Race IAT “study” at the Project Implicit (PI demonstration site includes completion of the Race IAT along with demographic questions, self-report measures of racial attitude, and various additional measures received by a portion of the participants. These data allow analyses involving changes in responding over time and interrelations among IAT and self-report measures of race attitudes, as well as the association of each of these with demographics. This archive is available at http://osf.io/project/52qxL/. Dataset The Data described in this paper is available from the Open Science Framework: https://osf.io/52qxl/ [1

  20. Use of a radiorespirometric assay for testing the antibiotic sensitivity of catheter-associated bacteria

    International Nuclear Information System (INIS)

    A 14C-radiorespirometric assay was used to show the sensitivity of fixed-film (sessile), catheter-associated and free-living (planktonic) cells of Pseudomonas aeruginosa to varying concentrations (100 micrograms/mL to 1000 micrograms/mL) tobramycin sulfate. This strain of P. aeruginosa has an MIC of 0.6 microgram/ml and an MBC of 50 micrograms/mL when tested by conventional methods. When 14C-glutamic acid was used as a substrate in this radiorespirometric assay, it could be completed in less than one hour and planktonic samples showed a significant reduction in mineralization activity (evolution of 14CO2) within eight hours of the antibiotic challenge. These changes in respiratory activity appeared to be dose and time dependent. Within 18 hr. at 1000 micrograms/mL, there was no significant residual respiratory activity in planktonic samples. Some residual respiratory activity was detected, however, in samples exposed to 100 micrograms/mL for 36 hours. The mineralization activity of sessile catheter-associated bacteria was unaffected by four hr. and eight hr. exposures to 1000 micrograms/mL of the antibiotic. A significant reduction in respiratory activity was recorded in catheter samples exposed for 18 hr. or more at each concentration examined. Unlike the planktonic samples, however, the antibiotic challenge failed to eradicate the metabolic activity of the attached bacteria. Antibiotic stressed, catheter-associated bacteria transferred to a post-exposure enrichment broth showed a limited ability to re-establish respiratory activity. This apparent recovery was limited to antibiotic exposures less than 24 hr. and was not observed in planktonic samples. The radioisotopic assay is a non-culture method which can be used to assess the antibiotic sensitivity of both planktonic bacteria and in situ biofilm populations

  1. Association between cervical lesion grade and micronucleus frequency in the Papanicolaou test

    Directory of Open Access Journals (Sweden)

    Caroline Tanski Bueno

    2014-09-01

    Full Text Available The aim of this study was to evaluate the association between the frequency of micronuclei (MN and the cellular changes detected in the conventional Papanicolaou test. One hundred and seventy-four Papanicolaou test smears with cellular changes were examined. MN screening was done in cytopathological smears by counting 1,000 cervical cells in a light microscope. MN frequencies were significantly higher in the group with cellular changes compared to the control group (p < 0.001. The mean MN frequencies were 0.95 ± 1.12 (mean ± SD in the control group (n = 223, 2.98 ± 1.20 in individuals with atypical squamous cells of undetermined significance (ASC-US (n = 50, 4.04 ± 1.45 in cervical intraepithelial neoplasia (CIN I (n = 52, 5.97 ± 1.83 in CIN II (n = 30, 7.29 ± 1.55 in CIN III (n = 17 and 8.64 ± 1.55 in invasive cancer (n = 25. These findings suggest that MN monitoring should be included as an additional criterion for the early detection of cytogenetic damage in routine examinations. This monitoring should be done in the same smear as used for cytopathological examination. More specific and systematic studies are necessary to confirm this proposal.

  2. Drilling and Production Testing the Methane Hydrate Resource Potential Associated with the Barrow Gas Fields

    Energy Technology Data Exchange (ETDEWEB)

    Steve McRae; Thomas Walsh; Michael Dunn; Michael Cook

    2010-02-22

    In November of 2008, the Department of Energy (DOE) and the North Slope Borough (NSB) committed funding to develop a drilling plan to test the presence of hydrates in the producing formation of at least one of the Barrow Gas Fields, and to develop a production surveillance plan to monitor the behavior of hydrates as dissociation occurs. This drilling and surveillance plan was supported by earlier studies in Phase 1 of the project, including hydrate stability zone modeling, material balance modeling, and full-field history-matched reservoir simulation, all of which support the presence of methane hydrate in association with the Barrow Gas Fields. This Phase 2 of the project, conducted over the past twelve months focused on selecting an optimal location for a hydrate test well; design of a logistics, drilling, completion and testing plan; and estimating costs for the activities. As originally proposed, the project was anticipated to benefit from industry activity in northwest Alaska, with opportunities to share equipment, personnel, services and mobilization and demobilization costs with one of the then-active exploration operators. The activity level dropped off, and this benefit evaporated, although plans for drilling of development wells in the BGF's matured, offering significant synergies and cost savings over a remote stand-alone drilling project. An optimal well location was chosen at the East Barrow No.18 well pad, and a vertical pilot/monitoring well and horizontal production test/surveillance well were engineered for drilling from this location. Both wells were designed with Distributed Temperature Survey (DTS) apparatus for monitoring of the hydrate-free gas interface. Once project scope was developed, a procurement process was implemented to engage the necessary service and equipment providers, and finalize project cost estimates. Based on cost proposals from vendors, total project estimated cost is $17.88 million dollars, inclusive of design work

  3. Cerebral correlates of faking: Evidence from a Brief Implicit Association Test on Doping Attitudes

    Directory of Open Access Journals (Sweden)

    Sebastian eSchindler

    2015-05-01

    Full Text Available Direct assessment of attitudes toward socially sensitive topics can be affected by deception attempts. Reaction-time based indirect measures, such as the Implicit Association Test (IAT, are less susceptible to such biases. Neuroscientific evidence shows that deception can evoke characteristic ERP differences. However, the cerebral processes involved in faking an IAT are still unknown. We randomly assigned 20 university students (15 females, 24.65 ± 3.50 years of age to a counterbalanced repeated-measurements design, requesting them to complete a Brief-IAT (BIAT on attitudes toward doping without deception instruction, and with the instruction to fake positive and negative doping attitudes. Cerebral activity during BIAT completion was assessed using high-density EEG. Event-related potentials during faking revealed enhanced frontal and reduced occipital negativity, starting around 150ms after stimulus presentation. Further, a decrease in the P300 and LPP components was observed. Source analyses showed enhanced activity in the right inferior frontal gyrus between 150 and 200ms during faking, thought to reflect the suppression of automatic responses. Further, more activity was found for faking in the bilateral middle occipital gyri and the bilateral temporoparietal junction. Results indicate that faking reaction-time based tests alter brain processes from early stages of processing and reveal the cortical sources of the effects. Analyzing the EEG helps to uncover response patterns in indirect attitude tests and broadens our understanding of the neural processes involved in such faking. This knowledge might be useful for uncovering faking in socially sensitive contexts, where attitudes are likely to be concealed.

  4. Characterization of human organ donors testing positive for type 1 diabetes-associated autoantibodies.

    Science.gov (United States)

    Wiberg, A; Granstam, A; Ingvast, S; Härkönen, T; Knip, M; Korsgren, O; Skog, O

    2015-12-01

    In this study we aim to describe the characteristics of non-diabetic organ donors with circulating diabetes-associated autoantibodies collected within the Nordic Network for Islet Transplantation. One thousand and thirty organ donors have been screened in Uppsala for antibodies against glutamic acid decarboxylase (GADA) and islet antigen-2 (IA-2A). The 32 non-diabetic donors that tested positive for GADA (3.3% of all non-diabetic donors) were studied in more detail, together with 32 matched controls. Mean age among the autoantibody-positive donors was 52.6 (range 21-74), family history of type 1 diabetes (T1D) was unknown, and no donor was genetically predisposed for T1D regarding the human leucocyte antigen (HLA) locus. Subjects were analysed for islet cell antibodies (ICA), insulin autoantibodies (IAA) and zinc transporter 8 antibodies (ZnT8A), and pancreas morphology and clinical data were examined. Eight non-diabetic donors tested positive for two antibodies and one donor tested positive for four antibodies. No insulitis or other signs of a diabetic process were found in any of the donors. While inflammatory cells were present in all donors, subjects with high GADA titres had significantly higher CD45 cell numbers in exocrine tissue than controls. The extent of fibrosis was more pronounced in autoantibody-positive donors, even in subjects with lower GADA titres. Notably, it is possible that events not related directly to T1D (e.g. subclinical pancreatitis) may induce autoantibodies in some cases. PMID:26313035

  5. Can social psychological attitude measures be used to study language attitudes? - A case study exploring the Personalized Implicit Association Test

    OpenAIRE

    Rosseel, Laura; Speelman, Dirk; Geeraerts, Dirk

    2015-01-01

    In the field of social psychology, a wide range of implicit attitude measures have recently been developed. These measures have hardly been used in linguistic attitude research so far. This paper presents a case study exploring the potential of one of these social psychological measures, the Personalized Implicit Association Test, in order to find out whether it can be useful for the study of language attitudes. In the case study, the Personalized Implicit Association Test is applied to measu...

  6. Clinical factors associated with a Candida albicans Germ Tube Antibody positive test in Intensive Care Unit patients

    OpenAIRE

    Martín-Mazuelos Estrella; Giménez María J; Ramírez Paula; Camarena Juan J; Cuétara María S; Alkorta Miriam; Quindós Guillermo; Zaragoza Rafael; Pemán Javier; Linares-Sicilia María J; Pontón José

    2011-01-01

    Abstract Background Poor outcomes of invasive candidiasis (IC) are associated with the difficulty in establishing the microbiological diagnosis at an early stage. New scores and laboratory tests have been developed in order to make an early therapeutic intervention in an attempt to reduce the high mortality associated with invasive fungal infections. Candida albicans IFA IgG has been recently commercialized for germ tube antibody detection (CAGTA). This test provides a rapid and simple diagno...

  7. Implicit and explicit attitudes towards conventional and complementary and alternative medicine treatments: Introduction of an Implicit Association Test.

    Science.gov (United States)

    Green, James A; Hohmann, Cynthia; Lister, Kelsi; Albertyn, Riani; Bradshaw, Renee; Johnson, Christine

    2016-06-01

    This study examined associations between anticipated future health behaviour and participants' attitudes. Three Implicit Association Tests were developed to assess safety, efficacy and overall attitude. They were used to examine preference associations between conventional versus complementary and alternative medicine among 186 participants. A structural equation model suggested only a single implicit association, rather than three separate domains. However, this single implicit association predicted additional variance in anticipated future use of complementary and alternative medicine beyond explicit. Implicit measures should give further insight into motivation for complementary and alternative medicine use. PMID:25104784

  8. Enhancing power of rare variant association test by Zoom-Focus Algorithm (ZFA) to locate optimal testing region

    OpenAIRE

    Wang, Maggie Haitian; Weng, Haoyi; Sun, Rui; Zee, Benny Chung-Ying

    2016-01-01

    Motivation: Exome or targeted sequencing data exerts analytical challenge to test single nucleotide polymorphisms (SNPs) with extremely small minor allele frequency (MAF). Various rare variant tests were proposed to increase power by aggregating SNPs within a fixed genomic region, such as a gene or pathway. However, a gene could contain from several to thousands of markers, and not all of them may be related to the phenotype. Combining functional and non-functional SNPs in arbitrary genomic r...

  9. Perceived characteristics of the environment associated with active travel: development and testing of a new scale

    Directory of Open Access Journals (Sweden)

    Mutrie Nanette

    2008-05-01

    Full Text Available Abstract Background Environmental characteristics may be associated with patterns of physical activity. However, the development of instruments to measure perceived characteristics of the local environment is still at a comparatively early stage, and published instruments are not necessarily suitable for application in all settings. We therefore developed and established the test-retest reliability of a new scale for use in a study of the correlates of active travel and overall physical activity in deprived urban neighbourhoods in Glasgow, Scotland. Methods We developed and piloted a 14-item scale based on seven constructs identified from the literature (aesthetics, green space, access to amenities, convenience of routes, traffic, road safety and personal safety. We administered the scale to all participants in a random postal survey (n = 1322 and readministered the scale to a subset of original respondents (n = 125 six months later. We used principal components analysis and Varimax rotation to identify three principal components (factors and derived summary scores for subscales based on these factors. We examined the internal consistency of these subscales using Cronbach's alpha and examined the test-retest reliability of the individual items, the subscale summary scores and an overall summary neighbourhood score using a combination of correlation coefficients and Cohen's kappa with and without weighting. Results Public transport and proximity to shops were the items most likely to be rated positively, whereas traffic volume, traffic noise and road safety for cyclists were most likely to be rated negatively. Three principal components – 'safe and pleasant surroundings', 'low traffic' and 'convenience for walking' – together explained 45% of the total variance. The test-retest reliability of individual items was comparable with that of items in other published scales (intraclass correlation coefficients (ICCs 0.34–0.70; weighted Cohen

  10. Bivariate distributions in statistical spectroscopy studies: Fixed-J level densities, fixed-J averages and spin cut-off factors

    International Nuclear Information System (INIS)

    Analytical studies with the TBRE ensemble, supplemented by numerical calcultions with realistic interactions show that for large particle numbers, the bivariate cumulants (ksub(rs)) defined for the Hamiltonian operator (H) and the Jsub(z) operator, are very small; vertical strokeksub(rs)vertical stroke< or approx.0.3 for 3<=r+s<=6. As a result the expansions around a bivariate normal density are meaningful for the fixed-M densities (rho(E,M)). We adopt a bivariate Edgeworth expansion for rho(E,M) and give a compact form for the same. Finally using this rho(E,M) (which also define fixed-J densities uniquely), new series expansions are given for fixed-M (and hence for fixed-J) averages of the powers of H and also for the spin cut-off factors. (orig.)

  11. A new powerful non-parametric two-stage approach for testing multiple phenotypes in family-based association studies

    NARCIS (Netherlands)

    Lange, C; Lyon, H; DeMeo, D; Raby, B; Silverman, EK; Weiss, ST

    2003-01-01

    We introduce a new powerful nonparametric testing strategy for family-based association studies in which multiple quantitative traits are recorded and the phenotype with the strongest genetic component is not known prior to the analysis. In the first stage, using a population-based test based on the

  12. The Creation Of A Formal Test Flying System Within The British Microlight Aircraft Association And A Discussion Of The Spin Testing Of Microlight Aircraft

    OpenAIRE

    Gratton, GB; Porteous, TC

    2000-01-01

    The UK microlight aircraft community, under the guidance of the British Microlight Aircraft Association (BMAA), has developed a formalised system for the training and qualification of civil test pilots on this class of aircraft. This system is unique in Britain where most of the rest of the industry relies upon a pool of military-trained test aircrew, most of whom have no experience of microlight aircraft. This paper describes the system operated by the BMAA for the training and qualifica...

  13. Gene-based multiple regression association testing for combined examination of common and low frequency variants in quantitative trait analysis

    OpenAIRE

    Yoo, Yun Joo; Sun, Lei; Shelley B Bull

    2013-01-01

    Multi-marker methods for genetic association analysis can be performed for common and low frequency SNPs to improve power. Regression models are an intuitive way to formulate multi-marker tests. In previous studies we evaluated regression-based multi-marker tests for common SNPs, and through identification of bins consisting of correlated SNPs, developed a multi-bin linear combination (MLC) test that is a compromise between a 1 df linear combination test and a multi-df global test. Bins of SN...

  14. Factors Associated with Recent HIV Testing among Heterosexuals at High-Risk for HIV Infection in New York City

    Directory of Open Access Journals (Sweden)

    Marya eGwadz

    2016-04-01

    Full Text Available Background. The CDC recommends persons at high-risk for HIV infection in the United States receive annual HIV testing to foster early HIV diagnosis and timely linkage to health care. Heterosexuals make up a significant proportion of incident HIV infections (>25%, but test for HIV less frequently than those in other risk categories. Yet factors that promote or impede annual HIV testing among heterosexuals are poorly understood. The present study examines individual/attitudinal-, social-, and structural-level factors associated with past-year HIV testing among heterosexuals at high-risk for HIV. Methods. Participants were African American/Black and Hispanic heterosexual adults (N=2307 residing in an urban area with both high poverty and HIV prevalence rates. Participants were recruited by respondent-driven sampling (RDS in 2012-2015 and completed a computerized structured assessment battery covering background factors, multi-level putative facilitators of HIV testing, and HIV testing history. Separate logistic regression analysis for males and females identified factors associated with past-year HIV testing.Results. Participants were mostly male (58%, African American/Black (75%, and 39 years old on average (SD = 12.06 years. Lifetime homelessness (54% and incarceration (62% were common. Half reported past-year HIV testing (50% and 37% engaged in regular, annual HIV testing. Facilitators of HIV testing common to both genders included sexually transmitted infection (STI testing or STI diagnosis, peer norms supporting HIV testing, and HIV testing access. Among women, access to general medical care and extreme poverty further predicted HIV testing, while recent drug use reduced the odds of past-year HIV testing. Among men, past-year HIV testing was also associated with lifetime incarceration and substance use treatment.Conclusions. The present study identified gaps in rates of HIV testing among heterosexuals at high-risk for HIV, and both common and

  15. Illegal performance enhancing drugs and doping in sport: a picture-based brief implicit association test for measuring athletes’ attitudes

    OpenAIRE

    Brand, Ralf; Heck, Philipp; Ziegler, Matthias

    2014-01-01

    Background Doping attitude is a key variable in predicting athletes’ intention to use forbidden performance enhancing drugs. Indirect reaction-time based attitude tests, such as the implicit association test, conceal the ultimate goal of measurement from the participant better than questionnaires. Indirect tests are especially useful when socially sensitive constructs such as attitudes towards doping need to be described. The present study serves the development and validation of a novel pict...

  16. Association studies with imputed variants using expectation-maximization likelihood-ratio tests.

    Directory of Open Access Journals (Sweden)

    Kuan-Chieh Huang

    Full Text Available Genotype imputation has become standard practice in modern genetic studies. As sequencing-based reference panels continue to grow, increasingly more markers are being well or better imputed but at the same time, even more markers with relatively low minor allele frequency are being imputed with low imputation quality. Here, we propose new methods that incorporate imputation uncertainty for downstream association analysis, with improved power and/or computational efficiency. We consider two scenarios: I when posterior probabilities of all potential genotypes are estimated; and II when only the one-dimensional summary statistic, imputed dosage, is available. For scenario I, we have developed an expectation-maximization likelihood-ratio test for association based on posterior probabilities. When only imputed dosages are available (scenario II, we first sample the genotype probabilities from its posterior distribution given the dosages, and then apply the EM-LRT on the sampled probabilities. Our simulations show that type I error of the proposed EM-LRT methods under both scenarios are protected. Compared with existing methods, EM-LRT-Prob (for scenario I offers optimal statistical power across a wide spectrum of MAF and imputation quality. EM-LRT-Dose (for scenario II achieves a similar level of statistical power as EM-LRT-Prob and, outperforms the standard Dosage method, especially for markers with relatively low MAF or imputation quality. Applications to two real data sets, the Cebu Longitudinal Health and Nutrition Survey study and the Women's Health Initiative Study, provide further support to the validity and efficiency of our proposed methods.

  17. Effects of computer-based immediate feedback on foreign language listening comprehension and test-associated anxiety.

    Science.gov (United States)

    Lee, Shu-Ping; Su, Hui-Kai; Lee, Shin-Da

    2012-06-01

    This study investigated the effects of immediate feedback on computer-based foreign language listening comprehension tests and on intrapersonal test-associated anxiety in 72 English major college students at a Taiwanese University. Foreign language listening comprehension of computer-based tests designed by MOODLE, a dynamic e-learning environment, with or without immediate feedback together with the state-trait anxiety inventory (STAI) were tested and repeated after one week. The analysis indicated that immediate feedback during testing caused significantly higher anxiety and resulted in significantly higher listening scores than in the control group, which had no feedback. However, repeated feedback did not affect the test anxiety and listening scores. Computer-based immediate feedback did not lower debilitating effects of anxiety but enhanced students' intrapersonal eustress-like anxiety and probably improved their attention during listening tests. Computer-based tests with immediate feedback might help foreign language learners to increase attention in foreign language listening comprehension. PMID:22913036

  18. Prevalence of Orthorexia nervosa among college students based on Bratman's test and associated tendencies.

    Science.gov (United States)

    Bundros, Joanna; Clifford, Dawn; Silliman, Kathryn; Neyman Morris, Michelle

    2016-06-01

    Disordered eating is prevalent among college student populations, and Orthorexia nervosa (ON) is being explored as a new type of eating disorder. There is currently no standardized ON diagnostic tool, and the majority of ON research has been conducted among European populations. The present study explored the Bratman Orthorexia Test (BOT) for ON diagnosis, and its relationship to validated tools for assessing disordered eating, body dysmorphic, and obsessive-compulsive tendencies among college students attending a western university. A convenience sample of 448 college students with a mean age of 22 years was recruited to complete an online survey that included the BOT, Eating Attitudes Test-26 (EAT-26), Body Dysmorphic Disorder Questionnaire (BDDQ), Obsessive Compulsive Inventory, Revised (OCI-R) and demographics. Spearman correlation, Mann-Whitney U, Kruskal-Wallis, chi-square, and multiple linear regressions were used for analyses. The average BOT score was 4.71, near the "health fanatic" range, with Hispanic/Latino subjects and overweight/obese students having significantly higher median BOT scores. Gender, age, and college major were not significantly associated with BOT score. Significant positive correlations were observed between total BOT and EAT-26 scores (r = .47, p < 0.01), BOT and BDDQ scores (r = .25, p < 0.01), and BOT and OCI-R scores (r = .19, p < 0.01). ON tendencies may exist among college students and Hispanic/Latino and overweight/obese students may be at increased risk. Further research is needed to determine ON risk factors among diverse student populations in order to inform prevention and treatment approaches on college campuses. PMID:26923745

  19. Evaluation of PCR in bronchoalveolar lavage fluid for diagnosis of Pneumocystis jirovecii pneumonia: a bivariate meta-analysis and systematic review.

    Directory of Open Access Journals (Sweden)

    Li-Chao Fan

    Full Text Available BACKGROUND: As a promising tool, PCR in bronchoalveolar lavage fluid (BALF has not been accepted as a diagnostic criterion for PJP. OBJECTIVE: We undertook a systematic review of published studies to evaluate the diagnostic accuracy of PCR assays in BALF for PJP. METHODS: Eligible studies from PubMed, Embase and Web of Science reporting PCR assays in BALF for diagnosing PJP were identified. A bivariate meta-analysis of the method's sensitivity, specificity, and positive and negative likelihood ratios with a 95% confidence interval (CI were analyzed. The post-test probability was performed to evaluate clinical usefulness. A summary receiver operating characteristics (SROC curve was used to evaluate overall performance. Subgroup analyses were carried out to analysis the potential heterogeneity. RESULTS: Sixteen studies published between 1994 and 2012 were included. The summary sensitivity and specificity values (95% CI of PCR in BALF for diagnosis of PJP were 98.3% (91.3%-99.7% and 91.0% (82.7%-95.5%, respectively. The positive and negative likelihood ratios were 10.894 (5.569-21.309 and 0.018 (0.003-0.099, respectively. In a setting of 20% prevalence of PJP, the probability of PJP would be over 3-fold if the BALF-PCR test was positive, and the probability of PJP would be less than 0.5% if it was negative. The area under the SROC curve was 0.98 (0.97-0.99. CONCLUSIONS: The method of PCR in BALF shows high sensitivity and good specificity for the diagnosis of PJP. However, clinical practice for the diagnosis of PJP should consider the consistent respiratory symptoms, radiographic changes and laboratory findings of the suspected patients.

  20. Simplifying consent for HIV testing is associated with an increase in HIV testing and case detection in highest risk groups, San Francisco January 2003-June 2007.

    Directory of Open Access Journals (Sweden)

    Nicola M Zetola

    Full Text Available BACKGROUND: Populations at highest risk for HIV infection face multiple barriers to HIV testing. To facilitate HIV testing procedures, the San Francisco General Hospital Medical Center eliminated required written patient consent for HIV testing in its medical settings in May 2006. To describe the change in HIV testing rates in different hospital settings and populations after the change in HIV testing policy in the SFDH medical center, we performed an observational study using interrupted time series analysis. METHODS: Data from all patients aged 18 years and older seen from January 2003 through June 2007 at the San Francisco Department of Public Health (SFDPH medical care system were included in the analysis. The monthly HIV testing rate per 1000 had patient-visits was calculated for the overall population and stratified by hospital setting, age, sex, race/ethnicity, homelessness status, insurance status and primary language. RESULTS: By June 2007, the average monthly rate of HIV tests per 1000 patient-visits increased 4.38 (CI, 2.17-6.60, p<0.001 over the number predicted if the policy change had not occurred (representing a 44% increase. The monthly average number of new positive HIV tests increased from 8.9 (CI, 6.3-11.5 to 14.9 (CI, 10.6-19.2, p<0.001, representing a 67% increase. Although increases in HIV testing were seen in all populations, populations at highest risk for HIV infection, particularly men, the homeless, and the uninsured experienced the highest increases in monthly HIV testing rates after the policy change. CONCLUSIONS: The elimination of the requirement for written consent in May 2006 was associated with a significant and sustained increase in HIV testing rates and HIV case detection in the SFDPH medical center. Populations facing the higher barriers to HIV testing had the highest increases in HIV testing rates and case detection in response to the policy change.

  1. Cognitive function is associated with risk aversion in community-based older persons

    Directory of Open Access Journals (Sweden)

    Buchman Aron S

    2011-09-01

    Full Text Available Abstract Background Emerging data from younger and middle-aged persons suggest that cognitive ability is negatively associated with risk aversion, but this association has not been studied among older persons who are at high risk of experiencing loss of cognitive function. Methods Using data from 369 community-dwelling older persons without dementia from the Rush Memory and Aging Project, an ongoing longitudinal epidemiologic study of aging, we examined the correlates of risk aversion and tested the hypothesis that cognition is negatively associated with risk aversion. Global cognition and five specific cognitive abilities were measured via detailed cognitive testing, and risk aversion was measured using standard behavioral economics questions in which participants were asked to choose between a certain monetary payment ($15 versus a gamble in which they could gain more than $15 or gain nothing; potential gamble gains ranged from $21.79 to $151.19 with the gain amounts varied randomly over questions. We first examined the bivariate associations of age, education, sex, income and cognition with risk aversion. Next, we examined the associations between cognition and risk aversion via mixed models adjusted for age, sex, education, and income. Finally, we conducted sensitivity analyses to ensure that our results were not driven by persons with preclinical cognitive impairment. Results In bivariate analyses, sex, education, income and global cognition were associated with risk aversion. However, in a mixed effect model, only sex (estimate = -1.49, standard error (SE = 0.39, p i.e., semantic memory, episodic memory, working memory, and perceptual speed; performance on visuospatial abilities was not. Conclusion A lower level of cognitive ability and female sex are associated with greater risk aversion in advanced age.

  2. Testing Students with Special Educational Needs in Large-Scale Assessments - Psychometric Properties of Test Scores and Associations with Test Taking Behavior.

    Science.gov (United States)

    Pohl, Steffi; Südkamp, Anna; Hardt, Katinka; Carstensen, Claus H; Weinert, Sabine

    2016-01-01

    Assessing competencies of students with special educational needs in learning (SEN-L) poses a challenge for large-scale assessments (LSAs). For students with SEN-L, the available competence tests may fail to yield test scores of high psychometric quality, which are-at the same time-measurement invariant to test scores of general education students. We investigated whether we can identify a subgroup of students with SEN-L, for which measurement invariant competence measures of adequate psychometric quality may be obtained with tests available in LSAs. We furthermore investigated whether differences in test-taking behavior may explain dissatisfying psychometric properties and measurement non-invariance of test scores within LSAs. We relied on person fit indices and mixture distribution models to identify students with SEN-L for whom test scores with satisfactory psychometric properties and measurement invariance may be obtained. We also captured differences in test-taking behavior related to guessing and missing responses. As a result we identified a subgroup of students with SEN-L for whom competence scores of adequate psychometric quality that are measurement invariant to those of general education students were obtained. Concerning test taking behavior, there was a small number of students who unsystematically picked response options. Removing these students from the sample slightly improved item fit. Furthermore, two different patterns of missing responses were identified that explain to some extent problems in the assessments of students with SEN-L. PMID:26941665

  3. Indirect measurement of motivation: Developing and testing a motivational recoding-free implicit association test (m-IAT-RF)

    DEFF Research Database (Denmark)

    Kraus, Alexandra Anita; Scholderer, Joachim

    2015-01-01

    For the indirect measurement of approach-avoidance tendencies, two procedures are introduced and compared. The procedures are modifications of the standard IAT and the Recoding-Free IAT (IAT-RF) and use a motivational attribute dimension (approach, avoidance) instead of an evaluative one. Study 1...... (N = 162) assesses their convergent and discriminant validity with respect to self-reported measures of motivation and evaluation, and their predictive validity with respect to actual behavior. Study 2 (N = 205) furthermore compares their validity to evaluative variants of the same test paradigms...

  4. Single test isolated lupus anticoagulant positivity is associated with increased plasma levels of inflammatory markers and dyslipidemia

    DEFF Research Database (Denmark)

    Just, S A; Nybo, M; Laustrup, H; Jensen Hansen, Inger Marie; Junker, P; Vinholt, P Just

    2016-01-01

    OBJECTIVE: To investigate whether a single positive test for lupus anticoagulant (LA) is associated with levels of inflammatory markers and traditional cardiovascular risk factors, independent of autoimmune disease, thrombophilia and occurrence of other antiphospholipid antibodies. METHODS: In a...... ratios (ORs) with 95% confidence intervals (95% CI) calculated. RESULTS: Of 381 individuals tested, 271 fulfilled the criteria, of whom 22 (8%) were LA positive and 249 (92%) LA negative. LA positivity was associated with higher body mass index (BMI) (OR 1.12, 95% CI: 1.03-1.23, p = 0.01); C.......02) compared with LA negative individuals. CONCLUSION: This study shows that single test isolated LA positivity is associated with increased levels of inflammatory markers, low HDL cholesterol, elevated triglyceride and high BMI....

  5. Studying Co-evolution of Production and Test Code Using Association Rule Mining

    OpenAIRE

    Lubsen, Z.; Zaidman, A.; Pinzger, M.

    2009-01-01

    Long version of the short paper accepted for publication in the proceedings of the 6th International Working Conference on Mining Software Repositories (MSR 2009). Unit tests are generally acknowledged as an important aid to produce high quality code, as they provide quick feedback to developers on the correctness of their code. In order to achieve high quality, well-maintained tests are needed. Ideally, tests co-evolve with the production code to test changes as soon as possible. In this pap...

  6. A remark on 'Decomposition of bivariate inequality indices by attributes' by Abul Naga and Geoffard, Economics Letters 90 (2006), pp. 362-367

    OpenAIRE

    Marco Giovanni Brambilla; Eugenio Peluso

    2010-01-01

    We correct the generalized version of the decomposition of multivariate inequality indices by attributes proposed by Abul Naga and Geoffard "Abul Naga, R. H. and Geoffard, P. Y., 2006. Decomposition of bivariate inequality indices by attributes. Economic Letters 90, pp. 362-367."

  7. Bivariate distributions in statistical spectroscopy studies. Pt. 4. Interacting particle Gamow-Teller strength densities and β-decay rate of fp-shell nuclei for presupernova stars

    International Nuclear Information System (INIS)

    A method to calculate temperature dependent β-decay rates is developed by writing the expression for the rates explicitly in terms of bivariate GT strength densities (IHO(GT)) for a given hamiltonian H = h + V and state densities of the parent nucleus besides having the usual phase space factors. The theory developed in the preceding paper (III) for constructing NIP strength densities is applied for generating IhO(GT) and then IHO(GT) is constructed using the bivariate convolution form IHO(GT) ΣSIh,SO(GT) x ρV,SO(GT);BIV-G. The spreading bivariate Gaussian ρVO(GT);BIV-G, for fp-shell nuclei, is constructed by assuming that the marginal centroids are zero, the marginal variances are same as the corresponding state density variances and fixing the bivariate correlation coefficient anti ζ using experimental β-decay half lifes. With the deduced values of anti ζ anti ζ ∼ 0.67, β-decay rates for 61,62Fe and 62-64Co isotopes are calculated at presupernova matter densities ρ = 107-109 gm/cc, temperatures T = (3 - 5) x 109 K and electron fractions Ye = 0.43 - 0.5. The convolution form for IHO(GT) led to a simple expression for calculating GT non-energy weighted sum rule strength and it describes (within 10%) the shell model results of fp-shell nuclei. (orig.)

  8. 二元实值正交周期Box样条小波%Bivariate Real-valued Orthogonal Periodic Box-spline Wavelets

    Institute of Scientific and Technical Information of China (English)

    李强; 梁学章

    2006-01-01

    In this paper, we construct a kind of bivariate real-valued orthogonal periodic box-spline wavelets. There are only 4 terms in the two-scale dilation equations.This implies that the corresponding decomposition and reconstruction algorithms involve only 4 terms respectively which are simple in practical computation. The relation between the periodic wavelets and Fourier series is also discussed.

  9. "Passageless" Administration of the Nelson-Denny Reading Comprehension Test: Associations with IQ and Reading Skills

    Science.gov (United States)

    Ready, Rebecca E.; Chaudhry, Maheen F.; Schatz, Kelly C.; Strazzullo, Sarah

    2013-01-01

    There are few tests that assess reading comprehension in adults, but these tests are needed for a comprehensive assessment of reading disorders (RD). "The Nelson-Denny Reading Test" (NDRT) has a long-passage reading comprehension component that can be used with adolescents and adults. A problem with the NDRT is that reading comprehension test…

  10. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies

    OpenAIRE

    Raine, Nigel E.; Chittka, Lars

    2012-01-01

    Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris) were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals ...

  11. Association of Seat Height and Arm Position on the Five Times Sit-to-Stand Test Times of Stroke Survivors

    OpenAIRE

    Ng, Shamay S. M.; Susanna Y. Cheung; Lauren S. W. Lai; Liu, Ann S. L.; Selena H. I. Ieong; Fong, Shirley S.M.

    2013-01-01

    Objectives. To investigate (1) the association of seat height and (2) the association of arm position on the five times sit-to-stand test (FTSTS) times of individuals with stroke. Design. A cross-sectional study. Setting. University-based rehabilitation centre. Subjects. Patients (n = 43) with chronic stroke. Methods. The times in completing the FTSTS with different seat height (85%, 100%, and 115% knee height) and arm positions (arms across chest, hands on thighs). Results. FTSTS times were ...

  12. Evaluating the Calibration and Power of Three Gene-Based Association Tests of Rare Variants for the X Chromosome.

    Science.gov (United States)

    Ma, Clement; Boehnke, Michael; Lee, Seunggeun

    2015-11-01

    Although genome-wide association studies (GWAS) have identified thousands of trait-associated genetic variants, there are relatively few findings on the X chromosome. For analysis of low-frequency variants (minor allele frequency kernel association test (SKAT), and optimal unified SKAT (SKAT-O). Using simulated case-control and quantitative trait (QT) data, we evaluate the calibration and power of these tests as a function of (1) male:female sample size ratio; and (2) coding of haploid male genotypes for variants under X-inactivation. For case-control studies, all three tests are reasonably well-calibrated for all scenarios we evaluated. As expected, power for gene-based tests depends on the underlying genetic architecture of the genomic region analyzed. Studies with more (haploid) males are generally less powerful due to decreased number of chromosomes. Power generally is slightly greater when the coding scheme for male genotypes matches the true underlying model, but the power loss for misspecifying the (generally unknown) model is small. For QT studies, type I error and power results largely mirror those for binary traits. We demonstrate the use of these three gene-based tests for X-chromosome association analysis in simulated data and sequencing data from the Genetics of Type 2 Diabetes (GoT2D) study. PMID:26454253

  13. The 2-Minute Step Test is Independently Associated with Cognitive Function in Older Adults with Heart Failure

    Science.gov (United States)

    Alosco, Michael L.; Spitznagel, Mary Beth; Raz, Naftali; Cohen, Ronald; Sweet, Lawrence H.; Colbert, Lisa H.; Josephson, Richard; Waechter, Donna; Hughes, Joel; Rosneck, Jim; Gunstad, John

    2016-01-01

    Background and Aims Cognitive impairment is common in persons with heart failure (HF), and measures like the 6-minute walk test (6MWT) are known to correspond to level of impairment. The 2-minute step test (2MST) has been suggested as a more practical alternative to the 6MWT, though no study has examined whether it is associated with cognitive impairment in persons with HF. This study examined whether the 2MST is associated with cognitive function in older adults with HF. Methods Older adults with HF (N = 145; 68.97±9.31 years) completed the 2MST and a neuropsychological test battery that assessed function in multiple cognitive domains. Results Consistent with past work, HF patients exhibited high rates of cognitive impairment. Hierarchical regression analyses adjusting for demographic and medical characteistics found that the 2MST accounted for unique variance in global cognitive function (ΔR2 = .09, p tests indicated that better 2MST performance was significantly correlated with better global, attention, executive, and language test performance. Conclusion The current results indicate that the 2MST is associated with cognitive function in older adults with HF. Further work is needed to clarify underlying mechanisms for this association and the value of implementing the 2MST during routine visits. PMID:22182711

  14. Simple Algorithms to Calculate Asymptotic Null Distributions of Robust Tests in Case-Control Genetic Association Studies in R

    Directory of Open Access Journals (Sweden)

    Wing Kam Fung

    2010-02-01

    Full Text Available The case-control study is an important design for testing association between genetic markers and a disease. The Cochran-Armitage trend test (CATT is one of the most commonly used statistics for the analysis of case-control genetic association studies. The asymptotically optimal CATT can be used when the underlying genetic model (mode of inheritance is known. However, for most complex diseases, the underlying genetic models are unknown. Thus, tests robust to genetic model misspecification are preferable to the model-dependant CATT. Two robust tests, MAX3 and the genetic model selection (GMS, were recently proposed. Their asymptotic null distributions are often obtained by Monte-Carlo simulations, because they either have not been fully studied or involve multiple integrations. In this article, we study how components of each robust statistic are correlated, and find a linear dependence among the components. Using this new finding, we propose simple algorithms to calculate asymptotic null distributions for MAX3 and GMS, which greatly reduce the computing intensity. Furthermore, we have developed the R package Rassoc implementing the proposed algorithms to calculate the empirical and asymptotic p values for MAX3 and GMS as well as other commonly used tests in case-control association studies. For illustration, Rassoc is applied to the analysis of case-control data of 17 most significant SNPs reported in four genome-wide association studies.

  15. Prospectively validated predictions of shock and organ failure in individual septic surgical patients: the Systemic Mediator Associated Response Test

    OpenAIRE

    Slotman, Gus J

    2000-01-01

    Introduction: Clinically useful predictions of end-organ function and failure in severe sepsis may be possible through analyzing the interactions among demographics, physiologic parameters, standard laboratory tests, and circulating markers of inflammation. The present study evaluated the ability of such a methodology, the Systemic Mediator Associated Response Test (SMART), to predict the clinical course of septic surgery patients from a database of medical and surgical patients with severe s...

  16. Detecting association of rare and common variants by testing an optimally weighted combination of variants with longitudinal data

    OpenAIRE

    Wang, Shuaicheng; Fang, Shurong; Sha, Qiuying; Zhang, Shuanglin

    2014-01-01

    Increasing evidence shows that complex diseases are caused by both common and rare variants. Recently, several statistical methods for detecting associations of rare variants have been developed, including the test for testing the effect of an optimally weighted combination of variants (TOW) developed by our group in 2012. These methodologies consider phenotype measurement at only one time point. Because many sequence data have been developed on population cohorts that contain phenotype measu...

  17. A cross-sectional study of the association between mobility test performance and personality among older adults

    OpenAIRE

    Agmon, Maayan; Armon, Galit

    2016-01-01

    Background Falls among the elderly are a major public health challenge. The Timed-Up and Go (TUG) test is commonly used to identify older adults with mobility limitations. This study explored the association between TUG test results and personality among community-dwelling older adults. Methods This cross-sectional study included 85 older adults. Personality was evaluated with the Five Factor Model. Times to complete the TUG as a single task (TUGST) alone and also with an additional cognitive...

  18. A Bivariate Space-time Downscaler Under Space and Time Misalignment

    Science.gov (United States)

    Ozone and particulate matter PM2:5 are co-pollutants that have long been associated with increased public health risks. Information on concentration levels for both pollutants come from two sources: monitoring sites and output from complex numerical models that produce...

  19. Test

    DEFF Research Database (Denmark)

    Bendixen, Carsten

    2014-01-01

    Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers.......Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers....

  20. PPARA intron polymorphism associated with power performance in 30-s anaerobic Wingate Test.

    Directory of Open Access Journals (Sweden)

    Miroslav Petr

    Full Text Available To date, polymorphisms in several genes have been associated with a strength/power performance including alpha 3 actinin, ciliary neurotrophic factor, vitamin D receptor, or angiotensin I converting enzyme, underlining the importance of genetic component of the multifactorial strength/power-related phenotypes. The single nucleotide variation in peroxisome proliferator-activated receptor alpha gene (PPARA intron 7 G/C (rs4253778; g.46630634G>C has been repeatedly found to play a significant role in response to different types of physical activity. We investigated the effect of PPARA intron 7 G/C polymorphism specifically on anaerobic power output in a group of 77 elite male Czech ice hockey players (18-36 y. We determined the relative peak power per body weight (Pmax.kg(-1 and relative peak power per fat free mass (W.kg(-1FFM during the 30-second Wingate Test (WT30 on bicycle ergometer (Monark 894E Peak bike, MONARK, Sweden. All WT30s were performed during the hockey season. Overall genotype frequencies were 50.6% GG homozygotes, 40.3% CG heterozygotes, and 9.1% CC homozygotes. We found statistically significant differences in Pmax.kg(-1 and marginally significant differences in Pmax.kg(-1FFM values in WT30 between carriers and non-carriers for C allele (14.6 ± 0.2 vs. 13.9 ± 0.3 W.kg(-1 and 15.8 ± 0.2 vs. 15.2 ± 0.3 W.kg(-1FFM, P = 0.036 and 0.12, respectively. Furthermore, Pmax.kg(-1FFM strongly positively correlated with the body weight only in individuals with GG genotypes (R = 0.55; p<0.001. Our results indicate that PPARA 7C carriers exhibited higher speed strength measures in WT30. We hypothesize that C allele carriers within the cohort of trained individuals may possess a metabolic advantage towards anaerobic metabolism.

  1. Instructions for additional qualitative scoring of the initial-letter Word-association Test.

    Science.gov (United States)

    Zivković, M

    1994-04-01

    An additional scoring method is based on grouping test-words according to whether the same sign is given by subjects to the test-words. In this way five test-word categories are formed, Eros (test-words with double plus signs), demi-Eros (single plus sign), demi-Thanatos (single minus), Thanatos (double minus), and Deviant (+/- and theta signs). The next step in scoring is to count the number of test-words in a given scoring category whose meanings do not conform. The greater the discrepancy between the test-word category and its meaning, the less well adapted is the subject. Several illustrative protocols are discussed. PMID:8022674

  2. Processing of results of software regression testing by the method of the associated hashes

    International Nuclear Information System (INIS)

    Within regression testing, a serious problem is the comparing of results of testing on the same test examples. Complexity consists in the need to localize a discrepancy of output data under condition of their large volume. For the solution of this problem it is offered to use a method of the connected hashes: a data logging method in case of which the registration records relating to different logged data, are connected with each other by means of system of hashes

  3. The Effect of Supplemental Instruction on Retention: A Bivariate Probit Model

    Science.gov (United States)

    Bowles, Tyler J.; Jones, Jason

    2004-01-01

    Single equation regression models have been used to test the effect of Supplemental Instruction (SI) on student retention. These models, however, fail to account for the two salient features of SI attendance and retention: (1) both SI attendance and retention are categorical variables, and (2) are jointly determined endogenous variables. Adopting…

  4. The effects of cognitive and emotional workload on physiological reactions in Word Association Test in healthy adults

    Czech Academy of Sciences Publication Activity Database

    Lukavský, Jiří

    2010-01-01

    Roč. 52, č. 1 (2010), s. 15-22. ISSN 0039-3320 Institutional research plan: CEZ:AV0Z70250504 Keywords : Word Association Test * electrodermal activity * pupillary activity Subject RIV: AN - Psychology Impact factor: 0.258, year: 2008

  5. Association between Education and Domestic Violence among Women Being Offered an HIV Test in Urban and Rural Areas in Kenya

    Science.gov (United States)

    Abuya, Benta A.; Onsomu, Elijah O.; Moore, DaKysha; Piper, Crystal N.

    2012-01-01

    The objective of this study was to examine the association between education and domestic violence among women being offered an HIV test in urban and rural areas in Kenya. A sample selection of women who experienced physical (n = 4,308), sexual (n = 4,309), and emotional violence (n = 4,312) aged 15 to 49 allowed for the estimation of the…

  6. Association between preoperative magnetic resonance imaging, pain intensity and quantitative sensory testing in patients awaiting lumbar diskectomy.

    LENUS (Irish Health Repository)

    Hegarty, Dominic

    2011-02-01

    Magnetic resonance imaging (MRI) offers important information regarding the morphology, location and size of a herniated disc, which influences the decision to offer lumbar diskectomy (LD). This study aims to examine the association between clinical neurophysiologic indices including pain intensity and quantitative sensory testing (QST), and the degree of lumbar nerve root compromise depicted on magnetic resonance (MR) in patients awaiting LD.

  7. Income Inequality and Social Outcomes: Bivariate Correlations at NUTS1 Level

    OpenAIRE

    ELIA LEANDRO; D'HOMBRES Beatrice; WEBER ANKE

    2013-01-01

    The last two decades have been marked by a growing concern about rising inequality. In a recent book (2012), Joseph Stiglitz, a former Nobel prize winner in Economics argues that rising income inequality is one of the main factors underlying the economic and financial crisis in the United States. The Economist magazine has also recently devoted a special report on income inequality in the world (issue 13th‐19th October 2012). The social and economic challenges associated with rising ...

  8. Diagnostic value of 14C urea breath test for Hp-associated peptic ulcer

    International Nuclear Information System (INIS)

    Purpose: To develop a method of 14C urea breath test and to evaluate the accuracy of the method in clinical diagnosis. Methods: Helicobacter pylori(Hp)-positive patients were defined either by positive bacterial culture or by positive rapid urease test of endoscopic biopsy specimens. 1384 patients with suspected peptic disease were underwent 14C urea breath test. Of them, 44 patients underwent dynamic test at various intervals to determine the optimal time for expiratory air collection. Results: Dynamic breath test showed that the highest point of 14C counts was at 30 min after administration of 14C urea. When a cut-off value of 3.5 was selected, the sensitivity and specificity was of the test for detecting Hp infection 96.7% and 96.5% respectively. Hp positive rate detected by 14C urea breath test in 1092 adults and 292 children was 50.4% and 81.2%. Conclusions: This study suggests that 14C urea breath test is a simple and reliable method for detection of Hp infection and is of high sensitivity and specificity

  9. Design and testing of the first 2D Prototype Vertically Integrated Pattern Recognition Associative Memory

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T.; Deptuch, G.; Hoff, J.; Jindariani, S.; Joshi, S.; Olsen, J.; Tran, N.; Trimpl, M.

    2015-02-01

    An associative memory-based track finding approach has been proposed for a Level 1 tracking trigger to cope with increasing luminosities at the LHC. The associative memory uses a massively parallel architecture to tackle the intrinsically complex combinatorics of track finding algorithms, thus avoiding the typical power law dependence of execution time on occupancy and solving the pattern recognition in times roughly proportional to the number of hits. This is of crucial importance given the large occupancies typical of hadronic collisions. The design of an associative memory system capable of dealing with the complexity of HL-LHC collisions and with the short latency required by Level 1 triggering poses significant, as yet unsolved, technical challenges. For this reason, an aggressive R&D program has been launched at Fermilab to advance state of-the-art associative memory technology, the so called VIPRAM (Vertically Integrated Pattern Recognition Associative Memory) project. The VIPRAM leverages emerging 3D vertical integration technology to build faster and denser Associative Memory devices. The first step is to implement in conventional VLSI the associative memory building blocks that can be used in 3D stacking, in other words, the building blocks are laid out as if it is a 3D design. In this paper, we report on the first successful implementation of a 2D VIPRAM demonstrator chip (protoVIPRAM00). The results show that these building blocks are ready for 3D stacking.

  10. Behavior observation during conformation evaluation at a field test for Danish Warmblood horses and associations with rideability and performance traits

    DEFF Research Database (Denmark)

    Rothmann, Janne; Christensen, Ole F.; Søndergaard, Eva;

    2014-01-01

    Reactivity in horses, defined as a state of high arousal, has an impact on the daily handling and welfare of horses and can have an impact on the risk of causing human injuries. Behavior tests have been developed to assess reactivity, but these tests are difficult to apply in practice. The...... objectives of this study were to investigate how reactivity measured in a practical situation associates with rideability and performance and to explore the association between the measured reactivity and reactivity assessed by the horse's owner. A total of 234 Danish Warmblood females, 3 years of age, were...... and reactivity (rp = −0.16, P = .02) and between reactivity and free jumping (rp = −0.14, P = .03). These results suggest that highly reactive horses received lower grades in rideability and free jumping. However, no association with performance traits in dressage was found. Likewise, low but...

  11. Optimal Unified Approach for Rare-Variant Association Testing with Application to Small-Sample Case-Control Whole-Exome Sequencing Studies

    OpenAIRE

    Lee, Seunggeun; Emond, Mary J.; Bamshad, Michael J.; Kathleen C. Barnes; Rieder, Mark J.; Nickerson, Deborah A.; Christiani, David C.; Wurfel, Mark M.; Lin, Xihong

    2012-01-01

    We propose in this paper a unified approach for testing the association between rare variants and phenotypes in sequencing association studies. This approach maximizes power by adaptively using the data to optimally combine the burden test and the nonburden sequence kernel association test (SKAT). Burden tests are more powerful when most variants in a region are causal and the effects are in the same direction, whereas SKAT is more powerful when a large fraction of the variants in a region ar...

  12. Earthquake simulator tests and associated study of an 1/6-scale nine-story RC model

    Institute of Scientific and Technical Information of China (English)

    Sun Jingjiang; Wang Tao; Qi Hu

    2007-01-01

    Earthquake simulator tests of a 1/6-scale nine-story reinforced concrete frame-wall model are described in the paper. The test results and associated numerical simulation are summarized and discussed. Based on the test data,a relationship between maximum inter-story drift and damage state is established. Equations of variation of structural characteristics (natural frequency and equivalent stiffness) with overall drifts are derived by data fitting, which can be used to estimate structural damage state if structural characteristics can be measured. A comparison of the analytical and experimental results show that both the commonly used equivalent beam and fiber element models can simulate the nonlinear seismic response of structures very well. Finally, conclusions associated with seismic design and damage evaluation of RC structures are presented.

  13. Exploring the potential benefits of false discovery rates for region-based testing of association with rare genetic variation

    Directory of Open Access Journals (Sweden)

    ChangJiang eXu

    2014-01-01

    Full Text Available When analyzing the data arising from exome or whole-genome sequencing studies, window-based tests, i.e. tests that jointly analyze all genetic data in a small genomic region, are very popular. However, power is known to be quite low for finding associations with phenotypes using these tests, and hence a variety of analytic strategies may be employed to potentially improve power. Using sequencing data from all of chromosome 3 in an interim release of data on 2,432 individuals from the UK10K project, we simulated phenotypes associated with rare genetic variation, and used the results to explore the window-based test power, and to ask two specific questions. Firstly, we asked whether there could be substantial benefits associated with incorporating information from external annotation on the genetic variants, and secondly we asked whether the false discovery rate (FDRs would be a useful metric for assessing significance. Although, as expected, there are benefits to using additional information (such as annotation when it is associated with causality, we confirmed the general pattern of low sensitivity and power for window-based tests. At least for our chosen example, even when power is high to detect some associations, many of the regions containing causal variants cannot be detected, despite using lax significance thresholds and optimal analytic methods. Furthermore, our estimated FDR values tended to be much smaller than the true FDRs. Long-range correlations between variants—due to linkage disequilibrium—likely explains some of this bias. A more sophisticated approach to using the annotation information may help the power, but many causal variants of realistic effect sizes may simply be undetectable, at least with this sample size. Perhaps annotation information could assist in distinguishing windows containing causal variants from windows that are merely correlated with causal variants.

  14. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies.

    Directory of Open Access Journals (Sweden)

    Nigel E Raine

    Full Text Available Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals that were fast to learn yellow as a predictor of reward were also quick to reverse this association. Furthermore, overnight memory retention tests suggest that faster learning individuals are also better at retaining previously learned information. There is also an effect of relatedness: colonies whose workers were fast to learn the association between yellow and reward also reversed this association rapidly. These results are inconsistent with a trade-off between learning speed and the reversal of a previously made association. On the contrary, they suggest that differences in learning performance and cognitive (behavioural flexibility could reflect more general differences in colony learning ability. Hence, this study provides additional evidence to support the idea that rapid learning and behavioural flexibility have adaptive value.

  15. Learning from an early start but late end epidemics via an incidence rate restricted bivariate distribution and data analysis

    Directory of Open Access Journals (Sweden)

    Ramalingam Shanmugam

    2015-09-01

    Full Text Available Background: An ideal expectation of public health administrators or field medical workers is to have a late start and quick ending of any epidemic. Instead, when an epidemic starts early but ends late, it is where much can be learned from the incidences. A case in point for discussion in this article is the pattern of 2009 H1N1 epidemic. Methods: With a parameter to portray an existing health environment as a deterrent for an epidemic like H1N1 to outbreak in any location at a week, a bivariate distribution is created and is used to analyze the data for a learning so that it helps to prevent a too long prevailing future epidemic. This new distribution is named Incidence Rate Restricted Bivariate Distribution (IRRBGD. Statistical properties of IRRBGD are derived and illustrated using 2009 H1N1 incidences in all five continental regions (Africa, Asia, Europe, Americas, and Oceanic across on earth. Results: The Asian continent, compared to other four continental regions, had most vulnerability for H1N1 incidences. The odds for no H1N1 to occur is lowest only in Oceanic among the four continental regions, namely Africa, Europe, Americas, and Oceanic. Since the beginning of the year 2009 with 52 weeks, the week number, Y in which the H1N1 appeared first and the number, X of weeks the H1N1 continued on in a region are consistently highly correlated in all five continental regions. Conclusions: From the data analyses of 2009 H1N1 incidences, no continental region is risk free with respect another round of H1N1 epidemic in future. The medical community and public healthcare administrators ought to identify the common and region specific unique deterrents of the epidemic like H1N1. The impact of such deterrents to H1N1 is captured in our model and analysis. By increasing the deterrent level, the outbreak of an epidemic like H1N1 could be delayed, according to our model and data information. [Int J Res Med Sci 2015; 3(9.000: 2181-2189

  16. Predictive and discriminative value of shoulder proprioception tests for patients with whiplash-associated disorders

    OpenAIRE

    Sandlund, Jonas; Djupsjöbacka, Mats; Ryhed, Bengt; Hamberg, Jern; Björklund, Martin

    2006-01-01

    Objective: To evaluate whether patients suffering from whiplash-associated disorders have impaired shoulder proprioception and whether the acuity of shoulder proprioception is reflected in the patients’ symptoms and self-rated function. Design: A comparative group design, including a correlation design for the patient group. Subjects: Patients with chronic whiplash-associated disorders (n/37) and healthy subjects (n/41). The groups were matched for age and gender. Methods: All subjects underw...

  17. Vehicle test report: Electric Vehicle Associates electric conversion of an AMC Pacer

    Science.gov (United States)

    Price, T. W.; Wirth, V. A., Jr.; Pompa, M. F.

    1981-01-01

    Tests were performed to characterize certain parameters of the EVA Pacer and to provide baseline data that can be used for the comparison of improved batteries that may be incorporated into the vehicle at a later time. The vehicle tests were concentrated on the electrical drive subsystem; i.e., the batteries, controller and motor. The tests included coastdowns to characterize the road load, and range evaluations for both cyclic and constant speed conditions. A qualitative evaluation of the vehicle's performance was made by comparing its constant speed range performance with other electric and hybrid vehicles. The Pacer performance was approximately equal to the majority of those vehicles assessed in 1977.

  18. Regulations associated with the hydrostatic testing of natural gas pipelines. Volume 2. Topical report, May 1992

    International Nuclear Information System (INIS)

    The report examines environmental regulatory issues related to the discharge of hydrostatic test waters generated from the integrity testing of natural gas pipelines. Hydrostatic testing, and proper environmental management of discharged waters is required by DOT regulations. However, disposal of water used to conduct a hydrostatic pipeline test is regulated on a state-by-state basis. State-specific requirements vary widely, ranging from an authorization letter to a complete NPDES permit. In some cases, both federal and state permits must be obtained. Monitoring may be required before and during discharge. While some states have established state-wide discharge limits, the majority of the monitoring requirements are determined on a site-specific basis and can include a variety of parameters. The report is Volume 2 of a 5-volume report series

  19. Associations of HIV testing and late diagnosis at a Japanese university hospital

    OpenAIRE

    Horino, Tetsuya; Sato, Fumiya; Kato, Tetsuro; Hosaka, Yumiko; Shimizu, Akihiro; Kawano, Shinji; Hoshina, Tokio; Nakaharai, Kazuhiko; Nakazawa, Yasushi; Yoshikawa, Koji; Yoshida, Masaki; Hori, Seiji

    2016-01-01

    OBJECTIVES: This study was conducted to clarify the rate of late diagnosis of HIV infection and to identify relationships between the reasons for HIV testing and a late diagnosis. METHODS: This retrospective cohort study was conducted among HIV-positive patients at the Jikei University Hospital between 2001 and 2014. Patient characteristics from medical records, including age, sex, sexuality, the reason for HIV testing and the number of CD4-positive lymphocytes at HIV diagnosis, were assessed...

  20. Associations of HIV testing and late diagnosis at a Japanese university hospital

    OpenAIRE

    Tetsuya Horino; Fumiya Sato; Tetsuro Kato; Yumiko Hosaka; Akihiro Shimizu; Shinji Kawano; Tokio Hoshina; Kazuhiko Nakaharai; Yasushi Nakazawa; Koji Yoshikawa; Masaki Yoshida; Seiji Hori

    2016-01-01

    OBJECTIVES: This study was conducted to clarify the rate of late diagnosis of HIV infection and to identify relationships between the reasons for HIV testing and a late diagnosis. METHODS: This retrospective cohort study was conducted among HIV-positive patients at the Jikei University Hospital between 2001 and 2014. Patient characteristics from medical records, including age, sex, sexuality, the reason for HIV testing and the number of CD4-positive lymphocytes at HIV diagnosis, were assesse...