WorldWideScience

Sample records for hypothesis testing methods

  1. Transform methods for testing the negative binomial hypothesis

    Directory of Open Access Journals (Sweden)

    Simos G. Meintanis

    2007-10-01

    Full Text Available We employ the empirical probability generating function in constructing a goodness-of-fit test for negative binomial distributions. The proposed tests, which are formed as weighted integrals, are shown to be consistent and their asymptotic null distribution is investigated. As the decay of the weight function tends to infinity, limit statistics are obtained. A small simulation study is presented.

  2. A Hybrid Positioning Method Based on Hypothesis Testing

    DEFF Research Database (Denmark)

    Amiot, Nicolas; Pedersen, Troels; Laaraiedh, Mohamed

    2012-01-01

    We consider positioning in the scenario where only two reliable range estimates, and few less reliable power observations are available. Such situations are difficult to handle with numerical maximum likelihood methods which require a very accurate initialization to avoid being stuck into local m...

  3. Bayesian Hypothesis Testing

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Stephen A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sigeti, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-15

    These are a set of slides about Bayesian hypothesis testing, where many hypotheses are tested. The conclusions are the following: The value of the Bayes factor obtained when using the median of the posterior marginal is almost the minimum value of the Bayes factor. The value of τ2 which minimizes the Bayes factor is a reasonable choice for this parameter. This allows a likelihood ratio to be computed with is the least favorable to H0.

  4. Hypothesis Testing, "p" Values, Confidence Intervals, Measures of Effect Size, and Bayesian Methods in Light of Modern Robust Techniques

    Science.gov (United States)

    Wilcox, Rand R.; Serang, Sarfaraz

    2017-01-01

    The article provides perspectives on p values, null hypothesis testing, and alternative techniques in light of modern robust statistical methods. Null hypothesis testing and "p" values can provide useful information provided they are interpreted in a sound manner, which includes taking into account insights and advances that have…

  5. GSMA: Gene Set Matrix Analysis, An Automated Method for Rapid Hypothesis Testing of Gene Expression Data

    Directory of Open Access Journals (Sweden)

    Chris Cheadle

    2007-01-01

    Full Text Available Background: Microarray technology has become highly valuable for identifying complex global changes in gene expression patterns. The assignment of functional information to these complex patterns remains a challenging task in effectively interpreting data and correlating results from across experiments, projects and laboratories. Methods which allow the rapid and robust evaluation of multiple functional hypotheses increase the power of individual researchers to data mine gene expression data more efficiently.Results: We have developed (gene set matrix analysis GSMA as a useful method for the rapid testing of group-wise up- or downregulation of gene expression simultaneously for multiple lists of genes (gene sets against entire distributions of gene expression changes (datasets for single or multiple experiments. The utility of GSMA lies in its flexibility to rapidly poll gene sets related by known biological function or as designated solely by the end-user against large numbers of datasets simultaneously.Conclusions: GSMA provides a simple and straightforward method for hypothesis testing in which genes are tested by groups across multiple datasets for patterns of expression enrichment.

  6. Bayesian Hypothesis Testing for Psychologists: A Tutorial on the Savage-Dickey Method

    Science.gov (United States)

    Wagenmakers, Eric-Jan; Lodewyckx, Tom; Kuriyal, Himanshu; Grasman, Raoul

    2010-01-01

    In the field of cognitive psychology, the "p"-value hypothesis test has established a stranglehold on statistical reporting. This is unfortunate, as the "p"-value provides at best a rough estimate of the evidence that the data provide for the presence of an experimental effect. An alternative and arguably more appropriate measure of evidence is…

  7. Polygyny among the Tsimane of Bolivia: an improved method for testing the polygyny–fertility hypothesis

    Science.gov (United States)

    Winking, Jeffrey; Stieglitz, Jonathan; Kurten, Jenna; Kaplan, Hillard; Gurven, Michael

    2013-01-01

    The polygyny–fertility hypothesis states that polygyny is associated with reduced fertility for women and is supported by a large body of literature. This finding is important, because theoretical models of polygyny often differentiate systems based on the degree to which women are forced or willingly choose to enter polygynous marriages. The fact that polygyny tends to be associated with reduced fertility has been presented as evidence that polygyny is often less favourable for women, and that women must, therefore, be pressured into accepting such arrangements. Previous studies, however, have been hampered by the non-random assignment of women into monogamous and polygynous unions (i.e. self-selection), as differences between these groups of women might explain some of the effects. Furthermore, the vast majority of such studies focus on sub-Saharan populations. We address these problems in our analysis of women's fertility in polygynous marriages among the Tsimane of Bolivia. We offer a more robust method for assessing the impact of polygynous marriage on reproductive outcomes by testing for intra-individual fertility effects among first wives as they transition from monogamous to polygynous marriage. We report a significant link between polygyny and reduced fertility when including all cases of polygyny; however, this association disappears when testing only for intra-individual effects. PMID:23407840

  8. Polygyny among the Tsimane of Bolivia: an improved method for testing the polygyny-fertility hypothesis.

    Science.gov (United States)

    Winking, Jeffrey; Stieglitz, Jonathan; Kurten, Jenna; Kaplan, Hillard; Gurven, Michael

    2013-04-07

    The polygyny-fertility hypothesis states that polygyny is associated with reduced fertility for women and is supported by a large body of literature. This finding is important, because theoretical models of polygyny often differentiate systems based on the degree to which women are forced or willingly choose to enter polygynous marriages. The fact that polygyny tends to be associated with reduced fertility has been presented as evidence that polygyny is often less favourable for women, and that women must, therefore, be pressured into accepting such arrangements. Previous studies, however, have been hampered by the non-random assignment of women into monogamous and polygynous unions (i.e. self-selection), as differences between these groups of women might explain some of the effects. Furthermore, the vast majority of such studies focus on sub-Saharan populations. We address these problems in our analysis of women's fertility in polygynous marriages among the Tsimane of Bolivia. We offer a more robust method for assessing the impact of polygynous marriage on reproductive outcomes by testing for intra-individual fertility effects among first wives as they transition from monogamous to polygynous marriage. We report a significant link between polygyny and reduced fertility when including all cases of polygyny; however, this association disappears when testing only for intra-individual effects.

  9. Hypothesis Designs for Three-Hypothesis Test Problems

    OpenAIRE

    Yan Li; Xiaolong Pu

    2010-01-01

    As a helpful guide for applications, the alternative hypotheses of the three-hypothesis test problems are designed under the required error probabilities and average sample number in this paper. The asymptotic formulas and the proposed numerical quadrature formulas are adopted, respectively, to obtain the hypothesis designs and the corresponding sequential test schemes under the Koopman-Darmois distributions. The example of the normal mean test shows that our methods are qu...

  10. Plant disease severity assessment - How rater bias, assessment method and experimental design affect hypothesis testing and resource use efficiency

    Science.gov (United States)

    The impact of rater bias and assessment method on hypothesis testing was studied for different experimental designs for plant disease assessment using balanced and unbalanced data sets. Data sets with the same number of replicate estimates for each of two treatments are termed ‘balanced’, and those ...

  11. Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture

    Science.gov (United States)

    Sanfilippo, Antonio P [Richland, WA; Cowell, Andrew J [Kennewick, WA; Gregory, Michelle L [Richland, WA; Baddeley, Robert L [Richland, WA; Paulson, Patrick R [Pasco, WA; Tratz, Stephen C [Richland, WA; Hohimer, Ryan E [West Richland, WA

    2012-03-20

    Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture are described according to some aspects. In one aspect, a hypothesis analysis method includes providing a hypothesis, providing an indicator which at least one of supports and refutes the hypothesis, using the indicator, associating evidence with the hypothesis, weighting the association of the evidence with the hypothesis, and using the weighting, providing information regarding the accuracy of the hypothesis.

  12. Action perception as hypothesis testing.

    Science.gov (United States)

    Donnarumma, Francesco; Costantini, Marcello; Ambrosini, Ettore; Friston, Karl; Pezzulo, Giovanni

    2017-04-01

    We present a novel computational model that describes action perception as an active inferential process that combines motor prediction (the reuse of our own motor system to predict perceived movements) and hypothesis testing (the use of eye movements to disambiguate amongst hypotheses). The system uses a generative model of how (arm and hand) actions are performed to generate hypothesis-specific visual predictions, and directs saccades to the most informative places of the visual scene to test these predictions - and underlying hypotheses. We test the model using eye movement data from a human action observation study. In both the human study and our model, saccades are proactive whenever context affords accurate action prediction; but uncertainty induces a more reactive gaze strategy, via tracking the observed movements. Our model offers a novel perspective on action observation that highlights its active nature based on prediction dynamics and hypothesis testing. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. ON ESTIMATION AND HYPOTHESIS TESTING OF THE GRAIN SIZE DISTRIBUTION BY THE SALTYKOV METHOD

    Directory of Open Access Journals (Sweden)

    Yuri Gulbin

    2011-05-01

    Full Text Available The paper considers the problem of validity of unfolding the grain size distribution with the back-substitution method. Due to the ill-conditioned nature of unfolding matrices, it is necessary to evaluate the accuracy and precision of parameter estimation and to verify the possibility of expected grain size distribution testing on the basis of intersection size histogram data. In order to review these questions, the computer modeling was used to compare size distributions obtained stereologically with those possessed by three-dimensional model aggregates of grains with a specified shape and random size. Results of simulations are reported and ways of improving the conventional stereological techniques are suggested. It is shown that new improvements in estimating and testing procedures enable grain size distributions to be unfolded more efficiently.

  14. Hypothesis testing in hydrology: Theory and practice

    Science.gov (United States)

    Kirchner, James; Pfister, Laurent

    2017-04-01

    Well-posed hypothesis tests have spurred major advances in hydrological theory. However, a random sample of recent research papers suggests that in hydrology, as in other fields, hypothesis formulation and testing rarely correspond to the idealized model of the scientific method. Practices such as "p-hacking" or "HARKing" (Hypothesizing After the Results are Known) are major obstacles to more rigorous hypothesis testing in hydrology, along with the well-known problem of confirmation bias - the tendency to value and trust confirmations more than refutations - among both researchers and reviewers. Hypothesis testing is not the only recipe for scientific progress, however: exploratory research, driven by innovations in measurement and observation, has also underlain many key advances. Further improvements in observation and measurement will be vital to both exploratory research and hypothesis testing, and thus to advancing the science of hydrology.

  15. Hypothesis tests for hydrologic alteration

    Science.gov (United States)

    Kroll, Charles N.; Croteau, Kelly E.; Vogel, Richard M.

    2015-11-01

    Hydrologic systems can be altered by anthropogenic and climatic influences. While there are a number of statistical frameworks for describing and evaluating the extent of hydrologic alteration, here we present a new framework for assessing whether statistically significant hydrologic alteration has occurred, or whether the shift in the hydrologic regime is consistent with the natural variability of the system. Four hypothesis tests based on shifts of flow duration curves (FDCs) are developed and tested using three different experimental designs based on different strategies for resampling of annual FDCs. The four hypothesis tests examined are the Kolmogorov-Smirnov (KS), Kuiper (K), confidence interval (CI), and ecosurplus and ecodeficit (Eco). Here 117 streamflow sites that have potentially undergone hydrologic alteration due to reservoir construction are examined. 20 years of pre-reservoir record is used to develop the critical value of the test statistic for type I errors of 5% and 10%, while 10 years of post-alteration record is used to examine the power of each test. The best experimental design, based on calculating the mean annual FDC from an exhaustive jackknife resampling regime, provided a larger number of unique values of each test statistic and properly reproduced type I errors. Of the four tests, the CI test consistently had the highest power, while the K test had the second highest power; KS and Eco always had the lowest power. The power of the CI test appeared related to the storage ratio of the reservoir, a rough measure of the hydrologic alteration of the system.

  16. Methods and baseline cardiovascular data from the Early versus Late Intervention Trial with Estradiol testing the menopausal hormone timing hypothesis.

    Science.gov (United States)

    Hodis, Howard N; Mack, Wendy J; Shoupe, Donna; Azen, Stanley P; Stanczyk, Frank Z; Hwang-Levine, Juliana; Budoff, Matthew J; Henderson, Victor W

    2015-04-01

    This study aims to present methods and baseline data from the Early versus Late Intervention Trial with Estradiol (ELITE), the only clinical trial designed to specifically test the timing hypothesis of postmenopausal hormone therapy (HT). The timing hypothesis posits that HT effects depend on the temporal initiation of HT relative to time since menopause. ELITE is a randomized, double-blind, placebo-controlled trial with a 2 × 2 factorial design. Six hundred forty-three healthy postmenopausal women without cardiovascular disease were randomized to oral estradiol or placebo for up to 6 to 7 years according to time since menopause (mean age (55.4 vs 65.4 y) and median time since menopause (3.5 vs 14.3 y). Expected risk factors (age, blood pressure, and body mass index) were associated with CIMT at baseline in both strata. In the early postmenopausal group, but not in the late postmenopausal group, we observed significant associations between CIMT and factors that may play a role in the responsiveness of atherosclerosis progression according to timing of HT initiation. These include low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, sex hormone-binding globulin, and serum total estradiol. The ELITE randomized controlled trial is timely and unique. Baseline data indicate that ELITE is well-positioned to test the HT timing hypothesis in relation to atherosclerosis progression and coronary artery disease.

  17. Robust Binary Hypothesis Testing Under Contaminated Likelihoods

    OpenAIRE

    Wei, Dennis; Varshney, Kush R.

    2014-01-01

    In hypothesis testing, the phenomenon of label noise, in which hypothesis labels are switched at random, contaminates the likelihood functions. In this paper, we develop a new method to determine the decision rule when we do not have knowledge of the uncontaminated likelihoods and contamination probabilities, but only have knowledge of the contaminated likelihoods. In particular we pose a minimax optimization problem that finds a decision rule robust against this lack of knowledge. The method...

  18. List-method directed forgetting: Evidence for the reset-of-encoding hypothesis employing item-recognition testing.

    Science.gov (United States)

    Pastötter, Bernhard; Kliegl, Oliver; Bäuml, Karl-Heinz T

    2016-01-01

    In list-method directed forgetting (LMDF), people are cued to forget a previously studied item list (List 1) and to learn a new list of items (List 2) instead. Such cuing typically enhances memory for the List 2 items, in both recall and (sometimes) item-recognition testing. It has recently been hypothesized that the enhancement effect for List 2 items (partly) reflects the result of a reset-of-encoding process. The proposal is that encoding efficacy decreases with an increase in study material, but the forget cue can reset the encoding process to make the encoding of early List 2 items as effective as the encoding of early List 1 items. An experiment is reported that examined the reset-of-encoding hypothesis with item-recognition testing, examining influences of items' serial learning position on the effects of the forget cue. Item-recognition tests were conducted separately for the two lists. Consistent with the reset-of-encoding hypothesis, the results showed strong enhancement effects for early List 2 items, but hardly any enhancement effects for middle and late List 2 items. Like in previous item-recognition studies, no cuing effects were found for List 1 items. The results support two-mechanism accounts of LMDF, which assume a critical role for a reset-of-encoding process for List 2 enhancement.

  19. Robust and distributed hypothesis testing

    CERN Document Server

    Gül, Gökhan

    2017-01-01

    This book generalizes and extends the available theory in robust and decentralized hypothesis testing. In particular, it presents a robust test for modeling errors which is independent from the assumptions that a sufficiently large number of samples is available, and that the distance is the KL-divergence. Here, the distance can be chosen from a much general model, which includes the KL-divergence as a very special case. This is then extended by various means. A minimax robust test that is robust against both outliers as well as modeling errors is presented. Minimax robustness properties of the given tests are also explicitly proven for fixed sample size and sequential probability ratio tests. The theory of robust detection is extended to robust estimation and the theory of robust distributed detection is extended to classes of distributions, which are not necessarily stochastically bounded. It is shown that the quantization functions for the decision rules can also be chosen as non-monotone. Finally, the boo...

  20. Improving your Hypothesis Testing: Determining Sample Sizes.

    Science.gov (United States)

    Luftig, Jeffrey T.; Norton, Willis P.

    1982-01-01

    This article builds on an earlier discussion of the importance of the Type II error (beta) and power to the hypothesis testing process (CE 511 484), and illustrates the methods by which sample size calculations should be employed so as to improve the research process. (Author/CT)

  1. Hypothesis testing of scientific Monte Carlo calculations

    Science.gov (United States)

    Wallerberger, Markus; Gull, Emanuel

    2017-11-01

    The steadily increasing size of scientific Monte Carlo simulations and the desire for robust, correct, and reproducible results necessitates rigorous testing procedures for scientific simulations in order to detect numerical problems and programming bugs. However, the testing paradigms developed for deterministic algorithms have proven to be ill suited for stochastic algorithms. In this paper we demonstrate explicitly how the technique of statistical hypothesis testing, which is in wide use in other fields of science, can be used to devise automatic and reliable tests for Monte Carlo methods, and we show that these tests are able to detect some of the common problems encountered in stochastic scientific simulations. We argue that hypothesis testing should become part of the standard testing toolkit for scientific simulations.

  2. A new method for sperm characterization for infertility treatment: hypothesis testing by using combination of watershed segmentation and graph theory.

    Science.gov (United States)

    Shojaedini, Seyed Vahab; Heydari, Masoud

    2014-10-01

    Shape and movement features of sperms are important parameters for infertility study and treatment. In this article, a new method is introduced for characterization sperms in microscopic videos. In this method, first a hypothesis framework is defined to distinguish sperms from other particles in captured video. Then decision about each hypothesis is done in following steps: Selecting some primary regions as candidates for sperms by watershed-based segmentation, pruning of some false candidates during successive frames using graph theory concept and finally confirming correct sperms by using their movement trajectories. Performance of the proposed method is evaluated on real captured images belongs to semen with high density of sperms. The obtained results show the proposed method may detect 97% of sperms in presence of 5% false detections and track 91% of moving sperms. Furthermore, it can be shown that better characterization of sperms in proposed algorithm doesn't lead to extracting more false sperms compared to some present approaches.

  3. Surrogate Data Generation By Gradual Wavelet Reconstruction (GWR): A General Method with Applications to Simulation, Hypothesis Testing and Uncertainty Analysis

    Science.gov (United States)

    Keylock, C. J.

    2015-12-01

    This presentation will introduce the Gradual Wavelet Reconstruction (GWR) method and highlight the diversity of potential applications of the technique in hydrology, geophysics and beyond. The starting point for the method is the Iterated Amplitude Adjusted Fourier Transform (IAAFT) method introduced nearly twenty years ago by Schreiber and Schmitz (Physical Review Letters, 1996). Given a chosen significance level, α, and a γ = {1,2}-tailed statistical test, if (γ/α) -1 surrogate series have been generated with IAAFT, if the value for a metric of nonlinearity for the original data lies outside the range for the surrogates then a significant difference is deemed to exist (the data are assumed non-linear). GWR generalises this idea, by postulating a continuum from ρ = 0 (phase randomised data) to ρ = 1 (the original data). Thus, given rejection of the null hypothesis using IAAFT surrogates, the question of how nonlinear the data are may be answered for the first time by determining the critical value for ρ. This then opens up other research possibilities including: (1) A method for generating synthetic data with an appropriate degree of nonlinearity; (2) Novel approaches to confidence limits for extreme value problems based on the surrogates in (1); and, (3) The testing of the sensitivity of different metrics for nonlinearity. GWR surrogates are produced in the wavelet domain rather than the Fourier one. The parameter ρ is the total energy of the time series that is fixed in place and not randomised. That is, given a wavelet coefficient, wj,k at scale, j, and position, k, the total wavelet energy is the summation of w2j,k over all scales and positions, Σw2j,k. If all the w2j,k are placed in descending rank order, GWR fixes in place n wavelet coefficients such that the total energy of these coefficients is ρ×Σw2j,k. The other coefficients are randomised such that the fidelity of the wavelet filtering operation is preserved. Because it is a completely

  4. Null hypothesis significance testing: a short tutorial

    Science.gov (United States)

    Pernet, Cyril

    2016-01-01

    Although thoroughly criticized, null hypothesis significance testing (NHST) remains the statistical method of choice used to provide evidence for an effect, in biological, biomedical and social sciences. In this short tutorial, I first summarize the concepts behind the method, distinguishing test of significance (Fisher) and test of acceptance (Newman-Pearson) and point to common interpretation errors regarding the p-value. I then present the related concepts of confidence intervals and again point to common interpretation errors. Finally, I discuss what should be reported in which context. The goal is to clarify concepts to avoid interpretation errors and propose reporting practices. PMID:29067159

  5. Testing the Markov hypothesis in fluid flows.

    Science.gov (United States)

    Meyer, Daniel W; Saggini, Frédéric

    2016-05-01

    Stochastic Markov processes are used very frequently to model, for example, processes in turbulence and subsurface flow and transport. Based on the weak Chapman-Kolmogorov equation and the strong Markov condition, we present methods to test the Markov hypothesis that is at the heart of these models. We demonstrate the capabilities of our methodology by testing the Markov hypothesis for fluid and inertial particles in turbulence, and fluid particles in the heterogeneous subsurface. In the context of subsurface macrodispersion, we find that depending on the heterogeneity level, Markov models work well above a certain scale of interest for media with different log-conductivity correlation structures. Moreover, we find surprising similarities in the velocity dynamics of the different media considered.

  6. Hypothesis Testing in the Real World

    Science.gov (United States)

    Miller, Jeff

    2017-01-01

    Critics of null hypothesis significance testing suggest that (a) its basic logic is invalid and (b) it addresses a question that is of no interest. In contrast to (a), I argue that the underlying logic of hypothesis testing is actually extremely straightforward and compelling. To substantiate that, I present examples showing that hypothesis…

  7. A default Bayesian hypothesis test for ANOVA designs

    NARCIS (Netherlands)

    Wetzels, R.; Grasman, R.P.P.P.; Wagenmakers, E.J.

    2012-01-01

    This article presents a Bayesian hypothesis test for analysis of variance (ANOVA) designs. The test is an application of standard Bayesian methods for variable selection in regression models. We illustrate the effect of various g-priors on the ANOVA hypothesis test. The Bayesian test for ANOVA

  8. Robust estimation and hypothesis testing

    CERN Document Server

    Tiku, Moti L

    2004-01-01

    In statistical theory and practice, a certain distribution is usually assumed and then optimal solutions sought. Since deviations from an assumed distribution are very common, one cannot feel comfortable with assuming a particular distribution and believing it to be exactly correct. That brings the robustness issue in focus. In this book, we have given statistical procedures which are robust to plausible deviations from an assumed mode. The method of modified maximum likelihood estimation is used in formulating these procedures. The modified maximum likelihood estimators are explicit functions of sample observations and are easy to compute. They are asymptotically fully efficient and are as efficient as the maximum likelihood estimators for small sample sizes. The maximum likelihood estimators have computational problems and are, therefore, elusive. A broad range of topics are covered in this book. Solutions are given which are easy to implement and are efficient. The solutions are also robust to data anomali...

  9. Hypothesis Testing as an Act of Rationality

    Science.gov (United States)

    Nearing, Grey

    2017-04-01

    Statistical hypothesis testing is ad hoc in two ways. First, setting probabilistic rejection criteria is, as Neyman (1957) put it, an act of will rather than an act of rationality. Second, physical theories like conservation laws do not inherently admit probabilistic predictions, and so we must use what are called epistemic bridge principles to connect model predictions with the actual methods of hypothesis testing. In practice, these bridge principles are likelihood functions, error functions, or performance metrics. I propose that the reason we are faced with these problems is because we have historically failed to account for a fundamental component of basic logic - namely the portion of logic that explains how epistemic states evolve in the presence of empirical data. This component of Cox' (1946) calculitic logic is called information theory (Knuth, 2005), and adding information theory our hypothetico-deductive account of science yields straightforward solutions to both of the above problems. This also yields a straightforward method for dealing with Popper's (1963) problem of verisimilitude by facilitating a quantitative approach to measuring process isomorphism. In practice, this involves data assimilation. Finally, information theory allows us to reliably bound measures of epistemic uncertainty, thereby avoiding the problem of Bayesian incoherency under misspecified priors (Grünwald, 2006). I therefore propose solutions to four of the fundamental problems inherent in both hypothetico-deductive and/or Bayesian hypothesis testing. - Neyman (1957) Inductive Behavior as a Basic Concept of Philosophy of Science. - Cox (1946) Probability, Frequency and Reasonable Expectation. - Knuth (2005) Lattice Duality: The Origin of Probability and Entropy. - Grünwald (2006). Bayesian Inconsistency under Misspecification. - Popper (1963) Conjectures and Refutations: The Growth of Scientific Knowledge.

  10. HYPOTHESIS TESTING USING NUMEROUS APPROXIMATING FUNCTIONAL FORMS

    OpenAIRE

    Norwood, F. Bailey; Lusk, Jayson L.; Ferrier, Peyton Michael

    2001-01-01

    While the combination of several or more models is often found to improve forecasts (Brandt and Bessler, Min and Zellner, Norwood and Schroeder), hypothesis tests are typically conducted using a single model approach 1 . Hypothesis tests and forecasts have similar goals; they seek to define a range over which a parameter should lie within a degree of confidence. If it is true that, on average, composite forecasts are more accurate than a single model's forecast, it might also be true that hyp...

  11. Quantization of Prior Probabilities for Hypothesis Testing

    OpenAIRE

    Varshney, Kush R.; Varshney, Lav R.

    2008-01-01

    Bayesian hypothesis testing is investigated when the prior probabilities of the hypotheses, taken as a random vector, are quantized. Nearest neighbor and centroid conditions are derived using mean Bayes risk error as a distortion measure for quantization. A high-resolution approximation to the distortion-rate function is also obtained. Human decision making in segregated populations is studied assuming Bayesian hypothesis testing with quantized priors.

  12. The discovered preference hypothesis - an empirical test

    DEFF Research Database (Denmark)

    Lundhede, Thomas; Ladenburg, Jacob; Olsen, Søren Bøye

    Using stated preference methods for valuation of non-market goods is known to be vulnerable to a range of biases. Some authors claim that these so-called anomalies in effect render the methods useless for the purpose. However, the Discovered Preference Hypothesis, as put forth by Plott [31], offers...... as respondents evaluate more and more choice sets. This finding supports the Discovered Preference Hypothesis interpretation and explanation of starting point bias....

  13. Statistical hypothesis testing with SAS and R

    CERN Document Server

    Taeger, Dirk

    2014-01-01

    A comprehensive guide to statistical hypothesis testing with examples in SAS and R When analyzing datasets the following questions often arise:Is there a short hand procedure for a statistical test available in SAS or R?If so, how do I use it?If not, how do I program the test myself? This book answers these questions and provides an overview of the most commonstatistical test problems in a comprehensive way, making it easy to find and performan appropriate statistical test. A general summary of statistical test theory is presented, along with a basicdescription for each test, including the

  14. Testing competing forms of the Milankovitch hypothesis

    DEFF Research Database (Denmark)

    Kaufmann, Robert K.; Juselius, Katarina

    2016-01-01

    We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical...... that the latter is consistent with a weak form of the Milankovitch hypothesis and that it should be restated as follows: Internal climate dynamics impose perturbations on glacial cycles that are driven by solar insolation. Our results show that these perturbations are likely caused by slow adjustment between land...... ice volume and solar insolation. The estimated adjustment dynamics show that solar insolation affects an array of climate variables other than ice volume, each at a unique rate. This implies that previous efforts to test the strong form of the Milankovitch hypothesis by examining the relationship...

  15. Groupthink: Hypothesis in Need of Testing.

    Science.gov (United States)

    Moorhead, Gregory

    1982-01-01

    Reviews the major tenets of the groupthink hypothesis of Irving Janis, as well as the research on which it is based. Reviews previous research on group dynamics related to groupthink. Proposes guidelines for research to test the propositions of groupthink. (Author/RC)

  16. Tests of the Giant Impact Hypothesis

    Science.gov (United States)

    Jones, J. H.

    1998-01-01

    The giant impact hypothesis has gained popularity as a means of explaining a volatile-depleted Moon that still has a chemical affinity to the Earth. As Taylor's Axiom decrees, the best models of lunar origin are testable, but this is difficult with the giant impact model. The energy associated with the impact would be sufficient to totally melt and partially vaporize the Earth. And this means that there should he no geological vestige of Barber times. Accordingly, it is important to devise tests that may be used to evaluate the giant impact hypothesis. Three such tests are discussed here. None of these is supportive of the giant impact model, but neither do they disprove it.

  17. Multi-agent sequential hypothesis testing

    KAUST Repository

    Kim, Kwang-Ki K.

    2014-12-15

    This paper considers multi-agent sequential hypothesis testing and presents a framework for strategic learning in sequential games with explicit consideration of both temporal and spatial coordination. The associated Bayes risk functions explicitly incorporate costs of taking private/public measurements, costs of time-difference and disagreement in actions of agents, and costs of false declaration/choices in the sequential hypothesis testing. The corresponding sequential decision processes have well-defined value functions with respect to (a) the belief states for the case of conditional independent private noisy measurements that are also assumed to be independent identically distributed over time, and (b) the information states for the case of correlated private noisy measurements. A sequential investment game of strategic coordination and delay is also discussed as an application of the proposed strategic learning rules.

  18. Dominance, submissivity (and homosexuality) in general population: testing of evolutionary hypothesis of sadomasochism by Internet-trap-method.

    Science.gov (United States)

    Jozifkova, Eva; Flegr, Jaroslav

    2006-12-01

    Dominance and submissiveness represent strong sexual arousal stimuli for a considerable part of population. In contrast to men's sexual dominance and women's sexual submissiveness, the opposite preferences represent an evolutionary enigma. Here, we studied prevalence and strength of particular preferences in general population by Internet-trap-method. The subjects who clicked the banner displayed in the web interface of e-mail boxes were allowed to choose icons with homosexual or heterosexual partner of different hierarchical position. Dominant partner was chosen by 13.8% men and 20.5% women, and submissive partner by 36.6% men and 19.8% women. Homosexual partners were chosen by 7.3% men and 12.2% women. The response times for the submissive and dominant stimuli did not differ while for the equal-status stimuli were significantly longer, suggesting that part of subjects with equal-status preferences probably intentionally mask their natural interests. Large number of people who chose unequal sexual partner suggests that hierarchical status plays important role in human mating system.

  19. The Method of Hypothesis in Plato's Philosophy

    Directory of Open Access Journals (Sweden)

    Malihe Aboie Mehrizi

    2016-09-01

    Full Text Available The article deals with the examination of method of hypothesis in Plato's philosophy. This method, respectively, will be examined in three dialogues of Meno, Phaedon and Republic in which it is explicitly indicated. It will be shown the process of change of Plato’s attitude towards the position and usage of the method of hypothesis in his realm of philosophy. In Meno, considering the geometry, Plato attempts to introduce a method that can be used in the realm of philosophy. But, ultimately in Republic, Plato’s special attention to the method and its importance in the philosophical investigations, leads him to revise it. Here, finally Plato introduces the particular method of philosophy, i.e., the dialectic

  20. Testing the null hypothesis: the forgotten legacy of Karl Popper?

    Science.gov (United States)

    Wilkinson, Mick

    2013-01-01

    Testing of the null hypothesis is a fundamental aspect of the scientific method and has its basis in the falsification theory of Karl Popper. Null hypothesis testing makes use of deductive reasoning to ensure that the truth of conclusions is irrefutable. In contrast, attempting to demonstrate the new facts on the basis of testing the experimental or research hypothesis makes use of inductive reasoning and is prone to the problem of the Uniformity of Nature assumption described by David Hume in the eighteenth century. Despite this issue and the well documented solution provided by Popper's falsification theory, the majority of publications are still written such that they suggest the research hypothesis is being tested. This is contrary to accepted scientific convention and possibly highlights a poor understanding of the application of conventional significance-based data analysis approaches. Our work should remain driven by conjecture and attempted falsification such that it is always the null hypothesis that is tested. The write up of our studies should make it clear that we are indeed testing the null hypothesis and conforming to the established and accepted philosophical conventions of the scientific method.

  1. Test of Taylor's Hypothesis with Distributed Temperature

    Science.gov (United States)

    Cheng, Y.; Gentine, P.; Sayde, C.; Tanner, E.; Ochsner, T. E.; Dong, J.

    2016-12-01

    Taylor's hypothesis[Taylor, 1938] assumes that mean wind speed carries the spatial pattern of turbulent motion past a fixed point in a "frozen" way, which has been widely used to relate streamwise wavenumber and angular frequency . Experiments[Fisher, 1964; Tong, 1996] have shown some deviation from Taylor's hypothesis at highly turbulent intensity flows and at high wavenumbers. However, the velocity or scalar measurements have always been fixed at a few spatial points rather than distributed in space. This experiment was designed for the first time to directly compare the time and spatial spectrum of temperature to test Taylor's hypothesis, measuring temperature with high resolution in both time and space by Distributed Temperature Sensing utilizing the attenuation difference of Raman scattering in the optic fiber at the MOISST site Oklahoma. The length of transact is 233 meters along the dominant wind direction. The temperature sampling distance is 0.127m and sampling time frequency is 1 Hz. The heights of the 4 fiber cables parallel to ground are 1m, 1.254m, 1.508m and 1.762m respectively. Also, eddy covariance instrument was set up near the Distributed Temperature Sensing as comparison for temperature data. The temperature spatial spectrum could be obtained with one fixed time point, while the temperature time spectrum could be obtained with one fixed spatial point in the middle of transact. The preliminary results would be presented in the AGU fall meeting. Reference Fisher, M. J., and Davies, P.O.A.L (1964), Correlation measurements in a non-frozen pattern of turbulence, Journal of fluid mechanics, 18(1), 97-116. Taylor, G. I. (1938), The spectrum of turbulence, Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 164(919), 476-490. Tong, C. (1996), Taylor's Hypothesis and Two-point Coherence Measurements, Boundary-Layer Meteorology, 81(3), 399-410.

  2. Gaussian Hypothesis Testing and Quantum Illumination.

    Science.gov (United States)

    Wilde, Mark M; Tomamichel, Marco; Lloyd, Seth; Berta, Mario

    2017-09-22

    Quantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal type-II error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the type-I error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a low-reflectivity object embedded in a target region with a bright thermal-noise bath. For the asymmetric-error setting, we find that a quantum illumination transmitter can achieve an error probability exponent stronger than a coherent-state transmitter of the same mean photon number, and furthermore, that it requires far fewer trials to do so. This occurs when the background thermal noise is either low or bright, which means that a quantum advantage is even easier to witness than in the symmetric-error setting because it occurs for a larger range of parameters. Going forward from here, we expect our formula to have applications in settings well beyond those considered in this paper, especially to quantum communication tasks involving quantum Gaussian channels.

  3. Gaussian Hypothesis Testing and Quantum Illumination

    Science.gov (United States)

    Wilde, Mark M.; Tomamichel, Marco; Lloyd, Seth; Berta, Mario

    2017-09-01

    Quantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal type-II error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the type-I error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a low-reflectivity object embedded in a target region with a bright thermal-noise bath. For the asymmetric-error setting, we find that a quantum illumination transmitter can achieve an error probability exponent stronger than a coherent-state transmitter of the same mean photon number, and furthermore, that it requires far fewer trials to do so. This occurs when the background thermal noise is either low or bright, which means that a quantum advantage is even easier to witness than in the symmetric-error setting because it occurs for a larger range of parameters. Going forward from here, we expect our formula to have applications in settings well beyond those considered in this paper, especially to quantum communication tasks involving quantum Gaussian channels.

  4. Debates—Hypothesis testing in hydrology: Theory and practice

    Science.gov (United States)

    Pfister, Laurent; Kirchner, James W.

    2017-03-01

    The basic structure of the scientific method—at least in its idealized form—is widely championed as a recipe for scientific progress, but the day-to-day practice may be different. Here, we explore the spectrum of current practice in hypothesis formulation and testing in hydrology, based on a random sample of recent research papers. This analysis suggests that in hydrology, as in other fields, hypothesis formulation and testing rarely correspond to the idealized model of the scientific method. Practices such as "p-hacking" or "HARKing" (Hypothesizing After the Results are Known) are major obstacles to more rigorous hypothesis testing in hydrology, along with the well-known problem of confirmation bias—the tendency to value and trust confirmations more than refutations—among both researchers and reviewers. Nonetheless, as several examples illustrate, hypothesis tests have played an essential role in spurring major advances in hydrological theory. Hypothesis testing is not the only recipe for scientific progress, however. Exploratory research, driven by innovations in measurement and observation, has also underlain many key advances. Further improvements in observation and measurement will be vital to both exploratory research and hypothesis testing, and thus to advancing the science of hydrology.

  5. A Test of the Urban Overload Hypothesis.

    Science.gov (United States)

    McCauley, Clark R.

    This paper briefly discusses three studies aimed at exploring the overload hypothesis posited by Stanley Milgram. That hypothesis suggests that impoverished social interaction in the city is an adaptation to overload of interpersonal contacts. The three studies examine various aspects of the phenomenon using different methodologies. Comparing city…

  6. Bayesian Hypothesis Testing for Planet Finding

    Science.gov (United States)

    Braems, I.; Kasdin, N. J.

    2003-12-01

    One of the most important performance metrics of any space planet finding system is integration time. The time needed to make a positive detection of an extrasolar planet determines the number of systems we can observe for the life of the mission and the stability requirements of the spacecraft and optical control systems. Most astronomical detection approaches rely on fairly simple signal-to-noise calculations and a threshold determined by the ability of the human eye to extract the planet image from the background (usually a signal-to-noise ratio of five). In this paper we present an alternative approach to detection using Bayesian hypothesis testing. This optimal approach provides a quantitative measure of the probability of detection under various conditions and integration times (such as known or unknown background levels) and under different prior assumptions. We also show how the technique allows for a much higher probability of detection for shorter integration times than the previous photometric approaches. We gratefully acknowledge the support of the Jet Propulsion Laboratory of the National Aeronautics and Space Administration for this work and Institut National de Recherche en Informatique et Automatique (INRIA) for its support of Ms. Braems.

  7. Segmentation by Large Scale Hypothesis Testing - Segmentation as Outlier Detection

    DEFF Research Database (Denmark)

    Darkner, Sune; Dahl, Anders Lindbjerg; Larsen, Rasmus

    2010-01-01

    locally. We propose a method based on large scale hypothesis testing with a consistent method for selecting an appropriate threshold for the given data. By estimating the background distribution we characterize the segment of interest as a set of outliers with a certain probability based on the estimated...... a microscope and we show how the method can handle transparent particles with significant glare point. The method generalizes to other problems. THis is illustrated by applying the method to camera calibration images and MRI of the midsagittal plane for gray and white matter separation and segmentation...

  8. Testing the single-state dominance hypothesis

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez-Rodríguez, R. [Universidad Politécnica de Madrid, Avda. Juan Herrera 4, E-28040 Madrid (Spain); Moreno, O.; Moya de Guerra, E. [Universidad Complutense de Madrid, Avda. Complutense, E-28040 Madrid (Spain); Sarriguren, P. [Instituto de Estructura de la Materia (CSIC), Serrano 123, E-28006 Madrid (Spain); Šimkovic, F. [Comenius University, SK-842 15 Bratislava (Slovakia); Faessler, A. [University of Tübingen, D-72076 Tübingen (Germany)

    2013-12-30

    We present a theoretical analysis of the single-state dominance hypothesis for the two-neutrino double-beta decay process. The theoretical framework is a proton-neutron QRPA based on a deformed Hartree-Fock mean field with BCS pairing correlations. We focus on the decays of {sup 100}Mo, {sup 116}Cd and {sup 128}Te. We do not find clear evidences for single-state dominance within the present approach.

  9. A critique of statistical hypothesis testing in clinical research.

    Science.gov (United States)

    Raha, Somik

    2011-07-01

    Many have documented the difficulty of using the current paradigm of Randomized Controlled Trials (RCTs) to test and validate the effectiveness of alternative medical systems such as Ayurveda. This paper critiques the applicability of RCTs for all clinical knowledge-seeking endeavors, of which Ayurveda research is a part. This is done by examining statistical hypothesis testing, the underlying foundation of RCTs, from a practical and philosophical perspective. In the philosophical critique, the two main worldviews of probability are that of the Bayesian and the frequentist. The frequentist worldview is a special case of the Bayesian worldview requiring the unrealistic assumptions of knowing nothing about the universe and believing that all observations are unrelated to each other. Many have claimed that the first belief is necessary for science, and this claim is debunked by comparing variations in learning with different prior beliefs. Moving beyond the Bayesian and frequentist worldviews, the notion of hypothesis testing itself is challenged on the grounds that a hypothesis is an unclear distinction, and assigning a probability on an unclear distinction is an exercise that does not lead to clarity of action. This critique is of the theory itself and not any particular application of statistical hypothesis testing. A decision-making frame is proposed as a way of both addressing this critique and transcending ideological debates on probability. An example of a Bayesian decision-making approach is shown as an alternative to statistical hypothesis testing, utilizing data from a past clinical trial that studied the effect of Aspirin on heart attacks in a sample population of doctors. As a big reason for the prevalence of RCTs in academia is legislation requiring it, the ethics of legislating the use of statistical methods for clinical research is also examined.

  10. A critique of statistical hypothesis testing in clinical research

    Directory of Open Access Journals (Sweden)

    Somik Raha

    2011-01-01

    Full Text Available Many have documented the difficulty of using the current paradigm of Randomized Controlled Trials (RCTs to test and validate the effectiveness of alternative medical systems such as Ayurveda. This paper critiques the applicability of RCTs for all clinical knowledge-seeking endeavors, of which Ayurveda research is a part. This is done by examining statistical hypothesis testing, the underlying foundation of RCTs, from a practical and philosophical perspective. In the philosophical critique, the two main worldviews of probability are that of the Bayesian and the frequentist. The frequentist worldview is a special case of the Bayesian worldview requiring the unrealistic assumptions of knowing nothing about the universe and believing that all observations are unrelated to each other. Many have claimed that the first belief is necessary for science, and this claim is debunked by comparing variations in learning with different prior beliefs. Moving beyond the Bayesian and frequentist worldviews, the notion of hypothesis testing itself is challenged on the grounds that a hypothesis is an unclear distinction, and assigning a probability on an unclear distinction is an exercise that does not lead to clarity of action. This critique is of the theory itself and not any particular application of statistical hypothesis testing. A decision-making frame is proposed as a way of both addressing this critique and transcending ideological debates on probability. An example of a Bayesian decision-making approach is shown as an alternative to statistical hypothesis testing, utilizing data from a past clinical trial that studied the effect of Aspirin on heart attacks in a sample population of doctors. As a big reason for the prevalence of RCTs in academia is legislation requiring it, the ethics of legislating the use of statistical methods for clinical research is also examined.

  11. Interpreting "statistical hypothesis testing" results in clinical research.

    Science.gov (United States)

    Sarmukaddam, Sanjeev B

    2012-04-01

    Difference between "Clinical Significance and Statistical Significance" should be kept in mind while interpreting "statistical hypothesis testing" results in clinical research. This fact is already known to many but again pointed out here as philosophy of "statistical hypothesis testing" is sometimes unnecessarily criticized mainly due to failure in considering such distinction. Randomized controlled trials are also wrongly criticized similarly. Some scientific method may not be applicable in some peculiar/particular situation does not mean that the method is useless. Also remember that "statistical hypothesis testing" is not for decision making and the field of "decision analysis" is very much an integral part of science of statistics. It is not correct to say that "confidence intervals have nothing to do with confidence" unless one understands meaning of the word "confidence" as used in context of confidence interval. Interpretation of the results of every study should always consider all possible alternative explanations like chance, bias, and confounding. Statistical tests in inferential statistics are, in general, designed to answer the question "How likely is the difference found in random sample(s) is due to chance" and therefore limitation of relying only on statistical significance in making clinical decisions should be avoided.

  12. Sequential hypothesis testing with Bayes factors: Efficiently testing mean differences.

    Science.gov (United States)

    Schönbrodt, Felix D; Wagenmakers, Eric-Jan; Zehetleitner, Michael; Perugini, Marco

    2017-06-01

    Unplanned optional stopping rules have been criticized for inflating Type I error rates under the null hypothesis significance testing (NHST) paradigm. Despite these criticisms, this research practice is not uncommon, probably because it appeals to researcher's intuition to collect more data to push an indecisive result into a decisive region. In this contribution, we investigate the properties of a procedure for Bayesian hypothesis testing that allows optional stopping with unlimited multiple testing, even after each participant. In this procedure, which we call Sequential Bayes Factors (SBFs), Bayes factors are computed until an a priori defined level of evidence is reached. This allows flexible sampling plans and is not dependent upon correct effect size guesses in an a priori power analysis. We investigated the long-term rate of misleading evidence, the average expected sample sizes, and the biasedness of effect size estimates when an SBF design is applied to a test of mean differences between 2 groups. Compared with optimal NHST, the SBF design typically needs 50% to 70% smaller samples to reach a conclusion about the presence of an effect, while having the same or lower long-term rate of wrong inference. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  13. Introduction to Robust Estimation and Hypothesis Testing

    CERN Document Server

    Wilcox, Rand R

    2012-01-01

    This revised book provides a thorough explanation of the foundation of robust methods, incorporating the latest updates on R and S-Plus, robust ANOVA (Analysis of Variance) and regression. It guides advanced students and other professionals through the basic strategies used for developing practical solutions to problems, and provides a brief background on the foundations of modern methods, placing the new methods in historical context. Author Rand Wilcox includes chapter exercises and many real-world examples that illustrate how various methods perform in different situations.Introduction to R

  14. Neural networks supporting switching, hypothesis testing, and rule application.

    Science.gov (United States)

    Liu, Zhiya; Braunlich, Kurt; Wehe, Hillary S; Seger, Carol A

    2015-10-01

    We identified dynamic changes in recruitment of neural connectivity networks across three phases of a flexible rule learning and set-shifting task similar to the Wisconsin Card Sort Task: switching, rule learning via hypothesis testing, and rule application. During fMRI scanning, subjects viewed pairs of stimuli that differed across four dimensions (letter, color, size, screen location), chose one stimulus, and received feedback. Subjects were informed that the correct choice was determined by a simple unidimensional rule, for example "choose the blue letter". Once each rule had been learned and correctly applied for 4-7 trials, subjects were cued via either negative feedback or visual cues to switch to learning a new rule. Task performance was divided into three phases: Switching (first trial after receiving the switch cue), hypothesis testing (subsequent trials through the last error trial), and rule application (correct responding after the rule was learned). We used both univariate analysis to characterize activity occurring within specific regions of the brain, and a multivariate method, constrained principal component analysis for fMRI (fMRI-CPCA), to investigate how distributed regions coordinate to subserve different processes. As hypothesized, switching was subserved by a limbic network including the ventral striatum, thalamus, and parahippocampal gyrus, in conjunction with cortical salience network regions including the anterior cingulate and frontoinsular cortex. Activity in the ventral striatum was associated with switching regardless of how switching was cued; visually cued shifts were associated with additional visual cortical activity. After switching, as subjects moved into the hypothesis testing phase, a broad fronto-parietal-striatal network (associated with the cognitive control, dorsal attention, and salience networks) increased in activity. This network was sensitive to rule learning speed, with greater extended activity for the slowest

  15. Hypothesis testing and statistical analysis of microbiome

    Directory of Open Access Journals (Sweden)

    Yinglin Xia

    2017-09-01

    Full Text Available After the initiation of Human Microbiome Project in 2008, various biostatistic and bioinformatic tools for data analysis and computational methods have been developed and applied to microbiome studies. In this review and perspective, we discuss the research and statistical hypotheses in gut microbiome studies, focusing on mechanistic concepts that underlie the complex relationships among host, microbiome, and environment. We review the current available statistic tools and highlight recent progress of newly developed statistical methods and models. Given the current challenges and limitations in biostatistic approaches and tools, we discuss the future direction in developing statistical methods and models for the microbiome studies.

  16. Seeking health information on the web: positive hypothesis testing.

    Science.gov (United States)

    Kayhan, Varol Onur

    2013-04-01

    The goal of this study is to investigate positive hypothesis testing among consumers of health information when they search the Web. After demonstrating the extent of positive hypothesis testing using Experiment 1, we conduct Experiment 2 to test the effectiveness of two debiasing techniques. A total of 60 undergraduate students searched a tightly controlled online database developed by the authors to test the validity of a hypothesis. The database had four abstracts that confirmed the hypothesis and three abstracts that disconfirmed it. Findings of Experiment 1 showed that majority of participants (85%) exhibited positive hypothesis testing. In Experiment 2, we found that the recommendation technique was not effective in reducing positive hypothesis testing since none of the participants assigned to this server could retrieve disconfirming evidence. Experiment 2 also showed that the incorporation technique successfully reduced positive hypothesis testing since 75% of the participants could retrieve disconfirming evidence. Positive hypothesis testing on the Web is an understudied topic. More studies are needed to validate the effectiveness of the debiasing techniques discussed in this study and develop new techniques. Search engine developers should consider developing new options for users so that both confirming and disconfirming evidence can be presented in search results as users test hypotheses using search engines. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  17. Stouffer's test in a large scale simultaneous hypothesis testing.

    Directory of Open Access Journals (Sweden)

    Sang Cheol Kim

    Full Text Available In microarray data analysis, we are often required to combine several dependent partial test results. To overcome this, many suggestions have been made in previous literature; Tippett's test and Fisher's omnibus test are most popular. Both tests have known null distributions when the partial tests are independent. However, for dependent tests, their (even, asymptotic null distributions are unknown and additional numerical procedures are required. In this paper, we revisited Stouffer's test based on z-scores and showed its advantage over the two aforementioned methods in the analysis of large-scale microarray data. The combined statistic in Stouffer's test has a normal distribution with mean 0 from the normality of the z-scores. Its variance can be estimated from the scores of genes in the experiment without an additional numerical procedure. We numerically compared the errors of Stouffer's test and the two p-value based methods, Tippett's test and Fisher's omnibus test. We also analyzed our microarray data to find differentially expressed genes by non-genotoxic and genotoxic carcinogen compounds. Both numerical study and the real application showed that Stouffer's test performed better than Tippett's method and Fisher's omnibus method with additional permutation steps.

  18. Teaching Hypothesis Testing by Debunking a Demonstration of Telepathy.

    Science.gov (United States)

    Bates, John A.

    1991-01-01

    Discusses a lesson designed to demonstrate hypothesis testing to introductory college psychology students. Explains that a psychology instructor demonstrated apparent psychic abilities to students. Reports that students attempted to explain the instructor's demonstrations through hypothesis testing and revision. Provides instructions on performing…

  19. Inflation uncertainty and a test of the Friedman hypothesis

    OpenAIRE

    Hafer, R.W.

    1985-01-01

    This paper tests Friedman's (1977) hypothesis that increases in inflation uncertainty, ceteris paribus, may yield higher levels of unemployment. Tests are made using quarterly measures of inflation uncertainty taken from the ASA-NBER survey. Using the 1972-1984 period, we find general support for the hypothesis.

  20. An Exercise for Illustrating the Logic of Hypothesis Testing

    Science.gov (United States)

    Lawton, Leigh

    2009-01-01

    Hypothesis testing is one of the more difficult concepts for students to master in a basic, undergraduate statistics course. Students often are puzzled as to why statisticians simply don't calculate the probability that a hypothesis is true. This article presents an exercise that forces students to lay out on their own a procedure for testing a…

  1. Hypothesis testing in animal social networks.

    Science.gov (United States)

    Croft, Darren P; Madden, Joah R; Franks, Daniel W; James, Richard

    2011-10-01

    Behavioural ecologists are increasingly using social network analysis to describe the social organisation of animal populations and to test hypotheses. However, the statistical analysis of network data presents a number of challenges. In particular the non-independent nature of the data violates the assumptions of many common statistical approaches. In our opinion there is currently confusion and uncertainty amongst behavioural ecologists concerning the potential pitfalls when hypotheses testing using social network data. Here we review what we consider to be key considerations associated with the analysis of animal social networks and provide a practical guide to the use of null models based on randomisation to control for structure and non-independence in the data. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Hypothesis versus significance testing for controlled clinical trials: a dialogue.

    Science.gov (United States)

    Salsburg, D

    1990-03-01

    The mathematical formulations of Neyman-Pearson hypothesis testing and the Fisherian concept of significance tests are examined as alternative ways of applying statistical models to data from clinical trials.

  3. Testing Happiness Hypothesis among the Elderly

    Directory of Open Access Journals (Sweden)

    Rossi Máximo

    2008-08-01

    Full Text Available We use a rich data set that allows us to test different happiness hypotheses employing four methodological approaches. We find that older people in Uruguay have a tendency to report themselves happy when they are married, when they have higher standards of health and when they earn higher levels of income or they consider that their income is suitable for their standard of living. On the contrary, they report lower levels of happiness when they live alone and when their nutrition is insufficient. We also find that education has no clear impact on happiness. We think that our study is a contribution to the study of those factors that can explain happiness among the elderly in Latin American countries. Future work will focus on enhanced empirical analysis and in extending our study to other countries.

  4. Experimental tests of the cellular tensegrity hypothesis.

    Science.gov (United States)

    Stamenović, Dimitrije; Mijailovich, Srboljub M; Tolić-Nørrelykke, Iva Marija; Wang, Ning

    2003-01-01

    The tensegrity model depicts the cytoskeleton (CSK) as a prestressed network of interconnected filaments. The prestress is generated by the CSK contractile apparatus and is partly balanced by traction at the cell-substrate interface and partly by CSK internal compression elements such as microtubules (MTs). A key feature of tensegrity is that the shear modulus (G) must increase in proportion with the prestress. Here we have tested that prediction as well as the idea that compression of MTs balance a portion of the cell prestress. Airway smooth muscle cells were studied. Traction microscopy was used to calculate traction. Because traction must be balanced by the stress within the cell, the prestress could be computed. Cell G was measured by oscillatory magnetic cytometry. The prestress was modulated using graded concentrations of contracting (histamine) or relaxing (isoproterenol) agonists and by disrupting MTs by colchicine. It was found that G increased in proportion with the prestress and that compression of MTs balanced a significant, but a relatively small fraction of the prestress. Taken together, these results do not disprove other models of cell deformability, nor they prove tensegrity. However, they do support a priori predictions of tensegrity. As such, it may not be necessary to invoke more complex mechanisms to explain these central features of cell deformability.

  5. Unscaled Bayes factors for multiple hypothesis testing in microarray experiments.

    Science.gov (United States)

    Bertolino, Francesco; Cabras, Stefano; Castellanos, Maria Eugenia; Racugno, Walter

    2015-12-01

    Multiple hypothesis testing collects a series of techniques usually based on p-values as a summary of the available evidence from many statistical tests. In hypothesis testing, under a Bayesian perspective, the evidence for a specified hypothesis against an alternative, conditionally on data, is given by the Bayes factor. In this study, we approach multiple hypothesis testing based on both Bayes factors and p-values, regarding multiple hypothesis testing as a multiple model selection problem. To obtain the Bayes factors we assume default priors that are typically improper. In this case, the Bayes factor is usually undetermined due to the ratio of prior pseudo-constants. We show that ignoring prior pseudo-constants leads to unscaled Bayes factor which do not invalidate the inferential procedure in multiple hypothesis testing, because they are used within a comparative scheme. In fact, using partial information from the p-values, we are able to approximate the sampling null distribution of the unscaled Bayes factor and use it within Efron's multiple testing procedure. The simulation study suggests that under normal sampling model and even with small sample sizes, our approach provides false positive and false negative proportions that are less than other common multiple hypothesis testing approaches based only on p-values. The proposed procedure is illustrated in two simulation studies, and the advantages of its use are showed in the analysis of two microarray experiments. © The Author(s) 2011.

  6. Approaches to informed consent for hypothesis-testing and hypothesis-generating clinical genomics research

    Directory of Open Access Journals (Sweden)

    Facio Flavia M

    2012-10-01

    Full Text Available Abstract Background Massively-parallel sequencing (MPS technologies create challenges for informed consent of research participants given the enormous scale of the data and the wide range of potential results. Discussion We propose that the consent process in these studies be based on whether they use MPS to test a hypothesis or to generate hypotheses. To demonstrate the differences in these approaches to informed consent, we describe the consent processes for two MPS studies. The purpose of our hypothesis-testing study is to elucidate the etiology of rare phenotypes using MPS. The purpose of our hypothesis-generating study is to test the feasibility of using MPS to generate clinical hypotheses, and to approach the return of results as an experimental manipulation. Issues to consider in both designs include: volume and nature of the potential results, primary versus secondary results, return of individual results, duty to warn, length of interaction, target population, and privacy and confidentiality. Summary The categorization of MPS studies as hypothesis-testing versus hypothesis-generating can help to clarify the issue of so-called incidental or secondary results for the consent process, and aid the communication of the research goals to study participants.

  7. Approaches to informed consent for hypothesis-testing and hypothesis-generating clinical genomics research.

    Science.gov (United States)

    Facio, Flavia M; Sapp, Julie C; Linn, Amy; Biesecker, Leslie G

    2012-10-10

    Massively-parallel sequencing (MPS) technologies create challenges for informed consent of research participants given the enormous scale of the data and the wide range of potential results. We propose that the consent process in these studies be based on whether they use MPS to test a hypothesis or to generate hypotheses. To demonstrate the differences in these approaches to informed consent, we describe the consent processes for two MPS studies. The purpose of our hypothesis-testing study is to elucidate the etiology of rare phenotypes using MPS. The purpose of our hypothesis-generating study is to test the feasibility of using MPS to generate clinical hypotheses, and to approach the return of results as an experimental manipulation. Issues to consider in both designs include: volume and nature of the potential results, primary versus secondary results, return of individual results, duty to warn, length of interaction, target population, and privacy and confidentiality. The categorization of MPS studies as hypothesis-testing versus hypothesis-generating can help to clarify the issue of so-called incidental or secondary results for the consent process, and aid the communication of the research goals to study participants.

  8. Hypothesis Testing of Parameters for Ordinary Linear Circular Regression

    Directory of Open Access Journals (Sweden)

    Abdul Ghapor Hussin

    2006-07-01

    Full Text Available This paper presents the hypothesis testing of parameters for ordinary linear circular regression model assuming the circular random error distributed as von Misses distribution. The main interests are in testing of the intercept and slope parameter of the regression line. As an illustration, this hypothesis testing will be used in analyzing the wind and wave direction data recorded by two different techniques which are HF radar system and anchored wave buoy.

  9. Moving beyond traditional null hypothesis testing: evaluating expectations directly

    NARCIS (Netherlands)

    van de Schoot, R.; Hoijtink, H.J.A.; Romeijn, J.W.

    2011-01-01

    This mini-review illustrates that testing the traditional null hypothesis is not always the appropriate strategy. Half in jest, we discuss Aristotle's scientific investigations into the shape of the earth in the context of evaluating the traditional null hypothesis. We conclude that Aristotle was

  10. Testing the Double-Deficit Hypothesis in an Adult Sample

    Science.gov (United States)

    Miller, Carlin J.; Miller, Scott R.; Bloom, Juliana S.; Jones, Lauren; Lindstrom, William; Craggs, Jason; Garcia-Barrera, Mauricio; Semrud-Clikeman, Margaret; Gilger, Jeffrey W.; Hynd, George W.

    2006-01-01

    The double-deficit hypothesis of dyslexia posits that reading deficits are more severe in individuals with weaknesses in phonological awareness and rapid naming than in individuals with deficits in only one of these reading composite skills. In this study, the hypothesis was tested in an adult sample as a model of reading achievement. Participants…

  11. Optimizing Field Campaigns Using A Hypothesis Testing Framework

    Science.gov (United States)

    Harken, B. J.; Over, M. W.; Rubin, Y.

    2012-12-01

    Field campaigns in hydrogeology often aim to characterize aquifers for modeling and predicting flow and transport of contaminants to facilitate in some objective related to environmental protection or public health and safety. Many times these objectives depend on predicting the answer to a yes/no question, such as: will contaminant concentration in an aquifer surpass a threshold value? Will a contaminant reach a river outflow before it degrades? Is water from an extraction well safe for consumption? It remains difficult, however, to predict the extent to which a field campaign will improve modeling and prediction efforts or the chance of success in the original objective. Presented here is a method for designing field campaigns around the original objective by posing it in a hypothesis testing framework and optimizing campaigns with minimizing probability of error as the goal. The first step in this process is to formulate the null and alternative hypotheses, which represent the two possible outcomes of the yes/no question in the objective. The alternative hypothesis is the desirable outcome which requires a specified level of certainty to be accepted. The null hypothesis, on the other hand, is the "safe" fallback assumption, which is accepted if the alternative hypothesis lacks sufficient supporting evidence. Of key concern in designing field campaigns is the probability of making an error (Type I or Type II). A level of significance is chosen based on the severity of each type of error and the level of risk that is considered acceptable for each case. A field campaign can then be designed to gain enough information to reduce the probability of error to the acceptable level while expending as few resources as possible. A case study examined here is attempting to predict the arrival time of a contaminant in an aquifer. A scenario is first established in which a contaminant is travelling from a point source to a control plane, which could represent, for example, a

  12. A default Bayesian hypothesis test for correlations and partial correlations

    NARCIS (Netherlands)

    Wetzels, R.; Wagenmakers, E.J.

    2012-01-01

    We propose a default Bayesian hypothesis test for the presence of a correlation or a partial correlation. The test is a direct application of Bayesian techniques for variable selection in regression models. The test is easy to apply and yields practical advantages that the standard frequentist tests

  13. Cross-system log file analysis for hypothesis testing

    NARCIS (Netherlands)

    Glahn, Christian

    2008-01-01

    Glahn, C. (2008). Cross-system log file analysis for hypothesis testing. Presented at Empowering Learners for Lifelong Competence Development: pedagogical, organisational and technological issues. 4th TENCompetence Open Workshop. April, 10, 2008, Madrid, Spain.

  14. Biostatistics Series Module 2: Overview of Hypothesis Testing.

    Science.gov (United States)

    Hazra, Avijit; Gogtay, Nithya

    2016-01-01

    Hypothesis testing (or statistical inference) is one of the major applications of biostatistics. Much of medical research begins with a research question that can be framed as a hypothesis. Inferential statistics begins with a null hypothesis that reflects the conservative position of no change or no difference in comparison to baseline or between groups. Usually, the researcher has reason to believe that there is some effect or some difference which is the alternative hypothesis. The researcher therefore proceeds to study samples and measure outcomes in the hope of generating evidence strong enough for the statistician to be able to reject the null hypothesis. The concept of the P value is almost universally used in hypothesis testing. It denotes the probability of obtaining by chance a result at least as extreme as that observed, even when the null hypothesis is true and no real difference exists. Usually, if P is hypothesis is rejected and sample results are deemed statistically significant. With the increasing availability of computers and access to specialized statistical software, the drudgery involved in statistical calculations is now a thing of the past, once the learning curve of the software has been traversed. The life sciences researcher is therefore free to devote oneself to optimally designing the study, carefully selecting the hypothesis tests to be applied, and taking care in conducting the study well. Unfortunately, selecting the right test seems difficult initially. Thinking of the research hypothesis as addressing one of five generic research questions helps in selection of the right hypothesis test. In addition, it is important to be clear about the nature of the variables (e.g., numerical vs. categorical; parametric vs. nonparametric) and the number of groups or data sets being compared (e.g., two or more than two) at a time. The same research question may be explored by more than one type of hypothesis test. While this may be of utility in

  15. Planned Hypothesis Tests Are Not Necessarily Exempt from Multiplicity Adjustment

    Science.gov (United States)

    Frane, Andrew V.

    2015-01-01

    Scientific research often involves testing more than one hypothesis at a time, which can inflate the probability that a Type I error (false discovery) will occur. To prevent this Type I error inflation, adjustments can be made to the testing procedure that compensate for the number of tests. Yet many researchers believe that such adjustments are…

  16. Nearly Efficient Likelihood Ratio Tests of the Unit Root Hypothesis

    DEFF Research Database (Denmark)

    Jansson, Michael; Nielsen, Morten Ørregaard

    Seemingly absent from the arsenal of currently available "nearly efficient" testing procedures for the unit root hypothesis, i.e. tests whose local asymptotic power functions are indistinguishable from the Gaussian power envelope, is a test admitting a (quasi-)likelihood ratio interpretation. We...

  17. On informal hypothesis testing in hydrology: the example of the "two water worlds" hypothesis

    Science.gov (United States)

    Geris, Josie; Soulsby, Chris; Tetzlaff, Doerthe

    2017-04-01

    Rigorous hypothesis tests provide useful tools for making statistical inferences about hydrological processes and have indeed led to major advances in the field of hydrology. However, the formulation of such (typically rather simple) tests with valid assumptions is not always realistic for complex hydrological problems with limited data. Moreover, ill-defined hypothesis tests can lead to meaningless results and increased risks of drawing ambiguous conclusions. In such cases, data plots can be more powerful than p-values. Nevertheless, the formulation and evaluation of (working) hypotheses can offer an important framework to structure data collection and analyses of a more exploratory nature. Here we demonstrate the power of such an approach using the example of the topical "two water worlds" hypothesis in (eco)hydrology. Several recent studies in this field have suggested that there may be "ecohydrological separation" of distinct soil water pools ("water worlds") comprising plant-available water on one hand and water that drains to streams on the other. However, contrary to findings in most other climates, preliminary investigations in humid northern environments did not find strong evidence to support the hypothesis, which has further highlighted the complex nature of subsurface soil water storage processes and vegetation water use. While unambiguously rejecting or verifying the "two water worlds" hypothesis might be an unrealistic aim, studies addressing it more informally have so far led to new insights into e.g. soil-vegetation water interactions, the potential drivers of such separation and advances in our commonly used data collection and analyses techniques.

  18. A novel hypothesis splitting method implementation for multi-hypothesis filters

    DEFF Research Database (Denmark)

    Bayramoglu, Enis; Ravn, Ole; Andersen, Nils Axel

    2013-01-01

    The paper presents a multi-hypothesis filter library featuring a novel method for splitting Gaussians into ones with smaller variances. The library is written in C++ for high performance and the source code is open and free1. The multi-hypothesis filters commonly approximate the distribution...... transformations better, if the covariances of the individual hypotheses are sufficiently small. We propose a look-up table based method to calculate a set of Gaussian hypotheses approximating a wider Gaussian in order to improve the filter approximation. Python bindings for the library are also provided for fast...

  19. Decentralized Hypothesis Testing in Energy Harvesting Wireless Sensor Networks

    Science.gov (United States)

    Tarighati, Alla; Gross, James; Jalden, Joakim

    2017-09-01

    We consider the problem of decentralized hypothesis testing in a network of energy harvesting sensors, where sensors make noisy observations of a phenomenon and send quantized information about the phenomenon towards a fusion center. The fusion center makes a decision about the present hypothesis using the aggregate received data during a time interval. We explicitly consider a scenario under which the messages are sent through parallel access channels towards the fusion center. To avoid limited lifetime issues, we assume each sensor is capable of harvesting all the energy it needs for the communication from the environment. Each sensor has an energy buffer (battery) to save its harvested energy for use in other time intervals. Our key contribution is to formulate the problem of decentralized detection in a sensor network with energy harvesting devices. Our analysis is based on a queuing-theoretic model for the battery and we propose a sensor decision design method by considering long term energy management at the sensors. We show how the performance of the system changes for different battery capacities. We then numerically show how our findings can be used in the design of sensor networks with energy harvesting sensors.

  20. Testing the hypothesis that treatment can eliminate HIV

    DEFF Research Database (Denmark)

    Okano, Justin T; Robbins, Danielle; Palk, Laurence

    2016-01-01

    . The elimination threshold is one new HIV infection per 1000 individuals. Here, we test the hypothesis that TasP can substantially reduce epidemics and eliminate HIV. We estimate the impact of TasP, between 1996 and 2013, on the Danish HIV epidemic in men who have sex with men (MSM), an epidemic UNAIDS has...... identified as a priority for elimination. METHODS: We use a CD4-staged Bayesian back-calculation approach to estimate incidence, and the hidden epidemic (the number of HIV-infected undiagnosed MSM). To develop the back-calculation model, we use data from an ongoing nationwide population-based study......: the Danish HIV Cohort Study. FINDINGS: Incidence, and the hidden epidemic, decreased substantially after treatment was introduced in 1996. By 2013, incidence was close to the elimination threshold: 1·4 (median, 95% Bayesian credible interval [BCI] 0·4-2·1) new HIV infections per 1000 MSM and there were only...

  1. Approaches to informed consent for hypothesis-testing and hypothesis-generating clinical genomics research

    OpenAIRE

    Facio Flavia M; Sapp Julie C; Linn Amy; Biesecker Leslie G

    2012-01-01

    Abstract Background Massively-parallel sequencing (MPS) technologies create challenges for informed consent of research participants given the enormous scale of the data and the wide range of potential results. Discussion We propose that the consent process in these studies be based on whether they use MPS to test a hypothesis or to generate hypotheses. To demonstrate the differences in these approaches to informed consent, we describe the consent processes for two MPS studies. The purpose of...

  2. Supporting shared hypothesis testing in the biomedical domain.

    Science.gov (United States)

    Agibetov, Asan; Jiménez-Ruiz, Ernesto; Ondrésik, Marta; Solimando, Alessandro; Banerjee, Imon; Guerrini, Giovanna; Catalano, Chiara E; Oliveira, Joaquim M; Patanè, Giuseppe; Reis, Rui L; Spagnuolo, Michela

    2018-02-08

    Pathogenesis of inflammatory diseases can be tracked by studying the causality relationships among the factors contributing to its development. We could, for instance, hypothesize on the connections of the pathogenesis outcomes to the observed conditions. And to prove such causal hypotheses we would need to have the full understanding of the causal relationships, and we would have to provide all the necessary evidences to support our claims. In practice, however, we might not possess all the background knowledge on the causality relationships, and we might be unable to collect all the evidence to prove our hypotheses. In this work we propose a methodology for the translation of biological knowledge on causality relationships of biological processes and their effects on conditions to a computational framework for hypothesis testing. The methodology consists of two main points: hypothesis graph construction from the formalization of the background knowledge on causality relationships, and confidence measurement in a causality hypothesis as a normalized weighted path computation in the hypothesis graph. In this framework, we can simulate collection of evidences and assess confidence in a causality hypothesis by measuring it proportionally to the amount of available knowledge and collected evidences. We evaluate our methodology on a hypothesis graph that represents both contributing factors which may cause cartilage degradation and the factors which might be caused by the cartilage degradation during osteoarthritis. Hypothesis graph construction has proven to be robust to the addition of potentially contradictory information on the simultaneously positive and negative effects. The obtained confidence measures for the specific causality hypotheses have been validated by our domain experts, and, correspond closely to their subjective assessments of confidences in investigated hypotheses. Overall, our methodology for a shared hypothesis testing framework exhibits

  3. Semiparametric Power Envelopes for Tests of the Unit Root Hypothesis

    DEFF Research Database (Denmark)

    Jansson, Michael

    This paper derives asymptotic power envelopes for tests of the unit root hypothesis in a zero-mean AR(1) model. The power envelopes are derived using the limits of experiments approach and are semiparametric in the sense that the underlying error distribution is treated as an unknown infinitedime......This paper derives asymptotic power envelopes for tests of the unit root hypothesis in a zero-mean AR(1) model. The power envelopes are derived using the limits of experiments approach and are semiparametric in the sense that the underlying error distribution is treated as an unknown...

  4. A large scale test of the gaming-enhancement hypothesis.

    Science.gov (United States)

    Przybylski, Andrew K; Wang, John C

    2016-01-01

    A growing research literature suggests that regular electronic game play and game-based training programs may confer practically significant benefits to cognitive functioning. Most evidence supporting this idea, the gaming-enhancement hypothesis, has been collected in small-scale studies of university students and older adults. This research investigated the hypothesis in a general way with a large sample of 1,847 school-aged children. Our aim was to examine the relations between young people's gaming experiences and an objective test of reasoning performance. Using a Bayesian hypothesis testing approach, evidence for the gaming-enhancement and null hypotheses were compared. Results provided no substantive evidence supporting the idea that having preference for or regularly playing commercially available games was positively associated with reasoning ability. Evidence ranged from equivocal to very strong in support for the null hypothesis over what was predicted. The discussion focuses on the value of Bayesian hypothesis testing for investigating electronic gaming effects, the importance of open science practices, and pre-registered designs to improve the quality of future work.

  5. A large scale test of the gaming-enhancement hypothesis

    Directory of Open Access Journals (Sweden)

    Andrew K. Przybylski

    2016-11-01

    Full Text Available A growing research literature suggests that regular electronic game play and game-based training programs may confer practically significant benefits to cognitive functioning. Most evidence supporting this idea, the gaming-enhancement hypothesis, has been collected in small-scale studies of university students and older adults. This research investigated the hypothesis in a general way with a large sample of 1,847 school-aged children. Our aim was to examine the relations between young people’s gaming experiences and an objective test of reasoning performance. Using a Bayesian hypothesis testing approach, evidence for the gaming-enhancement and null hypotheses were compared. Results provided no substantive evidence supporting the idea that having preference for or regularly playing commercially available games was positively associated with reasoning ability. Evidence ranged from equivocal to very strong in support for the null hypothesis over what was predicted. The discussion focuses on the value of Bayesian hypothesis testing for investigating electronic gaming effects, the importance of open science practices, and pre-registered designs to improve the quality of future work.

  6. Hypothesis testing in genetic linkage analysis via Gibbs sampling ...

    African Journals Online (AJOL)

    Genetic linkage analysis involves estimating parameters in a genetic model in which a genetic trait is regressed on some factors such as polygenic values and environmental effects. Since only phenotypes are observed, hypothesis testing in such cases needs calculation of likelihood function in which one needs to consider ...

  7. A sequential hypothesis test based on a generalized Azuma inequality

    NARCIS (Netherlands)

    Reijsbergen, D.P.; Scheinhardt, Willem R.W.; de Boer, Pieter-Tjerk

    We present a new power-one sequential hypothesis test based on a bound for the probability that a bounded zero-mean martingale ever crosses a curve of the form $a(n+k)^b$. The proof of the bound is of independent interest.

  8. Random Effects Structure for Confirmatory Hypothesis Testing: Keep It Maximal

    Science.gov (United States)

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.

    2013-01-01

    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the…

  9. Trust and health: testing the reverse causality hypothesis

    Science.gov (United States)

    Giordano, Giuseppe Nicola; Lindström, Martin

    2016-01-01

    Background Social capital research has consistently shown positive associations between generalised trust and health outcomes over 2 decades. Longitudinal studies attempting to test causal relationships further support the theory that trust is an independent predictor of health. However, as the reverse causality hypothesis has yet to be empirically tested, a knowledge gap remains. The aim of this study, therefore, was to investigate if health status predicts trust. Methods Data employed in this study came from 4 waves of the British Household Panel Survey between years 2000 and 2007 (N=8114). The sample was stratified by baseline trust to investigate temporal relationships between prior self-rated health (SRH) and changes in trust. We used logistic regression models with random effects, as trust was expected to be more similar within the same individuals over time. Results From the ‘Can trust at baseline’ cohort, poor SRH at time (t−1) predicted low trust at time (t) (OR=1.38). Likewise, good health predicted high trust within the ‘Cannot’ trust cohort (OR=1.30). These patterns of positive association remained after robustness checks, which adjusted for misclassification of outcome (trust) status and the existence of other temporal pathways. Conclusions This study offers empirical evidence to support the circular nature of trust/health relationship. The stability of association between prior health status and changes in trust over time differed between cohorts, hinting at the existence of complex pathways rather than a simple positive feedback loop. PMID:26546287

  10. Sensory discrimination and intelligence: testing Spearman's other hypothesis.

    Science.gov (United States)

    Deary, Ian J; Bell, P Joseph; Bell, Andrew J; Campbell, Mary L; Fazal, Nicola D

    2004-01-01

    At the centenary of Spearman's seminal 1904 article, his general intelligence hypothesis remains one of the most influential in psychology. Less well known is the article's other hypothesis that there is "a correspondence between what may provisionally be called 'General Discrimination' and 'General Intelligence' which works out with great approximation to one or absoluteness" (Spearman, 1904, p. 284). Studies that do not find high correlations between psychometric intelligence and single sensory discrimination tests do not falsify this hypothesis. This study is the first directly to address Spearman's general intelligence-general sensory discrimination hypothesis. It attempts to replicate his findings with a similar sample of schoolchildren. In a well-fitting structural equation model of the data, general intelligence and general discrimination correlated .92. In a reanalysis of data published byActon and Schroeder (2001), general intelligence and general sensory ability correlated .68 in men and women. One hundred years after its conception, Spearman's other hypothesis achieves some confirmation. The association between general intelligence and general sensory ability remains to be replicated and explained.

  11. Testing Van Gool’s Hypothesis: A Method to Predict Side Effects of Cholinesterase Inhibitors in Patients with Cellular Degenerative and Vascular Dementia

    Directory of Open Access Journals (Sweden)

    Liza van Eijk

    2015-01-01

    Full Text Available This study investigates a method to predict medical outcome of cholinesterase inhibitors in patients with Alzheimer’s disease (AD and vascular dementia (VaD. Van Gool predicts that patients with cholinergic deficit symptoms will benefit from treatment whereas patients without will experience side effects because of overstimulation of the cholinergic system. We predicted that AD and VaD patients with a longer RT experience fewer side effects than patients with a faster response and that VaD patients have a longer RT than AD patients. A number of 71 patients with AD or VaD diagnosis were included. A sustained attention task was administered, as well as the MMSE and a questionnaire about side effects. Results indicated that VaD patients with a longer RT reported fewer side effects. Furthermore, patients with VaD had a longer RT than patients with AD. MMSE was negatively correlated with RT in the VaD group. Thus, the performance on the attention task seems associated with suffering from side effects and thus tends to predict medical outcome in VaD, but not in AD. Perhaps this attention task was not sensitive enough to measure cholinergic deficit symptoms in AD patients. Furthermore, different doses of medication might confound the effect for the AD group.

  12. Hypothesis testing in students: Sequences, stages, and instructional strategies

    Science.gov (United States)

    Moshman, David; Thompson, Pat A.

    Six sequences in the development of hypothesis-testing conceptions are proposed, involving (a) interpretation of the hypothesis; (b) the distinction between using theories and testing theories; (c) the consideration of multiple possibilities; (d) the relation of theory and data; (e) the nature of verification and falsification; and (f) the relation of truth and falsity. An alternative account is then provided involving three global stages: concrete operations, formal operations, and a postformal metaconstructivestage. Relative advantages and difficulties of the stage and sequence conceptualizations are discussed. Finally, three families of teaching strategy are distinguished, which emphasize, respectively: (a) social transmission of knowledge; (b) carefully sequenced empirical experience by the student; and (c) self-regulated cognitive activity of the student. It is argued on the basis of Piaget's theory that the last of these plays a crucial role in the construction of such logical reasoning strategies as those involved in testing hypotheses.

  13. Mechanisms of eyewitness suggestibility: tests of the explanatory role hypothesis.

    Science.gov (United States)

    Rindal, Eric J; Chrobak, Quin M; Zaragoza, Maria S; Weihing, Caitlin A

    2017-10-01

    In a recent paper, Chrobak and Zaragoza (Journal of Experimental Psychology: General, 142(3), 827-844, 2013) proposed the explanatory role hypothesis, which posits that the likelihood of developing false memories for post-event suggestions is a function of the explanatory function the suggestion serves. In support of this hypothesis, they provided evidence that participant-witnesses were especially likely to develop false memories for their forced fabrications when their fabrications helped to explain outcomes they had witnessed. In three experiments, we test the generality of the explanatory role hypothesis as a mechanism of eyewitness suggestibility by assessing whether this hypothesis can predict suggestibility errors in (a) situations where the post-event suggestions are provided by the experimenter (as opposed to fabricated by the participant), and (b) across a variety of memory measures and measures of recollective experience. In support of the explanatory role hypothesis, participants were more likely to subsequently freely report (E1) and recollect the suggestions as part of the witnessed event (E2, source test) when the post-event suggestion helped to provide a causal explanation for a witnessed outcome than when it did not serve this explanatory role. Participants were also less likely to recollect the suggestions as part of the witnessed event (on measures of subjective experience) when their explanatory strength had been reduced by the presence of an alternative explanation that could explain the same outcome (E3, source test + warning). Collectively, the results provide strong evidence that the search for explanatory coherence influences people's tendency to misremember witnessing events that were only suggested to them.

  14. A review of multiple hypothesis testing in otolaryngology literature.

    Science.gov (United States)

    Kirkham, Erin M; Weaver, Edward M

    2015-03-01

    Multiple hypothesis testing (or multiple testing) refers to testing more than one hypothesis within a single analysis, and can inflate the type I error rate (false positives) within a study. The aim of this review was to quantify multiple testing in recent large clinical studies in the otolaryngology literature and to discuss strategies to address this potential problem. Original clinical research articles with >100 subjects published in 2012 in the four general otolaryngology journals with the highest Journal Citation Reports 5-year impact factors. Articles were reviewed to determine whether the authors tested greater than five hypotheses in at least one family of inferences. For the articles meeting this criterion for multiple testing, type I error rates were calculated, and statistical correction was applied to the reported results. Of the 195 original clinical research articles reviewed, 72% met the criterion for multiple testing. Within these studies, there was a mean 41% chance of a type I error and, on average, 18% of significant results were likely to be false positives. After the Bonferroni correction was applied, only 57% of significant results reported within the articles remained significant. Multiple testing is common in recent large clinical studies in otolaryngology and deserves closer attention from researchers, reviewers, and editors. Strategies for adjusting for multiple testing are discussed. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

  15. The non-existence in Bayesianism of alternative-free hypothesis tests is not a shortcoming

    Science.gov (United States)

    Garrett, Anthony J. M.

    2013-08-01

    Bayesian methods of hypothesis testing are comparative, and require hypotheses to be tested against each other with their probabilities summing to unity. In contrast the non-Bayesian literature contains tests for rejecting a hypothesis in isolation. Based on experimental data, intuition is also capable of rejecting (or accepting) a hypothesis in the absence of an alternative. Do non-Bayesian methods therefore encapsulate a principle of reasoning that is missing from Bayesian techniques? No: in such situations, data that spectacularly misfit a theory inspire a new hypothesis (often a generalisation of the old) that is more consistent with the data, and neither Bayesian nor non-Bayesian methods contain any principle for doing that. Alternative-free tests are inequivalent to Bayes' theorem, which has unique grounding in rationality. Such tests are therefore liable to mislead; this is demonstrated by example. A freshly inspired hypothesis should always be tested against the original in a Bayesian comparison. If the new hypothesis is a generalisation of the old, this involves the Bayesian `Ockham analysis'.

  16. Planned Hypothesis Tests Are Not Necessarily Exempt From Multiplicity Adjustment

    Directory of Open Access Journals (Sweden)

    Andrew V. Frane

    2015-10-01

    Full Text Available Scientific research often involves testing more than one hypothesis at a time, which can inflate the probability that a Type I error (false discovery will occur. To prevent this Type I error inflation, adjustments can be made to the testing procedure that compensate for the number of tests. Yet many researchers believe that such adjustments are inherently unnecessary if the tests were “planned” (i.e., if the hypotheses were specified before the study began. This longstanding misconception continues to be perpetuated in textbooks and continues to be cited in journal articles to justify disregard for Type I error inflation. I critically evaluate this myth and examine its rationales and variations. To emphasize the myth’s prevalence and relevance in current research practice, I provide examples from popular textbooks and from recent literature. I also make recommendations for improving research practice and pedagogy regarding this problem and regarding multiple testing in general.

  17. Why is muscularity sexy? Tests of the fitness indicator hypothesis.

    Science.gov (United States)

    Frederick, David A; Haselton, Martie G

    2007-08-01

    Evolutionary scientists propose that exaggerated secondary sexual characteristics are cues of genes that increase offspring viability or reproductive success. In six studies the hypothesis that muscularity is one such cue is tested. As predicted, women rate muscular men as sexier, more physically dominant and volatile, and less committed to their mates than nonmuscular men. Consistent with the inverted-U hypothesis of masculine traits, men with moderate muscularity are rated most attractive. Consistent with past research on fitness cues, across two measures, women indicate that their most recent short-term sex partners were more muscular than their other sex partners (ds = .36, .47). Across three studies, when controlling for other characteristics (e.g., body fat), muscular men rate their bodies as sexier to women (partial rs = .49-.62) and report more lifetime sex partners (partial rs = .20-.27), short-term partners (partial rs = .25-.28), and more affairs with mated women (partial r = .28).

  18. Reliability Evaluation of Concentric Butterfly Valve Using Statistical Hypothesis Test

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Mu Seong; Choi, Jong Sik; Choi, Byung Oh; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2015-12-15

    A butterfly valve is a type of flow-control device typically used to regulate a fluid flow. This paper presents an estimation of the shape parameter of the Weibull distribution, characteristic life, and B10 life for a concentric butterfly valve based on a statistical analysis of the reliability test data taken before and after the valve improvement. The difference in the shape and scale parameters between the existing and improved valves is reviewed using a statistical hypothesis test. The test results indicate that the shape parameter of the improved valve is similar to that of the existing valve, and that the scale parameter of the improved valve is found to have increased. These analysis results are particularly useful for a reliability qualification test and the determination of the service life cycles.

  19. A test of the substitution-habitat hypothesis in amphibians.

    Science.gov (United States)

    Martínez-Abraín, Alejandro; Galán, Pedro

    2017-12-08

    Most examples that support the substitution-habitat hypothesis (human-made habitats act as substitutes of original habitat) deal with birds and mammals. We tested this hypothesis in 14 amphibians by using percentage occupancy as a proxy of habitat quality (i.e., higher occupancy percentages indicate higher quality). We classified water body types as original habitat (no or little human influence) depending on anatomical, behavioral, or physiological adaptations of each amphibian species. Ten species had relatively high probabilities (0.16-0.28) of occurrence in original habitat, moderate probability of occurrence in substitution habitats (0.11-0.14), and low probability of occurrence in refuge habitats (0.05-0.08). Thus, the substitution-habitat hypothesis only partially applies to amphibians because the low occupancy of refuges could be due to the negligible human persecution of this group (indicating good conservation status). However, low occupancy of refuges could also be due to low tolerance of refuge conditions, which could have led to selective extinction or colonization problems due to poor dispersal capabilities. That original habitats had the highest probabilities of occupancy suggests amphibians have a good conservation status in the region. They also appeared highly adaptable to anthropogenic substitution habitats. © 2017 Society for Conservation Biology.

  20. The efficient market hypothesis: problems with interpretations of empirical tests

    Directory of Open Access Journals (Sweden)

    Denis Alajbeg

    2012-03-01

    Full Text Available Despite many “refutations” in empirical tests, the efficient market hypothesis (EMH remains the central concept of financial economics. The EMH’s resistance to the results of empirical testing emerges from the fact that the EMH is not a falsifiable theory. Its axiomatic definition shows how asset prices would behave under assumed conditions. Testing for this price behavior does not make much sense as the conditions in the financial markets are much more complex than the simplified conditions of perfect competition, zero transaction costs and free information used in the formulation of the EMH. Some recent developments within the tradition of the adaptive market hypothesis are promising regarding development of a falsifiable theory of price formation in financial markets, but are far from giving assurance that we are approaching a new formulation. The most that can be done in the meantime is to be very cautious while interpreting the empirical evidence that is presented as “testing” the EMH.

  1. Semantically enabled and statistically supported biological hypothesis testing with tissue microarray databases

    Science.gov (United States)

    2011-01-01

    Background Although many biological databases are applying semantic web technologies, meaningful biological hypothesis testing cannot be easily achieved. Database-driven high throughput genomic hypothesis testing requires both of the capabilities of obtaining semantically relevant experimental data and of performing relevant statistical testing for the retrieved data. Tissue Microarray (TMA) data are semantically rich and contains many biologically important hypotheses waiting for high throughput conclusions. Methods An application-specific ontology was developed for managing TMA and DNA microarray databases by semantic web technologies. Data were represented as Resource Description Framework (RDF) according to the framework of the ontology. Applications for hypothesis testing (Xperanto-RDF) for TMA data were designed and implemented by (1) formulating the syntactic and semantic structures of the hypotheses derived from TMA experiments, (2) formulating SPARQLs to reflect the semantic structures of the hypotheses, and (3) performing statistical test with the result sets returned by the SPARQLs. Results When a user designs a hypothesis in Xperanto-RDF and submits it, the hypothesis can be tested against TMA experimental data stored in Xperanto-RDF. When we evaluated four previously validated hypotheses as an illustration, all the hypotheses were supported by Xperanto-RDF. Conclusions We demonstrated the utility of high throughput biological hypothesis testing. We believe that preliminary investigation before performing highly controlled experiment can be benefited. PMID:21342584

  2. Omnibus hypothesis testing in dominance-based ordinal multiple regression.

    Science.gov (United States)

    Long, Jeffrey D

    2005-09-01

    Often quantitative data in the social sciences have only ordinal justification. Problems of interpretation can arise when least squares multiple regression (LSMR) is used with ordinal data. Two ordinal alternatives are discussed, dominance-based ordinal multiple regression (DOMR) and proportional odds multiple regression. The Q2 statistic is introduced for testing the omnibus null hypothesis in DOMR. A simulation study is discussed that examines the actual Type I error rate and power of Q2 in comparison to the LSMR omnibus F test under normality and non-normality. Results suggest that Q2 has favorable sampling properties as long as the sample size-to-predictors ratio is not too small, and Q2 can be a good alternative to the omnibus F test when the response variable is non-normal. Copyright 2005 APA, all rights reserved.

  3. Sequential hypothesis testing with spatially correlated presence-absence data.

    Science.gov (United States)

    DePalma, Elijah; Jeske, Daniel R; Lara, Jesus R; Hoddle, Mark

    2012-06-01

    A pest management decision to initiate a control treatment depends upon an accurate estimate of mean pest density. Presence-absence sampling plans significantly reduce sampling efforts to make treatment decisions by using the proportion of infested leaves to estimate mean pest density in lieu of counting individual pests. The use of sequential hypothesis testing procedures can significantly reduce the number of samples required to make a treatment decision. Here we construct a mean-proportion relationship for Oligonychus perseae Tuttle, Baker, and Abatiello, a mite pest of avocados, from empirical data, and develop a sequential presence-absence sampling plan using Bartlett's sequential test procedure. Bartlett's test can accommodate pest population models that contain nuisance parameters that are not of primary interest. However, it requires that population measurements be independent, which may not be realistic because of spatial correlation of pest densities across trees within an orchard. We propose to mitigate the effect of spatial correlation in a sequential sampling procedure by using a tree-selection rule (i.e., maximin) that sequentially selects each newly sampled tree to be maximally spaced from all other previously sampled trees. Our proposed presence-absence sampling methodology applies Bartlett's test to a hypothesis test developed using an empirical mean-proportion relationship coupled with a spatial, statistical model of pest populations, with spatial correlation mitigated via the aforementioned tree-selection rule. We demonstrate the effectiveness of our proposed methodology over a range of parameter estimates appropriate for densities of O. perseae that would be observed in avocado orchards in California.

  4. Testing the modernization hypothesis and the socialist ideology hypothesis : a comparative sibling analysis of educational attainment and occupational status

    NARCIS (Netherlands)

    Sieben, Inge; Graaf, Paul M. de

    2001-01-01

    In this study, we present a comparative sibling analysis. This enables us to test two major social mobility hypotheses, i.e. the modernization hypothesis and the socialist ideology hypothesis. We employ survey data on brothers in England, Hungary, the Netherlands, Scotland, Spain, and the USA,

  5. A tutorial on a practical Bayesian alternative to null-hypothesis significance testing.

    Science.gov (United States)

    Masson, Michael E J

    2011-09-01

    Null-hypothesis significance testing remains the standard inferential tool in cognitive science despite its serious disadvantages. Primary among these is the fact that the resulting probability value does not tell the researcher what he or she usually wants to know: How probable is a hypothesis, given the obtained data? Inspired by developments presented by Wagenmakers (Psychonomic Bulletin & Review, 14, 779-804, 2007), I provide a tutorial on a Bayesian model selection approach that requires only a simple transformation of sum-of-squares values generated by the standard analysis of variance. This approach generates a graded level of evidence regarding which model (e.g., effect absent [null hypothesis] vs. effect present [alternative hypothesis]) is more strongly supported by the data. This method also obviates admonitions never to speak of accepting the null hypothesis. An Excel worksheet for computing the Bayesian analysis is provided as supplemental material.

  6. Testing the white matter retrogenesis hypothesis of cognitive aging.

    Science.gov (United States)

    Brickman, Adam M; Meier, Irene B; Korgaonkar, Mayuresh S; Provenzano, Frank A; Grieve, Stuart M; Siedlecki, Karen L; Wasserman, Ben T; Williams, Leanne M; Zimmerman, Molly E

    2012-08-01

    The retrogenesis hypothesis postulates that late-myelinated white matter fibers are most vulnerable to age- and disease-related degeneration, which in turn mediate cognitive decline. While recent evidence supports this hypothesis in the context of Alzheimer's disease, it has not been tested systematically in normal cognitive aging. In the current study, we examined the retrogenesis hypothesis in a group (n = 282) of cognitively normal individuals, ranging in age from 7 to 87 years, from the Brain Resource International Database. Participants were evaluated with a comprehensive neuropsychological battery and were imaged with diffusion tensor imaging. Fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (DA), measures of white matter coherence, were computed in 2 prototypical early-myelinated fiber tracts (posterior limb of the internal capsule, cerebral peduncles) and 2 prototypical late-myelinated fiber tracts (superior longitudinal fasciculus, inferior longitudinal fasciculus) chosen to parallel previous studies; mean summary values were also computed for other early- and late-myelinated fiber tracts. We examined age-associated differences in FA, RD, and DA in the developmental trajectory (ages 7-30 years) and degenerative trajectory (ages 31-87 years), and tested whether the measures of white matter coherence mediated age-related cognitive decline in the older group. FA and DA values were greater for early-myelinated fibers than for late-myelinated fibers, and RD values were lower for early-myelinated than late-myelinated fibers. There were age-associated differences in FA, RD, and DA across early- and late-myelinated fiber tracts in the younger group, but the magnitude of differences did not vary as a function of early or late myelinating status. FA and RD in most fiber tracts showed reliable age-associated differences in the older age group, but the magnitudes were greatest for the late-myelinated tract summary measure, inferior

  7. An algorithm for testing the efficient market hypothesis.

    Science.gov (United States)

    Boboc, Ioana-Andreea; Dinică, Mihai-Cristian

    2013-01-01

    The objective of this research is to examine the efficiency of EUR/USD market through the application of a trading system. The system uses a genetic algorithm based on technical analysis indicators such as Exponential Moving Average (EMA), Moving Average Convergence Divergence (MACD), Relative Strength Index (RSI) and Filter that gives buying and selling recommendations to investors. The algorithm optimizes the strategies by dynamically searching for parameters that improve profitability in the training period. The best sets of rules are then applied on the testing period. The results show inconsistency in finding a set of trading rules that performs well in both periods. Strategies that achieve very good returns in the training period show difficulty in returning positive results in the testing period, this being consistent with the efficient market hypothesis (EMH).

  8. An algorithm for testing the efficient market hypothesis.

    Directory of Open Access Journals (Sweden)

    Ioana-Andreea Boboc

    Full Text Available The objective of this research is to examine the efficiency of EUR/USD market through the application of a trading system. The system uses a genetic algorithm based on technical analysis indicators such as Exponential Moving Average (EMA, Moving Average Convergence Divergence (MACD, Relative Strength Index (RSI and Filter that gives buying and selling recommendations to investors. The algorithm optimizes the strategies by dynamically searching for parameters that improve profitability in the training period. The best sets of rules are then applied on the testing period. The results show inconsistency in finding a set of trading rules that performs well in both periods. Strategies that achieve very good returns in the training period show difficulty in returning positive results in the testing period, this being consistent with the efficient market hypothesis (EMH.

  9. Testing for Marshall-Lerner hypothesis: A panel approach

    Science.gov (United States)

    Azizan, Nur Najwa; Sek, Siok Kun

    2014-12-01

    The relationship between real exchange rate and trade balances are documented in many theories. One of the theories is the so-called Marshall-Lerner condition. In this study, we seek to test for the validity of Marshall-Lerner hypothesis, i.e. to reveal if the depreciation of real exchange rate leads to the improvement in trade balances. We focus our study in ASEAN-5 countries and their main trade partners of U.S., Japan and China. The dynamic panel data of pooled mean group (PMG) approach is used to detect the Marshall-Lerner hypothesis among ASEAN-5, between ASEAN-5 and U.S., between ASEAN-5 and Japan and between ASEAN-5 and China respectively. The estimation is based on the autoregressive Distributed Lag or ARDL model for the period of 1970-2012. The paper concludes that Marshal Lerner theory does not hold in bilateral trades in four groups of countries. The trade balances of ASEAN5 are mainly determined by the domestic income level and foreign production cost.

  10. Immigration, political trust, and Brexit - Testing an aversion amplification hypothesis.

    Science.gov (United States)

    Abrams, Dominic; Travaglino, Giovanni A

    2018-01-10

    A few weeks prior to the EU referendum (23rd June 2016) two broadly representative samples of the electorate were drawn in Kent (the south-east of England, N = 1,001) and Scotland (N = 1,088) for online surveys that measured their trust in politicians, concerns about acceptable levels of immigration, threat from immigration, European identification, and voting intention. We tested an aversion amplification hypothesis that the impact of immigration concerns on threat and identification would be amplified when political trust was low. We hypothesized that the effect of aversion amplification on voting intentions would be mediated first by perceived threat from immigration, and then by (dis) identification with Europe. Results in both samples were consistent with this hypothesis and suggest that voters were most likely to reject the political status quo (choose Brexit) when concerns that immigration levels were too high were combined with a low level of trust in politicians. © 2018 The Authors. British Journal of Social Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

  11. Testing the depth-differentiation hypothesis in a deepwater octocoral

    Science.gov (United States)

    Quattrini, Andrea; Baums, Iliana B.; Shank, Timothy M.; Morrison, Cheryl L.; Cordes, Erik E.

    2015-01-01

    The depth-differentiation hypothesis proposes that the bathyal region is a source of genetic diversity and an area where there is a high rate of species formation. Genetic differentiation should thus occur over relatively small vertical distances, particularly along the upper continental slope (200–1000 m) where oceanography varies greatly over small differences in depth. To test whether genetic differentiation within deepwater octocorals is greater over vertical rather than geographical distances, Callogorgia delta was targeted. This species commonly occurs throughout the northern Gulf of Mexico at depths ranging from 400 to 900 m. We found significant genetic differentiation (FST = 0.042) across seven sites spanning 400 km of distance and 400 m of depth. A pattern of isolation by depth emerged, but geographical distance between sites may further limit gene flow. Water mass boundaries may serve to isolate populations across depth; however, adaptive divergence with depth is also a possible scenario. Microsatellite markers also revealed significant genetic differentiation (FST = 0.434) between C. delta and a closely related species, Callogorgia americana, demonstrating the utility of microsatellites in species delimitation of octocorals. Results provided support for the depth-differentiation hypothesis, strengthening the notion that factors covarying with depth serve as isolation mechanisms in deep-sea populations.

  12. Testing the implicit processing hypothesis of precognitive dream experience.

    Science.gov (United States)

    Valášek, Milan; Watt, Caroline; Hutton, Jenny; Neill, Rebecca; Nuttall, Rachel; Renwick, Grace

    2014-08-01

    Seemingly precognitive (prophetic) dreams may be a result of one's unconscious processing of environmental cues and having an implicit inference based on these cues manifest itself in one's dreams. We present two studies exploring this implicit processing hypothesis of precognitive dream experience. Study 1 investigated the relationship between implicit learning, transliminality, and precognitive dream belief and experience. Participants completed the Serial Reaction Time task and several questionnaires. We predicted a positive relationship between the variables. With the exception of relationships between transliminality and precognitive dream belief and experience, this prediction was not supported. Study 2 tested the hypothesis that differences in the ability to notice subtle cues explicitly might account for precognitive dream beliefs and experiences. Participants completed a modified version of the flicker paradigm. We predicted a negative relationship between the ability to explicitly detect changes and precognitive dream variables. This relationship was not found. There was also no relationship between precognitive dream belief and experience and implicit change detection. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. A direct communication proposal to test the Zoo Hypothesis

    CERN Document Server

    de Magalhaes, Joao Pedro

    2015-01-01

    Whether we are alone in the universe is one of the greatest mysteries facing humankind. Given the >100 billion stars in our galaxy, many have argued that it is statistically unlikely that life, including intelligent life, has not emerged anywhere else. The lack of any sign of extraterrestrial intelligence, even though on a cosmic timescale extraterrestrial civilizations would have enough time to cross the galaxy, is known as Fermi's Paradox. One possible explanation for Fermi's Paradox is the Zoo Hypothesis which states that one or more extraterrestrial civilizations know of our existence and can reach us, but have chosen not to disturb us or even make their existence known to us. I propose here a proactive test of the Zoo Hypothesis. Specifically, I propose to send a message using television and radio channels to any extraterrestrial civilization(s) that might be listening and inviting them to respond. Even though I accept this is unlikely to be successful in the sense of resulting in a response from extrate...

  14. Persistent Confusions about Hypothesis Testing in the Social Sciences

    Directory of Open Access Journals (Sweden)

    Christopher Thron

    2015-05-01

    Full Text Available This paper analyzes common confusions involving basic concepts in statistical hypothesis testing. One-third of the social science statistics textbooks examined in the study contained false statements about significance level and/or p-value. We infer that a large proportion of social scientists are being miseducated about these concepts. We analyze the causes of these persistent misunderstandings, and conclude that the conventional terminology is prone to abuse because it does not clearly represent the conditional nature of probabilities and events involved. We argue that modifications in terminology, as well as the explicit introduction of conditional probability concepts and notation into the statistics curriculum in the social sciences, are necessary to prevent the persistence of these errors.

  15. Graphic tests of Easterlin's hypothesis: science or art?

    Science.gov (United States)

    Rutten, A; Higgs, R

    1984-01-01

    Richard Easterlin believes that the postwar fertility cycle is uniquely consistent with the hypothesis of his relative income model of fertility, yet a closer examination of his evidence shows that the case for the relative income explanation is much weaker than initially appears. Easterlin finds the postwar baby boom a transparent event. Couples who entered the labor market in the postwar period have very low material aspirations. Having grown up during the Great Depression and World War II, they were content with a modest level of living. Their labor market experience was very good. Tight restrictions on immigration kept aliens from coming in to fill the gap. Thus the members of his generation occupied an unprecedented position. They could easily meet and even exceed their expectations. This high level of relative income meant that they could have more of everything they wanted, including children. For the children born during the baby boom, all this was reversed, and hence the needs of the baby bust were sown. To test this hypothesis, Easterlin compared the movements of relative income and fertility over the postwar years using a graph. 4 published versions of the graph are presented. The graph shows that relative income and fertility did move together over the cycle, apparently very closely. Easterlin's measure of fertility is the total fertility rate (TFR). There is no such direct measure of relative income. Easterlin develops 2 proxies based on changing economic conditions believed to shape the level of material aspirations. His preferred measure, labeled R or income in his graph, relates the income experience of young couples in the years previous to marriage to that of their parents in the years before the young people left home. Because of the available data limit construction of this index to the years after 1956, another measure, labeled Re or employment in Easterlin's graphs, is constructed for the pre-1956 period. This measure relates the average of

  16. Concerns regarding a call for pluralism of information theory and hypothesis testing

    Science.gov (United States)

    Lukacs, P.M.; Thompson, W.L.; Kendall, W.L.; Gould, W.R.; Doherty, P.F.; Burnham, K.P.; Anderson, D.R.

    2007-01-01

    1. Stephens et al . (2005) argue for `pluralism? in statistical analysis, combining null hypothesis testing and information-theoretic (I-T) methods. We show that I-T methods are more informative even in single variable problems and we provide an ecological example. 2. I-T methods allow inferences to be made from multiple models simultaneously. We believe multimodel inference is the future of data analysis, which cannot be achieved with null hypothesis-testing approaches. 3. We argue for a stronger emphasis on critical thinking in science in general and less reliance on exploratory data analysis and data dredging. Deriving alternative hypotheses is central to science; deriving a single interesting science hypothesis and then comparing it to a default null hypothesis (e.g. `no difference?) is not an efficient strategy for gaining knowledge. We think this single-hypothesis strategy has been relied upon too often in the past. 4. We clarify misconceptions presented by Stephens et al . (2005). 5. We think inference should be made about models, directly linked to scientific hypotheses, and their parameters conditioned on data, Prob(Hj| data). I-T methods provide a basis for this inference. Null hypothesis testing merely provides a probability statement about the data conditioned on a null model, Prob(data |H0). 6. Synthesis and applications. I-T methods provide a more informative approach to inference. I-T methods provide a direct measure of evidence for or against hypotheses and a means to consider simultaneously multiple hypotheses as a basis for rigorous inference. Progress in our science can be accelerated if modern methods can be used intelligently; this includes various I-T and Bayesian methods.

  17. Introduction to Permutation and Resampling-Based Hypothesis Tests

    Science.gov (United States)

    LaFleur, Bonnie J.; Greevy, Robert A.

    2009-01-01

    A resampling-based method of inference--permutation tests--is often used when distributional assumptions are questionable or unmet. Not only are these methods useful for obvious departures from parametric assumptions (e.g., normality) and small sample sizes, but they are also more robust than their parametric counterparts in the presences of…

  18. Confusion and clairvoyance: some remarks on the composite hypothesis testing problem

    Science.gov (United States)

    Theiler, James

    2012-06-01

    This paper discusses issues related to the inherent ambiguity of the composite hypothesis testing problem, a problem that is central to the detection of target signals in cluttered backgrounds. In particular, the paper examines the recently proposed method of continuum fusion (which, because it combines an ensemble of clairvoyant detectors, might also be called clairvoyant fusion), and its relationship to other strategies for composite hypothesis testing. A specific example involving the affine subspace model adds to the confusion by illustrating irreconcilable differences between Bayesian and non-Bayesian approaches to target detection.

  19. Mothers Who Kill Their Offspring: Testing Evolutionary Hypothesis in a 110-Case Italian Sample

    Science.gov (United States)

    Camperio Ciani, Andrea S.; Fontanesi, Lilybeth

    2012-01-01

    Objectives: This research aimed to identify incidents of mothers in Italy killing their own children and to test an adaptive evolutionary hypothesis to explain their occurrence. Methods: 110 cases of mothers killing 123 of their own offspring from 1976 to 2010 were analyzed. Each case was classified using 13 dichotomic variables. Descriptive…

  20. When Null Hypothesis Significance Testing Is Unsuitable for Research: A Reassessment

    Science.gov (United States)

    Szucs, Denes; Ioannidis, John P. A.

    2017-01-01

    Null hypothesis significance testing (NHST) has several shortcomings that are likely contributing factors behind the widely debated replication crisis of (cognitive) neuroscience, psychology, and biomedical science in general. We review these shortcomings and suggest that, after sustained negative experience, NHST should no longer be the default, dominant statistical practice of all biomedical and psychological research. If theoretical predictions are weak we should not rely on all or nothing hypothesis tests. Different inferential methods may be most suitable for different types of research questions. Whenever researchers use NHST they should justify its use, and publish pre-study power calculations and effect sizes, including negative findings. Hypothesis-testing studies should be pre-registered and optimally raw data published. The current statistics lite educational approach for students that has sustained the widespread, spurious use of NHST should be phased out. PMID:28824397

  1. When Null Hypothesis Significance Testing Is Unsuitable for Research: A Reassessment.

    Science.gov (United States)

    Szucs, Denes; Ioannidis, John P A

    2017-01-01

    Null hypothesis significance testing (NHST) has several shortcomings that are likely contributing factors behind the widely debated replication crisis of (cognitive) neuroscience, psychology, and biomedical science in general. We review these shortcomings and suggest that, after sustained negative experience, NHST should no longer be the default, dominant statistical practice of all biomedical and psychological research. If theoretical predictions are weak we should not rely on all or nothing hypothesis tests. Different inferential methods may be most suitable for different types of research questions. Whenever researchers use NHST they should justify its use, and publish pre-study power calculations and effect sizes, including negative findings. Hypothesis-testing studies should be pre-registered and optimally raw data published. The current statistics lite educational approach for students that has sustained the widespread, spurious use of NHST should be phased out.

  2. A Blind Test of the Younger Dryas Impact Hypothesis.

    Science.gov (United States)

    Holliday, Vance; Surovell, Todd; Johnson, Eileen

    2016-01-01

    The Younger Dryas Impact Hypothesis (YDIH) states that North America was devastated by some sort of extraterrestrial event ~12,800 calendar years before present. Two fundamental questions persist in the debate over the YDIH: Can the results of analyses for purported impact indicators be reproduced? And are the indicators unique to the lower YD boundary (YDB), i.e., ~12.8k cal yrs BP? A test reported here presents the results of analyses that address these questions. Two different labs analyzed identical splits of samples collected at, above, and below the ~12.8ka zone at the Lubbock Lake archaeological site (LL) in northwest Texas. Both labs reported similar variation in levels of magnetic micrograins (>300 mg/kg >12.8ka and <11.5ka, but <150 mg/kg 12.8ka to 11.5ka). Analysis for magnetic microspheres in one split, reported elsewhere, produced very low to nonexistent levels throughout the section. In the other split, reported here, the levels of magnetic microspherules and nanodiamonds are low or nonexistent at, below, and above the YDB with the notable exception of a sample <11,500 cal years old. In that sample the claimed impact proxies were recovered at abundances two to four orders of magnitude above that from the other samples. Reproducibility of at least some analyses are problematic. In particular, no standard criteria exist for identification of magnetic spheres. Moreover, the purported impact proxies are not unique to the YDB.

  3. Statistical sampling and hypothesis testing in orthopaedic research.

    Science.gov (United States)

    Bernstein, Joseph; McGuire, Kevin; Freedman, Kevin B

    2003-08-01

    The purpose of the current article was to review the process of hypothesis testing and statistical sampling and empower readers to critically appraise the literature. When the p value of a study lies above the alpha threshold, the results are said to be not statistically significant. It is possible, however, that real differences do exist, but the study was insufficiently powerful to detect them. In that case, the conclusion that two groups are equivalent is wrong. The probability of this mistake, the Type II error, is given by the beta statistic. The complement of beta, or 1-beta, representing the chance of avoiding a Type II error, is termed the statistical power of the study. We previously examined the statistical power and sample size in all of the studies published in 1997 in the American and British volumes of the Journal of Bone and Joint Surgery, and in Clinical Orthopaedics and Related Research. In the journals examined, only 3% of studies had adequate statistical power to detect a small effect size in this sample. In addition, a study examining only randomized control trials in these journals showed that none of 25 randomized control trials had adequate statistical power to detect a small effect size. However, beta, or power, is less well understood. Because of this, researchers and readers should be aware of the need to address issues of statistical power before a study begins and be cautious of studies that conclude that no difference exists between groups.

  4. A Blind Test of the Younger Dryas Impact Hypothesis.

    Directory of Open Access Journals (Sweden)

    Vance Holliday

    Full Text Available The Younger Dryas Impact Hypothesis (YDIH states that North America was devastated by some sort of extraterrestrial event ~12,800 calendar years before present. Two fundamental questions persist in the debate over the YDIH: Can the results of analyses for purported impact indicators be reproduced? And are the indicators unique to the lower YD boundary (YDB, i.e., ~12.8k cal yrs BP? A test reported here presents the results of analyses that address these questions. Two different labs analyzed identical splits of samples collected at, above, and below the ~12.8ka zone at the Lubbock Lake archaeological site (LL in northwest Texas. Both labs reported similar variation in levels of magnetic micrograins (>300 mg/kg >12.8ka and <11.5ka, but <150 mg/kg 12.8ka to 11.5ka. Analysis for magnetic microspheres in one split, reported elsewhere, produced very low to nonexistent levels throughout the section. In the other split, reported here, the levels of magnetic microspherules and nanodiamonds are low or nonexistent at, below, and above the YDB with the notable exception of a sample <11,500 cal years old. In that sample the claimed impact proxies were recovered at abundances two to four orders of magnitude above that from the other samples. Reproducibility of at least some analyses are problematic. In particular, no standard criteria exist for identification of magnetic spheres. Moreover, the purported impact proxies are not unique to the YDB.

  5. Synthetic oxytocin and breastfeeding: reasons for testing an hypothesis.

    Science.gov (United States)

    Odent, M R

    2013-11-01

    Synthetic oxytocin is widely used in developed countries and in emerging countries as well. It is the most common medical intervention in childbirth. A great variety of side effects are plausible. There are in particular theoretical reasons to test the hypothesis that the increasing incidence of breastfeeding difficulties and the frequent earlier than desired cessation of breastfeeding are related to the use of synthetic oxytocin during labour. There have already been some studies that tend to support this hypothesis. Four hundred of the 7465 children born in 2006 at the Carlos Haya University Hospital (Malaga, Spain) were randomly selected. By interviewing the mothers, information about feeding type and duration was obtained in 2011 for 316 children. Among the 189 children who were born after labours induced or augmented with synthetic oxytocin, the odds ratio for bottle-feeding was 1.451 and the odds ratio for withdrawal at 3 months was 2.294. In addition, the Battelle Developmental Inventory was used to assess at age five 148 children (84 born with synthetic oxytocin): the odds ratio for neuropsychological development disorders after use of oxytocin was 1.46. The main limitation of such a preliminary study is that in the context of a tertiary Spanish hospital the possible effects of synthetic oxytocin on the quality and duration of breastfeeding cannot be easily dissociated from the effects of other components of pharmacological assistance during labour, particularly epidural fentanyl (a synthetic opioid analgesic). This comment is valid for all studies exploring the side effects of synthetic oxytocin in obstetric units of developed countries, including explorations through videotapes of the effects of synthetic oxytocin on primitive neonatal reflexes. It is also valid for studies exploring the side effects of obstetric analgesia without taking into account the use of synthetic oxytocin. This is why we underline the importance of conducting such studies in

  6. Are drifting FADs essential for testing the ecological trap hypothesis ?

    OpenAIRE

    Dagorn, Laurent; Holland, K. N.; Filmalter, J.

    2010-01-01

    Because tropical tunas are known to aggregate around floating objects, it has been suggested that the large number of drifting fish aggregating devices (FADS) built and deployed by purse seiners could act as an 'ecological trap'. This hypothesis states that these networks of drifting FADS could take fish to areas where they would not normally go or retain them in places that they would otherwise leave. Because the ecological trap hypothesis was first advanced for drifting FADs, some have argu...

  7. Cohabitation and Divorce in Canada: Testing the Selectivity Hypothesis.

    Science.gov (United States)

    Hall, David R.; Zhao, John Z.

    1995-01-01

    Investigated hypothesis that cohabitors are a select group in ways that predispose them to divorce. Found that premarital cohabitation was associated with a greater risk of divorce even after accounting for the effects of parental divorce, marital status of first spouse, age heterogamy, and the presence of stepchildren. (RJM)

  8. The Harm Done to Reproducibility by the Culture of Null Hypothesis Significance Testing.

    Science.gov (United States)

    Lash, Timothy L

    2017-09-15

    In the last few years, stakeholders in the scientific community have raised alarms about a perceived lack of reproducibility of scientific results. In reaction, guidelines for journals have been promulgated and grant applicants have been asked to address the rigor and reproducibility of their proposed projects. Neither solution addresses a primary culprit, which is the culture of null hypothesis significance testing that dominates statistical analysis and inference. In an innovative research enterprise, selection of results for further evaluation based on null hypothesis significance testing is doomed to yield a low proportion of reproducible results and a high proportion of effects that are initially overestimated. In addition, the culture of null hypothesis significance testing discourages quantitative adjustments to account for systematic errors and quantitative incorporation of prior information. These strategies would otherwise improve reproducibility and have not been previously proposed in the widely cited literature on this topic. Without discarding the culture of null hypothesis significance testing and implementing these alternative methods for statistical analysis and inference, all other strategies for improving reproducibility will yield marginal gains at best. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Test of the Brink-Axel Hypothesis for the Pygmy Dipole Resonance

    Science.gov (United States)

    Martin, D.; von Neumann-Cosel, P.; Tamii, A.; Aoi, N.; Bassauer, S.; Bertulani, C. A.; Carter, J.; Donaldson, L.; Fujita, H.; Fujita, Y.; Hashimoto, T.; Hatanaka, K.; Ito, T.; Krugmann, A.; Liu, B.; Maeda, Y.; Miki, K.; Neveling, R.; Pietralla, N.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Shima, T.; Yamamoto, T.; Zweidinger, M.

    2017-11-01

    The gamma strength function and level density of 1- states in 96Mo have been extracted from a high-resolution study of the (p → , p→ ' ) reaction at 295 MeV and extreme forward angles. By comparison with compound nucleus γ decay experiments, this allows a test of the generalized Brink-Axel hypothesis in the energy region of the pygmy dipole resonance. The Brink-Axel hypothesis is commonly assumed in astrophysical reaction network calculations and states that the gamma strength function in nuclei is independent of the structure of the initial and final state. The present results validate the Brink-Axel hypothesis for 96Mo and provide independent confirmation of the methods used to separate gamma strength function and level density in γ decay experiments.

  10. Harold Jeffreys’s default Bayes factor hypothesis tests : Explanation, extension, and application in psychology

    NARCIS (Netherlands)

    Ly, A.; Verhagen, J.; Wagenmakers, E.-J.

    Harold Jeffreys pioneered the development of default Bayes factor hypothesis tests for standard statistical problems. Using Jeffreys’s Bayes factor hypothesis tests, researchers can grade the decisiveness of the evidence that the data provide for a point null hypothesis H0H0 versus a composite

  11. Distortion tolerant image recognition receiver by use of a multiple-hypothesis method.

    Science.gov (United States)

    Kishk, Sherif; Javidi, Bahram

    2002-04-10

    A multiple-hypothesis method is used to detect a target or a reference signal in the presence of additive noise with unknown statistics. The receiver is designed to detect the target and to be tolerant of the variations in rotation and illumination of the target. A multiple-hypothesis test with unknown-noise parameters is used to locate the target position. The proposed method does not use any specific distortion-invariant-filtering technique, but it relies on a multiple-hypothesis approach. Maximum-likelihood estimates of the illumination constant and the unknown noise parameters are obtained. Computer simulations are presented to evaluate the performance of the receiver for various distorted noisy true-class targets with varying illumination and false-class objects.

  12. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    Energy Technology Data Exchange (ETDEWEB)

    Dumazert, Jonathan, E-mail: jonathan.dumazert@cea.fr [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Moline, Yoann; Sannié, Guillaume; Gameiro, Jordan; Normand, Stéphane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Méchin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 14050 Caen (France)

    2015-09-21

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude.

  13. Tests of the EKC Hypothesis using CO2 Panel Data

    OpenAIRE

    Jianping Shi

    2004-01-01

    Environmental Kuznets Curve depicts the long-term relationship between pollution and economic growth. It hypothesizes that during the initial stages of economic growth environmental quality will deteriorate, then, after reaching some turning point, it will improve as the economy grows. In the past decade, lots of empirical literature provided both supports and criticism to this hypothesis. However, as we know from econometrics, when data contain stochastic trends, the conclusions drawn from s...

  14. Colour vision in ADHD: Part 1 - Testing the retinal dopaminergic hypothesis

    OpenAIRE

    Kim, Soyeon; Al-Haj, Mohamed; Chen, Samantha; Fuller, Stuart; Jain, Umesh; Carrasco, Marisa; Tannock, Rosemary

    2014-01-01

    Objectives To test the retinal dopaminergic hypothesis, which posits deficient blue color perception in ADHD, resulting from hypofunctioning CNS and retinal dopamine, to which blue cones are exquisitely sensitive. Also, purported sex differences in red color perception were explored. Methods 30 young adults diagnosed with ADHD and 30 healthy young adults, matched on age and gender, performed a psychophysical task to measure blue and red color saturation and contrast discrimination ability. Vi...

  15. Hypothesis testing on the fractal structure of behavioral sequences: the Bayesian assessment of scaling methodology.

    Science.gov (United States)

    Moscoso del Prado Martín, Fermín

    2013-12-01

    I introduce the Bayesian assessment of scaling (BAS), a simple but powerful Bayesian hypothesis contrast methodology that can be used to test hypotheses on the scaling regime exhibited by a sequence of behavioral data. Rather than comparing parametric models, as typically done in previous approaches, the BAS offers a direct, nonparametric way to test whether a time series exhibits fractal scaling. The BAS provides a simpler and faster test than do previous methods, and the code for making the required computations is provided. The method also enables testing of finely specified hypotheses on the scaling indices, something that was not possible with the previously available methods. I then present 4 simulation studies showing that the BAS methodology outperforms the other methods used in the psychological literature. I conclude with a discussion of methodological issues on fractal analyses in experimental psychology. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  16. A further test of the inverted-U hypothesis relating achievement anxiety and academic test performance.

    Science.gov (United States)

    Munz, S C; Costello, C T; Korabik, K

    1975-01-01

    The assumption that the inverted-U hypothesis, which shows performance as a function of activation level, mediates the relationship between achievement anxiety and academic test performance was tested by comparing Achievement Anxiety Test scores of 75 male and female college students with a self-report measure of activation taken prior to a classroom examination. Results supported the predicted relationship between achievement anxiety reaction type and academic performance (rho less than .05), but only partially supported the inverted-U hypothesis posited to account for this relationship. Results were further interpreted as suggesting that examinees experience two general types of arousal in the testing situationōne type that enhances performance and one that impedes performance. Further implications of the results were discussed.

  17. Hypothesis tests for the detection of constant speed radiation moving sources

    Energy Technology Data Exchange (ETDEWEB)

    Dumazert, Jonathan; Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Sannie, Guillaume; Gameiro, Jordan; Normand, Stephane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 99 Gif-sur-Yvette, (France); Mechin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 4050 Caen, (France)

    2015-07-01

    Radiation Portal Monitors are deployed in linear network to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal to noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive background, and a vehicle source carrier under the same respectively high and low count rate radioactive background, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm, while guaranteeing the stability of its optimization parameter regardless of signal to noise ratio variations between 2 to 0.8. (authors)

  18. Testing the reproductive groundplan hypothesis in ants (Hymenoptera: Formicidae).

    Science.gov (United States)

    Pamminger, Tobias; Hughes, William O H

    2017-01-01

    The evolution of complex societies with obligate reproductive division of labor represents one of the major transitions in evolution. In such societies, functionally sterile individuals (workers) perform many of fitness-relevant behaviors including allomaternal ones, without getting any direct fitness benefits. The question of how such worker division of labor has evolved remains controversial. The reproductive groundplan hypothesis (RGPH) offers a powerful proximate explanation for this evolutionary leap. The RGPH argues that the conserved genetic and endocrinological networks regulating fitness-relevant behavior (e g. foraging and brood care) in their solitary ancestors have become decoupled from actual reproduction in the worker caste and now generate worker behavioral phenotypes. However, the empirical support for this hypothesis remains limited to a handful of species making its general validity uncertain. In this study, we combine data from the literature with targeted sampling of key species and apply phylogenetically controlled comparative analysis to investigate if the key prediction of the RGPH, namely an association between allomaternal behavior and an allomaternal physiological state holds in the largest and most species-rich clade of social insects, the ants. Our findings clearly support the RPGH as a general framework to understand the evolution of the worker caste and shed light on one of the major transition in evolutionary history. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  19. Parameter Estimation And Hypothesis Testing In A Two Epoch Dam ...

    African Journals Online (AJOL)

    Also computed along with the least square solution and statistical testing were the minimum detectable Bias (MDB) and the Bias to Noise Ratio (BNR). All tests and adjustments were carried out using MOVE 3 software along with the LEICA SKI Pro 2.1. From the results of the tests, only observation to Rover station RF 8 ...

  20. A phylogenetic test of the Red Queen Hypothesis: outcrossing and parasitism in the Nematode phylum.

    Science.gov (United States)

    Gibson, Amanda Kyle; Fuentes, Jesualdo Arturo

    2015-02-01

    Sexual outcrossing is costly relative to selfing and asexuality, yet it is ubiquitous in nature, a paradox that has long puzzled evolutionary biologists. The Red Queen Hypothesis argues that outcrossing is maintained by antagonistic interactions between host and parasites. Most tests of this hypothesis focus on the maintenance of outcrossing in hosts. The Red Queen makes an additional prediction that parasitic taxa are more likely to be outcrossing than their free-living relatives. We test this prediction in the diverse Nematode phylum using phylogenetic comparative methods to evaluate trait correlations. In support of the Red Queen, we demonstrate a significant correlation between parasitism and outcrossing in this clade. We find that this correlation is driven by animal parasites, for which outcrossing is significantly enriched relative to both free-living and plant parasitic taxa. Finally, we test hypotheses for the evolutionary history underlying the correlation of outcrossing and animal parasitism. Our results demonstrate that selfing and asexuality are significantly less likely to arise on parasitic lineages than on free-living ones. The findings of this study are consistent with the Red Queen Hypothesis. Moreover, they suggest that the maintenance of genetic variation is an important factor in the persistence of parasitic lineages. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  1. Hypothesis testing for evaluating a multimodal pattern recognition framework applied to speaker detection

    Directory of Open Access Journals (Sweden)

    Kunt Murat

    2008-03-01

    Full Text Available Abstract Background Speaker detection is an important component of many human-computer interaction applications, like for example, multimedia indexing, or ambient intelligent systems. This work addresses the problem of detecting the current speaker in audio-visual sequences. The detector performs with few and simple material since a single camera and microphone meets the needs. Method A multimodal pattern recognition framework is proposed, with solutions provided for each step of the process, namely, the feature generation and extraction steps, the classification, and the evaluation of the system performance. The decision is based on the estimation of the synchrony between the audio and the video signals. Prior to the classification, an information theoretic framework is applied to extract optimized audio features using video information. The classification step is then defined through a hypothesis testing framework in order to get confidence levels associated to the classifier outputs, allowing thereby an evaluation of the performance of the whole multimodal pattern recognition system. Results Through the hypothesis testing approach, the classifier performance can be given as a ratio of detection to false-alarm probabilities. Above all, the hypothesis tests give means for measuring the whole pattern recognition process effciency. In particular, the gain offered by the proposed feature extraction step can be evaluated. As a result, it is shown that introducing such a feature extraction step increases the ability of the classifier to produce good relative instance scores, and therefore, the performance of the pattern recognition process. Conclusion The powerful capacities of hypothesis tests as an evaluation tool are exploited to assess the performance of a multimodal pattern recognition process. In particular, the advantage of performing or not a feature extraction step prior to the classification is evaluated. Although the proposed framework is

  2. LIKELIHOOD RATIO TESTS OF HYPOTHESES ON MULTIVARIATE POPULATIONS, VOLUME II, TEST OF HYPOTHESIS--STATISTICAL MODELS FOR THE EVALUATION AND INTERPRETATION OF EDUCATIONAL CRITERIA. PART 4.

    Science.gov (United States)

    SAW, J.G.

    THIS PAPER DEALS WITH SOME TESTS OF HYPOTHESIS FREQUENTLY ENCOUNTERED IN THE ANALYSIS OF MULTIVARIATE DATA. THE TYPE OF HYPOTHESIS CONSIDERED IS THAT WHICH THE STATISTICIAN CAN ANSWER IN THE NEGATIVE OR AFFIRMATIVE. THE DOOLITTLE METHOD MAKES IT POSSIBLE TO EVALUATE THE DETERMINANT OF A MATRIX OF HIGH ORDER, TO SOLVE A MATRIX EQUATION, OR TO…

  3. Informative hypotheses : How to move beyond classical null hypothesis testing

    NARCIS (Netherlands)

    Van de Schoot, R.

    2010-01-01

    In this dissertation I will show how subjective beliefs influence analyses in hidden ways and how they might be incorporated explicitly. I will argue that evaluating informative hypotheses produces more useful results than sequentially testing traditional null hypotheses against catch-all rivals.

  4. A paleointensity test of the geocentric axial dipole (GAD) hypothesis

    Science.gov (United States)

    Veikkolainen, Toni; Heimpel, Moritz; Evans, Michael E.; Pesonen, Lauri J.; Korhonen, Kimmo

    2017-04-01

    The geocentric axial dipole (GAD) model is central to many aspects of geophysics, including plate tectonics and paleoclimate. But its validity is by no means firmly established, particularly for the Precambrian. One test that has met with some success involves the distribution of paleomagnetic inclination angles. It works because any given field morphology has its own distinct probability distribution function (PDF) against which data compilations can be tested. Here, we investigate a second possible test using published paleointensity data. Once again, any given field morphology has a specific PDF of intensity. Likely field models consist of an underlying GAD on which is superimposed modest zonal quadrupole and octupole components. The corresponding paleointensity PDFs turn out to have more complicated shapes than their inclination counterparts, often having multiple maxima and minima. Given sufficient data, this complexity offers greater discrimination between models. In this paper, the potential of the paleointensity test is assessed using an extension of the PINT paleointensity database. We found it useful to analyse the Phanerozoic and Precambrian intervals separately. Despite the inherent limitations of this kind of analysis, a tripartite geodynamo with small zonal multipoles appears to be a good starting point on a way towards more fine-tuned models.

  5. Classroom-Based Strategies to Incorporate Hypothesis Testing in Functional Behavior Assessments

    Science.gov (United States)

    Lloyd, Blair P.; Weaver, Emily S.; Staubitz, Johanna L.

    2017-01-01

    When results of descriptive functional behavior assessments are unclear, hypothesis testing can help school teams understand how the classroom environment affects a student's challenging behavior. This article describes two hypothesis testing strategies that can be used in classroom settings: structural analysis and functional analysis. For each…

  6. What Are Null Hypotheses? The Reasoning Linking Scientific and Statistical Hypothesis Testing

    Science.gov (United States)

    Lawson, Anton E.

    2008-01-01

    We should dispense with use of the confusing term "null hypothesis" in educational research reports. To explain why the term should be dropped, the nature of, and relationship between, scientific and statistical hypothesis testing is clarified by explication of (a) the scientific reasoning used by Gregor Mendel in testing specific…

  7. Bayesian hypothesis testing for single-subject designs.

    Science.gov (United States)

    de Vries, Rivka M; Morey, Richard D

    2013-06-01

    Researchers using single-subject designs are typically interested in score differences between intervention phases, such as differences in means or trends. If intervention effects are suspected in data, it is desirable to determine how much evidence the data show for an intervention effect. In Bayesian statistics, Bayes factors quantify the evidence in the data for competing hypotheses. We introduce new Bayes factor tests for single-subject data with 2 phases, taking serial dependency into account: a time-series extension of Rouder, Speckman, Sun, Morey, and Iverson's (2009) Jeffreys-Zellner-Siow Bayes factor for mean differences, and a time-series Bayes factor for testing differences in intercepts and slopes. The models we describe are closely related to interrupted time-series models (McDowall, McCleary, Meidinger, & Hay, 1980). (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  8. Informative hypotheses : How to move beyond classical null hypothesis testing

    OpenAIRE

    Van de Schoot, R.

    2010-01-01

    In this dissertation I will show how subjective beliefs influence analyses in hidden ways and how they might be incorporated explicitly. I will argue that evaluating informative hypotheses produces more useful results than sequentially testing traditional null hypotheses against catch-all rivals. This is illustrated in the introduction chapter with an imaginary example of Aristotle’s investigations about the shape of the Earth. Then, I will take a philosophical approach with two chapters to t...

  9. Hypothesis testing in genetic linkage analysis via Gibbs sampling ( )

    African Journals Online (AJOL)

    hope&shola

    2010-12-06

    Dec 6, 2010 ... using statistical methods, these model parameters are estimated. When performing pedigree analysis, the basic statistical tool used is the likelihood function. We can use the conditional independence imposed by Mendel's laws to express the likelihood function L as a product of transmission probabilities (. ).

  10. The Bayesian New Statistics: Hypothesis testing, estimation, meta-analysis, and power analysis from a Bayesian perspective.

    Science.gov (United States)

    Kruschke, John K; Liddell, Torrin M

    2017-02-07

    In the practice of data analysis, there is a conceptual distinction between hypothesis testing, on the one hand, and estimation with quantified uncertainty on the other. Among frequentists in psychology, a shift of emphasis from hypothesis testing to estimation has been dubbed "the New Statistics" (Cumming 2014). A second conceptual distinction is between frequentist methods and Bayesian methods. Our main goal in this article is to explain how Bayesian methods achieve the goals of the New Statistics better than frequentist methods. The article reviews frequentist and Bayesian approaches to hypothesis testing and to estimation with confidence or credible intervals. The article also describes Bayesian approaches to meta-analysis, randomized controlled trials, and power analysis.

  11. Testing the efficiency market hypothesis for the Colombian stock market

    Directory of Open Access Journals (Sweden)

    Juan Benjamín Duarte-Duarte

    2014-01-01

    Full Text Available Uno de los supuestos básicos de los modelos de valoración de activos (CAPM y APT, es la eficiencia de los mercados. El presente trabajo busca comprobar este requisito en su forma débil, tanto al Índice General de la Bolsa de Valores de Colombia como a las acciones más representativas del mercado colombiano. Para tal fin se comprueba por diferentes métodos estadísticos que las series bursátiles no siguen el patrón de una distribución normal. Además, al indagar sobre la eficiencia del mercado colombiano, mediante los test de Rachas, BDS, LB y Bartlett, se evidencia no aleatoriedad en los principales activos financieros con excepción de Ecopetrol, mientras que para el IGBC se observa una mejora en la eficiencia del mercado del 2008 a 2010, periodo que coincide con el inicio de la crisis económica mundial.

  12. Different meaning of the p-value in exploratory and confirmatory hypothesis testing

    DEFF Research Database (Denmark)

    Gerke, Oke; Høilund-Carlsen, Poul Flemming; Vach, Werner

    2011-01-01

    The outcome of clinical studies is often reduced to the statistical significance of results by indicating a p-value below the 5% significance level. Hypothesis testing and, through that, the p-value is commonly used, but their meaning is frequently misinterpreted in clinical research. The concept...... of hypothesis testing is explained and some pitfalls including those of multiple testing are given. The conceptual difference between exploratory and confirmatory hypothesis testing is discussed, and a better use of p-values, which includes presenting p-values with two or three decimals, is suggested....

  13. Testing the Late-Veneer hypothesis with selenium isotopes

    Science.gov (United States)

    Labidi, J.; Koenig, S.; Bennett, N.; Kurzawa, T.; Aierken, E.; Shahar, A.; Schoenberg, R.

    2016-12-01

    Selenium (Se) is a siderophile element displaying an excess abundance in Earth's mantle compared to experimental predictions [1], which may be attributed to the Late-Veneer. As Se is also volatile, testing the late-veneer addition of Se can constrain the origin of other volatile elements on Earth. Here we combine high-precision Se isotope measurements of metal-silicate partitioning experiments and chondrites to assess whether planetary differentiation could leave a measurable Se isotopic signature on planetary mantles. We performed Se isotopic measurements of 5 metal-silicate partitioning experiments and 20 chondrites of all major classes. Experiments were conducted at 1 GPa and 1650 C for 1 to 4 hours using the piston-cylinder apparatus at Carnegie's Geophysical Laboratory. After wet chemistry, data were obtained on a ThermoFisher Scientific™ NeptunePlus MC-ICP-MS at the University of Tübingen with a 74Se/77Se double spike technique. δ82/76Se values are given relative to NIST SRM-3149 and the external reproducibility calculated from duplicate meteorite analyses is ≤ 0.1‰ (2 s.d.). Chondrites vary over a 0.8‰ range of δ82/76Se values. CIs and CMs show evidence for heavier 82Se/76Se ratios, likely due to mixing processes in the proto-planetary nebula. When these isotopically heavier meteorites are excluded, remaining chondrites have δ82/76Se values varying over a 0.3‰ range, within uncertainty of previous results [2]. We suggest that these chondrites may be used to estimate a δ82/76Se value of bulk planets. At the conditions of our experiments, the partition coefficients for Se log Dmetal-silicate range from 0.7±0.1 to 1.9±0.1, consistent with previous work [1]. A small but resolvable Se isotopic fractionation was observed: 82Se/76Se ratios were enriched by ≤ 0.5‰ in the silicates relative to the metals. Thus, given current uncertainties for Se isotopic measurements, marginal differences between planetary mantles and chondrites may be resolved

  14. Some consequences of using the Horsfall-Barratt scale for hypothesis testing.

    Science.gov (United States)

    Bock, C H; Gottwald, T R; Parker, P E; Ferrandino, F; Welham, S; van den Bosch, F; Parnell, S

    2010-10-01

    Comparing treatment effects by hypothesis testing is a common practice in plant pathology. Nearest percent estimates (NPEs) of disease severity were compared with Horsfall-Barratt (H-B) scale data to explore whether there was an effect of assessment method on hypothesis testing. A simulation model based on field-collected data using leaves with disease severity of 0 to 60% was used; the relationship between NPEs and actual severity was linear, a hyperbolic function described the relationship between the standard deviation of the rater mean NPE and actual disease, and a lognormal distribution was assumed to describe the frequency of NPEs of specific actual disease severities by raters. Results of the simulation showed standard deviations of mean NPEs were consistently similar to the original rater standard deviation from the field-collected data; however, the standard deviations of the H-B scale data deviated from that of the original rater standard deviation, particularly at 20 to 50% severity, over which H-B scale grade intervals are widest; thus, it is over this range that differences in hypothesis testing are most likely to occur. To explore this, two normally distributed, hypothetical severity populations were compared using a t test with NPEs and H-B midpoint data. NPE data had a higher probability to reject the null hypothesis (H0) when H0 was false but greater sample size increased the probability to reject H0 for both methods, with the H-B scale data requiring up to a 50% greater sample size to attain the same probability to reject the H0 as NPEs when H0 was false. The increase in sample size resolves the increased sample variance caused by inaccurate individual estimates due to H-B scale midpoint scaling. As expected, various population characteristics influenced the probability to reject H0, including the difference between the two severity distribution means, their variability, and the ability of the raters. Inaccurate raters showed a similar probability

  15. Are European Equity Style Indexes Mean Reverting? Testing the Validity of the Efficient Market Hypothesis

    OpenAIRE

    Berneburg, Marian

    2004-01-01

    The article tests for a random walk in European equity style indexes. After briefly introducing the efficient market hypothesis, equity styles in general and the used statistical techniques (Variance Ratio Test and modified Rescaled Range Test) it is shown that a random walk in European equity style indexes cannot be rejected. At least in the period since the mid 70s, for which this research has been conducted, the weak form efficient market hypothesis seems to hold.

  16. Adolescents' Body Image Trajectories: A Further Test of the Self-Equilibrium Hypothesis

    Science.gov (United States)

    Morin, Alexandre J. S.; Maïano, Christophe; Scalas, L. Francesca; Janosz, Michel; Litalien, David

    2017-01-01

    The self-equilibrium hypothesis underlines the importance of having a strong core self, which is defined as a high and developmentally stable self-concept. This study tested this hypothesis in relation to body image (BI) trajectories in a sample of 1,006 adolescents (M[subscript age] = 12.6, including 541 males and 465 females) across a 4-year…

  17. A checklist to facilitate objective hypothesis testing in social psychology research.

    Science.gov (United States)

    Washburn, Anthony N; Morgan, G Scott; Skitka, Linda J

    2015-01-01

    Social psychology is not a very politically diverse area of inquiry, something that could negatively affect the objectivity of social psychological theory and research, as Duarte et al. argue in the target article. This commentary offers a number of checks to help researchers uncover possible biases and identify when they are engaging in hypothesis confirmation and advocacy instead of hypothesis testing.

  18. Picture-Perfect Is Not Perfect for Metamemory: Testing the Perceptual Fluency Hypothesis with Degraded Images

    Science.gov (United States)

    Besken, Miri

    2016-01-01

    The perceptual fluency hypothesis claims that items that are easy to perceive at encoding induce an illusion that they will be easier to remember, despite the finding that perception does not generally affect recall. The current set of studies tested the predictions of the perceptual fluency hypothesis with a picture generation manipulation.…

  19. Testing of Hypothesis in Equivalence and Non Inferiority Trials-A Concept.

    Science.gov (United States)

    Juneja, Atul; Aggarwal, Abha R; Adhikari, Tulsi; Pandey, Arvind

    2016-04-01

    Establishing the appropriate hypothesis is one of the important steps for carrying out the statistical tests/analysis. Its understanding is important for interpreting the results of statistical analysis. The current communication attempts to provide the concept of testing of hypothesis in non inferiority and equivalence trials, where the null hypothesis is just reverse of what is set up for conventional superiority trials. It is similarly looked for rejection for establishing the fact the researcher is intending to prove. It is important to mention that equivalence or non inferiority cannot be proved by accepting the null hypothesis of no difference. Hence, establishing the appropriate statistical hypothesis is extremely important to arrive at meaningful conclusion for the set objectives in research.

  20. GeneTools – application for functional annotation and statistical hypothesis testing

    Directory of Open Access Journals (Sweden)

    Langaas Mette

    2006-10-01

    Full Text Available Abstract Background Modern biology has shifted from "one gene" approaches to methods for genomic-scale analysis like microarray technology, which allow simultaneous measurement of thousands of genes. This has created a need for tools facilitating interpretation of biological data in "batch" mode. However, such tools often leave the investigator with large volumes of apparently unorganized information. To meet this interpretation challenge, gene-set, or cluster testing has become a popular analytical tool. Many gene-set testing methods and software packages are now available, most of which use a variety of statistical tests to assess the genes in a set for biological information. However, the field is still evolving, and there is a great need for "integrated" solutions. Results GeneTools is a web-service providing access to a database that brings together information from a broad range of resources. The annotation data are updated weekly, guaranteeing that users get data most recently available. Data submitted by the user are stored in the database, where it can easily be updated, shared between users and exported in various formats. GeneTools provides three different tools: i NMC Annotation Tool, which offers annotations from several databases like UniGene, Entrez Gene, SwissProt and GeneOntology, in both single- and batch search mode. ii GO Annotator Tool, where users can add new gene ontology (GO annotations to genes of interest. These user defined GO annotations can be used in further analysis or exported for public distribution. iii eGOn, a tool for visualization and statistical hypothesis testing of GO category representation. As the first GO tool, eGOn supports hypothesis testing for three different situations (master-target situation, mutually exclusive target-target situation and intersecting target-target situation. An important additional function is an evidence-code filter that allows users, to select the GO annotations for the

  1. TEST OF THE CATCH-UP HYPOTHESIS IN AFRICAN AGRICULTURAL GROWTH RATES

    Directory of Open Access Journals (Sweden)

    Kalu Ukpai IFEGWU

    2015-11-01

    Full Text Available The paper tested the catch-up hypothesis in agricultural growth rates of twenty-six African countries. Panel data used was drawn from the Food and Agricultural Organization Statistics (FAOSTAT of the United Nations. The Data Envelopment Analysis Method for measuring productivity was used to estimate productivity growth rates. The cross-section framework consisting of sigma-convergence and beta-convergence was employed to test the catching up process. Catching up is said to exist if the value of beta is negative and significant. Since catching up does not necessarily imply narrowing of national productivity inequalities, sigma-convergence which measures inequality, was estimated for the same variables. The results showed evidence of the catch-up process, but failed to find a narrowing of productivity inequalities among countries.

  2. Binary Hypothesis Testing via Measure Transformed Quasi-Likelihood Ratio Test

    Science.gov (United States)

    Halay, Nir; Todros, Koby; Hero, Alfred O.

    2017-12-01

    In this paper, the Gaussian quasi likelihood ratio test (GQLRT) for non-Bayesian binary hypothesis testing is generalized by applying a transform to the probability distribution of the data. The proposed generalization, called measure-transformed GQLRT (MT-GQLRT), selects a Gaussian probability model that best empirically fits a transformed probability measure of the data. By judicious choice of the transform we show that, unlike the GQLRT, the proposed test is resilient to outliers and involves higher-order statistical moments leading to significant mitigation of the model mismatch effect on the decision performance. Under some mild regularity conditions we show that the MT-GQLRT is consistent and its corresponding test statistic is asymptotically normal. A data driven procedure for optimal selection of the measure transformation parameters is developed that maximizes an empirical estimate of the asymptotic power given a fixed empirical asymptotic size. A Bayesian extension of the proposed MT-GQLRT is also developed that is based on selection of a Gaussian probability model that best empirically fits a transformed conditional probability distribution of the data. In the Bayesian MT-GQLRT the threshold and the measure transformation parameters are selected via joint minimization of the empirical asymptotic Bayes risk. The non-Bayesian and Bayesian MT-GQLRTs are applied to signal detection and classification, in simulation examples that illustrate their advantages over the standard GQLRT and other robust alternatives.

  3. From Hypothesis Testing to Bayesian Model Comparison: Rigorous Tools to Characterize Earthquake Recurrence

    Science.gov (United States)

    Fitzenz, D. D.; Jalobeanu, A.

    2012-12-01

    There is quite some debate in the earthquake community about the complexity of the recurrence models that should be considered to describe the recurrence of events on given faults. The null-hypothesis testing approach seems to be favored as more rigorous and conservative, in particular for hazard assessment purposes, whereas still few Bayesian applications have been demonstrated. We do not only want to review the mathematical and philosophical bases for Bayesian methods, but we want to emphasize how constructive such a model-based approach can be to problem solving when the traditional datasets (earthquake dates) are short and have missing data. What shall we do when a p-value test does not reject a simple model ? it is not very informative to know that one hypothesis can not be rejected. It is not much more informative to list all hypotheses which can not be rejected, for a given p value and a given dataset. It is much more informative to compare the relative performances of the different models (hypotheses), given our current knowledge. The rigorous framework for such model comparison is the Bayesian framework. This framework also makes the use of physical models easy. This is important since more complex models can be more physics-based and be sequentially constrained by additional datasets.

  4. Asyntactic Thematic Role Assignment by Mandarin Aphasics: A Test of the Trace-Deletion Hypothesis and the Double Dependency Hypothesis

    Science.gov (United States)

    Su, Yi-ching.; Lee, Shu-er; Chung, Yuh-mei

    2007-01-01

    This study examines the comprehension patterns of various sentence types by Mandarin-speaking aphasic patients and evaluates the validity of the predictions from the Trace-Deletion Hypothesis (TDH) and the Double Dependency Hypothesis (DDH). Like English, the canonical word order in Mandarin is SVO, but the two languages differ in that the head…

  5. Information flows in the process of hypothesis testing, insights from Solomonoff inductive inference

    Science.gov (United States)

    Weijs, S. V.; van de Giesen, N.; Parlange, M. B.

    2012-04-01

    Hydrology is a science mostly dealing with making predictions about complex systems that are only partly observable. As a consequence, hydrology mainly deals with induction, i.e. the finding of general patterns and theories from observations. This is often done by sequentially forming plausible hypotheses, test them, and come up with other and improved hypotheses that might explain the data. In this presentation, we look at the information flows within this process and indicate possible problems with mixing prior and posterior information that could occur. This is remediated by a second approach, multi-model inference, where multiple hypotheses are simultaneously tested. A slightly complicating factor in hydrology is that all models are wrong. This leads to the zero prior problem, where a purely Bayesian approach is doomed to be forever stuck in wrong models, no matter how much information is gained from observations about models that were not in the prior. One part of the solution is to only consider hypotheses that make statements in probabilistic terms. These hypotheses are not being proven wrong by the data, but just more or less probable. This means that the error model should be given as part of the hypothesis and the likelihood completely defined by hypothesis and data. The solution of the zero prior problem lies in a universal prior, that gives a prior probability to all computable hypotheses, before seeing any data. Solomonoff's universal prior can be seen as a quantitative implementation of Occam's razor, based in algorithmic information theory. The prior probability of each model is inversely related to its complexity, as measured by its program length on a reference computer. The final predictions are a Bayesian mixture of outputs from all possible models. In Solomonoff induction, predictions are central, and hypotheses just a means to achieve good predictions. In the idealized case of infinite computational resources, the concept of hypothesis becomes

  6. Similar brain mechanism of hypothesis-testing between children and adults.

    Science.gov (United States)

    Li, Fuhong; Cao, Bihua; Cai, Xueli; Li, Hong

    2011-01-01

    Fourteen children and 15 adults were sequentially presented with triplets of cookies and were asked to learn what kinds of cookies were eatable while event-related potentials (ERPs) were recorded. The results locked to the third cookies that served to strengthen or reject a preliminary hypothesis showed that (1) the parietal P220 and frontal HRP (Hypothesis Reject Potential) was larger in reject condition than in strengthen condition for both age groups; (2) the intensive process of hypothesis testing activated most of the left brain. These results suggest that the logical function of the frontal lobe has been formed during the critical period of development of thinking.

  7. Stratified exact tests for the weak causal null hypothesis in randomized trials with a binary outcome.

    Science.gov (United States)

    Chiba, Yasutaka

    2017-09-01

    Fisher's exact test is commonly used to compare two groups when the outcome is binary in randomized trials. In the context of causal inference, this test explores the sharp causal null hypothesis (i.e. the causal effect of treatment is the same for all subjects), but not the weak causal null hypothesis (i.e. the causal risks are the same in the two groups). Therefore, in general, rejection of the null hypothesis by Fisher's exact test does not mean that the causal risk difference is not zero. Recently, Chiba (Journal of Biometrics and Biostatistics 2015; 6: 244) developed a new exact test for the weak causal null hypothesis when the outcome is binary in randomized trials; the new test is not based on any large sample theory and does not require any assumption. In this paper, we extend the new test; we create a version of the test applicable to a stratified analysis. The stratified exact test that we propose is general in nature and can be used in several approaches toward the estimation of treatment effects after adjusting for stratification factors. The stratified Fisher's exact test of Jung (Biometrical Journal 2014; 56: 129-140) tests the sharp causal null hypothesis. This test applies a crude estimator of the treatment effect and can be regarded as a special case of our proposed exact test. Our proposed stratified exact test can be straightforwardly extended to analysis of noninferiority trials and to construct the associated confidence interval. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Why does Income Relate to Depressive Symptoms? Testing the Income Rank Hypothesis Longitudinally.

    Science.gov (United States)

    Osafo Hounkpatin, Hilda; Wood, Alex M; Brown, Gordon D A; Dunn, Graham

    This paper reports a test of the relative income rank hypothesis of depression, according to which it is the rank position of an individual's income amongst a comparison group, rather than the individual's absolute income, that will be associated with depressive symptoms. A new methodology is developed to test between psychosocial and material explanations of why income relates to well-being. This method was used to test the income rank hypothesis as applied to depressive symptoms. We used data from a cohort of 10,317 individuals living in Wisconsin who completed surveys in 1992 and 2003. The utility assumed to arise from income was represented with a constant relative risk aversion function to overcome limitations of previous work in which inadequate specification of the relationship between absolute income and well-being may have inappropriately favoured relative income specifications. We compared models in which current and future depressive symptoms were predicted from: (a) income utility alone, (b) income rank alone, (c) the transformed difference between the individual's income and the mean income of a comparison group and (d) income utility, income rank and distance from the mean jointly. Model comparison overcomes problems involving multi-collinearity amongst the predictors. A rank-only model was consistently supported. Similar results were obtained for the association between depressive symptoms and wealth and rank of wealth in a cohort of 32,900 British individuals who completed surveys in 2002 and 2008. We conclude that it is the rank of a person's income or wealth within a social comparison group, rather than income or wealth themselves or their deviations from the mean within a reference group, that is more strongly associated with depressive symptoms.

  9. The greatest lower bound to the reliability of a test and the hypothesis of unidimensionality

    NARCIS (Netherlands)

    Ten Berge, JMF; Socan, G

    2004-01-01

    To assess the reliability of congeneric tests, specifically designed reliability measures have been proposed. This paper emphasizes that such measures rely on a unidimensionality hypothesis, which can neither be confirmed nor rejected when there are only three test parts, and will invariably be

  10. The Gumbel hypothesis test for left censored observations using regional earthquake records as an example

    Directory of Open Access Journals (Sweden)

    E. M. Thompson

    2011-01-01

    Full Text Available Annual maximum (AM time series are incomplete (i.e., censored when no events are included above the assumed censoring threshold (i.e., magnitude of completeness. We introduce a distrtibutional hypothesis test for left-censored Gumbel observations based on the probability plot correlation coefficient (PPCC. Critical values of the PPCC hypothesis test statistic are computed from Monte-Carlo simulations and are a function of sample size, censoring level, and significance level. When applied to a global catalog of earthquake observations, the left-censored Gumbel PPCC tests are unable to reject the Gumbel hypothesis for 45 of 46 seismic regions. We apply four different field significance tests for combining individual tests into a collective hypothesis test. None of the field significance tests are able to reject the global hypothesis that AM earthquake magnitudes arise from a Gumbel distribution. Because the field significance levels are not conclusive, we also compute the likelihood that these field significance tests are unable to reject the Gumbel model when the samples arise from a more complex distributional alternative. A power study documents that the censored Gumbel PPCC test is unable to reject some important and viable Generalized Extreme Value (GEV alternatives. Thus, we cannot rule out the possibility that the global AM earthquake time series could arise from a GEV distribution with a finite upper bound, also known as a reverse Weibull distribution. Our power study also indicates that the binomial and uniform field significance tests are substantially more powerful than the more commonly used Bonferonni and false discovery rate multiple comparison procedures.

  11. Linking multidimensional functional diversity to quantitative methods: a graphical hypothesis--evaluation framework.

    Science.gov (United States)

    Boersma, Kate S; Dee, Laura E; Miller, Steve J; Bogan, Michael T; Lytle, David A; Gitelman, Alix I

    2016-03-01

    Functional trait analysis is an appealing approach to study differences among biological communities because traits determine species' responses to the environment and their impacts on ecosystem functioning. Despite a rapidly expanding quantitative literature, it remains challenging to conceptualize concurrent changes in multiple trait dimensions ("trait space") and select quantitative functional diversity methods to test hypotheses prior to analysis. To address this need, we present a widely applicable framework for visualizing ecological phenomena in trait space to guide the selection, application, and interpretation of quantitative functional diversity methods. We describe five hypotheses that represent general patterns of responses to disturbance in functional community ecology and then apply a formal decision process to determine appropriate quantitative methods to test ecological hypotheses. As a part of this process, we devise a new statistical approach to test for functional turnover among communities. Our combination of hypotheses and metrics can be applied broadly to address ecological questions across a range of systems and study designs. We illustrate the framework with a case study of disturbance in freshwater communities. This hypothesis-driven approach will increase the rigor and transparency of applied functional trait studies.

  12. Sex-Biased Parental Investment among Contemporary Chinese Peasants: Testing the Trivers-Willard Hypothesis.

    Science.gov (United States)

    Luo, Liqun; Zhao, Wei; Weng, Tangmei

    2016-01-01

    The Trivers-Willard hypothesis predicts that high-status parents will bias their investment to sons, whereas low-status parents will bias their investment to daughters. Among humans, tests of this hypothesis have yielded mixed results. This study tests the hypothesis using data collected among contemporary peasants in Central South China. We use current family status (rated by our informants) and father's former class identity (assigned by the Chinese Communist Party in the early 1950s) as measures of parental status, and proportion of sons in offspring and offspring's years of education as measures of parental investment. Results show that (i) those families with a higher former class identity such as landlord and rich peasant tend to have a higher socioeconomic status currently, (ii) high-status parents are more likely to have sons than daughters among their biological offspring, and (iii) in higher-status families, the years of education obtained by sons exceed that obtained by daughters to a larger extent than in lower-status families. Thus, the first assumption and the two predictions of the hypothesis are supported by this study. This article contributes a contemporary Chinese case to the testing of the Trivers-Willard hypothesis.

  13. Sex-Biased Parental Investment among Contemporary Chinese Peasants: Testing the Trivers-Willard Hypothesis

    Directory of Open Access Journals (Sweden)

    Liqun Luo

    2016-08-01

    Full Text Available The Trivers-Willard hypothesis predicts that high-status parents will bias their investment to sons, whereas low-status parents will bias their investment to daughters. Among humans, tests of this hypothesis have yielded mixed results. This study tests the hypothesis using data collected among contemporary peasants in Central South China. We use current family status (rated by our informants and father’s former class identity (assigned by the Chinese Communist Party in the early 1950s as measures of parental status, and proportion of sons in offspring and offspring’s years of education as measures of parental investment. Results show that (i those families with a higher former class identity such as landlord and rich peasant tend to have a higher socioeconomic status currently, (ii high-status parents are more likely to have sons than daughters among their biological offspring, and (iii in higher-status families, the years of education obtained by sons exceed that obtained by daughters to a larger extent than in lower-status families. Thus, the first assumption and the two predictions of the hypothesis are supported by this study. This article contributes a contemporary Chinese case to the testing of the Trivers-Willard hypothesis.

  14. Testing the Axial Dipole Hypothesis for the Moon by Modeling the Direction of Crustal Magnetization

    Science.gov (United States)

    Oliveira, Joana S.; Wieczorek, Mark A.

    2017-04-01

    Magnetic field maps of the Moon show that there are strong magnetic anomalies of crustal origin distributed heterogeneously across the lunar surface. However, the origin of the fields that magnetized the crust are not understood and could be the result of either a long-lived core generated dynamo or transient fields associated with large impact events. Core-dynamo models usually predict that the field would be predominantly dipolar, with the dipole axis aligned with the rotation axis. In this case, the direction of crustal magnetization would vary with planetary latitude, just as on Earth. We test this hypothesis by modeling the direction of crustal magnetization using spacecraft-derived magnetic field data. From the direction of magnetization, we calculate the corresponding paleopole, which we define as the north magnetic pole of a predominantly dipolar core-generated field when the anomaly was formed. The dipolar core field hypothesis will be confirmed if the paleopoles cluster in one or two regions. We use the Parker method, originally developed to study seamounts magnetism, to invert for the direction of crustal magnetization associated with isolated lunar magnetic anomalies. This method largely bypasses the non-uniqueness associated with specifying the geometry of the magnetic sources. The only assumption is that when the region acquired a remnant magnetization, the main field was constant in direction. In practice, unidirectional equivalent source dipoles are placed on the surface within a circle of specified radius over a region that encompasses an isolated anomaly. For an assumed direction of magnetization, we solve for the magnetic moments of the dipoles and determine the misfit between the model and observations using a non-negative least squares inversions approach. The inversion naturally finds those dipoles that are non-zero, as well as their intensities. For our inversions we use global gridded magnetic field maps at 30 km altitude with a resolution

  15. Predictability of Exchange Rates in Sri Lanka: A Test of the Efficient Market Hypothesis

    OpenAIRE

    Guneratne B Wickremasinghe

    2007-01-01

    This study examined the validity of the weak and semi-strong forms of the efficient market hypothesis (EMH) for the foreign exchange market of Sri Lanka. Monthly exchange rates for four currencies during the floating exchange rate regime were used in the empirical tests. Using a battery of tests, empirical results indicate that the current values of the four exchange rates can be predicted from their past values. Further, the tests of semi-strong form efficiency indicate that exchange rate pa...

  16. Handling realistic assumptions in hypothesis testing of 3D co-localization of genomic elements.

    Science.gov (United States)

    Paulsen, Jonas; Lien, Tonje G; Sandve, Geir Kjetil; Holden, Lars; Borgan, Ornulf; Glad, Ingrid K; Hovig, Eivind

    2013-05-01

    The study of chromatin 3D structure has recently gained much focus owing to novel techniques for detecting genome-wide chromatin contacts using next-generation sequencing. A deeper understanding of the architecture of the DNA inside the nucleus is crucial for gaining insight into fundamental processes such as transcriptional regulation, genome dynamics and genome stability. Chromatin conformation capture-based methods, such as Hi-C and ChIA-PET, are now paving the way for routine genome-wide studies of chromatin 3D structure in a range of organisms and tissues. However, appropriate methods for analyzing such data are lacking. Here, we propose a hypothesis test and an enrichment score of 3D co-localization of genomic elements that handles intra- or interchromosomal interactions, both separately and jointly, and that adjusts for biases caused by structural dependencies in the 3D data. We show that maintaining structural properties during resampling is essential to obtain valid estimation of P-values. We apply the method on chromatin states and a set of mutated regions in leukemia cells, and find significant co-localization of these elements, with varying enrichment scores, supporting the role of chromatin 3D structure in shaping the landscape of somatic mutations in cancer.

  17. Bayesian hypothesis testing: Editorial to the Special Issue on Bayesian data analysis.

    Science.gov (United States)

    Hoijtink, Herbert; Chow, Sy-Miin

    2017-06-01

    In the past 20 years, there has been a steadily increasing attention and demand for Bayesian data analysis across multiple scientific disciplines, including psychology. Bayesian methods and the related Markov chain Monte Carlo sampling techniques offered renewed ways of handling old and challenging new problems that may be difficult or impossible to handle using classical approaches. Yet, such opportunities and potential improvements have not been sufficiently explored and investigated. This is 1 of 2 special issues in Psychological Methods dedicated to the topic of Bayesian data analysis, with an emphasis on Bayesian hypothesis testing, model comparison, and general guidelines for applications in psychology. In this editorial, we provide an overview of the use of Bayesian methods in psychological research and a brief history of the Bayes factor and the posterior predictive p value. Translational abstracts that summarize the articles in this issue in very clear and understandable terms are included in the Appendix. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. Is the Economic andTesting the Efficient Markets Hypothesis on the Romanian Capital Market

    Directory of Open Access Journals (Sweden)

    Dragoș Mînjină

    2013-11-01

    Full Text Available Informational efficiency of capital markets has been the subject of numerous empirical studies. Intensive research of the field is justified by the important implications of the knowledge of the of informational efficiency level in the financial practice. Empirical studies that have tested the efficient markets hypothesis on the Romanian capital market revealed mostly that this market is not characterised by the weak form of the efficient markets hypothesis. However, recent empirical studies have obtained results for the weak form of the efficient markets hypothesis. The present decline period of the Romanian capital market, recorded on the background of adverse economic developments internally and externally, will be an important test for the continuation of recent positive developments, manifested the level of informational efficiency too.

  19. Is it better to select or to receive? Learning via active and passive hypothesis testing.

    Science.gov (United States)

    Markant, Douglas B; Gureckis, Todd M

    2014-02-01

    People can test hypotheses through either selection or reception. In a selection task, the learner actively chooses observations to test his or her beliefs, whereas in reception tasks data are passively encountered. People routinely use both forms of testing in everyday life, but the critical psychological differences between selection and reception learning remain poorly understood. One hypothesis is that selection learning improves learning performance by enhancing generic cognitive processes related to motivation, attention, and engagement. Alternatively, we suggest that differences between these 2 learning modes derives from a hypothesis-dependent sampling bias that is introduced when a person collects data to test his or her own individual hypothesis. Drawing on influential models of sequential hypothesis-testing behavior, we show that such a bias (a) can lead to the collection of data that facilitates learning compared with reception learning and (b) can be more effective than observing the selections of another person. We then report a novel experiment based on a popular category learning paradigm that compares reception and selection learning. We additionally compare selection learners to a set of "yoked" participants who viewed the exact same sequence of observations under reception conditions. The results revealed systematic differences in performance that depended on the learner's role in collecting information and the abstract structure of the problem.

  20. Standard environmental test methods

    Energy Technology Data Exchange (ETDEWEB)

    Schafer, D R

    1983-12-01

    This guide to uniformity in testing is intended primarily as an aid to persons responsible for designing, developing, and performing environmental tests. It will also be of use to those concerned with production, evaluation, and quality control and assurance. Checklists for preparing the environmental testing portion of product specifications are included, as are copies of Process Standards covering the instrumentation, equipment, and methods for use in environmental testing of Sandia National Laboratories components. Techniques and equipment are constantly improving. This version of SC-4452 reflects current state-of-the-art and practice in environmental testing. Previously existing sections of the document have ben updated and new ones have been added, e.g., Transient Testing on Vibration Machines.

  1. Silicon-rich mineral water as a non-invasive test of the 'aluminum hypothesis' in Alzheimer's disease.

    Science.gov (United States)

    Davenward, Samantha; Bentham, Peter; Wright, Jan; Crome, Peter; Job, Deborah; Polwart, Anthony; Exley, Christopher

    2013-01-01

    There has been a plausible link between human exposure to aluminum and Alzheimer's disease for several decades. We contend that the only direct and ethically acceptable experimental test of the 'aluminum hypothesis', which would provide unequivocal data specific to the link, is to test the null hypothesis that a reduction in the body burden of aluminum to its lowest practical limit would have no influence upon the incidence, progression, or severity of Alzheimer's disease. Herein we are testing the hypothesis that silicon-rich mineral waters can be used as non-invasive methods to reduce the body burden of aluminum in individuals with Alzheimer's disease and a control group consisting of their carers and partners. We have shown that drinking up to 1 L of a silicon-rich mineral water each day for 12 weeks facilitated the removal of aluminum via the urine in both patient and control groups without any concomitant affect upon the urinary excretion of the essential metals, iron and copper. We have provided preliminary evidence that over 12 weeks of silicon-rich mineral water therapy the body burden of aluminum fell in individuals with Alzheimer's disease and, concomitantly, cognitive performance showed clinically relevant improvements in at least 3 out of 15 individuals. This is a first step in a much needed rigorous test of the 'aluminum hypothesis of Alzheimer's disease' and a longer term study involving many more individuals is now warranted.

  2. Testing the fire-sale FDI hypothesis for the European financial crisis

    NARCIS (Netherlands)

    Weitzel, G.U.; Kling, G.; Gerritsen, D.

    2014-01-01

    Using a panel of corporate transactions in 27 EU countries from 1999 to 2012, we investigate the impact of the financial crisis on the market for corporate assets. In particular, we test the ‘fire-sale FDI’ hypothesis by analyzing the number of cross-border transactions, the price of corporate

  3. Testing the Fire-Sale FDI Hypothesis for the European Financial Crisis

    NARCIS (Netherlands)

    Kling, G.; Gerritsen, Dirk; Weitzel, Gustav Utz

    2014-01-01

    Using a panel of corporate transactions in 27 EU countries from 1999 to 2012, we investigate the impact of the financial crisis on the market for corporate assets. In particular, we test the ‘fire-sale FDI’ hypothesis by analyzing the number of cross-border transactions, the price of corporate

  4. Robust Means Modeling: An Alternative for Hypothesis Testing of Independent Means under Variance Heterogeneity and Nonnormality

    Science.gov (United States)

    Fan, Weihua; Hancock, Gregory R.

    2012-01-01

    This study proposes robust means modeling (RMM) approaches for hypothesis testing of mean differences for between-subjects designs in order to control the biasing effects of nonnormality and variance inequality. Drawing from structural equation modeling (SEM), the RMM approaches make no assumption of variance homogeneity and employ robust…

  5. The Need for Nuance in the Null Hypothesis Significance Testing Debate

    Science.gov (United States)

    Häggström, Olle

    2017-01-01

    Null hypothesis significance testing (NHST) provides an important statistical toolbox, but there are a number of ways in which it is often abused and misinterpreted, with bad consequences for the reliability and progress of science. Parts of contemporary NHST debate, especially in the psychological sciences, is reviewed, and a suggestion is made…

  6. Acorn Caching in Tree Squirrels: Teaching Hypothesis Testing in the Park

    Science.gov (United States)

    McEuen, Amy B.; Steele, Michael A.

    2012-01-01

    We developed an exercise for a university-level ecology class that teaches hypothesis testing by examining acorn preferences and caching behavior of tree squirrels (Sciurus spp.). This exercise is easily modified to teach concepts of behavioral ecology for earlier grades, particularly high school, and provides students with a theoretical basis for…

  7. Different meaning of the p-value in exploratory and confirmatory hypothesis testing

    DEFF Research Database (Denmark)

    Gerke, Oke; Høilund-Carlsen, Poul Flemming; Vach, Werner

    2011-01-01

    The outcome of clinical studies is often reduced to the statistical significance of results by indicating a p-value below the 5% significance level. Hypothesis testing and, through that, the p-value is commonly used, but their meaning is frequently misinterpreted in clinical research. The concept...

  8. Visual Working Memory and Number Sense: Testing the Double Deficit Hypothesis in Mathematics

    Science.gov (United States)

    Toll, Sylke W. M.; Kroesbergen, Evelyn H.; Van Luit, Johannes E. H.

    2016-01-01

    Background: Evidence exists that there are two main underlying cognitive factors in mathematical difficulties: working memory and number sense. It is suggested that real math difficulties appear when both working memory and number sense are weak, here referred to as the double deficit (DD) hypothesis. Aims: The aim of this study was to test the DD…

  9. Speech production in people who stutter: Testing the motor plan assembly hypothesis

    NARCIS (Netherlands)

    Lieshout, P.H.H.M. van; Hulstijn, W.; Peters, H.F.M.

    1996-01-01

    The main purpose of the present study was to test the hypothesis that persons who stutter, when compared to persons who do not stutter, are less able to assemble abstract motor plans for short verbal responses. Subjects were adult males who stutter and age- and sex-matched control speakers, who were

  10. A critical discussion of null hypothesis significance testing and statistical power analysis within psychological research

    DEFF Research Database (Denmark)

    Jones, Allan; Sommerlund, Bo

    2007-01-01

    The uses of null hypothesis significance testing (NHST) and statistical power analysis within psychological research are critically discussed. The article looks at the problems of relying solely on NHST when dealing with small and large sample sizes. The use of power-analysis in estimating...... the potential error introduced by small and large samples is advocated. Power analysis is not recommended as a replacement to NHST but as an additional source of information about the phenomena under investigation. Moreover, the importance of conceptual analysis in relation to statistical analysis of hypothesis...

  11. Proper Image Subtraction—Optimal Transient Detection, Photometry, and Hypothesis Testing

    Science.gov (United States)

    Zackay, Barak; Ofek, Eran O.; Gal-Yam, Avishay

    2016-10-01

    Transient detection and flux measurement via image subtraction stand at the base of time domain astronomy. Due to the varying seeing conditions, the image subtraction process is non-trivial, and existing solutions suffer from a variety of problems. Starting from basic statistical principles, we develop the optimal statistic for transient detection, flux measurement, and any image-difference hypothesis testing. We derive a closed-form statistic that: (1) is mathematically proven to be the optimal transient detection statistic in the limit of background-dominated noise, (2) is numerically stable, (3) for accurately registered, adequately sampled images, does not leave subtraction or deconvolution artifacts, (4) allows automatic transient detection to the theoretical sensitivity limit by providing credible detection significance, (5) has uncorrelated white noise, (6) is a sufficient statistic for any further statistical test on the difference image, and, in particular, allows us to distinguish particle hits and other image artifacts from real transients, (7) is symmetric to the exchange of the new and reference images, (8) is at least an order of magnitude faster to compute than some popular methods, and (9) is straightforward to implement. Furthermore, we present extensions of this method that make it resilient to registration errors, color-refraction errors, and any noise source that can be modeled. In addition, we show that the optimal way to prepare a reference image is the proper image coaddition presented in Zackay & Ofek. We demonstrate this method on simulated data and real observations from the PTF data release 2. We provide an implementation of this algorithm in MATLAB and Python.

  12. Testing the Viewing Angle Hypothesis for Short GRBs with LIGO Events

    Science.gov (United States)

    Eichler, David

    2017-12-01

    It has been suggested that short gamma-ray bursts (GRBs) have shorter or undetectable spectral lags than longer GRBs because for the former, the observer's line of sight makes a larger angle with the GRB jet axis than it does for the latter. It is proposed that simultaneous gravitational-wave–short-GRB events could provide a simple test of this hypothesis. Multimessenger astronomy eventually may test whether event horizons are a necessary ingredient for GRBs.

  13. On the origins of cultural differences in conformity: four tests of the pathogen prevalence hypothesis.

    Science.gov (United States)

    Murray, Damian R; Trudeau, Russell; Schaller, Mark

    2011-03-01

    What are the origins of cultural differences in conformity? The authors deduce the hypothesis that these cultural differences may reflect historical variability in the prevalence of disease-causing pathogens: Where pathogens were more prevalent, there were likely to emerge cultural norms promoting greater conformity. The authors conducted four tests of this hypothesis, using countries as units of analysis. Results support the pathogen prevalence hypothesis. Pathogen prevalence positively predicts cultural differences in effect sizes that emerge from behavioral conformity experiments (r=.49, n=17) and in the percentage of the population who prioritize obedience (r=.48, n=83). Pathogen prevalence also negatively predicted two indicators of tolerance for nonconformity: within-country dispositional variability (r=-.48, n=33) and the percentage of the population who are left-handed (r=-.73, n=20). Additional analyses address plausible alternative causal explanations. Discussion focuses on plausible underlying mechanisms (e.g., genetic, developmental, cognitive).

  14. Timing and proximate causes of mortality in wild bird populations: testing Ashmole’s hypothesis

    Science.gov (United States)

    Barton, Daniel C.; Martin, Thomas E.

    2012-01-01

    Fecundity in birds is widely recognized to increase with latitude across diverse phylogenetic groups and regions, yet the causes of this variation remain enigmatic. Ashmole’s hypothesis is one of the most broadly accepted explanations for this pattern. This hypothesis suggests that increasing seasonality leads to increasing overwinter mortality due to resource scarcity during the lean season (e.g., winter) in higher latitude climates. This mortality is then thought to yield increased per-capita resources for breeding that allow larger clutch sizes at high latitudes. Support for this hypothesis has been based on indirect tests, whereas the underlying mechanisms and assumptions remain poorly explored. We used a meta-analysis of over 150 published studies to test two underlying and critical assumptions of Ashmole’s hypothesis: first, that ad ult mortality is greatest during the season of greatest resource scarcity, and second, t hat most mortality is caused by starvation. We found that the lean season (winter) was generally not the season of greatest mortality. Instead, spring or summer was most frequently the season of greatest mortality. Moreover, monthly survival rates were not explained by monthly productivity, again opposing predictions from Ashmole’s hypothesis. Finally, predation, rather than starvation, was the most frequent proximate cause o f mortality. Our results do not support the mechanistic predictions of Ashmole‘s hypothesis, and suggest alternative explanations of latitudinal variation in clutch size should remain under consideration. Our meta-analysis also highlights a paucity of data available on the timing and causes of mortality in many bird populations, particularly tropical bird populations, despite the clear theoretical and empirical importance of such data.

  15. Correlates of androgens in wild male Barbary macaques: Testing the challenge hypothesis.

    Science.gov (United States)

    Rincon, Alan V; Maréchal, Laëtitia; Semple, Stuart; Majolo, Bonaventura; MacLarnon, Ann

    2017-10-01

    Investigating causes and consequences of variation in hormonal expression is a key focus in behavioral ecology. Many studies have explored patterns of secretion of the androgen testosterone in male vertebrates, using the challenge hypothesis (Wingfield, Hegner, Dufty, & Ball, 1990; The American Naturalist, 136(6), 829-846) as a theoretical framework. Rather than the classic association of testosterone with male sexual behavior, this hypothesis predicts that high levels of testosterone are associated with male-male reproductive competition but also inhibit paternal care. The hypothesis was originally developed for birds, and subsequently tested in other vertebrate taxa, including primates. Such studies have explored the link between testosterone and reproductive aggression as well as other measures of mating competition, or between testosterone and aspects of male behavior related to the presence of infants. Very few studies have simultaneously investigated the links between testosterone and male aggression, other aspects of mating competition and infant-related behavior. We tested predictions derived from the challenge hypothesis in wild male Barbary macaques (Macaca sylvanus), a species with marked breeding seasonality and high levels of male-infant affiliation, providing a powerful test of this theoretical framework. Over 11 months, 251 hr of behavioral observations and 296 fecal samples were collected from seven adult males in the Middle Atlas Mountains, Morocco. Fecal androgen levels rose before the onset of the mating season, during a period of rank instability, and were positively related to group mating activity across the mating season. Androgen levels were unrelated to rates of male-male aggression in any period, but higher ranked males had higher levels in both the mating season and in the period of rank instability. Lower androgen levels were associated with increased rates of male-infant grooming during the mating and unstable periods. Our results

  16. Test anxiety and intelligence testing: a closer examination of the stage-fright hypothesis and the influence of stressful instruction.

    Science.gov (United States)

    Meijer, Joost; Oostdam, Ron

    2007-03-01

    The influence of test anxiety and the content of instruction (stressful versus reassuring) on measurements of intelligence were investigated. It was expected that components of test anxiety would show differential effects on test performance. A Latin Square design was used to unravel the effects of test type and test order. Furthermore, effects of type of instruction, stressful versus reassuring, were studied by means of a within-subjects design. Test anxiety was measured with the Revised Worry-Emotionality Questionnaire. Measurements for verbal ability, reasoning, and memory were administered. Performance on memory tests showed less vulnerability to test anxiety compared with the other tests, with a picture recall test being insensitive. The negative effect of test anxiety was mostly confined to the beginning of a test session, independent of the type of test. Partial support for the so-called stage-fright hypothesis was found. The effect of instructional content was equivocal.

  17. Congruence analysis of geodetic networks - hypothesis tests versus model selection by information criteria

    Science.gov (United States)

    Lehmann, Rüdiger; Lösler, Michael

    2017-12-01

    Geodetic deformation analysis can be interpreted as a model selection problem. The null model indicates that no deformation has occurred. It is opposed to a number of alternative models, which stipulate different deformation patterns. A common way to select the right model is the usage of a statistical hypothesis test. However, since we have to test a series of deformation patterns, this must be a multiple test. As an alternative solution for the test problem, we propose the p-value approach. Another approach arises from information theory. Here, the Akaike information criterion (AIC) or some alternative is used to select an appropriate model for a given set of observations. Both approaches are discussed and applied to two test scenarios: A synthetic levelling network and the Delft test data set. It is demonstrated that they work but behave differently, sometimes even producing different results. Hypothesis tests are well-established in geodesy, but may suffer from an unfavourable choice of the decision error rates. The multiple test also suffers from statistical dependencies between the test statistics, which are neglected. Both problems are overcome by applying information criterions like AIC.

  18. SAR-based change detection using hypothesis testing and Markov random field modelling

    Science.gov (United States)

    Cao, W.; Martinis, S.

    2015-04-01

    The objective of this study is to automatically detect changed areas caused by natural disasters from bi-temporal co-registered and calibrated TerraSAR-X data. The technique in this paper consists of two steps: Firstly, an automatic coarse detection step is applied based on a statistical hypothesis test for initializing the classification. The original analytical formula as proposed in the constant false alarm rate (CFAR) edge detector is reviewed and rewritten in a compact form of the incomplete beta function, which is a builtin routine in commercial scientific software such as MATLAB and IDL. Secondly, a post-classification step is introduced to optimize the noisy classification result in the previous step. Generally, an optimization problem can be formulated as a Markov random field (MRF) on which the quality of a classification is measured by an energy function. The optimal classification based on the MRF is related to the lowest energy value. Previous studies provide methods for the optimization problem using MRFs, such as the iterated conditional modes (ICM) algorithm. Recently, a novel algorithm was presented based on graph-cut theory. This method transforms a MRF to an equivalent graph and solves the optimization problem by a max-flow/min-cut algorithm on the graph. In this study this graph-cut algorithm is applied iteratively to improve the coarse classification. At each iteration the parameters of the energy function for the current classification are set by the logarithmic probability density function (PDF). The relevant parameters are estimated by the method of logarithmic cumulants (MoLC). Experiments are performed using two flood events in Germany and Australia in 2011 and a forest fire on La Palma in 2009 using pre- and post-event TerraSAR-X data. The results show convincing coarse classifications and considerable improvement by the graph-cut post-classification step.

  19. Assessment of resampling methods for causality testing

    NARCIS (Netherlands)

    Papana, A.; Kyrtsou, C.; Kugiumtzis, D.; Diks, C.

    2014-01-01

    Different resampling methods for the null hypothesis of non-causality are assessed. As test statistic the partial transfer entropy (PTE), an information and model-free measure, is used. Two resampling techniques,1) the time shifted surrogates and 2) the stationary bootstrap, are combined with the

  20. A test of the herbivore optimization hypothesis using muskoxen and a graminoid meadow plant community

    Directory of Open Access Journals (Sweden)

    David L. Smith

    1996-01-01

    Full Text Available A prediction from the herbivore optimization hypothesis is that grazing by herbivores at moderate intensities will increase net above-ground primary productivity more than at lower or higher intensities. I tested this hypothesis in an area of high muskox {Ovibos moschatus density on north-central Banks Island, Northwest Territories, Canada (73°50'N, 119°53'W. Plots (1 m2 in graminoid meadows dominated by cottongrass (Eriophorum triste were either clipped, exposed to muskoxen, protected for part of one growing season, or permanently protected. This resulted in the removal of 22-44%, 10-39%, 0-39% or 0%, respectively, of shoot tissue during each growing season. Contrary to the predictions of the herbivore optimization hypothesis, productivity did not increase across this range of tissue removal. Productivity of plants clipped at 1.5 cm above ground once or twice per growing season, declined by 60+/-5% in 64% of the tests. The productivity of plants grazed by muskoxen declined by 56+/-7% in 25% of the tests. No significant change in productivity was observed in 36% and 75% of the tests in clipped and grazed treatments, respecrively. Clipping and grazing reduced below-ground standing crop except where removals were small. Grazing and clipping did not stimulate productivity of north-central Banks Island graminoid meadows.

  1. Is conscious stimulus identification dependent on knowledge of the perceptual modality? Testing the “source misidentifcation hypothesis"

    DEFF Research Database (Denmark)

    Overgaard, Morten; Lindeløv, Jonas Kristoffer; Svejstrup, Stinna

    2013-01-01

    This paper reports an experiment intended to test a particular hypothesis derived from blindsight research, which we name the “source misidentification hypothesis.” According to this hypothesis, a subject may be correct about a stimulus without being correct about how she had access to this knowl...

  2. Habitat fragmentation, vole population fluctuations, and the ROMPA hypothesis: An experimental test using model landscapes.

    Science.gov (United States)

    Batzli, George O

    2016-11-01

    Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches. The ROMPA hypothesis (ratio of optimal to marginal patch area) uniquely links vole population fluctuations to the composition of the landscape. It states that as ROMPA decreases (fragmentation increases), vole population fluctuations will increase (including the tendency to display multi-annual cycles in abundance) because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season. To date, only comparative observations in the field have supported the hypothesis. This paper reports the results of the first experimental test. I used prairie voles, Microtus ochrogaster, and mowed grassland to create model landscapes with 3 levels of ROMPA (high with 25% mowed, medium with 50% mowed and low with 75% mowed). As ROMPA decreased, distances between patches of favorable habitat (high cover) increased owing to a greater proportion of unfavorable (mowed) habitat. Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed (inversely density dependent emigration and, as ROMPA decreased, increased per capita mortality and decreased per capita movement between optimal patches). Nevertheless, contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability, 5 years of trapping indicated that variability was lowest with medium ROMPA. The design of field experiments may never be perfect, but these results indicate that the ROMPA hypothesis needs further rigorous testing. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  3. Statistical hypothesis testing and common misinterpretations: Should we abandon p-value in forensic science applications?

    Science.gov (United States)

    Taroni, F; Biedermann, A; Bozza, S

    2016-02-01

    Many people regard the concept of hypothesis testing as fundamental to inferential statistics. Various schools of thought, in particular frequentist and Bayesian, have promoted radically different solutions for taking a decision about the plausibility of competing hypotheses. Comprehensive philosophical comparisons about their advantages and drawbacks are widely available and continue to span over large debates in the literature. More recently, controversial discussion was initiated by an editorial decision of a scientific journal [1] to refuse any paper submitted for publication containing null hypothesis testing procedures. Since the large majority of papers published in forensic journals propose the evaluation of statistical evidence based on the so called p-values, it is of interest to expose the discussion of this journal's decision within the forensic science community. This paper aims to provide forensic science researchers with a primer on the main concepts and their implications for making informed methodological choices. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Testing the circadian gene hypothesis in prostate cancer: a population-based case-control study

    OpenAIRE

    Zhu, Yong; Stevens, Richard G.; Hoffman, Aaron E.; FitzGerald, Liesel M.; Kwon, Erika M.; Ostrander, Elaine A.; Davis, Scott; Zheng, Tongzhang; Stanford, Janet L

    2009-01-01

    Circadian genes are responsible for maintaining the ancient adaptation of a 24-hour circadian rhythm and influence a variety of cancer-related biological pathways, including the regulation of sex hormone levels. However, few studies have been undertaken to investigate the role of circadian genes in the development of prostate cancer, the most common cancer type among men (excluding non-melanoma skin cancer). The current genetic association study tested the circadian gene hypothesis in relatio...

  5. Testing the binaural equal-loudness-ratio hypothesis with hearing-impaired listeners1

    OpenAIRE

    Marozeau, Jeremy; Florentine, Mary

    2009-01-01

    The primary purpose of the present experiment was to test whether the binaural equal-loudness-ratio hypothesis (i.e., the loudness ratio between monaural and binaural tones presented at the same Sound Pressure Level, SPL, is independent of SPL) holds for hearing-impaired listeners with bilaterally symmetrical hearing losses. The outcome of this experiment provided a theoretical construct for modeling loudness-growth functions. A cross-modality matching task between string length and tones was...

  6. A two-step hierarchical hypothesis set testing framework, with applications to gene expression data on ordered categories

    Science.gov (United States)

    2014-01-01

    Background In complex large-scale experiments, in addition to simultaneously considering a large number of features, multiple hypotheses are often being tested for each feature. This leads to a problem of multi-dimensional multiple testing. For example, in gene expression studies over ordered categories (such as time-course or dose-response experiments), interest is often in testing differential expression across several categories for each gene. In this paper, we consider a framework for testing multiple sets of hypothesis, which can be applied to a wide range of problems. Results We adopt the concept of the overall false discovery rate (OFDR) for controlling false discoveries on the hypothesis set level. Based on an existing procedure for identifying differentially expressed gene sets, we discuss a general two-step hierarchical hypothesis set testing procedure, which controls the overall false discovery rate under independence across hypothesis sets. In addition, we discuss the concept of the mixed-directional false discovery rate (mdFDR), and extend the general procedure to enable directional decisions for two-sided alternatives. We applied the framework to the case of microarray time-course/dose-response experiments, and proposed three procedures for testing differential expression and making multiple directional decisions for each gene. Simulation studies confirm the control of the OFDR and mdFDR by the proposed procedures under independence and positive correlations across genes. Simulation results also show that two of our new procedures achieve higher power than previous methods. Finally, the proposed methodology is applied to a microarray dose-response study, to identify 17 β-estradiol sensitive genes in breast cancer cells that are induced at low concentrations. Conclusions The framework we discuss provides a platform for multiple testing procedures covering situations involving two (or potentially more) sources of multiplicity. The framework is easy to

  7. Testing the social identity-intergroup differentiation hypothesis: 'We're not American eh!'.

    Science.gov (United States)

    Lalonde, Richard N

    2002-12-01

    The social identity-intergroup differentiation hypothesis is a hotly debated issue among social identity researchers (Brown, 2000; Turner, 1999); it states that individuals having a stronger in-group identification will perceive greater differences between their in-group and a relevant out-group. This study examines the importance of three factors when testing this hypothesis: the strength and salience of in-group identification, the relevance of the out-group for social comparison, and the relevance of the dimension of social comparison. The hypothesis was examined in relation to the national identity of a sample of Canadian students. Perceptions of the in-group and out-groups were measured at Time 1 (N =171). The same measures were given at Time 2 (N = 77), along with a variety of measures of social identity. It was predicted that this hypothesis would be supported when the dimension of social comparison was of high relevance and only for an important social comparison group (i.e. Americans). Finally, the ability of identity to predict differentiation at another point in time was examined in order to examine the issue of identity salience and stability. Results generally supported the hypotheses and are discussed in relation to prior research and the conceptualization of a minority identity.

  8. Testing the Glucose Hypothesis among Capuchin Monkeys: Does Glucose Boost Self-Control?

    Science.gov (United States)

    Parrish, Audrey E; Emerson, Ishara D; Rossettie, Mattea S; Beran, Michael J

    2016-08-03

    The ego-depletion hypothesis states that self-control diminishes over time and with exertion. Accordingly, the glucose hypothesis attributes this depletion of self-control resources to decreases in blood glucose levels. Research has led to mixed findings among humans and nonhuman animals, with limited evidence for such a link between glucose and self-control among closely-related nonhuman primate species, but some evidence from more distantly related species (e.g., honeybees and dogs). We tested this hypothesis in capuchin monkeys by manipulating the sugar content of a calorie-matched breakfast meal following a nocturnal fast, and then presenting each monkey with the accumulation self-control task. Monkeys were presented with food items one-by-one until the subject retrieved and ate the accumulating items, which required continual inhibition of food retrieval in the face of an increasingly desirable reward. Results indicated no relationship between self-control performance on the accumulation task and glucose ingestion levels following a fast. These results do not provide support for the glucose hypothesis of self-control among capuchin monkeys within the presented paradigm. Further research assessing self-control and its physiological correlates among closely- and distantly-related species is warranted to shed light on the mechanisms underlying self-control behavior.

  9. The comprehension of sentences with unaccusative verbs in aphasia: a test of the intervener hypothesis.

    Science.gov (United States)

    Sullivan, Natalie; Walenski, Matthew; Love, Tracy; Shapiro, Lewis P

    2017-01-01

    It is well accepted that individuals with agrammatic Broca's aphasia have difficulty comprehending some sentences with filler-gap dependencies. While investigations of these difficulties have been conducted with several different sentence types (e.g., object relatives, Wh -questions), we explore sentences containing unaccusative verbs, which arguably have a single noun phrase (NP) that is base-generated in object position but then is displaced to surface subject position. Unaccusative verbs provide an ideal test case for a particular hypothesis about the comprehension disorder-the Intervener Hypothesis-that posits that the difficulty individuals with agrammatic Broca's aphasia have comprehending sentences containing filler-gap dependencies results from similarity-based interference caused by the presence of an intervening NP between the two elements of a syntactic chain. To assess a particular account of the comprehension deficit in agrammatic Broca's aphasia-the Intervener Hypothesis. We used a sentence-picture matching task to determine if listeners with agrammatic Broca's aphasia (LWBA) and age-matched neurologically unimpaired controls (AMC) have difficulty comprehending unaccusative verbs when placed in subject relative and complement phrase (CP) constructions. We found above-chance comprehension of both sentence constructions with the AMC participants. In contrast, we found above-chance comprehension of CP sentences containing unaccusative verbs but poor comprehension of subject relative sentences containing unaccusative verbs for the LWBA. These results provide support for the Intervener Hypothesis, wherein the presence of an intervening NP between two elements of a filler-gap dependency adversely affects sentence comprehension.

  10. Testing the sexual imagination hypothesis for gender differences in response to infidelity.

    Science.gov (United States)

    Kato, Tsukasa

    2014-11-29

    Evolutionary psychologists hypothesized that men are more upset by sexual infidelity than women are, whereas women are more upset by emotional infidelity than men are. On the other hand, the sexual imagination hypothesis states that gender differences in infidelity responses are derived from explicit men's sexual imagery. Based on the latter hypothesis, we hypothesized that although men would report being more distressed by sexual infidelity than women who were not in a committed relationship (NCR), no gender difference would be reported in a committed relationship (CR). These two hypotheses were tested with 598 participants in a CR and 1,643 participants in a NCR. No significant gender difference was found sexual infidelity response in the CR group (d=0.008, a power of .956), whereas men were more upset than women about sexual infidelity in the NCR group. Moreover, a significant interaction between gender and infidelity type was found in the NCR, whereas no significant interaction between gender and infidelity type was observed in the CR group (partial η2=0.005, a power of .943). Our findings supported the sexual imagination hypothesis but were inconsistent with the EJM hypothesis.

  11. On-line Flagging of Anomalies and Adaptive Sequential Hypothesis Testing for Fine-feature Characterization of Geosynchronous Satellites

    Science.gov (United States)

    2015-10-18

    1 AMOS Technical Conference 2015 On-line Flagging of Anomalies and Adaptive Sequential Hypothesis Testing for Fine-feature Characterization of...features will be reported along with the probabilities of type I and type II errors. The objective of adaptive sequential hypothesis testing in this...chosen fine feature. The combined objective of on-line flagging and adaptive sequential hypothesis testing is to progressively discover new

  12. Advertising investment as a tool for boosting consumption: testing Galbraith's hypothesis for Spain

    Directory of Open Access Journals (Sweden)

    Valentín-Alejandro Martínez-Fernández

    2014-12-01

    Full Text Available The recession that most of the world economies have been facing in the last years has caused a great interest in the study of its macroeconomic effects. In this context, a debate has resurged regarding the advertising investment, as for its potential capacity to impel the consumer spending and to impact positively on the economic recovery. This idea, sustained in the so-called Galbraith's hypothesis, constitutes the core of this paper, where the main objective is to test that hypothesis by means of an empirical analysis. In this study, we focus on the Spanish case and the data correspond to the period 1976 -2010. A cointegration analysis is carried out, using two different approaches (Engle-Granger test and Gregory-Hansen test, respectively, to determine if there is any relationship between the advertising investment and six macromagnitudes (GDP, National Income, Consumption, Savings and Fixed Capital Formation, as well as the registered unemployment rate. Based on the results obtained, we conclude that Galbraith's hypothesis is not fulfilled for the Spanish case.

  13. The null hypothesis significance test in health sciences research (1995-2006): statistical analysis and interpretation.

    Science.gov (United States)

    Silva-Ayçaguer, Luis Carlos; Suárez-Gil, Patricio; Fernández-Somoano, Ana

    2010-05-19

    The null hypothesis significance test (NHST) is the most frequently used statistical method, although its inferential validity has been widely criticized since its introduction. In 1988, the International Committee of Medical Journal Editors (ICMJE) warned against sole reliance on NHST to substantiate study conclusions and suggested supplementary use of confidence intervals (CI). Our objective was to evaluate the extent and quality in the use of NHST and CI, both in English and Spanish language biomedical publications between 1995 and 2006, taking into account the International Committee of Medical Journal Editors recommendations, with particular focus on the accuracy of the interpretation of statistical significance and the validity of conclusions. Original articles published in three English and three Spanish biomedical journals in three fields (General Medicine, Clinical Specialties and Epidemiology - Public Health) were considered for this study. Papers published in 1995-1996, 2000-2001, and 2005-2006 were selected through a systematic sampling method. After excluding the purely descriptive and theoretical articles, analytic studies were evaluated for their use of NHST with P-values and/or CI for interpretation of statistical "significance" and "relevance" in study conclusions. Among 1,043 original papers, 874 were selected for detailed review. The exclusive use of P-values was less frequent in English language publications as well as in Public Health journals; overall such use decreased from 41% in 1995-1996 to 21% in 2005-2006. While the use of CI increased over time, the "significance fallacy" (to equate statistical and substantive significance) appeared very often, mainly in journals devoted to clinical specialties (81%). In papers originally written in English and Spanish, 15% and 10%, respectively, mentioned statistical significance in their conclusions. Overall, results of our review show some improvements in statistical management of statistical results

  14. Low Self-Control Among South Korean Adolescents: A Test of Gottfredson and Hirschi's Generality Hypothesis.

    Science.gov (United States)

    Yun, Ilhong; Kim, Seung-Gon; Kwon, Sangro

    2016-08-01

    Theoretical propositions and empirical tests of Gottfredson and Hirschi's general theory continue to permeate the criminological literature. Nevertheless, the vast majority of studies have been conducted in North America and some European countries. Only a handful of empirical works have been conducted in East Asia. To further test the generality assertion of Gottfredson and Hirschi, the current study examines low self-control's efficacy in predicting the involvement of South Korean adolescents in typical delinquency, drinking, smoking, Internet addiction, and smartphone addiction. The presented findings largely support the generality hypothesis, although the theorists' assertion seems to be somewhat overstated. © The Author(s) 2015.

  15. Evaluation of the cholinergic hypothesis in Alzheimer's disease with neuropsychological methods.

    Science.gov (United States)

    Fotiou, Dimitrios; Kaltsatou, Antonia; Tsiptsios, Dimitrios; Nakou, Maria

    2015-10-01

    This study aimed at evaluating the cholinergic hypothesis in Alzheimer's disease (AD) patients utilizing the pupillometry method, cognitive tests and Hamilton Depression Rating Scale (HAM-D), as well as to examine whether a correlation between cognitive tests and pupillometry exists. Forty-two patients with mean age 69.2 ± 7.0 years and documented AD volunteered to participate in this study, while 33 healthy matched subjects served as controls. All subjects underwent a pupillometric measurement and performed the Wechsler Memory Scale (WMS) and Mini Mental State Examination (MMSE). Also, HAM-D was used to assess the severity of depressive symptoms. The pupillometric parameters studied were (1) latency for the onset of constriction (T1), (2) maximum constriction velocity (VCmax), and (3) maximum constriction acceleration (ACmax). In AD patients MMSE and WMS score were correlated with ACmax (r = -0.409, p mean scores of VCmax and ACmax were significantly decreased in AD patients by 46 % (p < 0.05) and by 47 % (p < 0.05), respectively, as compared to healthy subjects. There was no significant difference between the two groups for HAM-D. Additionally, AD patients showed decreased score in WMS by 40 % (p < 0.05) and in MMSE by 28.5 % (p < 0.05) compared to healthy subjects. Of the indices that were studied VCmax and ACmax are governed mainly by the action of the Parasympathetic Nervous System. The results of this study demonstrated that there is a correlation between cognitive tests and pupillometry in AD patients. Thus, pupillometry could be considered as a sensitive technique for the investigation of cholinergic deficits, which indirectly lead to memory and cognitive disorders in AD patients.

  16. Neuroticism, intelligence, and intra-individual variability in elementary cognitive tasks: testing the mental noise hypothesis.

    Science.gov (United States)

    Colom, Roberto; Quiroga, Ma Angeles

    2009-08-01

    Some studies show positive correlations between intraindividual variability in elementary speed measures (reflecting processing efficiency) and individual differences in neuroticism (reflecting instability in behaviour). The so-called neural noise hypothesis assumes that higher levels of noise are related both to smaller indices of processing efficiency and greater levels of neuroticism. Here, we test this hypothesis measuring mental speed by means of three elementary cognitive tasks tapping similar basic processes but varying systematically their content (verbal, numerical, and spatial). Neuroticism and intelligence are also measured. The sample comprised 196 undergraduate psychology students. The results show that (1) processing efficiency is generally unrelated to individual differences in neuroticism, (2) processing speed and efficiency correlate with intelligence, and (3) only the efficiency index is genuinely related to intelligence when the colinearity between speed and efficiency is controlled.

  17. Perceptual and linguistic interactions in speeded classification: tests of the semantic coding hypothesis.

    Science.gov (United States)

    Martino, G; Marks, L E

    1999-01-01

    We tested the semantic coding hypothesis, which states that cross-modal interactions observed in speeded classification tasks arise after perceptual information is recoded into an abstract format common to perceptual and linguistic systems. Using a speeded classification task, we first confirmed the presence of congruence interactions between auditory pitch and visual lightness and observed Garner-type interference with nonlinguistic (perceptual) stimuli (low-frequency and high-frequency tones, black and white squares). Subsequently, we found that modifying the visual stimuli by (a) making them lexical (related words) or (b) reducing their compactness or figural 'goodness' altered congruence effects and Garner interference. The results are consistent with the semantic coding hypothesis, but only in part, and suggest the need for additional assumptions regarding the role of perceptual organization in cross-modal dimensional interactions.

  18. Chunking away task-switch costs: a test of the chunk-point hypothesis.

    Science.gov (United States)

    Schneider, Darryl W; Logan, Gordon D

    2015-06-01

    Previous research has revealed that task-switch costs (worse performance for task switches than for task repetitions) at the first position of an explicit task sequence are eliminated or reduced when repeating or switching sequences. The authors hypothesize that such effects are restricted to points in the sequence representation that are associated with sequence-level processing such as chunk retrieval that changes the contents of working memory. In an experiment testing this chunk-point hypothesis, subjects memorized and performed explicit task sequences under different chunking instructions that induced chunk points at different positions within the sequences. Regardless of position, performance was slower at chunk points than at non-chunk points, providing direct evidence of chunking, and task-switch costs were reduced or eliminated at chunk points while they remained large and robust at non-chunk points. These findings support the chunk-point hypothesis and are discussed in relation to task-set inhibition and associative interference.

  19. More individuals but fewer species: testing the 'more individuals hypothesis' in a diverse tropical fauna.

    Science.gov (United States)

    McGlynn, Terrence P; Weiser, Michael D; Dunn, Robert R

    2010-08-23

    A positive relationship between species richness and productivity is often observed in nature, but the causes remain contentious. One mechanism, the 'more individuals hypothesis' (MIH), predicts richness increases monotonically with density, as a function of resource flux. To test the MIH, we manipulated resource abundance in a community of tropical rainforest litter ants and measured richness and density responses. A unimodal relationship between richness and density most closely fitted the control and disturbance (resource removal) treatments in contrast to expectations of the MIH. Resource addition resulted in a monotonic increase in richness relative to density, a shift from the pattern in the control. In the disturbance treatment, richness was greater than in the control, opposite to expectations of the MIH. While large-scale correlations between ant diversity and net primary productivity or temperature are reconcilable with the MIH, key elements of the hypothesis are not supported.

  20. A General Class of Test Statistics for Van Valen's Red Queen Hypothesis.

    Science.gov (United States)

    Wiltshire, Jelani; Huffer, Fred W; Parker, William C

    2014-09-01

    Van Valen's Red Queen hypothesis states that within a homogeneous taxonomic group the age is statistically independent of the rate of extinction. The case of the Red Queen hypothesis being addressed here is when the homogeneous taxonomic group is a group of similar species. Since Van Valen's work, various statistical approaches have been used to address the relationship between taxon age and the rate of extinction. We propose a general class of test statistics that can be used to test for the effect of age on the rate of extinction. These test statistics allow for a varying background rate of extinction and attempt to remove the effects of other covariates when assessing the effect of age on extinction. No model is assumed for the covariate effects. Instead we control for covariate effects by pairing or grouping together similar species. Simulations are used to compare the power of the statistics. We apply the test statistics to data on Foram extinctions and find that age has a positive effect on the rate of extinction. A derivation of the null distribution of one of the test statistics is provided in the supplementary material.

  1. Phi Index: A New Metric to Test the Flush Early and Avoid the Rush Hypothesis

    Science.gov (United States)

    Samia, Diogo S. M.; Blumstein, Daniel T.

    2014-01-01

    Optimal escape theory states that animals should counterbalance the costs and benefits of flight when escaping from a potential predator. However, in apparent contradiction with this well-established optimality model, birds and mammals generally initiate escape soon after beginning to monitor an approaching threat, a phenomena codified as the “Flush Early and Avoid the Rush” (FEAR) hypothesis. Typically, the FEAR hypothesis is tested using correlational statistics and is supported when there is a strong relationship between the distance at which an individual first responds behaviorally to an approaching predator (alert distance, AD), and its flight initiation distance (the distance at which it flees the approaching predator, FID). However, such correlational statistics are both inadequate to analyze relationships constrained by an envelope (such as that in the AD-FID relationship) and are sensitive to outliers with high leverage, which can lead one to erroneous conclusions. To overcome these statistical concerns we develop the phi index (Φ), a distribution-free metric to evaluate the goodness of fit of a 1∶1 relationship in a constraint envelope (the prediction of the FEAR hypothesis). Using both simulation and empirical data, we conclude that Φ is superior to traditional correlational analyses because it explicitly tests the FEAR prediction, is robust to outliers, and it controls for the disproportionate influence of observations from large predictor values (caused by the constrained envelope in AD-FID relationship). Importantly, by analyzing the empirical data we corroborate the strong effect that alertness has on flight as stated by the FEAR hypothesis. PMID:25405872

  2. [Training in iterative hypothesis testing as part of psychiatric education. A randomized study].

    Science.gov (United States)

    Lampen-Imkamp, S; Alte, C; Sipos, V; Kordon, A; Hohagen, F; Schweiger, U; Kahl, K G

    2012-01-01

    The improvement of medical education is at the center of efforts to reform the studies of medicine. Furthermore, an excellent teaching program for students is a quality feature of medical universities. Besides teaching of disease-specific contents, the acquisition of interpersonal and decision-making skills is important. However, the cognitive style of senior physicians leading to a diagnosis cannot easily be taught. Therefore, the following study aimed at examining whether specific training in iterative hypothesis testing (IHT) may improve the correctness of the diagnostic process. Seventy-one medical students in their 9th-11th terms were randomized to medical teaching as usual or to IHT training for 4 weeks. The intervention group received specific training according to the method of IHT. All students were examined by a multiple choice (MC) exam and additionally by simulated patients (SP). The SPs were instructed to represent either a patient with depression and comorbid anxiety and substance use disorder (SP1) or to represent a patient with depression, obsessive-compulsive disorder and acute suicidal tendencies (SP2). All students identified the diagnosis of major depression in the SPs, but IHT-trained students recognized more diagnostic criteria. Furthermore, IHT-trained students recognized acute suicide tendencies in SP2 more often and identified more comorbid psychiatric disorders. The results of the MC exam were comparable in both groups. An analysis of the satisfaction with the different training programs revealed that the IHT training received a better appraisal. Our results point to the role of IHT in teaching diagnostic skills. However, the results of the MC exam were not influenced by IHT training. Furthermore, our results show that students are in need of training in practical clinical skills.

  3. Paranormal psychic believers and skeptics: a large-scale test of the cognitive differences hypothesis.

    Science.gov (United States)

    Gray, Stephen J; Gallo, David A

    2016-02-01

    Belief in paranormal psychic phenomena is widespread in the United States, with over a third of the population believing in extrasensory perception (ESP). Why do some people believe, while others are skeptical? According to the cognitive differences hypothesis, individual differences in the way people process information about the world can contribute to the creation of psychic beliefs, such as differences in memory accuracy (e.g., selectively remembering a fortune teller's correct predictions) or analytical thinking (e.g., relying on intuition rather than scrutinizing evidence). While this hypothesis is prevalent in the literature, few have attempted to empirically test it. Here, we provided the most comprehensive test of the cognitive differences hypothesis to date. In 3 studies, we used online screening to recruit groups of strong believers and strong skeptics, matched on key demographics (age, sex, and years of education). These groups were then tested in laboratory and online settings using multiple cognitive tasks and other measures. Our cognitive testing showed that there were no consistent group differences on tasks of episodic memory distortion, autobiographical memory distortion, or working memory capacity, but skeptics consistently outperformed believers on several tasks tapping analytical or logical thinking as well as vocabulary. These findings demonstrate cognitive similarities and differences between these groups and suggest that differences in analytical thinking and conceptual knowledge might contribute to the development of psychic beliefs. We also found that psychic belief was associated with greater life satisfaction, demonstrating benefits associated with psychic beliefs and highlighting the role of both cognitive and noncognitive factors in understanding these individual differences.

  4. Coal - testing methods

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-04-01

    This Standard specifies the method for the particle-size analysis, the method for determination of the float and sink characteristics, the method for determination of Hardgrove grindability indices, the method for determination of the crucible swelling number, the method for determination of the swelling properties, the method for determination of the fluidity properties, the method for determination of the coking properties, the method for determination of the fusibility of ash, and the method for determination of Roga indices of coal.

  5. Hypothesis Testing of Inclusion of the Tolerance Interval for the Assessment of Food Safety.

    Directory of Open Access Journals (Sweden)

    Hungyen Chen

    Full Text Available In the testing of food quality and safety, we contrast the contents of the newly proposed food (genetically modified food against those of conventional foods. Because the contents vary largely between crop varieties and production environments, we propose a two-sample test of substantial equivalence that examines the inclusion of the tolerance intervals of the two populations, the population of the contents of the proposed food, which we call the target population, and the population of the contents of the conventional food, which we call the reference population. Rejection of the test hypothesis guarantees that the contents of the proposed foods essentially do not include outliers in the population of the contents of the conventional food. The existing tolerance interval (TI0 is constructed to have at least a pre-specified level of the coverage probability. Here, we newly introduce the complementary tolerance interval (TI1 that is guaranteed to have at most a pre-specified level of the coverage probability. By applying TI0 and TI1 to the samples from the target population and the reference population respectively, we construct a test statistic for testing inclusion of the two tolerance intervals. To examine the performance of the testing procedure, we conducted a simulation that reflects the effects of gene and environment, and residual from a crop experiment. As a case study, we applied the hypothesis testing to test if the distribution of the protein content of rice in Kyushu area is included in the distribution of the protein content in the other areas in Japan.

  6. Human skin-color sexual dimorphism: a test of the sexual selection hypothesis.

    Science.gov (United States)

    Madrigal, Lorena; Kelly, William

    2007-03-01

    Applied to skin color, the sexual selection hypothesis proposes that male preference for light-skinned females explains the presence of light skin in areas of low solar radiation. According to this proposal, in areas of high solar radiation, natural selection for dark skin overrides the universal preference of males for light females. But in areas in which natural selection ceases to act, sexual selection becomes more important, and causes human populations to become light-skinned, and females to be lighter than males. The sexual selection hypothesis proposes that human sexual dimorphism of skin color should be positively correlated with distance from the equator. We tested the prediction that sexual dimorphism should increase with increasing latitude, using adult-only data sets derived from measurements with standard reflectance spectrophotometric devices. Our analysis failed to support the prediction of a positive correlation between increasing distance from the equator and increased sexual dimorphism. We found no evidence in support of the sexual selection hypothesis. (c) 2006 Wiley-Liss, Inc.

  7. Sexual and physical abuse in women with fibromyalgia syndrome: a test of the trauma hypothesis.

    Science.gov (United States)

    Ciccone, Donald S; Elliott, Deborah K; Chandler, Helena K; Nayak, Sangeetha; Raphael, Karen G

    2005-01-01

    According to the trauma hypothesis, women with fibromyalgia syndrome (FMS) are more likely to report a history of sexual and/or physical abuse than women without FMS. In this study, we rely on a community sample to test this hypothesis and the related prediction that women with FMS are more likely to have posttraumatic stress disorder than women without FMS. Eligibility for the present study was limited to an existing community sample in which FMS and major depressive disorder were prevalent. The unique composition of the original sample allowed us to recruit women with and without FMS from the community. A total of 52 female participants were enrolled in the present FMS group and 53 in the control (no FMS) group. Sexual and physical abuse were assessed retrospectively using a standardized telephone interview. Except for rape, sexual and physical abuse were reported equally often by women in the FMS and control groups. Women who reported rape were 3.1 times more likely to have FMS than women who did not report rape (Prape, no self-reported sexual or physical abuse event was associated with FMS in this community sample. In accord with the trauma hypothesis, however, posttraumatic stress disorder was more prevalent in the FMS group. Chronic stress in the form of posttraumatic stress disorder but not major depressive disorder may mediate the relationship between rape and FMS.

  8. A test of the hypothesis that time to tumor in humans fits the "one-hit" model.

    Science.gov (United States)

    Dorvlo, A S; Enslein, K; Salsburg, D

    1980-08-01

    Data from the Connecticut Tumor Registry for 1935-1968 for 14 tumor sites were subjected to formal statistical tests of the hypothesis that the time to tumor has an exponential distribution (and hence is a result of one random "hit"). All of the resulting 270 test statistics rejected the hypothesis.

  9. How are lung cancer risk perceptions and cigarette smoking related?-testing an accuracy hypothesis.

    Science.gov (United States)

    Chen, Lei-Shih; Kaphingst, Kimberly A; Tseng, Tung-Sung; Zhao, Shixi

    2016-10-01

    Subjective risk perception is an important theoretical construct in the field of cancer prevention and control. Although the relationship between subjective risk perception and health behaviors has been widely studied in many health contexts, the causalities and associations between the risk perception of developing lung cancer and cigarette smoking have been inconsistently reported among studies. Such inconsistency may be from discrepancies between study designs (cross-sectional versus longitudinal designs) and the three hypotheses (i.e., the behavior motivation hypothesis, the risk reappraisals hypothesis, and the accuracy hypothesis) testing different underlying associations between risk perception and cigarette-smoking behaviors. To clarify this issue, as an initial step, we examined the association between absolute and relative risk perceptions of developing lung cancer and cigarette-smoking behaviors among a large, national representative sample of 1,680 U.S. adults by testing an accuracy hypothesis (i.e., people who smoke accurately perceived a higher risk of developing lung cancer). Data from the U.S. Health Information National Trends Survey (HINTS) were analyzed using logistic regression and multivariate linear regression to examine the associations between risk perception and cigarette-smoking behaviors among 1,680 U.S. adults. Findings from this cross-sectional survey suggest that absolute and relative risk perceptions were positively and significantly correlated with having smoked >100 cigarettes during lifetime and the frequency of cigarette smoking. Only absolute risk perception was significantly associated with the number of cigarettes smoked per day among current smokers. Because both absolute and relative risk perceptions are positively related to most cigarette-smoking behaviors, this study supports the accuracy hypothesis. Moreover, absolute risk perception might be a more sensitive measurement than relative risk perception for perceived lung

  10. A SIMPLE BUT EFFICIENT SCHEME FOR COLOUR IMAGE RETRIEVAL BASED ON STATISTICAL TESTS OF HYPOTHESIS

    Directory of Open Access Journals (Sweden)

    K. Seetharaman

    2011-02-01

    Full Text Available This paper proposes a simple but efficient scheme for colour image retrieval, based on statistical tests of hypothesis, namely test for equality of variance, test for equality of mean. The test for equality of variance is performed to test the similarity of the query and target images. If the images pass the test, then the test for equality of mean is performed on the same images to examine whether the two images have the same attributes / characteristics. If the query and target images pass the tests then it is inferred that the two images belong to the same class i.e. both the images are same; otherwise, it is assumed that the images belong to different classes i.e. both the images are different. The obtained test statistic values are indexed in ascending order and the image corresponding to the least value is identified as same / similar images. The proposed system is invariant for translation, scaling, and rotation, since the proposed system adjusts itself and treats either the query image or the target image is sample of other. The proposed scheme provides cent percent accuracy if the query and target images are same, whereas there is a slight variation for similar, transformed.

  11. Acceptance sampling for attributes via hypothesis testing and the hypergeometric distribution

    Science.gov (United States)

    Samohyl, Robert Wayne

    2017-10-01

    This paper questions some aspects of attribute acceptance sampling in light of the original concepts of hypothesis testing from Neyman and Pearson (NP). Attribute acceptance sampling in industry, as developed by Dodge and Romig (DR), generally follows the international standards of ISO 2859, and similarly the Brazilian standards NBR 5425 to NBR 5427 and the United States Standards ANSI/ASQC Z1.4. The paper evaluates and extends the area of acceptance sampling in two directions. First, by suggesting the use of the hypergeometric distribution to calculate the parameters of sampling plans avoiding the unnecessary use of approximations such as the binomial or Poisson distributions. We show that, under usual conditions, discrepancies can be large. The conclusion is that the hypergeometric distribution, ubiquitously available in commonly used software, is more appropriate than other distributions for acceptance sampling. Second, and more importantly, we elaborate the theory of acceptance sampling in terms of hypothesis testing rigorously following the original concepts of NP. By offering a common theoretical structure, hypothesis testing from NP can produce a better understanding of applications even beyond the usual areas of industry and commerce such as public health and political polling. With the new procedures, both sample size and sample error can be reduced. What is unclear in traditional acceptance sampling is the necessity of linking the acceptable quality limit (AQL) exclusively to the producer and the lot quality percent defective (LTPD) exclusively to the consumer. In reality, the consumer should also be preoccupied with a value of AQL, as should the producer with LTPD. Furthermore, we can also question why type I error is always uniquely associated with the producer as producer risk, and likewise, the same question arises with consumer risk which is necessarily associated with type II error. The resolution of these questions is new to the literature. The

  12. Statistical power analysis a simple and general model for traditional and modern hypothesis tests

    CERN Document Server

    Murphy, Kevin R; Wolach, Allen

    2014-01-01

    Noted for its accessible approach, this text applies the latest approaches of power analysis to both null hypothesis and minimum-effect testing using the same basic unified model. Through the use of a few simple procedures and examples, the authors show readers with little expertise in statistical analysis how to obtain the values needed to carry out the power analysis for their research. Illustrations of how these analyses work and how they can be used to choose the appropriate criterion for defining statistically significant outcomes are sprinkled throughout. The book presents a simple and g

  13. Spatio-temporal conditional inference and hypothesis tests for neural ensemble spiking precision

    Science.gov (United States)

    Harrison, Matthew T.; Amarasingham, Asohan; Truccolo, Wilson

    2014-01-01

    The collective dynamics of neural ensembles create complex spike patterns with many spatial and temporal scales. Understanding the statistical structure of these patterns can help resolve fundamental questions about neural computation and neural dynamics. Spatio-temporal conditional inference (STCI) is introduced here as a semiparametric statistical framework for investigating the nature of precise spiking patterns from collections of neurons that is robust to arbitrarily complex and nonstationary coarse spiking dynamics. The main idea is to focus statistical modeling and inference, not on the full distribution of the data, but rather on families of conditional distributions of precise spiking given different types of coarse spiking. The framework is then used to develop families of hypothesis tests for probing the spatio-temporal precision of spiking patterns. Relationships among different conditional distributions are used to improve multiple hypothesis testing adjustments and to design novel Monte Carlo spike resampling algorithms. Of special note are algorithms that can locally jitter spike times while still preserving the instantaneous peri-stimulus time histogram (PSTH) or the instantaneous total spike count from a group of recorded neurons. The framework can also be used to test whether first-order maximum entropy models with possibly random and time-varying parameters can account for observed patterns of spiking. STCI provides a detailed example of the generic principle of conditional inference, which may be applicable in other areas of neurostatistical analysis. PMID:25380339

  14. Hypothesis to Explain the Size Effect Observed in APO-BMI Compression Tests

    Energy Technology Data Exchange (ETDEWEB)

    Schembri, Philip Edward [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Siranosian, Antranik Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kingston, Lance Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-01-07

    In 2013 compression tests were performed on cylindrical specimens of carbon-microballoon-APOBMI syntactic foam machined to different lengths (0.25, 0.5, and 2.8 inches1) (Kingston, 2013). In 2014 similar tests were performed on glass-microballoon-APO-BMI of different lengths (~0.15”, ~0.32”, and ~0.57”). In all these tests it was observed that, when strains were calculated from the platen displacement (corrected for machine compliance), the apparent Young’s modulus of the material decreased with specimen size, as shown in Table 1. The reason for this size effect was speculated to be a layer of damage on or near the top and bottom machined surfaces of the specimens (Kingston, Schembri, & Siranosian, 2014). This report examines that hypothesis in further detail.

  15. Exact Hypothesis Tests for Log-linear Models with exactLoglinTest

    Directory of Open Access Journals (Sweden)

    Brian Caffo

    2006-11-01

    Full Text Available This manuscript overviews exact testing of goodness of fit for log-linear models using the R package exactLoglinTest. This package evaluates model fit for Poisson log-linear models by conditioning on minimal sufficient statistics to remove nuisance parameters. A Monte Carlo algorithm is proposed to estimate P values from the resulting conditional distribution. In particular, this package implements a sequentially rounded normal approximation and importance sampling to approximate probabilities from the conditional distribution. Usually, this results in a high percentage of valid samples. However, in instances where this is not the case, a Metropolis Hastings algorithm can be implemented that makes more localized jumps within the reference set. The manuscript details how some conditional tests for binomial logit models can also be viewed as conditional Poisson log-linear models and hence can be performed via exactLoglinTest. A diverse battery of examples is considered to highlight use, features and extensions of the software. Notably, potential extensions to evaluating disclosure risk are also considered.

  16. Test of the Brink-Axel hypothesis for the pygmy dipole resonance

    CERN Document Server

    Martin, D; Tamii, A; Aoi, N; Bassauer, S; Bertulani, C A; Carter, J; Donaldson, L; Fujita, H; Fujita, Y; Hashimoto, T; Hatanaka, K; Ito, T; Krugmann, A; Liu, B; Maeda, Y; Miki, K; Neveling, R; Pietralla, N; Poltoratska, I; Ponomarev, V Yu; Richter, A; Shima, T; Yamamoto, T; Zweidinger, M

    2016-01-01

    The gamma strength function (GSF) and level density (LD) of 1- states in 96Mo have been extracted from a high-resolution study of the (p,p') reaction at 295 MeV and extreme forward angles. The GSF agrees with results of compound nucleus gamma decay experiments in the energy region of the Pygmy Dipole Resonance (PDR), validating the generalized Brink-Axel hypothesis commonly assumed in astrophysical reaction network calculations. The consistency of the LD deduced from the present data with those of the gamma decay experiments provides independent confirmation of the methods used to separate GSF and LD in Oslo-type experiments.

  17. An experimental test of the habitat-amount hypothesis for saproxylic beetles in a forested region.

    Science.gov (United States)

    Seibold, Sebastian; Bässler, Claus; Brandl, Roland; Fahrig, Lenore; Förster, Bernhard; Heurich, Marco; Hothorn, Torsten; Scheipl, Fabian; Thorn, Simon; Müller, Jörg

    2017-06-01

    The habitat-amount hypothesis challenges traditional concepts that explain species richness within habitats, such as the habitat-patch hypothesis, where species number is a function of patch size and patch isolation. It posits that effects of patch size and patch isolation are driven by effects of sample area, and thus that the number of species at a site is basically a function of the total habitat amount surrounding this site. We tested the habitat-amount hypothesis for saproxylic beetles and their habitat of dead wood by using an experiment comprising 190 plots with manipulated patch sizes situated in a forested region with a high variation in habitat amount (i.e., density of dead trees in the surrounding landscape). Although dead wood is a spatio-temporally dynamic habitat, saproxylic insects have life cycles shorter than the time needed for habitat turnover and they closely track their resource. Patch size was manipulated by adding various amounts of downed dead wood to the plots (~800 m³ in total); dead trees in the surrounding landscape (~240 km2 ) were identified using airborne laser scanning (light detection and ranging). Over 3 yr, 477 saproxylic species (101,416 individuals) were recorded. Considering 20-1,000 m radii around the patches, local landscapes were identified as having a radius of 40-120 m. Both patch size and habitat amount in the local landscapes independently affected species numbers without a significant interaction effect, hence refuting the island effect. Species accumulation curves relative to cumulative patch size were not consistent with either the habitat-patch hypothesis or the habitat-amount hypothesis: several small dead-wood patches held more species than a single large patch with an amount of dead wood equal to the sum of that of the small patches. Our results indicate that conservation of saproxylic beetles in forested regions should primarily focus on increasing the overall amount of dead wood without considering its

  18. Efficient Market Hypothesis in South Africa: Evidence from Linear and Nonlinear Unit Root Tests

    Directory of Open Access Journals (Sweden)

    Andrew Phiri

    2015-12-01

    Full Text Available This study investigates the weak form efficient market hypothesis (EMH for five generalized stock indices in the Johannesburg Stock Exchange (JSE using weekly data collected from 31st January 2000 to 16th December 2014. In particular, we test for weak form market efficiency using a battery of linear and nonlinear unit root testing procedures comprising of the classical augmented Dickey-Fuller (ADF tests, the two-regime threshold autoregressive (TAR unit root tests described in Enders and Granger (1998 as well as the three-regime unit root tests described in Bec, Salem, and Carrasco (2004. Based on our empirical analysis, we are able to demonstrate that whilst the linear unit root tests advocate for unit roots within the time series, the nonlinear unit root tests suggest that most stock indices are threshold stationary processes. These results bridge two opposing contentions obtained from previous studies by concluding that under a linear framework the JSE stock indices offer support in favour of weak form market efficiency whereas when nonlinearity is accounted for, a majority of the indices violate the weak form EMH.

  19. Testing the EKC hypothesis by considering trade openness, urbanization, and financial development: the case of Turkey.

    Science.gov (United States)

    Ozatac, Nesrin; Gokmenoglu, Korhan K; Taspinar, Nigar

    2017-07-01

    This study investigates the environmental Kuznets curve (EKC) hypothesis for the case of Turkey from 1960 to 2013 by considering energy consumption, trade, urbanization, and financial development variables. Although previous literature examines various aspects of the EKC hypothesis for the case of Turkey, our model augments the basic model with several covariates to develop a better understanding of the relationship among the variables and to refrain from omitted variable bias. The results of the bounds test and the error correction model under autoregressive distributed lag mechanism suggest long-run relationships among the variables as well as proof of the EKC and the scale effect in Turkey. A conditional Granger causality test reveals that there are causal relationships among the variables. Our findings can have policy implications including the imposition of a "polluter pays" mechanism, such as the implementation of a carbon tax for pollution trading, to raise the urban population's awareness about the importance of adopting renewable energy and to support clean, environmentally friendly technology.

  20. Recurrence network measures for hypothesis testing using surrogate data: Application to black hole light curves

    Science.gov (United States)

    Jacob, Rinku; Harikrishnan, K. P.; Misra, R.; Ambika, G.

    2018-01-01

    Recurrence networks and the associated statistical measures have become important tools in the analysis of time series data. In this work, we test how effective the recurrence network measures are in analyzing real world data involving two main types of noise, white noise and colored noise. We use two prominent network measures as discriminating statistic for hypothesis testing using surrogate data for a specific null hypothesis that the data is derived from a linear stochastic process. We show that the characteristic path length is especially efficient as a discriminating measure with the conclusions reasonably accurate even with limited number of data points in the time series. We also highlight an additional advantage of the network approach in identifying the dimensionality of the system underlying the time series through a convergence measure derived from the probability distribution of the local clustering coefficients. As examples of real world data, we use the light curves from a prominent black hole system and show that a combined analysis using three primary network measures can provide vital information regarding the nature of temporal variability of light curves from different spectroscopic classes.

  1. The interaction of implicit learning, explicit hypothesis testing learning and implicit-to-explicit knowledge extraction.

    Science.gov (United States)

    Sun, Ron; Zhang, Xi; Slusarz, Paul; Mathews, Robert

    2007-01-01

    To further explore the interaction between the implicit and explicit learning processes in skill acquisition (which have been tackled before, e.g. in [Sun, R., Merrill, E., & Peterson, T. (2001). From implicit skill to explicit knowledge: A bottom-up model of skill learning. Cognitive Science, 25(2), 203-244; Sun, R., Slusarz, P., & Terry, C. (2005). The interaction of the explicit and the implicit in skill learning: A dual-process approach. Psychological Review, 112(1), 159-192]), this paper explores details of the interaction of different learning modes: implicit learning, explicit hypothesis testing learning, and implicit-to-explicit knowledge extraction. Contrary to the common tendency in the literature to study each type of learning in isolation, this paper highlights the interaction among them and various effects of the interaction on learning, including the synergy effect. This work advocates an integrated model of skill learning that takes into account both implicit and explicit learning processes; moreover, it also uniquely embodies a bottom-up (implicit-to-explicit) learning approach in addition to other types of learning. The paper shows that this model accounts for various effects in the human behavioural data from the psychological experiments with the process control task, in addition to accounting for other data in other psychological experiments (which has been reported elsewhere). The paper shows that to account for these effects, implicit learning, bottom-up implicit-to-explicit extraction and explicit hypothesis testing learning are all needed.

  2. A TEST OF THE SIB-COMPETITION HYPOTHESIS FOR OUTCROSSING ADVANTAGE IN IMPATIENS CAPENSIS.

    Science.gov (United States)

    Schmitt, Johanna; Ehrhardt, David W

    1987-05-01

    One of the potential selective mechanisms invoked in discussions of breeding-system evolution is that competition within sibships increases the fitness of outcrossed progeny relative to selfed progeny. We tested this sib-competition hypothesis using cleistogamous (CL) and chasmogamous (CH) seeds of Impatiens capensis in a large greenhouse experiment. The experimental design was a double replacement series which also allowed us to test for inbreeding depression and overall resource partitioning among sibships. We found no evidence for strong inbreeding depression in the study population; although plants from CH seeds had a slight advantage over plants from CL seeds in total flower and pod production, CL plants had slightly higher growth. We also could not detect significant resource partitioning among sibships nor any evidence to support the sib-competition hypothesis for outcrossing advantage. CH sibships were not significantly more variable than CL sibships in any of the phenotypic traits measured. These results suggest that sibling competition may have little importance in the evolution of Impatiens breeding systems. © 1987 The Society for the Study of Evolution.

  3. Bayesian hypothesis testing for human threat conditioning research: an introduction and the condir R package.

    Science.gov (United States)

    Krypotos, Angelos-Miltiadis; Klugkist, Irene; Engelhard, Iris M

    2017-01-01

    Threat conditioning procedures have allowed the experimental investigation of the pathogenesis of Post-Traumatic Stress Disorder. The findings of these procedures have also provided stable foundations for the development of relevant intervention programs (e.g. exposure therapy). Statistical inference of threat conditioning procedures is commonly based on p-values and Null Hypothesis Significance Testing (NHST). Nowadays, however, there is a growing concern about this statistical approach, as many scientists point to the various limitations of p-values and NHST. As an alternative, the use of Bayes factors and Bayesian hypothesis testing has been suggested. In this article, we apply this statistical approach to threat conditioning data. In order to enable the easy computation of Bayes factors for threat conditioning data we present a new R package named condir, which can be used either via the R console or via a Shiny application. This article provides both a non-technical introduction to Bayesian analysis for researchers using the threat conditioning paradigm, and the necessary tools for computing Bayes factors easily.

  4. Method of constructing a fundamental equation of state based on a scaling hypothesis

    Science.gov (United States)

    Rykov, V. A.; Rykov, S. V.; Kudryavtseva, I. V.; Sverdlov, A. V.

    2017-11-01

    The work studies the issues associated with the construction of the equation of state (EOS) taking due account of substance behavior in the critical region and associated with the scaling theory of critical phenomena (ST). The authors have developed a new version of the scaling hypothesis; this approach uses the following: a) substance equation of state having a form of a Schofield-Litster-Ho linear model (LM) and b) the Benedek hypothesis. The Benedek hypothesis has found a similar behavior character for a number of properties (isochoric and isobaric heat capacities, isothermal compressibility coefficient) at critical and near-critical isochors in the vicinity of the critical point. A method is proposed to build the fundamental equation of state (FEOS) which satisfies the ST power laws. The FEOS building method is verified by building the equation of state for argon within the state parameters range: up to 1000 MPa in terms of pressure, and from 83.056 К to 13000 К in terms of temperature. The executed comparison with the fundamental equations of state of Stewart-Jacobsen (1989), of Kozlov at al (1996), of Tegeler-Span-Wagner (1999), of has shown that the FEOS describes the known experimental data with an essentially lower error.

  5. Testing the fecundity advantage hypothesis with Sitobion avenae, Rhopalosiphum padi, and Schizaphis graminum (Hemiptera: Aphididae) feeding on ten wheat accessions.

    Science.gov (United States)

    Hu, Xiang-Shun; Liu, Xiao-Feng; Thieme, Thomas; Zhang, Gai-Sheng; Liu, Tong-Xian; Zhao, Hui-Yan

    2015-12-18

    The fecundity advantage hypothesis suggests that females with a large body size produce more offspring than smaller females. We tested this hypothesis by exploring the correlations between life-history traits of three aphid species feeding on ten wheat accessions at three levels of analysis with respect to the host plant: overall, inter-accession, and intra-accession. We found that fecundity was significantly correlated with mean relative growth rate (MRGR), weight gain, and development time, and that the faster aphid develops the greater body and fecundity, depending on aphid species, wheat accession, and analyses level. Larger aphids of all three species produced more offspring overall; this held true for Sitobion avenae and Schizaphis graminum at the inter-accession level, and for S. avenae, Rhopalosiphum padi, and S. graminum for three, five, and eight accessions respectively at the intra-accession level. Only one correlation, between intrinsic rates of natural increase (rm) and MRGR, was significant for all aphid species at all three analysis levels. A more accurate statement of the fecundity advantage hypothesis is that cereal aphids with greater MRGR generally maintain higher rm on wheat. Our results also provide a method for exploring relationships between individual life-history traits and population dynamics for insects on host plants.

  6. Resemblance profiles as clustering decision criteria: Estimating statistical power, error, and correspondence for a hypothesis test for multivariate structure.

    Science.gov (United States)

    Kilborn, Joshua P; Jones, David L; Peebles, Ernst B; Naar, David F

    2017-04-01

    Clustering data continues to be a highly active area of data analysis, and resemblance profiles are being incorporated into ecological methodologies as a hypothesis testing-based approach to clustering multivariate data. However, these new clustering techniques have not been rigorously tested to determine the performance variability based on the algorithm's assumptions or any underlying data structures. Here, we use simulation studies to estimate the statistical error rates for the hypothesis test for multivariate structure based on dissimilarity profiles (DISPROF). We concurrently tested a widely used algorithm that employs the unweighted pair group method with arithmetic mean (UPGMA) to estimate the proficiency of clustering with DISPROF as a decision criterion. We simulated unstructured multivariate data from different probability distributions with increasing numbers of objects and descriptors, and grouped data with increasing overlap, overdispersion for ecological data, and correlation among descriptors within groups. Using simulated data, we measured the resolution and correspondence of clustering solutions achieved by DISPROF with UPGMA against the reference grouping partitions used to simulate the structured test datasets. Our results highlight the dynamic interactions between dataset dimensionality, group overlap, and the properties of the descriptors within a group (i.e., overdispersion or correlation structure) that are relevant to resemblance profiles as a clustering criterion for multivariate data. These methods are particularly useful for multivariate ecological datasets that benefit from distance-based statistical analyses. We propose guidelines for using DISPROF as a clustering decision tool that will help future users avoid potential pitfalls during the application of methods and the interpretation of results.

  7. The ecological stoichiometry of toxins produced by harmful cyanobacteria: an experimental test of the carbon-nutrient balance hypothesis

    NARCIS (Netherlands)

    Van de Waal, D.B.; Verspagen, J.M.H.; Lürling, M.; Van Donk, E.; Visser, P.M.; Huisman, J.

    2009-01-01

    The elemental composition of primary producers reflects the availability of light, carbon and nutrients in their environment. According to the carbon-nutrient balance hypothesis, this has implications for the production of secondary metabolites. To test this hypothesis, we investigated a family of

  8. The ecological stoichiometry of toxins produced by harmful cyanobacteria: An experimental test of the carbon-nutrient balance hypothesis

    NARCIS (Netherlands)

    van de Waal, D.B.; Verspagen, J.M.H.; Lürling, M.; van Donk, E.; Visser, P.M.; Huisman, J.

    2009-01-01

    The elemental composition of primary producers reflects the availability of light, carbon and nutrients in their environment. According to the carbon-nutrient balance hypothesis, this has implications for the production of secondary metabolites. To test this hypothesis, we investigated a family of

  9. Gratitude facilitates private conformity: A test of the social alignment hypothesis.

    Science.gov (United States)

    Ng, Jomel W X; Tong, Eddie M W; Sim, Dael L Y; Teo, Samantha W Y; Loy, Xingqi; Giesbrecht, Timo

    2017-03-01

    Past research has established clear support for the prosocial function of gratitude in improving the well-being of others. The present research provides evidence for another hypothesized function of gratitude: the social alignment function, which enhances the tendency of grateful individuals to follow social norms. We tested the social alignment hypothesis of gratitude in 2 studies with large samples. Using 2 different conformity paradigms, participants were subjected to a color judgment task (Experiment 1) and a material consumption task (Experiment 2). They were provided with information showing choices allegedly made by others, but were allowed to state their responses in private. Supporting the social alignment hypothesis, the results showed that induced gratitude increased private conformity. Specifically, participants induced to feel gratitude were more likely to conform to the purportedly popular choice, even if the option was factually incorrect (Experiment 1). This effect appears to be specific to gratitude; induction of joy produced significantly less conformity than gratitude (Experiment 2). We discuss whether the social alignment function provides a behavioral pathway in the role of gratitude in building social relationships. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  10. TESTS OF THE PLANETARY HYPOTHESIS FOR PTFO 8-8695b

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Liang; Winn, Joshua N.; Rappaport, Saul; Dai, Fei; Triaud, Amaury H. M. J. [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Gillon, Michaël; Delrez, Laetitia; Jehin, Emmanuel; Lendl, Monika [Institut d’Astrophysique et de Géophysique, Université de Liège, allée du 6 Août 17, B-4000 Liège (Belgium); Albrecht, Simon [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Bieryla, Allyson; Holman, Matthew J.; Montet, Benjamin T. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Hillenbrand, Lynne [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA, 91125 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Huang, Chelsea X. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Isaacson, Howard; Sanchis-Ojeda, Roberto [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Muirhead, Philip, E-mail: yuliang@mit.edu [Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, MA 02215 (United States)

    2015-10-10

    The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted to be a consequence of orbital precession. We observed 28 fading events spread over several years and did not see the expected changes. Instead, we found that the fading events are not strictly periodic. Second, we attempted to detect the planet's radiation, based on infrared observations spanning the predicted times of occultations. We ruled out a signal of the expected amplitude. Third, we attempted to detect the Rossiter–McLaughlin effect by performing high-resolution spectroscopy throughout a fading event. No effect was seen at the expected level, ruling out most (but not all) possible orientations for the hypothetical planetary orbit. Our spectroscopy also revealed strong, time-variable, high-velocity Hα and Ca H and K emission features. All these observations cast doubt on the planetary hypothesis, and suggest instead that the fading events represent starspots, eclipses by circumstellar dust, or occultations of an accretion hotspot.

  11. Testing a hypothesis of unidirectional hybridization in plants: Observations on Sonneratia, Bruguiera and Ligularia

    Directory of Open Access Journals (Sweden)

    Wu Chung-I

    2008-05-01

    Full Text Available Abstract Background When natural hybridization occurs at sites where the hybridizing species differ in abundance, the pollen load delivered to the rare species should be predominantly from the common species. Previous authors have therefore proposed a hypothesis on the direction of hybridization: interspecific hybrids are more likely to have the female parent from the rare species and the male parent from the common species. We wish to test this hypothesis using data of plant hybridizations both from our own experimentation and from the literature. Results By examining the maternally inherited chloroplast DNA of 6 cases of F1 hybridization from four genera of plants, we infer unidirectional hybridization in most cases. In all 5 cases where the relative abundance of the parental species deviates from parity, however, the direction is predominantly in the direction opposite of the prediction based strictly on numerical abundance. Conclusion Our results show that the observed direction of hybridization is almost always opposite of the predicted direction based on the relative abundance of the hybridizing species. Several alternative hypotheses, including unidirectional postmating isolation and reinforcement of premating isolation, were discussed.

  12. Testing Bergmann's rule and the Rosenzweig hypothesis with craniometric studies of the South American sea lion.

    Science.gov (United States)

    Sepúlveda, Maritza; Oliva, Doris; Duran, L René; Urra, Alejandra; Pedraza, Susana N; Majluf, Patrícia; Goodall, Natalie; Crespo, Enrique A

    2013-04-01

    We tested the validity of Bergmann's rule and Rosenzweig's hypothesis through an analysis of the geographical variation of the skull size of Otaria flavescens along the entire distribution range of the species (except Brazil). We quantified the sizes of 606 adult South American sea lion skulls measured in seven localities of Peru, Chile, Uruguay, Argentina, and the Falkland/Malvinas Islands. Geographical and environmental variables included latitude, longitude, and monthly minimum, maximum, and mean air and ocean temperatures. We also included information on fish landings as a proxy for productivity. Males showed a positive relationship between condylobasal length (CBL) and latitude, and between CBL and the six temperature variables. By contrast, females showed a negative relationship between CBL and the same variables. Finally, female skull size showed a significant and positive correlation with fish landings, while males did not show any relationship with this variable. The body size of males conformed to Bergmann's rule, with larger individuals found in southern localities of South America. Females followed the converse of Bergmann's rule at the intraspecific level, but showed a positive relationship with the proxy for productivity, thus supporting Rosenzweig's hypothesis. Differences in the factors that drive body size in females and males may be explained by their different life-history strategies. Our analyses demonstrate that latitude and temperature are not the only factors that explain spatial variation in body size: others such as food availability are also important for explaining the ecogeographical patterns found in O. flavescens.

  13. Testing the sexually abused-sexual abuser hypothesis: A prospective longitudinal birth cohort study.

    Science.gov (United States)

    Leach, Chelsea; Stewart, Anna; Smallbone, Stephen

    2016-01-01

    The sexually abused-sexual abuser hypothesis posits that persons, especially males, who are sexually abused as children are at particular risk of sexually abusing others later in life. We tested this hypothesis by prospectively examining associations between maltreatment and offending in a birth cohort of 38,282 males with a maltreatment history and/or at least one finalized offense. We examined these associations within the context of the wider birth population. Proportionally few boys were the subject of official notifications for sexual abuse (14.8% of maltreated boys, and 1.4% of the birth population); proportionally very few of these sexually abused boys (3%) went on to become sexual offenders; and, contrary to findings typically reported in retrospective clinical studies, proportionally few sexual offenders (4%) had a confirmed history of sexual abuse. Poly-victimization (exposure to multiple types of maltreatment) was significantly associated with sexual offending, violent offending, and general (nonsexual, nonviolent) offending. We found no specific association between sexual abuse and sexual offending, and nor did we find any association between sexual abuse and sexual offending specifically within the poly-victimized group. The total number of sexual abuse notifications did make a small unique contribution to the variance in sexual offending compared to other offending. Implications concerning maltreated boys and male sexual offenders are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Testing the Coulomb stress triggering hypothesis for three recent megathrust earthquakes

    Science.gov (United States)

    Ishibe, Takeo; Ogata, Yosihiko; Tsuruoka, Hiroshi; Satake, Kenji

    2017-12-01

    We test the static Coulomb stress triggering hypothesis for three recent megathrust earthquakes (the 2004 Sumatra-Andaman earthquake, the 2010 Maule earthquake, and the 2011 Tohoku-Oki earthquake) using focal mechanism solutions for actual earthquakes as receiver faults to calculate Coulomb stress changes. For the 2004 Sumatra-Andaman and 2011 Tohoku-Oki earthquakes, the median values of the Coulomb stress changes for 100 consecutive earthquakes revealed temporal changes from approximately zero before the megathrust earthquake to significant positive values following the mainshock, followed by decay over time. Furthermore, the ratio of the number of positively to negatively stressed receiver faults increased after the megathrust. These results support the triggering hypothesis that the static stress changes imparted by megathrust earthquakes cause seismicity changes. This is in contrast to the results of a previous study that used optimally orientated receiver faults to calculate Coulomb stress changes, and this difference indicates the importance of considering the spatial and temporal heterogeneities of receiver fault distributions. For the 2010 Maule earthquake, however, the results are strongly dependent on fault-slip models. Since most receiver faults are concentrated in the mainshock source region, slip models significantly affect the computed Coulomb stress changes and sometimes cause anomalous stress concentrations along the edge of each sub-fault.

  15. Testing the lexical hypothesis: are socially important traits more densely reflected in the English lexicon?

    Science.gov (United States)

    Wood, Dustin

    2015-02-01

    Using a set of 498 English words identified by Saucier (1997) as common person-descriptor adjectives or trait terms, I tested 3 instantiations of the lexical hypothesis, which posit that more socially important person descriptors show greater density in the lexicon. Specifically, I explored whether trait terms that have greater relational impact (i.e., more greatly influence how others respond to a person) have more synonyms, are more frequently used, and are more strongly correlated with other trait terms. I found little evidence to suggest that trait terms rated as having greater relational impact were more frequently used or had more synonyms. However, these terms correlated more strongly with other trait terms in the set. Conversely, a trait term's loadings on structural factors (e.g., the Big Five, HEXACO) were extremely good predictors of the term's relational impact. The findings suggest that the lexical hypothesis may not be strongly supported in some ways it is commonly understood but is supported in the manner most important to investigations of trait structure. Specifically, trait terms with greater relational impact tend to more strongly correlate with other terms in lexical sets and thus have a greater role in driving the location of factors in analyses of trait structure. Implications for understanding the meaning of lexical factors such as the Big Five are discussed. PsycINFO Database Record (c) 2015 APA, all rights reserved.

  16. Aerial Refueling Test Methods

    Science.gov (United States)

    2015-04-13

    support of the AR Clearance Process. Covered topics include the ground and flight testing of boom/receptacle systems and probe/ drogue systems, test...REFUELING SYSTEMS ADVISORY GROUP 41-09-15 13 April 2015 v REFERENCES N° TITLE REFERENCE IS S U E DATE SOURCE 1. Probe and Drogue Aerial Refueling Data...Equipment: Probe- Drogue Interface Characteristics STANAG 3447 Ed 4 May ‘08 NATO AERIAL REFUELING SYSTEMS ADVISORY GROUP 41-09-15 13 April 2015 vi

  17. Secretive Food Concocting in Binge Eating: Test of a Famine Hypothesis

    Science.gov (United States)

    Boggiano, Mary M.; Turan, Bulent; Maldonado, Christine R.; Oswald, Kimberly D.; Shuman, Ellen S.

    2016-01-01

    Objective Food concocting, or making strange food mixtures, is well documented in the famine and experimental semistarvation literature and appears anecdotally in rare descriptions of eating disorder (ED) patients but has never been scientifically investigated. Here we do so in the context of binge-eating using a “famine hypothesis of concocting.” Method A sample of 552 adults varying in binge eating and dieting traits completed a Concocting Survey created for this study. Exploratory ED groups were created to obtain predictions as to the nature of concocting in clinical populations. Results Binge eating predicted the 24.6% of participants who reported having ever concocted but dietary restraint, independently, even after controlling for binge eating, predicted its frequency and salience. Craving was the main motive. Emotions while concocting mirrored classic high-arousal symptoms associated with drug use; while eating the concoctions were associated with intensely negative/self-deprecating emotions. Concocting prevalence and salience was greater in the anorexia > bulimia > BED > no ED groups, consistent with their respectively incrementing dieting scores. Discussion Concocting distinguishes binge eating from other overeating and, consistent with the famine hypothesis, is accounted for by dietary restraint. Unlike its adaptive function in famine, concocting could worsen binge-eating disorders by increasing negative effect, shame, and secrecy. Its assessment in these disorders may prove therapeutically valuable. PMID:23255044

  18. A test of the submentalizing hypothesis: Apes' performance in a false belief task inanimate control.

    Science.gov (United States)

    Krupenye, Christopher; Kano, Fumihiro; Hirata, Satoshi; Call, Josep; Tomasello, Michael

    2017-01-01

    Much debate concerns whether any nonhuman animals share with humans the ability to infer others' mental states, such as desires and beliefs. In a recent eye-tracking false-belief task, we showed that great apes correctly anticipated that a human actor would search for a goal object where he had last seen it, even though the apes themselves knew that it was no longer there. In response, Heyes proposed that apes' looking behavior was guided not by social cognitive mechanisms but rather domain-general cueing effects, and suggested the use of inanimate controls to test this alternative submentalizing hypothesis. In the present study, we implemented the suggested inanimate control of our previous false-belief task. Apes attended well to key events but showed markedly fewer anticipatory looks and no significant tendency to look to the correct location. We thus found no evidence that submentalizing was responsible for apes' anticipatory looks in our false-belief task.

  19. Improving space domain awareness through unequal-cost multiple hypothesis testing in the space surveillance telescope.

    Science.gov (United States)

    Hardy, Tyler; Cain, Stephen; Jeon, Jae; Blake, Travis

    2015-06-10

    This paper investigates algorithms to improve the detection of space objects with the space surveillance telescope (SST) system. These space objects include natural objects such as asteroids and artificial satellites in Earth orbit. Using a proposed multiple hypothesis test (MHT), the detection performance is compared to the currently used algorithm as well as a matched filter and an equal-cost MHT algorithm. To compare these algorithms, a data set collected by the SST of a geosynchronous Earth orbit satellite, ANIK-F1 entering the Earth's eclipse, is utilized. It is found that an unequal-cost MHT gives increased performance over a point detector, a matched filter, and equal-cost MHT over a large range of potential intensities. Results are presented as probability of detection and receiver operating characteristic curves. In addition, the performance of the algorithm as a function of number of hypotheses used is investigated.

  20. How slow breeding can be selected in seabirds: testing Lack's hypothesis.

    Science.gov (United States)

    Dobson, F Stephen; Jouventin, Pierre

    2007-01-22

    The historical debate of the 1960s between group and individual selection hinged on how the slow breeding of seabirds could be explained. While this debate was settled by the ascendance of individual selection, championed by David Lack, explanations for slow breeding in seabirds remain to be tested. We examined the slowest breeding of these birds, the albatrosses and petrels (order Procellariiformes), using analyses that statistically controlled for variations in body size and phylogeny. Incubation and fledging periods appeared strongly correlated, but this turned out to be largely explained by phylogeny. Nonetheless, developmental and reproductive rates were associated with the distance to the foraging range, as predicted under the hypothesis of ecological constraints on breeding pairs, and these results were independent of body size and phylogeny. Slower breeding in these seabirds appeared associated with the rigors of farther pelagic feeding, as Lack originally hypothesized.

  1. Note on the Cardoso-Pani-Rico parametrization to test the Kerr black hole hypothesis

    Science.gov (United States)

    Bambi, Cosimo

    2014-08-01

    The construction of a generic parametrization to describe the spacetime geometry around astrophysical black hole candidates is an important step to test the Kerr black hole hypothesis. In the last few years, the Johannsen-Psaltis metric has been the most common framework to study possible deviations from the Kerr solution with present and near-future observations. Recently, Cardoso, Pani, and Rico have proposed a more general parametrization. The aim of the present paper is to study this new metric in a specific context, namely, the thermal spectrum of geometrically thin and optically thick accretion disks. The most relevant finding is that the spacetime geometry around objects that look like very-fast-rotating Kerr black holes may still have large deviations from the Kerr solution. This is not the case with the Johannsen-Psaltis metric, which means the latter is missing an important class of non-Kerr spacetimes.

  2. Psychopathic traits and preattentive threat processing in children: a novel test of the fearlessness hypothesis.

    Science.gov (United States)

    Sylvers, Patrick D; Brennan, Patricia A; Lilienfeld, Scott O

    2011-10-01

    We tested the fearlessness hypothesis of psychopathy in an at-risk sample of 88 preadolescent children. Psychopathy was measured using combined child- and parent-reported scores on the Antisocial Process Screening Device (APSD). Using a continuous-flash-suppression paradigm, we evaluated threat processing at the preattentive level for the first time in a study of psychopathy. Scores for the APSD Callous/Unemotional factor, which assesses the core affective deficits of psychopathy, predicted preattentive face-recognition deficits for fearful faces and, to a lesser extent, for disgusted faces. This finding contradicts recent suggestions that the fearlessness associated with psychopathy is solely a consequence of overt attentional artifacts. Future research should focus on preattentive processing of fear in individuals with callous-unemotional traits, and on the implications of preattentive-processing deficits for treatment and theory development.

  3. Testing the Cuckoldry Risk Hypothesis of Partner Sexual Coercion in Community and Forensic Samples

    Directory of Open Access Journals (Sweden)

    Joseph A. Camilleri

    2009-04-01

    Full Text Available Evolutionary theory has informed the investigation of male sexual coercion but has seldom been applied to the analysis of sexual coercion within established couples. The cuckoldry risk hypothesis, that sexual coercion is a male tactic used to reduce the risk of extrapair paternity, was tested in two studies. In a community sample, indirect cues of infidelity predicted male propensity for sexual coaxing in the relationship, and direct cues predicted propensity for sexual coercion. In the forensic sample, we found that most partner rapists experienced cuckoldry risk prior to committing their offence and experienced more types of cuckoldry risk events than non-sexual partner assaulters. These findings suggest that cuckoldry risk influences male sexual coercion in established sexual relationships.

  4. Testing of hypothesis of two-dimensional random variables independence on the basis of algorithm of pattern recognition

    Science.gov (United States)

    Lapko, A. V.; Lapko, V. A.; Yuronen, E. A.

    2016-11-01

    The new technique of testing of hypothesis of random variables independence is offered. Its basis is made by nonparametric algorithm of pattern recognition. The considered technique doesn't demand sampling of area of values of random variables.

  5. Is intuition really cooperative? Improved tests support the social heuristics hypothesis.

    Science.gov (United States)

    Isler, Ozan; Maule, John; Starmer, Chris

    2018-01-01

    Understanding human cooperation is a major scientific challenge. While cooperation is typically explained with reference to individual preferences, a recent cognitive process view hypothesized that cooperation is regulated by socially acquired heuristics. Evidence for the social heuristics hypothesis rests on experiments showing that time-pressure promotes cooperation, a result that can be interpreted as demonstrating that intuition promotes cooperation. This interpretation, however, is highly contested because of two potential confounds. First, in pivotal studies compliance with time-limits is low and, crucially, evidence shows intuitive cooperation only when noncompliant participants are excluded. The inconsistency of test results has led to the currently unresolved controversy regarding whether or not noncompliant subjects should be included in the analysis. Second, many studies show high levels of social dilemma misunderstanding, leading to speculation that asymmetries in understanding might explain patterns that are otherwise interpreted as intuitive cooperation. We present evidence from an experiment that employs an improved time-pressure protocol with new features designed to induce high levels of compliance and clear tests of understanding. Our study resolves the noncompliance issue, shows that misunderstanding does not confound tests of intuitive cooperation, and provides the first independent experimental evidence for intuitive cooperation in a social dilemma using time-pressure.

  6. Evaluation of modal testing methods

    Science.gov (United States)

    Chen, J.-C.

    1984-01-01

    Modal tests are playing an increasingly important role in structural dynamics efforts which are in need of analytical model verification or trouble shootings. In the meantime, the existing modal testing methods are undergoing great changes as well as new methods are being created. Although devoted advocates of each method can be found to argue the relative advantages and disadvantages, the general superiority, if any, of one or the other is not yet evident. The Galileo spacecraft, a realistic, complex structural system, will be used as a test article for performing modal tests by various methods. The results will be used to evaluate the relative merits of the various modal testing methods.

  7. Testing the circadian gene hypothesis in prostate cancer: a population-based case-control study.

    Science.gov (United States)

    Zhu, Yong; Stevens, Richard G; Hoffman, Aaron E; Fitzgerald, Liesel M; Kwon, Erika M; Ostrander, Elaine A; Davis, Scott; Zheng, Tongzhang; Stanford, Janet L

    2009-12-15

    Circadian genes are responsible for maintaining the ancient adaptation of a 24-hour circadian rhythm and influence a variety of cancer-related biological pathways, including the regulation of sex hormone levels. However, few studies have been undertaken to investigate the role of circadian genes in the development of prostate cancer, the most common cancer type among men (excluding nonmelanoma skin cancer). The current genetic association study tested the circadian gene hypothesis in relation to prostate cancer by genotyping a total of 41 tagging and amino acid-altering single nucleotide polymorphisms (SNP) in 10 circadian-related genes in a population-based case-control study of Caucasian men (n = 1,308 cases and 1,266 controls). Our results showed that at least one SNP in nine core circadian genes (rs885747 and rs2289591 in PER1; rs7602358 in PER2; rs1012477 in PER3; rs1534891 in CSNK1E; rs12315175 in CRY1; rs2292912 in CRY2; rs7950226 in ARNTL; rs11133373 in CLOCK; and rs1369481, rs895521, and rs17024926 in NPAS2) was significantly associated with susceptibility to prostate cancer (either overall risk or risk of aggressive disease), and the risk estimate for four SNPs in three genes (rs885747 and rs2289591 in PER1, rs1012477 in PER3, and rs11133373 in CLOCK) varied by disease aggressiveness. Further analyses of haplotypes were consistent with these genotyping results. Findings from this candidate gene association study support the hypothesis of a link between genetic variants in circadian genes and prostate cancer risk, warranting further confirmation and mechanistic investigation of circadian biomarkers in prostate tumorigenesis.

  8. Maternal smoking during pregnancy and infant stress response: test of a prenatal programming hypothesis.

    Science.gov (United States)

    Stroud, Laura R; Papandonatos, George D; Rodriguez, Daniel; McCallum, Meaghan; Salisbury, Amy L; Phipps, Maureen G; Lester, Barry; Huestis, Marilyn A; Niaura, Raymond; Padbury, James F; Marsit, Carmen J

    2014-10-01

    Maternal smoking during pregnancy (MSDP) is associated with early and long-term neurobehavioral deficits; however mechanisms remain unknown. We tested the hypothesis that MSDP programs the hypothalamic pituitary adrenocortical (HPA) axis of the offspring leading to adverse outcomes. In an intensive, prospective study, we investigated associations between MSDP and infant cortisol stress response and explored whether alterations in cortisol response were mediated by epigenetic modulation of the placental glucocorticoid receptor gene (NR3C1). Participants were 100 healthy mother-infant pairs (53% MSDP-exposed; 42% female) from a low income, racially/ethnically diverse sample (55% minorities). MSDP was assessed by timeline followback interview verified by saliva and meconium cotinine. Infant cortisol responses to a neurobehavioral exam were assessed seven times over the first postnatal month. Methylation of placental NR3C1 promoter exon 1F was assessed using bisulfite pyrosequencing in a subsample (n=45). MSDP-exposed infants showed significantly and persistently attenuated basal and reactive cortisol levels over the first postnatal month vs. unexposed infants. Exploratory analyses revealed that MSDP was associated with altered methylation of the placental NR3C1 promoter; degree of methylation of the placental NR3C1 was associated with infant basal and reactive cortisol over the first postnatal month and mediated effects of MSDP on infant basal cortisol. Results provide initial support for our hypothesis that MSDP programs offspring HPA (dys)regulation. Epigenetic regulation of placental GR may serve as a novel underlying mechanism. Results may have implications for delineating pathways to adverse outcomes from MSDP. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Colour vision in ADHD: part 1--testing the retinal dopaminergic hypothesis.

    Science.gov (United States)

    Kim, Soyeon; Al-Haj, Mohamed; Chen, Samantha; Fuller, Stuart; Jain, Umesh; Carrasco, Marisa; Tannock, Rosemary

    2014-10-24

    To test the retinal dopaminergic hypothesis, which posits deficient blue color perception in ADHD, resulting from hypofunctioning CNS and retinal dopamine, to which blue cones are exquisitely sensitive. Also, purported sex differences in red color perception were explored. 30 young adults diagnosed with ADHD and 30 healthy young adults, matched on age and gender, performed a psychophysical task to measure blue and red color saturation and contrast discrimination ability. Visual function measures, such as the Visual Activities Questionnaire (VAQ) and Farnsworth-Munsell 100 hue test (FMT), were also administered. Females with ADHD were less accurate in discriminating blue and red color saturation relative to controls but did not differ in contrast sensitivity. Female control participants were better at discriminating red saturation than males, but no sex difference was present within the ADHD group. Poorer discrimination of red as well as blue color saturation in the female ADHD group may be partly attributable to a hypo-dopaminergic state in the retina, given that color perception (blue-yellow and red-green) is based on input from S-cones (short wavelength cone system) early in the visual pathway. The origin of female superiority in red perception may be rooted in sex-specific functional specialization in hunter-gather societies. The absence of this sexual dimorphism for red colour perception in ADHD females warrants further investigation.

  10. Unequal a priori probability multiple hypothesis testing in space domain awareness with the space surveillance telescope.

    Science.gov (United States)

    Hardy, Tyler; Cain, Stephen; Blake, Travis

    2016-05-20

    This paper investigates the ability to improve Space Domain Awareness (SDA) by increasing the number of detectable Resident Space Objects (RSOs) from space surveillance sensors. With matched filter based techniques, the expected impulse response, or Point Spread Function (PSF), is compared against the received data. In the situation where the images are spatially undersampled, the modeled PSF may not match the received data if the RSO does not fall in the center of the pixel. This aliasing can be accounted for with a Multiple Hypothesis Test (MHT). Previously, proposed MHTs have implemented a test with an equal a priori prior probability assumption. This paper investigates using an unequal a priori probability MHT. To determine accurate a priori probabilities, three metrics are computed; they are correlation, physical distance, and empirical. Using the calculated a priori probabilities, a new algorithm is developed, and images from the Space Surveillance Telescope (SST) are analyzed. The number of detected objects by both an equal and unequal prior probabilities are compared while keeping the false alarm rate constant. Any additional number of detected objects will help improve SDA capabilities.

  11. Interpretations of Directed Information in Portfolio Theory, Data Compression, and Hypothesis Testing

    CERN Document Server

    Permuter, Haim H; Weissman, Tsachy

    2009-01-01

    We investigate the role of Massey's directed information in portfolio theory, data compression, and statistics with causality constraints. In particular, we show that directed information is an upper bound on the increment in growth rates of optimal portfolios in a stock market due to {causal} side information. This upper bound is tight for gambling in a horse race, which is an extreme case of stock markets. Directed information also characterizes the value of {causal} side information in instantaneous compression and quantifies the benefit of {causal} inference in joint compression of two stochastic processes. In hypothesis testing, directed information evaluates the best error exponent for testing whether a random process $Y$ {causally} influences another process $X$ or not. These results give a natural interpretation of directed information $I(Y^n \\to X^n)$ as the amount of information that a random sequence $Y^n = (Y_1,Y_2,..., Y_n)$ {causally} provides about another random sequence $X^n = (X_1,X_2,...,X_...

  12. Depression as sickness behavior? A test of the host defense hypothesis in a high pathogen population.

    Science.gov (United States)

    Stieglitz, Jonathan; Trumble, Benjamin C; Thompson, Melissa Emery; Blackwell, Aaron D; Kaplan, Hillard; Gurven, Michael

    2015-10-01

    Sadness is an emotion universally recognized across cultures, suggesting it plays an important functional role in regulating human behavior. Numerous adaptive explanations of persistent sadness interfering with daily functioning (hereafter "depression") have been proposed, but most do not explain frequent bidirectional associations between depression and greater immune activation. Here we test several predictions of the host defense hypothesis, which posits that depression is part of a broader coordinated evolved response to infection or tissue injury (i.e. "sickness behavior") that promotes energy conservation and reallocation to facilitate immune activation. In a high pathogen population of lean and relatively egalitarian Bolivian forager-horticulturalists, we test whether depression and its symptoms are associated with greater baseline concentration of immune biomarkers reliably associated with depression in Western populations (i.e. tumor necrosis factor alpha [TNF-α], interleukin-1 beta [IL-1β], interleukin-6 [IL-6], and C-reactive protein [CRP]). We also test whether greater pro-inflammatory cytokine responses to ex vivo antigen stimulation are associated with depression and its symptoms, which is expected if depression facilitates immune activation. These predictions are largely supported in a sample of older adult Tsimane (mean±SD age=53.2±11.0, range=34-85, n=649) after adjusting for potential confounders. Emotional, cognitive and somatic symptoms of depression are each associated with greater immune activation, both at baseline and in response to ex vivo stimulation. The association between depression and greater immune activation is therefore not unique to Western populations. While our findings are not predicted by other adaptive hypotheses of depression, they are not incompatible with those hypotheses and future research is necessary to isolate and test competing predictions. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Combining Multiple Hypothesis Testing with Machine Learning Increases the Statistical Power of Genome-wide Association Studies

    Science.gov (United States)

    Mieth, Bettina; Kloft, Marius; Rodríguez, Juan Antonio; Sonnenburg, Sören; Vobruba, Robin; Morcillo-Suárez, Carlos; Farré, Xavier; Marigorta, Urko M.; Fehr, Ernst; Dickhaus, Thorsten; Blanchard, Gilles; Schunk, Daniel; Navarro, Arcadi; Müller, Klaus-Robert

    2016-01-01

    The standard approach to the analysis of genome-wide association studies (GWAS) is based on testing each position in the genome individually for statistical significance of its association with the phenotype under investigation. To improve the analysis of GWAS, we propose a combination of machine learning and statistical testing that takes correlation structures within the set of SNPs under investigation in a mathematically well-controlled manner into account. The novel two-step algorithm, COMBI, first trains a support vector machine to determine a subset of candidate SNPs and then performs hypothesis tests for these SNPs together with an adequate threshold correction. Applying COMBI to data from a WTCCC study (2007) and measuring performance as replication by independent GWAS published within the 2008–2015 period, we show that our method outperforms ordinary raw p-value thresholding as well as other state-of-the-art methods. COMBI presents higher power and precision than the examined alternatives while yielding fewer false (i.e. non-replicated) and more true (i.e. replicated) discoveries when its results are validated on later GWAS studies. More than 80% of the discoveries made by COMBI upon WTCCC data have been validated by independent studies. Implementations of the COMBI method are available as a part of the GWASpi toolbox 2.0. PMID:27892471

  14. Combining Multiple Hypothesis Testing with Machine Learning Increases the Statistical Power of Genome-wide Association Studies

    Science.gov (United States)

    Mieth, Bettina; Kloft, Marius; Rodríguez, Juan Antonio; Sonnenburg, Sören; Vobruba, Robin; Morcillo-Suárez, Carlos; Farré, Xavier; Marigorta, Urko M.; Fehr, Ernst; Dickhaus, Thorsten; Blanchard, Gilles; Schunk, Daniel; Navarro, Arcadi; Müller, Klaus-Robert

    2016-11-01

    The standard approach to the analysis of genome-wide association studies (GWAS) is based on testing each position in the genome individually for statistical significance of its association with the phenotype under investigation. To improve the analysis of GWAS, we propose a combination of machine learning and statistical testing that takes correlation structures within the set of SNPs under investigation in a mathematically well-controlled manner into account. The novel two-step algorithm, COMBI, first trains a support vector machine to determine a subset of candidate SNPs and then performs hypothesis tests for these SNPs together with an adequate threshold correction. Applying COMBI to data from a WTCCC study (2007) and measuring performance as replication by independent GWAS published within the 2008-2015 period, we show that our method outperforms ordinary raw p-value thresholding as well as other state-of-the-art methods. COMBI presents higher power and precision than the examined alternatives while yielding fewer false (i.e. non-replicated) and more true (i.e. replicated) discoveries when its results are validated on later GWAS studies. More than 80% of the discoveries made by COMBI upon WTCCC data have been validated by independent studies. Implementations of the COMBI method are available as a part of the GWASpi toolbox 2.0.

  15. The Late Ordovician crisis: the Large Igneous Province hypothesis tested by global carbon cycle modeling.

    Science.gov (United States)

    Lefebvre, Vincent; Servais, Thomas; François, Louis; Averbuch, Olivier

    2010-05-01

    The causes of the well-known Late Ordovician-Hirnantian glaciation remain largely debated. This global cooling event is generally attributed to a severe decrease of atmospheric pCO2 during a time of general greenhouse climate but its duration is not fully determined. The climate perturbation is synchronous with one of the biggest biotic crisis of the Earth history. Some authors have shown that, considering the Ashgillian paleogeography, a drop in pCO2 below a threshold of 8x to 10x PAL (Present Atmospheric Level) may induce a decrease in temperature in high latitudes so that the installation of an ice-sheet on Gondwana could be possible. Such a process requires an intensification of silicate weathering and/or organic carbon burial that are the two major processes potentially driving a decrease in atmospheric pCO2 at the geologic time scale. The Late Ordovician is known to be a period of high mantellic activity marked by a lack of reversal magnetic field and high volcanic activity. Barnes (2004) and Courtillot and Olson (2007) link this process to a superplume event that may give rise to continental basalt flooding. In the present study, we tested this hypothesis with a global carbon cycle numerical box-model coupled with an Energy Balance Climate Model. The Model is an upgrade of that used by Grard et al. (2005) to simulate the environmental impact of the Siberian traps at the P/T boundary. The configuration of the box-model has been set using the Late Ordovician paleogeography. In each oceanic box, the model calculates the evolution of carbon, phosphorus and oxygen concentrations and alkalinity. It also calculates atmospheric pCO2, atmospheric and oceanic δ13C. We tested different scenarios of Large Igneous Province (LIP) emplacements and organic carbon cycle interactions simulating atmospheric pCO2 drops of amplitude large enough to produce the Hirnantian glaciation. We show that the hypothesis of low latitude LIP well accounts for the Late Ordovician climate

  16. Brood desertion by female shorebirds : a test of the differential parental capacity hypothesis on Kentish plovers

    NARCIS (Netherlands)

    Amat, JA; Visser, GH; Perez-Hurtado, A; Arroyo, GM

    2000-01-01

    The aim of this study was to examine whether the energetic costs of reproduction explain offspring desertion by female shorebirds, as is suggested by the differential parental capacity hypothesis. A prediction of the hypothesis is that, in species with biparental incubation in which females desert

  17. Testing the cultural group selection hypothesis in Northern Ghana and Oaxaca.

    Science.gov (United States)

    Acedo-Carmona, Cristina; Gomila, Antoni

    2016-01-01

    We examine the cultural group selection (CGS) hypothesis in light of our fieldwork in Northern Ghana and Oaxaca, highly multi-ethnic regions. Our evidence fails to corroborate two central predictions of the hypothesis: that the cultural group is the unit of evolution, and that cultural homogenization is to be expected as the outcome of a selective process.

  18. On the Flexibility of Social Source Memory: A Test of the Emotional Incongruity Hypothesis

    Science.gov (United States)

    Bell, Raoul; Buchner, Axel; Kroneisen, Meike; Giang, Trang

    2012-01-01

    A popular hypothesis in evolutionary psychology posits that reciprocal altruism is supported by a cognitive module that helps cooperative individuals to detect and remember cheaters. Consistent with this hypothesis, a source memory advantage for faces of cheaters (better memory for the cheating context in which these faces were encountered) was…

  19. Testing the hypothesis of the natural suicide rates: Further evidence from OECD data

    DEFF Research Database (Denmark)

    Andres, Antonio Rodriguez; Halicioglu, Ferda

    2011-01-01

    This paper provides further evidence on the hypothesis of the natural rate of suicide using the time series data for 15 OECD countries over the period 1970–2004. This hypothesis suggests that the suicide rate of a society could never be zero even if both the economic and the social conditions were...

  20. The impact of letter spacing on reading: a test of the bigram coding hypothesis.

    Science.gov (United States)

    Vinckier, Fabien; Qiao, Emilie; Pallier, Christophe; Dehaene, Stanislas; Cohen, Laurent

    2011-05-12

    Identifying letters and their relative positions is the basis of reading in literate adults. The Local Combinations Detector model hypothesizes that this ability results from the general organization of the visual system, whereby object encoding proceeds through a hierarchy of neural detectors that, in the case of reading, would be tuned to letters, bigrams, or other letter combinations. Given the increase of receptive fields by a factor of 2 to 3 from one neural level to the next, detectors should integrate information only for letters separated by at most 2 other characters. We test this prediction by measuring the impact of letter spacing on reading, purifying this effect from confounding variables. We establish that performance deteriorates non-linearly whenever letters are separated by at least 2 blank spaces, with the concomitant emergence of a word length effect. We then show that this cannot be reduced to an effect of physical size nor of visual eccentricity. Finally, we demonstrate that the threshold of about 2 spaces is constant across variations in font size. Those results support the hypothesis that the fast recognition of combinations of nearby letters plays a central role in the coding of words, such that interfering with this representation prevents the parallel analysis of letter strings.

  1. Testing the thermal-niche oxygen-squeeze hypothesis for estuarine striped bass

    Science.gov (United States)

    Kraus, Richard T.; Secor, D.H.; Wingate, Rebecca L.

    2015-01-01

    In many stratified coastal ecosystems, conceptual and bioenergetics models predict seasonal reduction in quality and quantity of fish habitat due to high temperatures and hypoxia. We tested these predictions using acoustic telemetry of 2 to 4 kg striped bass (Morone saxatilis Walbaum) and high-resolution spatial water quality sampling in the Patuxent River, a sub-estuary of the Chesapeake Bay, during 2008 and 2009. Striped bass avoided hypoxic (dissolved oxygen ≤2 mg·l−1) subpycnocline waters, but frequently occupied habitats with high temperatures (>25 °C) in the summer months, as cooler habitats were typically not available. Using traditional concepts of the seasonal thermal-niche oxygen-squeeze, most of the Patuxent estuary would beconsidered unsuitable habitat for adult striped bass during summer. Application of a bioenergetics model revealed that habitats selected by striped bass during summer would support positive growth rates assuming fish could feed at one-half ofmaximum consumption. Occupancy of the estuary during summer by striped bass in this study was likely facilitated by sufficient prey and innate tolerance of high temperatures by sub-adult fish of the size range that we tagged. Our results help extend the thermalniche oxygen-squeeze hypothesis to native populations of striped bass in semi-enclosed coastal systems. Tolerance of for supraoptimal temperatures in our study supports recent suggestions by others that the thermal-niche concept for striped bass should be revised to include warmer temperatures.

  2. Temporal variability and cooperative breeding: testing the bet-hedging hypothesis in the acorn woodpecker.

    Science.gov (United States)

    Koenig, Walter D; Walters, Eric L

    2015-10-07

    Cooperative breeding is generally considered an adaptation to ecological constraints on dispersal and independent breeding, usually due to limited breeding opportunities. Although benefits of cooperative breeding are typically thought of in terms of increased mean reproductive success, it has recently been proposed that this phenomenon may be a bet-hedging strategy that reduces variance in reproductive success (fecundity variance) in populations living in highly variable environments. We tested this hypothesis using long-term data on the polygynandrous acorn woodpecker (Melanerpes formicivorus). In general, fecundity variance decreased with increasing sociality, at least when controlling for annual variation in ecological conditions. Nonetheless, decreased fecundity variance was insufficient to compensate for reduced per capita reproductive success of larger, more social groups, which typically suffered lower estimated mean fitness. We did, however, find evidence that sociality in the form of larger group size resulted in increased fitness in years following a small acorn crop due to reduced fecundity variance. Bet-hedging, although not the factor driving sociality in general, may play a role in driving acorn woodpecker group living when acorns are scarce and ecological conditions are poor. © 2015 The Author(s).

  3. Matched, mismatched, and robust scatter matrix estimation and hypothesis testing in complex t-distributed data

    Science.gov (United States)

    Fortunati, Stefano; Gini, Fulvio; Greco, Maria S.

    2016-12-01

    Scatter matrix estimation and hypothesis testing are fundamental inference problems in a wide variety of signal processing applications. In this paper, we investigate and compare the matched, mismatched, and robust approaches to solve these problems in the context of the complex elliptically symmetric (CES) distributions. The matched approach is when the estimation and detection algorithms are tailored on the correct data distribution, whereas the mismatched approach refers to the case when the scatter matrix estimator and the decision rule are derived under a model assumption that is not correct. The robust approach aims at providing good estimation and detection performance, even if suboptimal, over a large set of possible data models, irrespective of the actual data distribution. Specifically, due to its central importance in both the statistical and engineering applications, we assume for the input data a complex t-distribution. We analyze scatter matrix estimators derived under the three different approaches and compare their mean square error (MSE) with the constrained Cramér-Rao bound (CCRB) and the constrained misspecified Cramér-Rao bound (CMCRB). In addition, the detection performance and false alarm rate (FAR) of the various detection algorithms are compared with that of the clairvoyant optimum detector.

  4. Testing the hypothesis on the relationship between aerodynamic roughness length and albedo using vegetation structure parameters.

    Science.gov (United States)

    Cho, Jaeil; Miyazaki, Shin; Yeh, Pat J-F; Kim, Wonsik; Kanae, Shinjiro; Oki, Taikan

    2012-03-01

    Surface albedo (α) and aerodynamic roughness length (z(0)), which partition surface net radiation into energy fluxes, are critical land surface properties for biosphere-atmosphere interactions and climate variability. Previous studies suggested that canopy structure parameters influence both α and z(0); however, no field data have been reported to quantify their relationships. Here, we hypothesize that a functional relationship between α and z(0) exists for a vegetated surface, since both land surface parameters can be conceptually related to the characteristics of canopy structure. We test this hypothesis by using the observed data collected from 50 site-years of field measurements from sites worldwide covering various vegetated surfaces. On the basis of these data, a negative linear relationship between α and log(z(0)) was found, which is related to the canopy structural parameter. We believe that our finding is a big step toward the estimation of z(0) with high accuracy. This can be used, for example, in the parameterization of land properties and the observation of z(0) using satellite remote sensing.

  5. FADTTSter: accelerating hypothesis testing with functional analysis of diffusion tensor tract statistics

    Science.gov (United States)

    Noel, Jean; Prieto, Juan C.; Styner, Martin

    2017-03-01

    Functional Analysis of Diffusion Tensor Tract Statistics (FADTTS) is a toolbox for analysis of white matter (WM) fiber tracts. It allows associating diffusion properties along major WM bundles with a set of covariates of interest, such as age, diagnostic status and gender, and the structure of the variability of these WM tract properties. However, to use this toolbox, a user must have an intermediate knowledge in scripting languages (MATLAB). FADTTSter was created to overcome this issue and make the statistical analysis accessible to any non-technical researcher. FADTTSter is actively being used by researchers at the University of North Carolina. FADTTSter guides non-technical users through a series of steps including quality control of subjects and fibers in order to setup the necessary parameters to run FADTTS. Additionally, FADTTSter implements interactive charts for FADTTS' outputs. This interactive chart enhances the researcher experience and facilitates the analysis of the results. FADTTSter's motivation is to improve usability and provide a new analysis tool to the community that complements FADTTS. Ultimately, by enabling FADTTS to a broader audience, FADTTSter seeks to accelerate hypothesis testing in neuroimaging studies involving heterogeneous clinical data and diffusion tensor imaging. This work is submitted to the Biomedical Applications in Molecular, Structural, and Functional Imaging conference. The source code of this application is available in NITRC.

  6. Testing the stress gradient hypothesis in herbivore communities facilitation peaks at intermediate nutrient levels.

    Science.gov (United States)

    Bakker, Elisabeth S; Dobrescu, Ioana; Straile, Dietmar; Holmgren, Milena

    2013-08-01

    The role of positive interactions in structuring plant and animal communities is increasingly recognized, but the generality of current theoretical models has remained practically unexplored in animal communities. The stress gradient hypothesis predicts a linear increase in the intensity of facilitation as environmental conditions become increasingly stressful, whereas other theoretical models predict a maximum at intermediate environmental stress. We tested how competition and facilitation between herbivores change over a manipulated gradient of nutrient availability. We studied the effect of grazing by pond snails (Lymnaea stagnalis L.) as bulk grazers on aquatic caterpillars (Acentria ephemerella Denis and Schiffermüller) as small specialist grazers along an experimental gradient of environmental nutrient concentration. Higher nutrient levels increased overall total plant biomass but induced a shift toward dominance of filamentous algae at the expense of macrophytes. Facilitation of caterpillars by snail presence peaked at intermediate nutrient levels. Both caterpillar biomass and caterpillar grazing on macrophytes were highest at intermediate nutrient levels. Snails facilitated caterpillars possibly by removing filamentous algae and increasing access to the macrophyte resource, whereas they did not affect macrophyte biomass or C: nutrient ratios, a measure of food quality. We conclude that competition and facilitation in herbivore communities change along nutrient availability gradients that affect plant biomass and community composition. Understanding how interspecific interactions may change in strength and direction along environmental gradients is important to predict how the diversity and structure of communities may respond to the introduction or removal of herbivore species in ecosystems.

  7. Testing the Identification/Production Hypothesis of Implicit Memory in Schizophrenia: The Role of Response Competition.

    Science.gov (United States)

    Marques, Valéria R S; Spataro, Pietro; Cestari, Vincenzo; Sciarretta, Antonio; Rossi-Arnaud, Clelia

    2016-03-01

    Previous evidence indicates that patients with schizophrenia exhibit reduced repetition priming in production tasks (in which each response cue engenders a competition between alternative responses), but not in identification tasks (in which each response cue allows a unique response). However, cross-task comparisons may lead to inappropriate conclusions, because implicit tests vary on several dimensions in addition to the critical dimension of response competition. The present study sought to isolate the role of response competition, by varying the number of solutions in the context of the same implicit tasks. Two experiments investigated the performance of patients with schizophrenia and healthy controls in the high-competition and low-competition versions of word-stem completion (Exp.1) and verb generation (Exp.2). Response competition affected both the proportions of stems completed (higher to few-solution than to many-solution stems) and the reaction times of verb generation (slower to nouns having no dominant verb associates than to nouns having one dominant verb associate). Patients with schizophrenia showed significant (non-zero) priming in both experiments: crucially, the magnitude of this facilitation was equivalent to that observed in healthy controls and was not reduced in the high-competition versions of the two tasks. These findings suggest that implicit memory is spared in schizophrenia, irrespective of the degree of response competition during the retrieval phase; in addition, they add to the ongoing debate regarding the validity of the identification/production hypothesis of repetition priming.

  8. Toward a New Application of Real-Time Electrophysiology: Online Optimization of Cognitive Neurosciences Hypothesis Testing

    Directory of Open Access Journals (Sweden)

    Gaëtan Sanchez

    2014-01-01

    Full Text Available Brain-computer interfaces (BCIs mostly rely on electrophysiological brain signals. Methodological and technical progress has largely solved the challenge of processing these signals online. The main issue that remains, however, is the identification of a reliable mapping between electrophysiological measures and relevant states of mind. This is why BCIs are highly dependent upon advances in cognitive neuroscience and neuroimaging research. Recently, psychological theories became more biologically plausible, leading to more realistic generative models of psychophysiological observations. Such complex interpretations of empirical data call for efficient and robust computational approaches that can deal with statistical model comparison, such as approximate Bayesian inference schemes. Importantly, the latter enable the optimization of a model selection error rate with respect to experimental control variables, yielding maximally powerful designs. In this paper, we use a Bayesian decision theoretic approach to cast model comparison in an online adaptive design optimization procedure. We show how to maximize design efficiency for individual healthy subjects or patients. Using simulated data, we demonstrate the face- and construct-validity of this approach and illustrate its extension to electrophysiology and multiple hypothesis testing based on recent psychophysiological models of perception. Finally, we discuss its implications for basic neuroscience and BCI itself.

  9. The Effects of Social Anxiety and State Anxiety on Visual Attention: Testing the Vigilance-Avoidance Hypothesis.

    Science.gov (United States)

    Singh, J Suzanne; Capozzoli, Michelle C; Dodd, Michael D; Hope, Debra A

    2015-01-01

    A growing theoretical and research literature suggests that trait and state social anxiety can predict attentional patterns in the presence of emotional stimuli. The current study adds to this literature by examining the effects of state anxiety on visual attention and testing the vigilance-avoidance hypothesis, using a method of continuous visual attentional assessment. Participants were 91 undergraduate college students with high or low trait fear of negative evaluation (FNE), a core aspect of social anxiety, who were randomly assigned to either a high or low state anxiety condition. Participants engaged in a free view task in which pairs of emotional facial stimuli were presented and eye movements were continuously monitored. Overall, participants with high FNE avoided angry stimuli and participants with high state anxiety attended to positive stimuli. Participants with high state anxiety and high FNE were avoidant of angry faces, whereas participants with low state and low FNE exhibited a bias toward angry faces. The study provided partial support for the vigilance-avoidance hypothesis. The findings add to the mixed results in the literature that suggest that both positive and negative emotional stimuli may be important in understanding the complex attention patterns associated with social anxiety. Clinical implications and suggestions for future research are discussed.

  10. Testing the Hypothesis that Methanol Maser Rings Trace Circumstellar Disks: High Resolution Near-IR and Mid-IR Imaging

    OpenAIRE

    De Buizer, James M.; Bartkiewicz, Anna; Szymczak, Marian

    2012-01-01

    Milliarcsecond VLBI maps of regions containing 6.7 GHz methanol maser emission have lead to the recent discovery of ring-like distributions of maser spots and the plausible hypothesis that they may be tracing circumstellar disks around forming high mass stars. We aimed to test this hypothesis by imaging these regions in the near and mid-infrared at high spatial resolution and compare the observed emission to the expected infrared morphologies as inferred from the geometries of the maser rings...

  11. Testing the Marine Hypothesis for The Opportunity Landing Site at Victoria Crater

    Science.gov (United States)

    Parker, T. J.

    2006-12-01

    Hypothesis Summary: 1. Meridiani Planum is a marine sulfate platform deposit, analogous to terrestrial carbonate platforms but with sulfate mineralogy, laid down during one or multiple marine transgressions over the landing site region. 2. Outcrop laminations, ripples, and larger, dune-scale bedforms are subaqueous in origin, produced by tidal currents. Aqueous deposits may be interbedded with crossbedded aeolian deposits of same composition derived from subjacent water-lain deposits during lowstands. At the scale of observations made by Opportunity, the marine hypothesis differs from the consensus, sabkha model, in two relatively minor ways (but with important differences in the inferred paleoenvironments). 3. Blueberry and cobble "lag" on top of outcrop is a lag, but indicates erosion of perhaps many meters, even tens of meters or more of outcrop material from the region by water. Wind erosion has been very limited over geologic time (perhaps less than a meter locally). 4. Remarkably-flat, horizontal geomorphic surface of outcrop was produced by shallow standing water locally, controlling both deposition and erosion of the sulfate outcrop material to within a few meters of sea level. 5. Craters in the landing site exhibit a continuum of degradation states, with Endurance and Victoria typifying the best preserved craters visited (or to be visited) by Opportunity, and Erebus and Terra Nova representing the most degraded craters visited that are larger than 100 meters across. Terra Nova is similar to numerous kilometer-scale "rock ring" craters in the Meridiani Planum landing site. 6. "Serrated" rim at Victoria is similar to, but fresher in expression, rim morphology at Erebus Crater, and may indicate water pouring over crater rim during tidal or storm surges in water level across the region. Predictions to be tested at Victoria Crater: 1. The crater's ejecta and raised rim have been destroyed by tidal currents in shallow standing water. There is no Endurance

  12. Underwater Dendrochronology of the Sierra Nevada: Testing the Medieval Mega-Drought Hypothesis

    Science.gov (United States)

    Biondi, F.; Kleppe, J. A.; Brothers, D.; Kent, G.

    2006-12-01

    As stated in the NAS STR Report, "regional and large-scale reconstructions of changes in other climatic variables, such as precipitation, over the last 2,000 years would provide a valuable complement to those made for temperature." In this context, we focus on the 'Medieval Mega-drought Hypothesis', which is based on radiocarbon dating of dead trees and stumps found underwater in Sierra Nevada lakes and streambeds, and states that century-long dry periods caused lakes to retreat and streams to dry up, with the most recent mega-droughts happening during medieval times. While several paleoclimatic records support this hypothesis, some do not, and the possibility exists that geomorphic processes, such as landslides caused by seismic events, were responsible for the presence of trees and stumps under current bodies of water. Given the relevance of this hypothesis, not only for sustainable water management but also for social stability and security, it is necessary to test it beyond reasonable doubt. One way to do so is by measuring the location, orientation, and time of origin of underwater trees, to determine if they were transported or grew in situ. For example, during 2005 wood samples were retrieved from submerged trees at Fallen Leaf Lake, California. The trees had been previously located and documented using an ROV that can obtain high resolution color video, and collect small surface samples using a gripper, down to a water depth of about 150 m. For tree-ring dating, a reference chronology from AD 543 to 2003 was developed using live and dead western juniper trees located near the lake. One underwater sample, i.e. a branch cross section that included 69 rings, was then dated to AD 1085-1153. This shows that it is feasible to obtain calendar dates and continuous ring-width series from underwater trees in the Sierra Nevada. Submerged trees in Fallen Leaf Lake were mapped in summer 2006 using an EdgeTech 4200 side-scan system capable of decimeter resolution. The 5

  13. Three ways to test the validity of the Geocentric Axial Dipole (GAD) hypothesis in the Precambrian

    Science.gov (United States)

    Veikkolainen, T.; Pesonen, L. J.; Korhonen, K.

    2012-12-01

    One of the most fundamental aspects of paleomagnetism is the assumption that the temporal mean of the geomagnetic field is indistinguishable from a field generated by a geocentric axial dipole (GAD hypothesis). When the theory became mainstream, various ways to test its functionality were presented, based on e.g. deep-sea sediment cores, paleoclimatic indicators and paleointensity. Most suspicion of the dipolar nature of the geomagnetic field has dealt with the Precambrian. To analyze this bias, we have used the data from the novel paleomagnetic database, collected by University of Helsinki, and Yale University for over a decade's time. Altogether 3016 observations from all major Precambrian continents were gathered, and a thorough compilation of reversals of the Archean and Proterozoic geomagnetic field was done. Observations were filtered using different criteria, e.g. geologic age, rock type (igneous vs. metamorphic vs. sedimentary) and reliability according to the modified Voo-grading. Testing the GAD has rested on a) inclination frequency analysis, b) asymmetries in reversal data, and c) paleosecular variation (PSV) using CALS7K, CALS3K, GUFM and IGRF models as references. The results suggest that the geomagnetic field of the Precambrian is not far from the field predicted by the GAD model. The inclination frequency analysis supports the existence of a small octupolar (ca. 6 % of GAD) component and a quadrupole of 0-8 % of GAD as evaluated using chi-square testing. Conclusions drawn from the asymmetry analysis and PSV are statistically indifferent from this. The deviation from the GAD is smallest for the highest-quality observations, especially so called key poles. They have well-defined isotopic ages, small error parameters in their Fisher data and their primary remanent magnetization has been properly isolated. This also means that the observed functionality of GAD cannot be a misconception caused by secondary magnetizations acquired in the Phanerozoic

  14. Testing the Stress Gradient Hypothesis in herbivore communities: facilitation peaks at intermediate nutrient levels

    NARCIS (Netherlands)

    Bakker, E.S.; Dobrescu, I.; Straile, D.; Holmgren, M.

    2013-01-01

    The role of positive interactions in structuring plant and animal communities is increasingly recognized but the generality of current theoretical models has remained practically unexplored in animal communities. The Stress Gradient Hypothesis predicts a linear increase in the intensity of

  15. Testing the stress gradient hypothesis in herbivore communities: facilitation peaks at intermediate nutrient levels

    NARCIS (Netherlands)

    Bakker, E.S.; Dobrescu, I.; Straile, D.; Holmgren, M.

    2013-01-01

    The role of positive interactions in structuring plant and animal communities is increasingly recognized, but the generality of current theoretical models has remained practically unexplored in animal communities. The stress gradient hypothesis predicts a linear increase in the intensity of

  16. Possible Solution to Publication Bias Through Bayesian Statistics, Including Proper Null Hypothesis Testing

    NARCIS (Netherlands)

    Konijn, Elly A.; van de Schoot, Rens; Winter, Sonja D.; Ferguson, Christopher J.

    2015-01-01

    The present paper argues that an important cause of publication bias resides in traditional frequentist statistics forcing binary decisions. An alternative approach through Bayesian statistics provides various degrees of support for any hypothesis allowing balanced decisions and proper null

  17. Spearman's hypothesis tested comparing Libyan adults with various other groups of adults on the items of the Standard Progressive Matrices

    NARCIS (Netherlands)

    te Nijenhuis, J.; Al-Shahomee, A.A.; van den Hoek, M.; Grigoriev, A.; Repko, J.

    2015-01-01

    Spearman's hypothesis tested at the level of items states that differences between groups on the items of an IQ test are a function of the g loadings of these items, such that there are small differences between groups on items with low g loadings and large differences between groups on items with

  18. Methods for Equating Mental Tests.

    Science.gov (United States)

    1984-11-01

    1983) compared conventional and IRT methods for equating the Test of English as a Foreign Language ( TOEFL ) after chaining. Three conventional and...ID-A149 544 METHODS FOR ’EQUATING MENTAL TESTS (U) ASSESSMENT SYSTEMS 1/2 CORP ST PAUL MN K A GIRLLUCA ET AL. NOV 84 AFHRL-TR-84-35 F4i689-82-C-0023... TEST CHART NATIONAL BUREAU Of STANDARDS- 1963-A -I% AFHRL-TR-84-35 AIR FORCE 0, METHODS FOR EQUATING MENTAL TESTS H U By Kathleen A. Gialluca Leslie I

  19. Proform-Antecedent Linking in Individuals with Agrammatic Aphasia: A Test of the Intervener Hypothesis.

    Science.gov (United States)

    Engel, Samantha; Shapiro, Lewis P; Love, Tracy

    2018-02-01

    To evaluate processing and comprehension of pronouns and reflexives in individuals with agrammatic (Broca's) aphasia and age-matched control participants. Specifically, we evaluate processing and comprehension patterns in terms of a specific hypothesis -- the Intervener Hypothesis - that posits that the difficulty of individuals with agrammatic (Broca's) aphasia results from similarity-based interference caused by the presence of an intervening NP between two elements of a dependency chain. We used an eye tracking-while-listening paradigm to investigate real-time processing (Experiment 1) and a sentence-picture matching task to investigate final interpretive comprehension (Experiment 2) of sentences containing proforms in complement phrase and subject relative constructions. Individuals with agrammatic aphasia demonstrated a greater proportion of gazes to the correct referent of reflexives relative to pronouns and significantly greater comprehension accuracy of reflexives relative to pronouns. These results provide support for the Intervener Hypothesis, previous support for which comes from studies of Wh- questions and unaccusative verbs, and we argue that this account provides an explanation for the deficits of individuals with agrammatic aphasia across a growing set of sentence constructions. The current study extends this hypothesis beyond filler-gap dependencies to referential dependencies and allows us to refine the hypothesis in terms of the structural constraints that meet the description of the Intervener Hypothesis.

  20. Simulation-based hypothesis testing of high dimensional means under covariance heterogeneity.

    Science.gov (United States)

    Chang, Jinyuan; Zheng, Chao; Zhou, Wen-Xin; Zhou, Wen

    2017-12-01

    In this article, we study the problem of testing the mean vectors of high dimensional data in both one-sample and two-sample cases. The proposed testing procedures employ maximum-type statistics and the parametric bootstrap techniques to compute the critical values. Different from the existing tests that heavily rely on the structural conditions on the unknown covariance matrices, the proposed tests allow general covariance structures of the data and therefore enjoy wide scope of applicability in practice. To enhance powers of the tests against sparse alternatives, we further propose two-step procedures with a preliminary feature screening step. Theoretical properties of the proposed tests are investigated. Through extensive numerical experiments on synthetic data sets and an human acute lymphoblastic leukemia gene expression data set, we illustrate the performance of the new tests and how they may provide assistance on detecting disease-associated gene-sets. The proposed methods have been implemented in an R-package HDtest and are available on CRAN. © 2017, The International Biometric Society.

  1. Effects of native biodiversity on grape loss of four castes: testing the biotic resistance hypothesis

    Directory of Open Access Journals (Sweden)

    M. Nereu

    2018-02-01

    Full Text Available Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the main biotic causes of crop losses in four grape castes, two red (Touriga Nacional and Baga and two white (Arinto and Chardonnay, and evaluated the potential effect of native biodiversity to provide biotic resistance to pest outbreaks and grape losses. Specifically, the diversity and abundance of bird and insect communities in these vineyards were quantified and divided into functional guilds (pest, neutral or auxiliary, to test whether these natural communities hold the potential to naturally control grape pests (biotic resistance hypothesis under normal vineyard management (including pesticide application regimes. A potential association between distance to the vineyard edge and grape losses was also evaluated. We recorded a very small proportion of grape losses (mean  =  0.6 %; max  =  7.5 %, with insect pests showing a preference for the castes Baga (red and Chardonnay (white, while bird pests avoided the caste Arinto (white. Grape color did not influence losses caused by insect pests, but birds showed a preference for red castes. The caste Baga was also more vulnerable to losses caused by fungi. Despite their low impact on grape production, most insects and birds detected in the six vineyards were pests, which entails a potentially low level of biotic resistance in this highly managed agricultural ecosystem. Further research is necessary to fully evaluate the role of functional biodiversity in vineyards, particularly if alternative production processes

  2. Nevus density and melanoma risk in women: a pooled analysis to test the divergent pathway hypothesis

    Science.gov (United States)

    Olsen, Catherine M.; Zens, Michael S.; Stukel, Therese A.; Sacerdote, Carlotta; Chang, Yu-mei; Armstrong, Bruce K.; Bataille, Veronique; Berwick, Marianne; Elwood, J. Mark; Holly, Elizabeth A.; Kirkpatrick, Connie; Mack, Thomas; Bishop, Julia Newton; Østerlind, Anne; Swerdlow, Anthony J.; Zanetti, Roberto; Green, Adèle C.; Karagas, Margaret R.; Whiteman, David C

    2009-01-01

    A “divergent pathway” model for the development of cutaneous melanoma has been proposed. The model hypothesizes that melanomas occurring in people with a low tendency to develop nevi will, on average, arise more commonly on habitually sun-exposed body sites such as the head and neck. In contrast, people with an inherent propensity to develop nevi will tend to develop melanomas most often on body sites with large melanocyte populations, such as on the back. We conducted a collaborative analysis to test this hypothesis using the original data from ten case-control studies of melanoma in women (2406 cases and 3119 controls), with assessment of the potential confounding effects of socioeconomic, pigmentary, and sun exposure-related factors. Higher nevus count on the arm was associated specifically with an increased risk of melanoma of the trunk (p for trend=0.0004) and limbs (both upper and lower limb p for trends=0.01), but not of the head and neck (p for trend=0.25). The pooled odds ratios for the highest quartile of non-zero nevus count versus none were 4.6 (95% confidence interval (CI) 2.7–7.6) for melanoma of the trunk, 2.0 (95% CI 0.9–4.5) for the head and neck, 4.2 (95% CI 2.3–7.5) for the upper limbs and 3.4 (95% CI 1.5–7.9) for the lower limbs. Aggregate data from these studies suggest that high nevus counts are strongly associated with melanoma of the trunk but less so if at all of the head and neck. This finding supports different etiologic pathways of melanoma development by anatomic site. PMID:19035450

  3. Community-Driven Hypothesis Testing: A Solution for the Tragedy of the Anticommons.

    Science.gov (United States)

    Palma-Oliveira, José Manuel; Trump, Benjamin D; Wood, Matthew D; Linkov, Igor

    2017-07-11

    Shared ownership of property and resources is a longstanding challenge throughout history that has been amplifying with the increasing development of industrial and postindustrial societies. Where governments, project planners, and commercial developers seek to develop new infrastructure, industrial projects, and various other land-and resource-intensive tasks, veto power shared by various local stakeholders can complicate or halt progress. Risk communication has been used as an attempt to address stakeholder concerns in these contexts, but has demonstrated shortcomings. These coordination failures between project planners and stakeholders can be described as a specific kind of social dilemma that we describe as the "tragedy of the anticommons." To overcome such dilemmas, we demonstrate how a two-step process can directly address public mistrust of project planners and public perceptions of limited decision-making authority. This approach is examined via two separate empirical field experiments in Portugal and Tunisia, where public resistance and anticommons problems threatened to derail emerging industrial projects. In both applications, an intervention is undertaken to address initial public resistance to such projects, where specific public stakeholders and project sponsors collectively engaged in a hypothesis-testing process to identify and assess human and environmental health risks associated with proposed industrial facilities. These field experiments indicate that a rigorous attempt to address public mistrust and perceptions of power imbalances and change the pay-off structure of the given dilemma may help overcome such anticommons problems in specific cases, and may potentially generate enthusiasm and support for such projects by local publics moving forward. © 2017 Society for Risk Analysis.

  4. Predictors of orbital convergence in primates: a test of the snake detection hypothesis of primate evolution.

    Science.gov (United States)

    Wheeler, Brandon C; Bradley, Brenda J; Kamilar, Jason M

    2011-09-01

    Traditional explanations for the evolution of high orbital convergence and stereoscopic vision in primates have focused on how stereopsis might have aided early primates in foraging or locomoting in an arboreal environment. It has recently been suggested that predation risk by constricting snakes was the selective force that favored the evolution of orbital convergence in early primates, and that later exposure to venomous snakes favored further degrees of convergence in anthropoid primates. Our study tests this snake detection hypothesis (SDH) by examining whether orbital convergence among extant primates is indeed associated with the shared evolutionary history with snakes or the risk that snakes pose for a given species. We predicted that orbital convergence would be higher in species that: 1) have a longer history of sympatry with venomous snakes, 2) are likely to encounter snakes more frequently, 3) are less able to detect or deter snakes due to group size effects, and 4) are more likely to be preyed upon by snakes. Results based on phylogenetically independent contrasts do not support the SDH. Orbital convergence shows no relationship to the shared history with venomous snakes, likelihood of encountering snakes, or group size. Moreover, those species less likely to be targeted as prey by snakes show significantly higher values of orbital convergence. Although an improved ability to detect camouflaged snakes, along with other cryptic stimuli, is likely a consequence of increased orbital convergence, this was unlikely to have been the primary selective force favoring the evolution of stereoscopic vision in primates. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Hypothesis-driven methods to augment human cognition by optimizing cortical oscillations

    Directory of Open Access Journals (Sweden)

    Jörn M. Horschig

    2014-06-01

    Full Text Available Cortical oscillations have been shown to represent fundamental functions of a working brain, e.g. communication, stimulus binding, error monitoring, and inhibition, and are directly linked to behavior. Recent studies intervening with these oscillations have demonstrated effective modulation of both the oscillations and behavior. In this review, we collect evidence in favor of how hypothesis-driven methods can be used to augment cognition by optimizing cortical oscillations. We elaborate their potential usefulness for three target groups: healthy elderly, patients with attention deficit/hyperactivity disorder, and healthy young adults. We discuss the relevance of neuronal oscillations in each group and show how each of them can benefit from the manipulation of functionally-related oscillations. Further, we describe methods for manipulation of neuronal oscillations including direct brain stimulation as well as indirect task alterations. We also discuss practical considerations about the proposed techniques. In conclusion, we propose that insights from neuroscience should guide techniques to augment human cognition, which in turn can provide a better understanding of how the human brain works.

  6. Hypothesis-driven methods to augment human cognition by optimizing cortical oscillations

    Science.gov (United States)

    Horschig, Jörn M.; Zumer, Johanna M.; Bahramisharif, Ali

    2014-01-01

    Cortical oscillations have been shown to represent fundamental functions of a working brain, e.g., communication, stimulus binding, error monitoring, and inhibition, and are directly linked to behavior. Recent studies intervening with these oscillations have demonstrated effective modulation of both the oscillations and behavior. In this review, we collect evidence in favor of how hypothesis-driven methods can be used to augment cognition by optimizing cortical oscillations. We elaborate their potential usefulness for three target groups: healthy elderly, patients with attention deficit/hyperactivity disorder, and healthy young adults. We discuss the relevance of neuronal oscillations in each group and show how each of them can benefit from the manipulation of functionally-related oscillations. Further, we describe methods for manipulation of neuronal oscillations including direct brain stimulation as well as indirect task alterations. We also discuss practical considerations about the proposed techniques. In conclusion, we propose that insights from neuroscience should guide techniques to augment human cognition, which in turn can provide a better understanding of how the human brain works. PMID:25018706

  7. Prevalence of hardcore smoking in the Netherlands between 2001 and 2012: a test of the hardening hypothesis

    Directory of Open Access Journals (Sweden)

    Jeroen Bommelé

    2016-08-01

    Full Text Available Abstract Background Hardcore smokers are smokers who have smoked for many years and who do not intend to quit smoking. The “hardening hypothesis” states that light smokers are more likely to quit smoking than heavy smokers (such as hardcore smokers. Therefore, the prevalence of hardcore smoking among smokers would increase over time. If this is true, the smoking population would become harder to reach with tobacco control measures. In this study we tested the hardening hypothesis. Methods We calculated the prevalence of hardcore smoking in the Netherlands from 2001 to 2012. Smokers were ‘hardcore’ if they a smoked every day, b smoked on average 15 cigarettes per day or more, c had not attempted to quit in the past 12 months, and d had no intention to quit within 6 months. We used logistic regression models to test whether the prevalence changed over time. We also investigated whether trends differed between educational levels. Results Among smokers, the prevalence of hardcore smoking decreased from 40.8 % in 2001 to 32.2 % in 2012. In the general population, it decreased from 12.2 to 8.2 %. Hardcore smokers were significantly lower educated than non-hardcore smokers. Among the general population, the prevalence of hardcore smoking decreased more among higher educated people than among lower educated people. Conclusions We found no support for the hardening hypothesis in the Netherlands between 2001 and 2012. Instead, the decrease of hardcore smoking among smokers suggests a ‘softening’ of the smoking population.

  8. Testing the Kerr black hole hypothesis: Comparison between the gravitational wave and the iron line approaches

    Energy Technology Data Exchange (ETDEWEB)

    Cárdenas-Avendaño, Alejandro [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Programa de Matemática, Fundación Universitaria Konrad Lorenz, 110231 Bogotá (Colombia); Jiang, Jiachen [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Bambi, Cosimo, E-mail: bambi@fudan.edu.cn [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 200433 Shanghai (China); Theoretical Astrophysics, Eberhard-Karls Universität Tübingen, 72076 Tübingen (Germany)

    2016-09-10

    The recent announcement of the detection of gravitational waves by the LIGO/Virgo Collaboration has opened a new window to test the nature of astrophysical black holes. Konoplya & Zhidenko have shown how the LIGO data of GW 150914 can constrain possible deviations from the Kerr metric. In this letter, we compare their constraints with those that can be obtained from accreting black holes by fitting their X-ray reflection spectrum, the so-called iron line method. We simulate observations with eXTP, a next generation X-ray mission, finding constraints much stronger than those obtained by Konoplya & Zhidenko. Our results can at least show that, contrary to what is quite commonly believed, it is not obvious that gravitational waves are the most powerful approach to test strong gravity. In the presence of high quality data and with the systematics under control, the iron line method may provide competitive constraints.

  9. Standard Test Method for Sandwich Corrosion Test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method defines the procedure for evaluating the corrosivity of aircraft maintenance chemicals, when present between faying surfaces (sandwich) of aluminum alloys commonly used for aircraft structures. This test method is intended to be used in the qualification and approval of compounds employed in aircraft maintenance operations. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements appear in Section 9.

  10. A comparison of mean partialing and dual-hypothesis testing to evaluate stereotype effects when assessing profile similarity.

    Science.gov (United States)

    Conroy, David E; Pincus, Aaron L

    2006-04-01

    Assessing profile similarity is an important task in research and clinical practice, but conclusions about profile similarity may be confounded by stereotype effects that create artificially similar profiles. In this article, we review the impact of stereotype effects on profile similarity and a conventional approach to addressing this confound (i.e., mean partialing). We argue that a dual-hypothesis testing approach distinguishing the no-effect null hypothesis (i.e., is the observed similarity different from zero?) from the chance-effect null hypothesis (i.e., is the observed similarity different from chance given the distribution of profile elements?) can provide a more nuanced understanding of profile similarity. To compare results from these 2 perspectives, we analyzed data from 2 samples using within-persons correlations as indexes of similar profile shapes. Results indicated that a dual-hypothesis testing approach led to more conservative conclusions about profile similarity (i.e., fewer Type 1 errors) than mean partialing and may be especially valuable when dealing with moderate-sized stereotype effects. Both approaches led to identical conclusions when stereotype effects were largest. Conclusions emphasize the relative merits and limitations of the dual-hypothesis testing approach as well as potential future applications in the personality assessment domain.

  11. A note on Using regression models to analyze randomized trials: asymptotically valid hypothesis tests despite incorrectly specified models.

    Science.gov (United States)

    Kim, Jane Paik

    2013-03-01

    In the context of randomized trials, Rosenblum and van der Laan (2009, Biometrics 63, 937-945) considered the null hypothesis of no treatment effect on the mean outcome within strata of baseline variables. They showed that hypothesis tests based on linear regression models and generalized linear regression models are guaranteed to have asymptotically correct Type I error regardless of the actual data generating distribution, assuming the treatment assignment is independent of covariates. We consider another important outcome in randomized trials, the time from randomization until failure, and the null hypothesis of no treatment effect on the survivor function conditional on a set of baseline variables. By a direct application of arguments in Rosenblum and van der Laan (2009), we show that hypothesis tests based on multiplicative hazards models with an exponential link, i.e., proportional hazards models, and multiplicative hazards models with linear link functions where the baseline hazard is parameterized, are asymptotically valid under model misspecification provided that the censoring distribution is independent of the treatment assignment given the covariates. In the case of the Cox model and linear link model with unspecified baseline hazard function, the arguments in Rosenblum and van der Laan (2009) cannot be applied to show the robustness of a misspecified model. Instead, we adopt an approach used in previous literature (Struthers and Kalbfleisch, 1986, Biometrika 73, 363-369) to show that hypothesis tests based on these models, including models with interaction terms, have correct type I error. Copyright © 2013, The International Biometric Society.

  12. Functional imaging of brain responses to different outcomes of hypothesis testing: revealed in a category induction task.

    Science.gov (United States)

    Li, Fuhong; Cao, Bihua; Luo, Yuejia; Lei, Yi; Li, Hong

    2013-02-01

    Functional magnetic resonance imaging (fMRI) was used to examine differences in brain activation that occur when a person receives the different outcomes of hypothesis testing (HT). Participants were provided with a series of images of batteries and were asked to learn a rule governing what kinds of batteries were charged. Within each trial, the first two charged batteries were sequentially displayed, and participants would generate a preliminary hypothesis based on the perceptual comparison. Next, a third battery that served to strengthen, reject, or was irrelevant to the preliminary hypothesis was displayed. The fMRI results revealed that (1) no significant differences in brain activation were found between the 2 hypothesis-maintain conditions (i.e., strengthen and irrelevant conditions); and (2) compared with the hypothesis-maintain conditions, the hypothesis-reject condition activated the left medial frontal cortex, bilateral putamen, left parietal cortex, and right cerebellum. These findings are discussed in terms of the neural correlates of the subcomponents of HT and working memory manipulation. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Does mediator use contribute to the spacing effect for cued recall? Critical tests of the mediator hypothesis.

    Science.gov (United States)

    Morehead, Kayla; Dunlosky, John; Rawson, Katherine A; Bishop, Melissa; Pyc, Mary A

    2018-04-01

    When study is spaced across sessions (versus massed within a single session), final performance is greater after spacing. This spacing effect may have multiple causes, and according to the mediator hypothesis, part of the effect can be explained by the use of mediator-based strategies. This hypothesis proposes that when study is spaced across sessions, rather than massed within a session, more mediators will be generated that are longer lasting and hence more mediators will be available to support criterion recall. In two experiments, participants were randomly assigned to study paired associates using either a spaced or massed schedule. They reported strategy use for each item during study trials and during the final test. Consistent with the mediator hypothesis, participants who had spaced (as compared to massed) practice reported using more mediators on the final test. This use of effective mediators also statistically accounted for some - but not all of - the spacing effect on final performance.

  14. What would judgment and decision making research be like if we took a Bayesian approach to hypothesis testing?

    Directory of Open Access Journals (Sweden)

    William J. Matthews

    2011-12-01

    Full Text Available Judgment and decision making research overwhelmingly uses null hypothesis significance testing as the basis for statistical inference. This article examines an alternative, Bayesian approach which emphasizes the choice between two competing hypotheses and quantifies the balance of evidence provided by the data---one consequence of which is that experimental results may be taken to strongly favour the null hypothesis. We apply a recently-developed ``Bayesian $t$-test'' to existing studies of the anchoring effect in judgment, and examine how the change in approach affects both the tone of hypothesis testing and the substantive conclusions that one draws. We compare the Bayesian approach with Fisherian and Neyman-Pearson testing, examining its relationship to conventional $p$-values, the influence of effect size, and the importance of prior beliefs about the likely state of nature. The results give a sense of how Bayesian hypothesis testing might be applied to judgment and decision making research, and of both the advantages and challenges that a shift to this approach would entail.

  15. Hypothesis test of mediation effect in causal mediation model with high-dimensional continuous mediators.

    Science.gov (United States)

    Huang, Yen-Tsung; Pan, Wen-Chi

    2016-06-01

    Causal mediation modeling has become a popular approach for studying the effect of an exposure on an outcome through a mediator. However, current methods are not applicable to the setting with a large number of mediators. We propose a testing procedure for mediation effects of high-dimensional continuous mediators. We characterize the marginal mediation effect, the multivariate component-wise mediation effects, and the L2 norm of the component-wise effects, and develop a Monte-Carlo procedure for evaluating their statistical significance. To accommodate the setting with a large number of mediators and a small sample size, we further propose a transformation model using the spectral decomposition. Under the transformation model, mediation effects can be estimated using a series of regression models with a univariate transformed mediator, and examined by our proposed testing procedure. Extensive simulation studies are conducted to assess the performance of our methods for continuous and dichotomous outcomes. We apply the methods to analyze genomic data investigating the effect of microRNA miR-223 on a dichotomous survival status of patients with glioblastoma multiforme (GBM). We identify nine gene ontology sets with expression values that significantly mediate the effect of miR-223 on GBM survival. © 2015, The International Biometric Society.

  16. Relating past occupation patterns to (paleo)environmental properties - hypothesis testing

    Science.gov (United States)

    Zeeden, Christian; Duwe, Anja; Bösken, Janina; Pipaud, Isabel; Chu, Wei; Hauck, Thomas; Lehmkuhl, Frank

    2016-04-01

    Current archaeological discussions suggest that early human settlement distribution patterns, as preserved by the geological record, may be related to geospatial properties such as altitude, vicinity to water and habitat variability. However, to date, no quantitative analyses have been undertaken to either verify or falsify these hypotheses. In this study, data-driven methods were applied to test these hypotheses, specifically correlation and comparison of dataset variabilities. We compare the standard deviation and range from site altitude (as one example geospatial property) to random draws from an area comprising these sites to make a statement whether settlement distribution is random in altitude or linked to a specific altitudinal belt. This set of methods was applied to a dataset of mid-Upper Paleolithic (Gravettian) settlements from the Bohemian-Moravian Highlands and the Western Carpathians. It was possible to quantitatively and reproducibly demonstrate that settlements are related to a specific altitudinal belt around 200-300 m, as suggested earlier in a qualitative way. The discussed set of methods can be extended by incorporating additional geospatial parameters, potentially allowing comprehensive statements on the influence of these parameters on the distribution of early human settlements. Selecting a reference area used for testing and its (paleo)environmental properties is an important input, and several options are compared.

  17. Testing Munk's hypothesis for submesoscale eddy generation using observations in the North Atlantic

    Science.gov (United States)

    Buckingham, Christian E.; Khaleel, Zammath; Lazar, Ayah; Martin, Adrian P.; Allen, John T.; Naveira Garabato, Alberto C.; Thompson, Andrew F.; Vic, Clément

    2017-08-01

    A high-resolution satellite image that reveals a train of coherent, submesoscale (6 km) vortices along the edge of an ocean front is examined in concert with hydrographic measurements in an effort to understand formation mechanisms of the submesoscale eddies. The infrared satellite image consists of ocean surface temperatures at ˜390 m resolution over the midlatitude North Atlantic (48.69°N, 16.19°W). Concomitant altimetric observations coupled with regular spacing of the eddies suggest the eddies result from mesoscale stirring, filamentation, and subsequent frontal instability. While horizontal shear or barotropic instability (BTI) is one mechanism for generating such eddies (Munk's hypothesis), we conclude from linear theory coupled with the in situ data that mixed layer or submesoscale baroclinic instability (BCI) is a more plausible explanation for the observed submesoscale vortices. Here we assume that the frontal disturbance remains in its linear growth stage and is accurately described by linear dynamics. This result likely has greater applicability to the open ocean, i.e., regions where the gradient Rossby number is reduced relative to its value along coasts and within strong current systems. Given that such waters comprise an appreciable percentage of the ocean surface and that energy and buoyancy fluxes differ under BTI and BCI, this result has wider implications for open-ocean energy/buoyancy budgets and parameterizations within ocean general circulation models. In summary, this work provides rare observational evidence of submesoscale eddy generation by BCI in the open ocean.Plain Language SummaryHere, we test Munk's theory for small-scale eddy generation using a unique set of satellite- and ship-based observations. We find that for one particular set of observations in the North Atlantic, the mechanism for eddy generation is not pure horizontal shear, as proposed by Munk et al. () and Munk (), but is instead vertical shear, or baroclinic instability

  18. Modeling Reader and Text Interactions during Narrative Comprehension: A Test of the Lexical Quality Hypothesis

    Science.gov (United States)

    Hamilton, Stephen T.; Freed, Erin M.; Long, Debra L.

    2013-01-01

    The goal of this study was to examine predictions derived from the Lexical Quality Hypothesis regarding relations among word decoding, working-memory capacity, and the ability to integrate new concepts into a developing discourse representation. Hierarchical Linear Modeling was used to quantify the effects of three text properties (length,…

  19. Radio spectrum measurements of artificial ball lightning and testing the hypothesis on its plasmochemical nature

    Science.gov (United States)

    Kopeikin, V. V.

    2014-01-01

    Spectral measurements of radiowaves emitted by artificial ball lightning are presented. The measurements were carried out using two different facilities: a pulsed power generator (PPG) and a three-contour Tesla transformer. The results of these measurements confirm the hypothesis that ball lightning is a self-oscillator of high-voltage pulses in the radio range.

  20. Motor Resonance as a Function of Narrative Time: Further Tests of the Linguistic Focus Hypothesis

    Science.gov (United States)

    Zwaan, Rolf A.; Taylor, Lawrence J.; de Boer, Mirte

    2010-01-01

    Neuroimaging and behavioral studies have revealed involvement of the brain's motor system in language comprehension. The Linguistic-Focus Hypothesis [Taylor, L. J., & Zwaan, R. A. (2008). Motor resonance and linguistic focus. "Quarterly Journal of Experimental Psychology,61", 869-904.] postulates that engagement of the motor system during language…

  1. What Constitutes Science and Scientific Evidence: Roles of Null Hypothesis Testing

    Science.gov (United States)

    Chang, Mark

    2017-01-01

    We briefly discuss the philosophical basis of science, causality, and scientific evidence, by introducing the hidden but most fundamental principle of science: the similarity principle. The principle's use in scientific discovery is illustrated with Simpson's paradox and other examples. In discussing the value of null hypothesis statistical…

  2. Testing the Double Bind Hypothesis: Faculty Recommendations of Minority Women Fellowship Applicants.

    Science.gov (United States)

    Brown, Shirley Vining

    1995-01-01

    Examines faculty and scientist recommendations of applicants to the National Science Foundation's (NSF) Graduate Fellowship Program, 1976-91. Data from the Cumulative Index on National Science Foundation Fellowships Applicants and Awardees are used. Data analysis supports the double bind hypothesis that minority women are doubly disadvantaged…

  3. Testing the Münch hypothesis of long distance phloem transport in plants

    DEFF Research Database (Denmark)

    Knoblauch, Michael; Knoblauch, Jan; Mullendore, Daniel L.

    2016-01-01

    , but this hypothesis has long faced major challenges. The key issue is whether the conductance of sieve tubes, including sieve plate pores, is sufficient to allow pressure flow. We show that with increasing distance between source and sink, sieve tube conductivity and turgor increases dramatically in Ipomoea nil. Our...

  4. Induction of Monocular Stereopsis by Altering Focus Distance: A Test of Ames’s Hypothesis

    Directory of Open Access Journals (Sweden)

    Dhanraj Vishwanath

    2016-04-01

    Full Text Available Viewing a real three-dimensional scene or a stereoscopic image with both eyes generates a vivid phenomenal impression of depth known as stereopsis. Numerous reports have highlighted the fact that an impression of stereopsis can be induced in the absence of binocular disparity. A method claimed by Ames (1925 involved altering accommodative (focus distance while monocularly viewing a picture. This claim was tested on naïve observers using a method inspired by the observations of Gogel and Ogle on the equidistance tendency. Consistent with Ames’s claim, most observers reported that the focus manipulation induced an impression of stereopsis comparable to that obtained by monocular-aperture viewing.

  5. Why does Rhinopithecus bieti prefer the highest elevation range in winter? A test of the sunshine hypothesis.

    Directory of Open Access Journals (Sweden)

    Rui-Chang Quan

    Full Text Available Environmental factors that affect spatiotemporal distribution patterns of animals usually include resource availability, temperature, and the risk of predation. However, they do not explain the counterintuitive preference of high elevation range in winter by the black-and-white snub-nosed monkey (Rhinopithecus bieti. We asked whether variation of sunshine along with elevations is the key driving force. To test this hypothesis, we conducted field surveys to demonstrate that there was a statistically significant pattern of high elevation use during winter. We then asked whether this pattern can be explained by certain environmental factors, namely temperature, sunshine duration and solar radiation. Finally, we concluded with a possible ecological mechanism for this pattern. In this study, we employed GIS technology to quantify solar radiation and sunshine duration across the monkey's range. Our results showed that: 1 R. bieti used the high altitude range between 4100-4400 m in winter although the yearly home range spanned from 3500-4500 m; 2 both solar radiation and sunshine duration increased with elevation while temperature decreased with elevation; 3 within the winter range, the use of range was significantly correlated with solar radiation and sunshine duration; 4 monkeys moved to the areas with high solar radiation and duration following a snowfall, where the snow melts faster and food is exposed earlier. We concluded that sunshine was the main factor that influences selection of high elevation habitat for R. bieti in winter. Since some other endotherms in the area exhibit similar winter distributional patterns, we developed a sunshine hypothesis to explain this phenomenon. In addition, our work also represented a new method of integrating GIS models into traditional field ecology research to study spatiotemporal distribution pattern of wildlife. We suggest that further theoretical and empirical studies are necessary for better understanding

  6. A new, sophisticated test of the Binary Black Hole Hypothesis for Quasars with Double-peaked Broad Balmer Lines.

    Science.gov (United States)

    Nguyen Duy Doan, Anh; Eracleous, Michael; Runnoe, Jessie; Halpern, Jules P.; Liu, Jia; Mathes, Gavin; Flohic, Helene M. L. G.

    2018-01-01

    Displaced peaks in the Balmer lines of quasars could serve as indirect evidence for the existence of close, bound supermassive black hole binaries (SBHBs) at sub-parsec separations. In this work, we test the SBHB hypothesis for 14 quasars with double-peaked emission lines using their long-term radial velocity curves. We make use of a Markov Chain Monte Carlo method to explore the parameter space efficiently. Compared to previous works, we have relaxed the assumption of circular orbits, adding two parameters (eccentricity and argument of periapsis) to the parameter space. We also account for jitter, i.e., short-term fluctuations in the radial velocity curves due to processes that are intrinsic to an individual broad-line region. We have found that the distribution of jitter about a smooth radial velocity curve resembles a Gaussian. Thus, jitter is equivalent to increasing measurement uncertainty in individual measurements. The resulting posterior distributions show the lower mass limit of the SBHBs to be in the range of 10^8 - 10^11 solar masses. For several objects, the mass limit drops by a few orders of magnitude compared to previous results by Liu et. al. However, we note that solutions corresponding to minimum masses often require very high orbital eccentricity ( > 0.9). We also calculate the orbital decay timescale of the binaries due to gravitational radiation, finding values in the range 10^6 - 10^11 years; these values correspond to the minimum-mass solutions. For one third of our targets, we can confidently disfavor the SBHB hypothesis on the basis that the minimum mass exceeds even the most massive black holes measured so far (2 x 10^10 solar masses). For the remaining objects, we must take into account the plausibility of a variety of parameters (e.g. eccentricity, lifetime, etc.) in our evaluation.

  7. A Bayesian sequential design with adaptive randomization for 2-sided hypothesis test.

    Science.gov (United States)

    Yu, Qingzhao; Zhu, Lin; Zhu, Han

    2017-11-01

    Bayesian sequential and adaptive randomization designs are gaining popularity in clinical trials thanks to their potentials to reduce the number of required participants and save resources. We propose a Bayesian sequential design with adaptive randomization rates so as to more efficiently attribute newly recruited patients to different treatment arms. In this paper, we consider 2-arm clinical trials. Patients are allocated to the 2 arms with a randomization rate to achieve minimum variance for the test statistic. Algorithms are presented to calculate the optimal randomization rate, critical values, and power for the proposed design. Sensitivity analysis is implemented to check the influence on design by changing the prior distributions. Simulation studies are applied to compare the proposed method and traditional methods in terms of power and actual sample sizes. Simulations show that, when total sample size is fixed, the proposed design can obtain greater power and/or cost smaller actual sample size than the traditional Bayesian sequential design. Finally, we apply the proposed method to a real data set and compare the results with the Bayesian sequential design without adaptive randomization in terms of sample sizes. The proposed method can further reduce required sample size. Copyright © 2017 John Wiley & Sons, Ltd.

  8. The Effect of Retention Interval Task Difficulty on Young Children's Prospective Memory: Testing the Intention Monitoring Hypothesis

    Science.gov (United States)

    Mahy, Caitlin E. V.; Moses, Louis J.

    2015-01-01

    The current study examined the impact of retention interval task difficulty on 4- and 5-year-olds' prospective memory (PM) to test the hypothesis that children periodically monitor their intentions during the retention interval and that disrupting this monitoring may result in poorer PM performance. In addition, relations among PM, working memory,…

  9. High-School Students' Need for Cognition, Self-Control Capacity, and School Achievement: Testing a Mediation Hypothesis

    Science.gov (United States)

    Bertrams, Alex; Dickhauser, Oliver

    2009-01-01

    In the present article, we examine the hypothesis that high-school students' motivation to engage in cognitive endeavors (i.e., their need for cognition; NFC) is positively related to their dispositional self-control capacity. Furthermore, we test the prediction that the relation between NFC and school achievement is mediated by self-control…

  10. The Influence of Maternal Acculturation, Neighborhood Disadvantage, and Parenting on Chinese American Adolescents' Conduct Problems: Testing the Segmented Assimilation Hypothesis

    Science.gov (United States)

    Liu, Lisa L.; Lau, Anna S.; Chen, Angela Chia-Chen; Dinh, Khanh T.; Kim, Su Yeong

    2009-01-01

    Associations among neighborhood disadvantage, maternal acculturation, parenting and conduct problems were investigated in a sample of 444 Chinese American adolescents. Adolescents (54% female, 46% male) ranged from 12 to 15 years of age (mean age = 13.0 years). Multilevel modeling was employed to test the hypothesis that the association between…

  11. Test of the hypothesis; a lymphoma stem cells exist which is capable of self-renewal

    DEFF Research Database (Denmark)

    Kjeldsen, Malene Krag

      Test of the hypothesis; a lymphoma stem cell exist which is capable of self-renewal   Malene Krag Pedersen, Karen Dybkaer, Hans E. Johnsen   The Research Laboratory, Department of Haematology, Aalborg Hospital, Århus University   Failure of current therapeutics in the treatment of diffuse large B...

  12. A Global comparison of surface soil characteristics across five cities: A test of the urban ecosystem convergence hypothesis.

    Science.gov (United States)

    Richard V. Pouyat; Ian D. Yesilonis; Miklos Dombos; Katalin Szlavecz; Heikki Setala; Sarel Cilliers; Erzsebet Hornung; D. Johan Kotze; Stephanie. Yarwood

    2015-01-01

    As part of the Global Urban Soil Ecology and Education Network and to test the urban ecosystem convergence hypothesis, we report on soil pH, organic carbon (OC), total nitrogen (TN), phosphorus (P), and potassium (K) measured in four soil habitat types (turfgrass, ruderal, remnant, and reference) in five metropolitan areas (Baltimore, Budapest,...

  13. Is Variability in Mate Choice Similar for Intelligence and Personality Traits? Testing a Hypothesis about the Evolutionary Genetics of Personality

    Science.gov (United States)

    Stone, Emily A.; Shackelford, Todd K.; Buss, David M.

    2012-01-01

    This study tests the hypothesis presented by Penke, Denissen, and Miller (2007a) that condition-dependent traits, including intelligence, attractiveness, and health, are universally and uniformly preferred as characteristics in a mate relative to traits that are less indicative of condition, including personality traits. We analyzed…

  14. Received social support and exercising: An intervention study to test the enabling hypothesis.

    Science.gov (United States)

    Rackow, Pamela; Scholz, Urte; Hornung, Rainer

    2015-11-01

    Received social support is considered important for health-enhancing exercise participation. The enabling hypothesis of social support suggests an indirect association of social support and exercising via constructs of self-regulation, such as self-efficacy. This study aimed at examining an expanded enabling hypothesis by examining effects of different kinds of social support (i.e., emotional and instrumental) on exercising not only via self-efficacy but also via self-monitoring and action planning. An 8-week online study was conducted. Participants were randomly assigned to an intervention or a control group. The intervention comprised finding and then exercising regularly with a new exercise companion. Intervention and control group effects were compared by a manifest multigroup model. Received emotional social support predicted self-efficacy, self-monitoring, and action planning in the intervention group. Moreover, received emotional social support was indirectly connected with exercise via the examined mediators. The indirect effect from received emotional social support via self-efficacy mainly contributed to the total effect. No direct or indirect effect of received instrumental social support on exercise emerged. In the control group, neither emotional nor instrumental social support was associated with any of the self-regulation constructs nor with exercise. Actively looking for a new exercise companion and exercising together seems to be beneficial for the promotion of received emotional and instrumental social support. Emotional support in turn promotes exercise by enabling better self-regulation, in particular self-efficacy. Statement of contribution What is already known on this subject? With the 'enabling hypothesis', Benight and Bandura (2004, Behav. Res. Ther., 42, 1129) claimed that social support indirectly affects behaviour via self-efficacy. Research in the domain of physical exercise has provided evidence for this enabling hypothesis on a

  15. Socioeconomic inequality in health in the British household panel: Tests of the social causation, health selection and the indirect selection hypothesis using dynamic fixed effects panel models.

    Science.gov (United States)

    Foverskov, Else; Holm, Anders

    2016-02-01

    Despite social inequality in health being well documented, it is still debated which causal mechanism best explains the negative association between socioeconomic position (SEP) and health. This paper is concerned with testing the explanatory power of three widely proposed causal explanations for social inequality in health in adulthood: the social causation hypothesis (SEP determines health), the health selection hypothesis (health determines SEP) and the indirect selection hypothesis (no causal relationship). We employ dynamic data of respondents aged 30 to 60 from the last nine waves of the British Household Panel Survey. Household income and location on the Cambridge Scale is included as measures of different dimensions of SEP and health is measured as a latent factor score. The causal hypotheses are tested using a time-based Granger approach by estimating dynamic fixed effects panel regression models following the method suggested by Anderson and Hsiao. We propose using this method to estimate the associations over time since it allows one to control for all unobserved time-invariant factors and hence lower the chances of biased estimates due to unobserved heterogeneity. The results showed no proof of the social causation hypothesis over a one to five year period and limited support for the health selection hypothesis was seen only for men in relation to HH income. These findings were robust in multiple sensitivity analysis. We conclude that the indirect selection hypothesis may be the most important in explaining social inequality in health in adulthood, indicating that the well-known cross-sectional correlations between health and SEP in adulthood seem not to be driven by a causal relationship, but instead by dynamics and influences in place before the respondents turn 30 years old that affect both their health and SEP onwards. The conclusion is limited in that we do not consider the effect of specific diseases and causal relationships in adulthood may be

  16. Sex differences in spatial ability: a test of the range size hypothesis in the order Carnivora.

    Science.gov (United States)

    Perdue, Bonnie M; Snyder, Rebecca J; Zhihe, Zhang; Marr, M Jackson; Maple, Terry L

    2011-06-23

    Sex differences in spatial cognition have been reported for many species ranging from voles to humans. The range size hypothesis predicts that sex differences in spatial ability will only occur in species in which the mating system selects for differential range size. Consistent with this prediction, we observed sex differences in spatial ability in giant pandas, a promiscuous species in which males inhabit larger ranges than females, but did not observe sex differences in Asian small-clawed otters, a related monogamous species in which males and females share home ranges. These results provide the first evidence of sex differences in spatial ability in the order Carnivora, and are consistent with the range size hypothesis.

  17. Do football teams learn from changing coaches? A test of the deceleration hypothesis

    Directory of Open Access Journals (Sweden)

    Agnieszka Bielinska-Kwapisz

    2014-12-01

    Full Text Available The paper explores the nature of change and finds evidence in favor of deceleration hypothesis: prior changes of a given type decrease the likelihood of a subsequent change of the same type while controlling for unobserved heterogeneity. We analyze leadership changes by explaining factors that influence football teams to replace their coaches. We use panel data for 33 National Football League’s teams from 1976 to 2008.

  18. Sex differences in spatial ability: a test of the range size hypothesis in the order Carnivora

    OpenAIRE

    Perdue, Bonnie M.; Snyder, Rebecca J.; Zhihe, Zhang; Marr, M. Jackson; Maple, Terry L

    2011-01-01

    Sex differences in spatial cognition have been reported for many species ranging from voles to humans. The range size hypothesis predicts that sex differences in spatial ability will only occur in species in which the mating system selects for differential range size. Consistent with this prediction, we observed sex differences in spatial ability in giant pandas, a promiscuous species in which males inhabit larger ranges than females, but did not observe sex differences in Asian small-clawed ...

  19. Testing the ``tropical storm'' hypothesis of Yucatan Peninsula climate variability during the Maya Terminal Classic Period

    Science.gov (United States)

    Medina-Elizalde, Martín; Polanco-Martínez, Josué Moises; Lases-Hernández, Fernanda; Bradley, Raymond; Burns, Stephen

    2016-09-01

    We examine the "tropical storm" hypothesis that precipitation variability in the Yucatan Peninsula (YP) was linked to the frequency of tropical cyclones during the demise of the Classic Maya civilization, in the Terminal Classic Period (TCP, AD 750-950). Evidence that supports the hypothesis includes: (1) a positive relationship between tropical storm frequency and precipitation amount over the YP today (proof of feasibility), (2) a statistically significant correlation between a stalagmite (Chaac) quantitative precipitation record from the YP and the number of named tropical cyclones affecting this region today (1852-2004) (calibration sensu lato), and, (3) correlations between the stalagmite Chaac precipitation record and an Atlantic basin tropical cyclone count record and two proxy records of shifts in macro-scale climate and ocean states that influence Atlantic tropical cyclongenesis. At face value, regional paleotempestology proxy records suggest that tropical storm activity in the YP was either similar or significantly lower than today during the TCP. The "tropical storm" hypothesis has implications for our understanding of the role the hydrological cycle played in the collapse of Classic Maya polities and the role of tropical storms in possibly ameliorating future drought in the YP and other tropical regions.

  20. The relation between sexual behavior and religiosity subtypes: a test of the secularization hypothesis.

    Science.gov (United States)

    Farmer, Melissa A; Trapnell, Paul D; Meston, Cindy M

    2009-10-01

    Previous literature on religion and sexual behavior has focused on narrow definitions of religiosity, including religious affiliation, religious participation, or forms of religiousness (e.g., intrinsic religiosity). Trends toward more permissive premarital sexual activity in the North American Christian-Judeo religion support the secularization hypothesis of religion, which posits an increasing gap between religious doctrine and behavior. However, the recent rise of fundamentalist and new age religious movements calls for a reexamination of the current link between religion and sexual behavior. The use of dual definitions of religiosity, including religious affiliation and dimensional subtypes, may further characterize this link. The present cross-sectional study evaluated patterns of sexual behavior in a young adult sample (N = 1302, M age = 18.77 years) in the context of the secularization hypothesis using religious affiliation and a liberal-conservative continuum of religious subtypes: paranormal belief, spirituality, intrinsic religiosity, and fundamentalism. Results indicated few affiliation differences in sexual behavior in men or women. Sexual behaviors were statistically predicted by spirituality, fundamentalism, and paranormal belief, and the endorsement of fundamentalism in particular was correlated with lower levels of female sexual behavior. The secularization hypothesis was supported by consistent levels of sexual activity across affiliations and is contradicted by the differential impact of religiosity subtypes on sexual behavior. Findings suggested that the use of religious subtypes to evaluate religious differences, rather than solely affiliation, may yield useful insights into the link between religion and sexual behavior.

  1. Test equating methods and practices

    CERN Document Server

    Kolen, Michael J

    1995-01-01

    In recent years, many researchers in the psychology and statistical communities have paid increasing attention to test equating as issues of using multiple test forms have arisen and in response to criticisms of traditional testing techniques This book provides a practically oriented introduction to test equating which both discusses the most frequently used equating methodologies and covers many of the practical issues involved The main themes are - the purpose of equating - distinguishing between equating and related methodologies - the importance of test equating to test development and quality control - the differences between equating properties, equating designs, and equating methods - equating error, and the underlying statistical assumptions for equating The authors are acknowledged experts in the field, and the book is based on numerous courses and seminars they have presented As a result, educators, psychometricians, professionals in measurement, statisticians, and students coming to the subject for...

  2. [Inappropriate test methods in allergy].

    Science.gov (United States)

    Kleine-Tebbe, J; Herold, D A

    2010-11-01

    Inappropriate test methods are increasingly utilized to diagnose allergy. They fall into two categories: I. Tests with obscure theoretical basis, missing validity and lacking reproducibility, such as bioresonance, electroacupuncture, applied kinesiology and the ALCAT-test. These methods lack both the technical and clinical validation needed to justify their use. II. Tests with real data, but misleading interpretation: Detection of IgG or IgG4-antibodies or lymphocyte proliferation tests to foods do not allow to separate healthy from diseased subjects, neither in case of food intolerance, allergy or other diagnoses. The absence of diagnostic specificity induces many false positive findings in healthy subjects. As a result unjustified diets might limit quality of life and lead to malnutrition. Proliferation of lymphocytes in response to foods can show elevated rates in patients with allergies. These values do not allow individual diagnosis of hypersensitivity due to their broad variation. Successful internet marketing, infiltration of academic programs and superficial reporting by the media promote the popularity of unqualified diagnostic tests; also in allergy. Therefore, critical observation and quick analysis of and clear comments to unqualified methods by the scientific medical societies are more important than ever.

  3. Testing the phenotype-linked fertility hypothesis in the presence and absence of inbreeding.

    Science.gov (United States)

    Forstmeier, W; Ihle, M; Opatová, P; Martin, K; Knief, U; Albrechtová, J; Albrecht, T; Kempenaers, B

    2017-05-01

    The phenotype-linked fertility hypothesis suggests that females can judge male fertility by inspecting male phenotypic traits. This is because male sexually selected traits might correlate with sperm quality if both are sensitive to factors that influence male condition. A recent meta-analysis found little support for this hypothesis, suggesting little or no shared condition dependence. However, we recently reported that in captive zebra finches (Taeniopygia guttata) inbreeding had detrimental effects both on phenotypic traits and on measures of sperm quality, implying that variation in inbreeding could induce positive covariance between indicator traits and sperm quality. Therefore, we here assess empirically the average strength of correlations between phenotypic traits (courtship rate, beak colour, tarsus length) and measures of sperm quality (proportion of functional sperm, sperm velocity, sperm length) in populations of only outbred individuals and in mixed populations consisting of inbreds (F = 0.25) and outbreds (F = 0). As expected, phenotype sperm-trait correlations were stronger when the population contained a mix of inbred and outbred individuals. We also found unexpected heterogeneity between our two study populations, with correlations being considerably stronger in a domesticated population than in a recently wild-derived population. Correlations ranged from essentially zero among outbred-only wild-derived birds (mean Fisher's Zr ± SE = 0.03 ± 0.10) to moderately strong among domesticated birds of mixed inbreeding status (Zr ± SE = 0.38 ± 0.08). Our results suggest that, under some conditions, the phenotype-linked fertility hypothesis might apply. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  4. A Test of the Adaptive Market Hypothesis using a Time-Varying AR Model in Japan

    OpenAIRE

    Akihiko Noda

    2012-01-01

    This study examines the adaptive market hypothesis (AMH) in Japanese stock markets (TOPIX and TSE2). In particular, we measure the degree of market efficiency by using a time-varying model approach. The empirical results show that (1) the degree of market efficiency changes over time in the two markets, (2) the level of market efficiency of the TSE2 is lower than that of the TOPIX in most periods, and (3) the market efficiency of the TOPIX has evolved, but that of the TSE2 has not. We conclud...

  5. Test of the neurolinguistic programming hypothesis that eye-movements relate to processing imagery.

    Science.gov (United States)

    Wertheim, E H; Habib, C; Cumming, G

    1986-04-01

    Bandler and Grinder's hypothesis that eye-movements reflect sensory processing was examined. 28 volunteers first memorized and then recalled visual, auditory, and kinesthetic stimuli. Changes in eye-positions during recall were videotaped and categorized by two raters into positions hypothesized by Bandler and Grinder's model to represent visual, auditory, and kinesthetic recall. Planned contrast analyses suggested that visual stimulus items, when recalled, elicited significantly more upward eye-positions and stares than auditory and kinesthetic items. Auditory and kinesthetic items, however, did not elicit more changes in eye-position hypothesized by the model to represent auditory and kinesthetic recall, respectively.

  6. Evaluation of Climate Model Output Against Observations in a Hypothesis Testing Framework

    Science.gov (United States)

    Braverman, A. J.; Quam, B. M.

    2016-12-01

    A ubiquitous problem in the evaluation of climate models is determining whether two time series or two maps are similar. For example, the quality of a climate model is often identified with its ability to reproduce, to some level of accuracy, an observed time series or spatial field. The criterion for determining the level of accuracy required differs from problem to problem, analyst to analyst, variable to variable, and a host of other circumstances. It often boils down to ad hoc judgements. In this talk we describe recent work to evaluate the CMIP5 historical climate model runs that quantifies the similarity between climate-model-generated and observed data as a probability. That probability is a measure of the compatiblity of the climate-model-generated output under the null hypothesis that the model output and the observed data come from processes that share the same climate-scale behavior. If the probability is small, this suggests that the two sets of data do not come from the same process. The definition of "small" can be determined in a game-theoretic framework, in which a loss function specifies the cost of incorrectly rejecting the null hypothesis and the consquences of this for specific decsions that are to be made based on the model output.

  7. External attentional focus enhances movement automatization: a comprehensive test of the constrained action hypothesis.

    Science.gov (United States)

    Kal, E C; van der Kamp, J; Houdijk, H

    2013-08-01

    An external focus of attention has been shown to result in superior motor performance compared to an internal focus of attention. This study investigated whether this is due to enhanced levels of movement automatization, as predicted by the constrained action hypothesis (McNevin, Shea, & Wulf, 2003). Thirty healthy participants performed a cyclic one-leg extension-flexion task with both the dominant and non-dominant leg. Focus of attention was manipulated via instructions. The degree of automatization of movement was assessed by measuring dual task costs as well as movement execution parameters (i.e., EMG activity, movement fluency, and movement regularity). Results revealed that an external focus of attention led to significantly better motor performance (i.e., shorter movement duration) than an internal focus. Although dual task costs of the motor task did not differ as a function of attentional focus, cognitive dual task costs were significantly higher when attention was directed internally. An external focus of attention resulted in more fluent and more regular movement execution than an internal focus, whereas no differences were found concerning muscular activity. These results indicate that an external focus of attention results in more automatized movements than an internal focus and, therefore, provide support for the constrained action hypothesis. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Testing the social competition hypothesis of depression using a simple economic game.

    Science.gov (United States)

    Kupferberg, Aleksandra; Hager, Oliver M; Fischbacher, Urs; Brändle, Laura S; Haynes, Melanie; Hasler, Gregor

    2016-03-01

    Price's social competition hypothesis interprets the depressive state as an unconscious, involuntary losing strategy, which enables individuals to yield and accept defeat in competitive situations. We investigated whether patients who suffer from major depressive disorder (MDD) would avoid competition more often than either patients suffering from borderline personality disorder (BPD) or healthy controls. In a simple paper-folding task healthy participants and patiens with MDD and BPD were matched with two opponents, one with an unknown diagnosis and one who shared their clinical diagnosis, and they had to choose either a competitive or cooperative payment scheme for task completion. When playing against an unknown opponent, but not the opponent with the same diagnosis, the patients with depression chose the competitive payment scheme statistically less often than healthy controls and patients diagnosed with BPD. The competition avoidance against the unknown opponent is consistent with Price's social competition hypothesis. G.H. received research support, consulting fees and speaker honoraria from Lundbeck, AstraZeneca, Servier, Eli Lilly, Roche and Novartis. © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

  9. Ploidy evolution in the yeast Saccharomyces cerevisiae: a test of the nutrient limitation hypothesis.

    Science.gov (United States)

    Mable, B K

    2001-01-08

    The nutrient limitation hypothesis provides a nongenetic explanation for the evolution of life cycles that retain both haploid and diploid phases: differences in nutrient requirements and uptake allow haploids to override the potential genetic advantages provided by diploidy under certain nutrient limiting conditions. The relative fitness of an isogenic series of haploid, diploid and tetraploid yeast cells (Saccharomyces cerevisiae), which were also equivalent at the mating type locus, was measured. Fitness was measured both by growth rate against a common competitor and by intrinsic growth rate in isolated cultures, under four environmental conditions: (1) rich medium (YPD) at the preferred growth temperature (30 °C); (2) nutrient poor medium (MM) at 30 °C; (3) YPD at a nonpreferred temperature (37 °C); and (4) MM at 37 °C. In contrast to the predictions of the nutrient limitation hypothesis, haploids grew significantly faster than diploids under nutrient rich conditions, but there were no apparent differences between them when fitness was determined by relative competitive ability. In addition, temperature affected the relative growth of haploids and diploids, with haploids growing proportionately faster at higher temperatures. Tetraploids performed very poorly under all conditions compared. Cell geometric parameters were not consistent predictors of fitness under the conditions measured.

  10. The cointegration analysis in hypothesis of heteroschedasticity: the wild bootstrap test

    Directory of Open Access Journals (Sweden)

    Margherita Gerolimetto

    2007-10-01

    Full Text Available We consider the problem of comparing, by simulations, the robustness as regards heteroschedasticity GARCH (1,1 of some of the most important procedures proposed in literature for the cointegration analysis. In particular, we consider the Johansen test and some "two steps" "procedures", i.e. Dickey-Fuller test, Sargan-Bhargava test and an External Bootstrap test. The Bootstrap test performs very well, particularly for the lowest sample size.

  11. Approach/avoidance motivation, message framing and skin cancer prevention: a test of the congruency hypothesis.

    Science.gov (United States)

    Hevey, David; Dolan, Michelle

    2014-08-01

    The congruency hypothesis posits that approach-orientated individuals are persuaded to engage in prevention behaviours by positively framed messages; conversely, negatively framed messages are more persuasive in encouraging those who are avoidance-orientated. A 2 (frame: loss vs gain) × 2 (motivation: avoidance vs approach) design examined the effects of skin cancer information on sun-protective intentions and free sunscreen sample requests among 533 young adults. Gain-framed messages had the strongest effect on sun-protective intentions for approach-oriented individuals, whereas loss-framed messages had the strongest effect on avoidance-oriented individuals. Message framing effects on precautionary sun behaviour intentions were moderated by motivational differences. © The Author(s) 2013.

  12. Sexual deception in a cannibalistic mating system? Testing the Femme Fatale hypothesis

    Science.gov (United States)

    Barry, Katherine L.

    2015-01-01

    Animal communication theory holds that in order to be evolutionarily stable, signals must be honest on average, but significant dishonesty (i.e. deception) by a subset of the population may also evolve. A typical praying mantid mating system involves active mate searching by males, which is guided by airborne sex pheromones in most species for which mate-searching cues have been studied. The Femme Fatale hypothesis suggests that female mantids may be selected to exploit conspecific males as prey if they benefit nutritionally from cannibalism. Such a benefit exists in the false garden mantid Pseudomantis albofimbriata—females use the resources gained from male consumption to significantly increase their body condition and reproductive output. This study aimed to examine the potential for chemical deception among the subset of females most likely to benefit from cannibalism (poorly fed females). Females were placed into one of four feeding treatments (‘Very Poor’, ‘Poor’, ‘Medium’ and ‘Good’), and males were given the opportunity to choose between visually obscured females in each of the treatments. Female body condition and fecundity varied linearly with food quantity; however, female attractiveness did not. That is, Very Poor females attracted significantly more males than any of the other female treatments, even though these females were in significantly poorer condition, less fecund (in this study) and more likely to cannibalise (in a previous study). In addition, there was a positive correlation between fecundity and attractiveness if Very Poor females were removed from the analysis, suggesting an inherently honest signalling system with a subset of dishonest individuals. This is the first empirical study to provide evidence of sexual deception via chemical cues, and the first to provide support for the Femme Fatale hypothesis. PMID:25520352

  13. Sexual deception in a cannibalistic mating system? Testing the Femme Fatale hypothesis.

    Science.gov (United States)

    Barry, Katherine L

    2015-02-07

    Animal communication theory holds that in order to be evolutionarily stable, signals must be honest on average, but significant dishonesty (i.e. deception) by a subset of the population may also evolve. A typical praying mantid mating system involves active mate searching by males, which is guided by airborne sex pheromones in most species for which mate-searching cues have been studied. The Femme Fatale hypothesis suggests that female mantids may be selected to exploit conspecific males as prey if they benefit nutritionally from cannibalism. Such a benefit exists in the false garden mantid Pseudomantis albofimbriata-females use the resources gained from male consumption to significantly increase their body condition and reproductive output. This study aimed to examine the potential for chemical deception among the subset of females most likely to benefit from cannibalism (poorly fed females). Females were placed into one of four feeding treatments ('Very Poor', 'Poor', 'Medium' and 'Good'), and males were given the opportunity to choose between visually obscured females in each of the treatments. Female body condition and fecundity varied linearly with food quantity; however, female attractiveness did not. That is, Very Poor females attracted significantly more males than any of the other female treatments, even though these females were in significantly poorer condition, less fecund (in this study) and more likely to cannibalise (in a previous study). In addition, there was a positive correlation between fecundity and attractiveness if Very Poor females were removed from the analysis, suggesting an inherently honest signalling system with a subset of dishonest individuals. This is the first empirical study to provide evidence of sexual deception via chemical cues, and the first to provide support for the Femme Fatale hypothesis. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  14. The Neuropsychology of Adolescent Sexual Offending: Testing an Executive Dysfunction Hypothesis.

    Science.gov (United States)

    Morais, Hugo B; Joyal, Christian C; Alexander, Apryl A; Fix, Rebecca L; Burkhart, Barry R

    2016-12-01

    Although executive dysfunctions are commonly hypothesized to contribute to sexual deviance or aggression, evidence of this relationship is scarce and its specificity is unproven, especially among adolescents. The objective of this study was to compare the executive functioning (EF) of adolescents with sexual offense convictions (ASOC) to that of non-sex-delinquents (NSD). A secondary goal was to assess the relationship among specific sexual offense characteristics (i.e., victim age), history of childhood sexual abuse (CSA), and EF. It was hypothesized that as a group, ASOC would present similar EF profiles as NSD. It was further hypothesized that ASOC with child victims would present significantly higher rates of CSA and more severe impairment of EF than ASOC with peer-aged or older victims and NSD. A total of 183 male adolescents (127 ASOC and 56 NSD) were interviewed to collect demographic information, sexual development history, history of CSA, an assessment of living conditions, and history of delinquency and sexual offending. Participants were administered the Delis-Kaplan Executive Functioning System and the Hare Psychopathy Checklist-Youth Version. In accord with the first hypothesis, ASOC and NSD presented similar EF scores, well below normative values. Thus, EF deficits may not characterize the profiles of adolescents with sexual behavior problems. Contrarily to our second hypothesis, however, offending against children and or experiencing CSA were not associated with poorer EF performance. On the contrary, ASOC with child victims obtained significantly higher scores on measures of higher order EF than both ASOC with peer-aged or older victims and NSD. Implications of these results and future directions are discussed. © The Author(s) 2015.

  15. An Ice-and-Snow Hypothesis for Early Mars, and the Runoff-Production Test

    Science.gov (United States)

    Kite, E. S.

    2017-10-01

    Cold (snowmelt) models for Early Mars climate can be tested by measuring paleochannel widths and meander wavelengths for Early Mars watersheds with well-defined drainage area. I will review snowmelt models, and report results of these tests.

  16. Sequential hypothesis testing for automatic detection of task-related changes in cerebral perfusion in a brain-computer interface.

    Science.gov (United States)

    Faulkner, Hayley G; Myrden, Andrew; Li, Michael; Mamun, Khondaker; Chau, Tom

    2015-11-01

    Evidence suggests that the cerebral blood flow patterns accompanying cognitive activity are retained in many locked-in patients. These patterns can be monitored using transcranial Doppler ultrasound (TCD), a medical imaging technique that measures bilateral cerebral blood flow velocities. Recently, TCD has been proposed as an alternative imaging modality for brain-computer interfaces (BCIs). However, most previous TCD-BCI studies have performed offline analyses with impractically lengthy tasks. In this study, we designed a BCI that automatically differentiates between counting and verbal fluency tasks using sequential hypothesis testing to make decisions as quickly as possible. Ten able-bodied participants silently alternated between counting and verbal fluency tasks within the paradigm of a simulated on-screen keyboard. During this experiment, blood flow velocities were recorded within the left and right middle cerebral arteries using bilateral TCD. Twelve features were used to characterize TCD signals. In a simulated online analysis, sequential hypothesis testing was used to update estimates of class probability every 250 ms as TCD data were processed. Classification was terminated once a threshold level of certainty was reached. Mean classification accuracy across all participants was 72% after an average of 23s, compared to an offline analysis which obtained a classification accuracy of 80% after 45 s. This represents a substantial gain in data transmission rate, while maintaining classification accuracies exceeding 70%. Furthermore, a range of decision times between 19 and 28s was observed, suggesting that the ability of sequential hypothesis testing to adapt the task duration for each individual participant is critical to achieving consistent performance across participants. These results indicate that sequential hypothesis testing is a promising alternative for online TCD-BCIs. Copyright © 2015 Elsevier Ireland Ltd and the Japan Neuroscience Society. All

  17. [What does "p" mean at conclusion of a test of hypothesis in a randomized controlled clinical trial of superiority?].

    Science.gov (United States)

    Marubini, Ettore; Gallo, Fabio; Pizzamiglio, Sara; Verderio, Paolo

    2006-10-01

    The aim of this statistical note, the sixth in the series, is to introduce the rationale of the test of hypothesis suitable for comparing the effect of two treatments in a randomized controlled clinical trial of superiority. The presentation takes advantage of the analogy with a criminal trial debate based upon circumstantial evidence in an Italian Court. The results of three randomized controlled clinical trials: ISIS-1, AIMS and RESTORE are introduced and proper ways for their interpretation are suggested.

  18. Are implicit motives revealed in mere words? Testing the marker-word hypothesis with computer-based text analysis

    OpenAIRE

    Schultheiss, Oliver C.

    2013-01-01

    Traditionally, implicit motives (i.e., non-conscious preferences for specific classes of incentives) are assessed through semantic coding of imaginative stories. The present research tested the marker-word hypothesis, which states that implicit motives are reflected in the frequencies of specific words. Using Linguistic Inquiry and Word Count (LIWC; Pennebaker et al., 2001), Study 1 identified word categories that converged with a content-coding measure of the implicit motives for power, achi...

  19. Personality and Behavior in Social Dilemmas: Testing the Situational Strength Hypothesis and the Role of Hypothetical Versus Real Incentives.

    Science.gov (United States)

    Lozano, José H

    2016-02-01

    Previous research aimed at testing the situational strength hypothesis suffers from serious limitations regarding the conceptualization of strength. In order to overcome these limitations, the present study attempts to test the situational strength hypothesis based on the operationalization of strength as reinforcement contingencies. One dispositional factor of proven effect on cooperative behavior, social value orientation (SVO), was used as a predictor of behavior in four social dilemmas with varying degree of situational strength. The moderating role of incentive condition (hypothetical vs. real) on the relationship between SVO and behavior was also tested. One hundred undergraduates were presented with the four social dilemmas and the Social Value Orientation Scale. One-half of the sample played the social dilemmas using real incentives, whereas the other half used hypothetical incentives. Results supported the situational strength hypothesis in that no behavioral variability and no effect of SVO on behavior were found in the strongest situation. However, situational strength did not moderate the effect of SVO on behavior in situations where behavior showed variability. No moderating effect was found for incentive condition either. The implications of these results for personality theory and assessment are discussed. © 2014 Wiley Periodicals, Inc.

  20. The Avalanche Hypothesis and Compression of Morbidity: Testing Assumptions through Cohort-Sequential Analysis

    Science.gov (United States)

    Silberman, Jordan; Wang, Chun; Mason, Shawn T.; Schwartz, Steven M.; Hall, Matthew; Morrissette, Jason L.; Tu, Xin M.; Greenhut, Janet

    2015-01-01

    Background The compression of morbidity model posits a breakpoint in the adult lifespan that separates an initial period of relative health from a subsequent period of ever increasing morbidity. Researchers often assume that such a breakpoint exists; however, this assumption is hitherto untested. Purpose To test the assumption that a breakpoint exists—which we term a morbidity tipping point—separating a period of relative health from a subsequent deterioration in health status. An analogous tipping point for healthcare costs was also investigated. Methods Four years of adults’ (N = 55,550) morbidity and costs data were retrospectively analyzed. Data were collected in Pittsburgh, PA between 2006 and 2009; analyses were performed in Rochester, NY and Ann Arbor, MI in 2012 and 2013. Cohort-sequential and hockey stick regression models were used to characterize long-term trajectories and tipping points, respectively, for both morbidity and costs. Results Morbidity increased exponentially with age (Pmorbidity tipping point was observed at age 45.5 (95% CI, 41.3-49.7). An exponential trajectory was also observed for costs (Pmorbidity and costs increased substantially (Psmorbidity tipping point, confirming an important but untested assumption. This tipping point, however, may occur earlier in the lifespan than is widely assumed. An “avalanche of morbidity” occurred after the morbidity tipping point—an ever increasing rate of morbidity progression. For costs, an analogous tipping point and “avalanche” were observed. The time point at which costs began to increase substantially occurred approximately 6 years before health status began to deteriorate. PMID:25962130

  1. Sex- and age-related mortality profiles during famine: testing the 'body fat' hypothesis.

    Science.gov (United States)

    Speakman, John R

    2013-11-01

    During famines females generally have a mortality advantage relative to males, and the highest levels of mortality occur in the very young and the elderly. One popular hypothesis is that the sex differential in mortality may reflect the greater body fatness combined with lower metabolism of females, which may also underpin the age-related patterns of mortality among adults. This study evaluated the 'body fat' hypothesis using a previously published and validated mathematical model of survival during total starvation. The model shows that at a given body weight females would indeed be expected to survive considerably longer than males in the absence of food. At a mass of 70 kg for example a female aged 30 would survive for 144 days compared with life expectancy of only 95 days for a male of the same age and weight. This effect is contributed to by both the higher body fatness and lower metabolism of the females at a given body weight. However, females are generally smaller than males and in addition to a sex effect there was also a major effect of body size - heavier individuals survive longer. When this body size effect was removed by considering survival in relation to BMI the sex effect was much reduced, and could be offset by a relatively small difference in pre-famine BMI between the sexes. Nevertheless, combining these predictions with observed mean BMIs of males and females across 48 countries at the low end of the obesity spectrum suggests that in the complete absence of food females would survive on average about 40% longer (range 6 to 64.5%) than males. The energy balance model also predicted that older adult individuals should survive much longer than younger adult individuals, by virtue of their lower resting metabolic rates and lower activity levels. Observations of the female survival advantage in multiple famines span a much wider range than the model prediction (5% to 210%). This suggests in some famines body fatness may be a significant factor

  2. Can retinal adhesion mechanisms determine cell-sorting patterns: a test of the differential adhesion hypothesis.

    Science.gov (United States)

    Thomas, W A; Yancey, J

    1988-05-01

    Embryonic chick neural retina cells possess two classes of adhesion mechanism, one Ca2+-independent, one Ca2+-dependent, responsible for short-term cell aggregation. This study investigates the role of these mechanisms in the long-term cell sorting potentially relevant to in vivo histogenesis. Retina cells are prepared either with both (E cells) or with only one mechanism (TC cells, CD; LTE cells, CI), respectively. The two types of cell preparations are differentially labelled using fluorescein or rhodamine isothiocyanate, mixed and allowed to aggregate in the presence or absence of cycloheximide at 0.5 microgram ml-1 to retard metabolic recovery of the removed adhesive mechanism. When observed by fluorescence and phase-contrast microscopy, the aggregates formed in cycloheximide show cell sorting, the cells with both mechanisms assuming a more interior position relative to those with a single adhesion mechanism. In parallel hanging-drop experiments, preformed aggregates of cells with a single adhesion mechanism are seen to spread upon aggregates of cells with both mechanisms. No sorting occurs amongst cells from a given stage prepared using any single dissociation protocol. The observed cell sorting would thus seem to derive exclusively from differential cell adhesiveness dependent upon the different dissociation conditions and maintained in the presence of cycloheximide. The experiments support the hypothesis that the dual CI and CD adhesion mechanisms in question can play a central role in governing cell-sorting behaviour during normal histogenesis.

  3. Testing the water hypothesis: Quantitative morphological analysis of terrestrial and martian mid-latitude gullies

    Science.gov (United States)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2017-10-01

    Although Martian gullies resemble terrestrial counterparts, two conflicting hypotheses exist for their formation still invoke fluvial processes on the one hand or lubricated CO2 flows on the other. In this work we compared the quantitative morphology of terrestrial gullies, known to have formed by liquid water, and mid-latitude Martian gullies in the Martian southern hemisphere. We also compared these results with measurements of Martian dry ravines adjacent to the gullies. Our results show a similarity between Martian and terrestrial gully formation, supporting the hypothesis that liquid water was involved in their erosion. Our results show dry ravines differ morphologically from gullies, further suggesting fluidised flows as a likely origin of the latter. Variations in the relationships across various terrestrial and Martian gullies indicate the significance of local environmental and geological conditions. Our work supports the idea that Martian gullies may not have been formed by just one single process but may have evolved through a more complex interaction of processes and environment.

  4. Why Do Fast-Growing Bacteria Enter Overflow Metabolism? Testing the Membrane Real Estate Hypothesis.

    Science.gov (United States)

    Szenk, Mariola; Dill, Ken A; de Graff, Adam M R

    2017-08-23

    Bacteria and other cells show a puzzling behavior. At high growth rates, E. coli switch from respiration (which is ATP-efficient) to using fermentation for additional ATP (which is inefficient). This overflow metabolism results in a several-fold decrease in ATP produced per glucose molecule provided as food. By integrating diverse types of experimental data into a simple biophysical model, we give evidence that this onset is the result of the membrane real estate hypothesis: Fast growth drives cells to be bigger, reducing their surface-to-volume ratios. This decreases the membrane area available for respiratory proteins despite growing demand, causing increased crowding. Only when respiratory proteins reach their crowding limit does the cell activate fermentation, since fermentation allows faster ATP production per unit membrane area. Surface limitation thus creates a Pareto trade-off between membrane efficiency and ATP yield that links metabolic choice to the size and shape of a bacterial cell. By exploring the predictions that emerge from this trade-off, we show how consideration of molecular structures, energetics, rates, and equilibria can provide important insight into cellular behavior. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Catalysis in glycine N-methyltransferase: testing the electrostatic stabilization and compression hypothesis.

    Science.gov (United States)

    Soriano, Alejandro; Castillo, Raquel; Christov, Christo; Andrés, Juan; Moliner, Vicente; Tuñón, Iñaki

    2006-12-19

    Glycine N-methyltransferase (GNMT) is an S-adenosyl-l-methionine dependent enzyme that catalyzes glycine transformation to sarcosine. Here, we present a hybrid quantum mechanics/molecular mechanics (QM/MM) computational study of the reaction compared to the counterpart process in water. The process takes place through an SN2 mechanism in both media with a transition state in which the transferring methyl group is placed in between the donor (SAM) and the acceptor (the amine group of glycine). Comparative analysis of structural, electrostatic, and electronic characteristics of the in-solution and enzymatic transition states allows us to get a deeper insight into the origins of the enzyme's catalytic power. We found that the enzyme is able to stabilize the substrate in its more active basic form by means of a positively charged residue (Arg175) placed in the active site. However, the maximum stabilization is attained for the transition state. In this case, the enzyme is able to form stronger hydrogen bonds with the positively charged amine group. Finally, we show that in agreement with previous computational studies on other methyltransferases, there is no computational evidence for the compression hypothesis, as was formulated by Schowen (Hegazi, M. F., Borchardt, R. T., and Schowen, R. L. (1979) J. Am. Chem. Soc. 101, 4359-4365).

  6. Men's preference for women's facial features: testing homogamy and the paternity uncertainty hypothesis.

    Science.gov (United States)

    Bovet, Jeanne; Barthes, Julien; Durand, Valérie; Raymond, Michel; Alvergne, Alexandra

    2012-01-01

    Male mate choice might be based on both absolute and relative strategies. Cues of female attractiveness are thus likely to reflect both fitness and reproductive potential, as well as compatibility with particular male phenotypes. In humans, absolute clues of fertility and indices of favorable developmental stability are generally associated with increased women's attractiveness. However, why men exhibit variable preferences remains less studied. Male mate choice might be influenced by uncertainty of paternity, a selective factor in species where the survival of the offspring depends on postnatal paternal care. For instance, in humans, a man might prefer a woman with recessive traits, thereby increasing the probability that his paternal traits will be visible in the child and ensuring paternity. Alternatively, attractiveness is hypothesized to be driven by self-resembling features (homogamy), which would reduce outbreeding depression. These hypotheses have been simultaneously evaluated for various facial traits using both real and artificial facial stimuli. The predicted preferences were then compared to realized mate choices using facial pictures from couples with at least 1 child. No evidence was found to support the paternity uncertainty hypothesis, as recessive features were not preferred by male raters. Conversely, preferences for self-resembling mates were found for several facial traits (hair and eye color, chin dimple, and thickness of lips and eyebrows). Moreover, realized homogamy for facial traits was also found in a sample of long-term mates. The advantages of homogamy in evolutionary terms are discussed.

  7. Effects of Prematurity on the Development of Contrast Sensitivity: Testing the Visual Experience Hypothesis

    Science.gov (United States)

    Bosworth, Rain G.; Dobkins, Karen R.

    2013-01-01

    In order to investigate the effects of visual experience on early visual development, the current study compared contrast sensitivity across infants born with different levels of moderate-to-late prematurity. Here the logic is that at any given postterm age, the most premature infants will have the oldest postnatal age. Given that postnatal age is a proxy for visual experience, the visual experience hypothesis predicts that infants who are more premature, yet healthy, should have higher sensitivity. Luminance (light/dark) and chromatic (red/green) contrast sensitivities (CS) were measured in 236 healthy infants (born −10 to +2 weeks relative to due date) between 5 and 32 weeks postterm age from due date and 8 to 38 weeks postnatal from birth date. For chromatic CS, we found clear evidence that infants who were most premature within our sample had the highest sensitivity. Specifically, 4 to 10 additional weeks of visual experience, by virtue of being born early, enhanced chromatic CS. For luminance CS, similar but weaker results were seen. Here, only infants with an additional 6 to 10 weeks of visual experience, and only at later age points in development, showed enhanced sensitivity. However, CS in preterm infants was still below that of fullterm infants with equivalent postnatal age. In sum, these results suggest that chromatic CS is influenced more by prematurity (and possibly visual experience) than is luminance CS, which has implications for differential development of Parvocellular and Magnocellular pathways. PMID:23485427

  8. Men's preference for women's facial features: testing homogamy and the paternity uncertainty hypothesis.

    Directory of Open Access Journals (Sweden)

    Jeanne Bovet

    Full Text Available Male mate choice might be based on both absolute and relative strategies. Cues of female attractiveness are thus likely to reflect both fitness and reproductive potential, as well as compatibility with particular male phenotypes. In humans, absolute clues of fertility and indices of favorable developmental stability are generally associated with increased women's attractiveness. However, why men exhibit variable preferences remains less studied. Male mate choice might be influenced by uncertainty of paternity, a selective factor in species where the survival of the offspring depends on postnatal paternal care. For instance, in humans, a man might prefer a woman with recessive traits, thereby increasing the probability that his paternal traits will be visible in the child and ensuring paternity. Alternatively, attractiveness is hypothesized to be driven by self-resembling features (homogamy, which would reduce outbreeding depression. These hypotheses have been simultaneously evaluated for various facial traits using both real and artificial facial stimuli. The predicted preferences were then compared to realized mate choices using facial pictures from couples with at least 1 child. No evidence was found to support the paternity uncertainty hypothesis, as recessive features were not preferred by male raters. Conversely, preferences for self-resembling mates were found for several facial traits (hair and eye color, chin dimple, and thickness of lips and eyebrows. Moreover, realized homogamy for facial traits was also found in a sample of long-term mates. The advantages of homogamy in evolutionary terms are discussed.

  9. Chronic fatigue syndrome and fibromyalgia in diagnosed sleep disorders: a further test of the 'unitary' hypothesis.

    Science.gov (United States)

    Pejovic, Slobodanka; Natelson, Benjamin H; Basta, Maria; Fernandez-Mendoza, Julio; Mahr, Fauzia; Vgontzas, Alexandros N

    2015-04-12

    Since chronic fatigue syndrome (CFS) and fibromyalgia (FM) often co-exist, some believe they reflect the same process, somatization. Against that hypothesis are data suggesting FM but not CFS was common in patients with sleep-disordered breathing (SDB). The presence of discrete case definitions for CFS and FM allowed us to explore rates of CFS alone, CFS with FM, and FM alone in SDB patients compared to those with sleep complaints that fulfilled criteria for insomnia. Participants were 175 sequential patients with sleep-related symptoms (122 had SDB and 21 had insomnia) and 39 healthy controls. Diagnoses were made by questionnaires, tender point count, and rule out labs; sleepiness was assessed with Epworth Sleepiness Scale and mood with Beck Depression Inventory. Rates of CFS, FM or CFS + FM were high: 13% in SDB and 48% in insomnia. CFS occurred frequently in SDB and insomnia, but FM occurred frequently only in insomnia. SDB patients with CFS and/or FM had higher daytime sleepiness than those without these disorders. CFS patients should complete Epworth scales, and sleep evaluation should be considered for those with scores ≥ 16 before receiving the diagnosis of CFS; the coexistence of depressed mood in these patients suggests some may be helped by treatment of their depression. That FM was underrepresented in SDB suggests FM and CFS may have different underlying pathophysiological causes.

  10. Testing the heterospecific attraction hypothesis with time-series data on species co-occurrence

    Science.gov (United States)

    Sebastián-González, Esther; Sánchez-Zapata, José Antonio; Botella, Francisco; Ovaskainen, Otso

    2010-01-01

    The distributional patterns of actively moving animals are influenced by the cues that the individuals use for choosing sites into which they settle. Individuals may gather information about habitat quality using two types of strategies, either directly assessing the relevant environmental factors, or using the presence of conspecifics or heterospecifics as an indirect measure of habitat quality. We examined patterns of heterospecific attraction with observational time-series data on a community of seven waterbird species breeding in artificial irrigation ponds. We fitted to the data a multivariate logistic regression model, which attributes the presence–absence of each species to a set of environmental and spatial covariates, to the presence of con- and heterospecifics in the previous year and to the presence of heterospecifics in the same year. All species showed a clear tendency to continue breeding in the same sites where they were observed in the previous year. Additionally, the presence of heterospecifics, both in the previous year and in the same year, generally increased the probability that the focal species was found breeding on a given pond. Our data thus give support for the heterospecific attraction hypothesis, though causal inference should be confirmed with manipulative experiments. PMID:20462909

  11. Cross-Border Mergers and Acquisitions in China: A Test of the Free Cash Flow Hypothesis

    Directory of Open Access Journals (Sweden)

    Yane Chandera

    2014-08-01

    Full Text Available This research investigates whether Chinese cross-border investments have positive impact onshareholders wealth and whether the amount of bidders’ free cash flow influences the shareholderreturns resulted from the acquisitions. The sample is based on 77 top Chinese cross-border investmentsduring the years 2005-2009 with each deal value of minimum US$100 million. The assessmentsof acquisition abnormal returns are based on the event study methodology (Brown & Warner, 1985.Cross-sectional regression analysis is used to determine the bidding firms factors which significantlyaffect the returns. Factors are examined using OLS with White’s heteroscedasticity-corrected standarderrors, since the assumption of homoscedasticity is likely to be violated. The study proves Chinesecross- border acquisitions result in positive abnormal returns which is consistent with synergyhypothesis. The amount of bidders’ free cash flow is also found to be marginally but positively associatedwith shareholders return which is consistent with Myers and Majluf’s pecking order hypothesisbut unsupportive of Jensen’s free cash flow hypothesis.

  12. A Powerful Test of the Autoregressive Unit Root Hypothesis Based on a Tuning Parameter Free Statistic

    DEFF Research Database (Denmark)

    Nielsen, Morten Ørregaard

    This paper presents a family of simple nonparametric unit root tests indexed by one parameter, d, and containing Breitung's (2002) test as the special case d = 1. It is shown that (i) each member of the family with d > 0 is consistent, (ii) the asymptotic distribution depends on d, and thus refle...

  13. Pollen flow in the distylous Palicourea fendleri (Rubiaceae): an experimental test of the Disassortative Pollen Flow Hypothesis.

    Science.gov (United States)

    Lau, Pablo; Bosque, Carlos

    2003-05-01

    The Disassortative Pollen Flow Hypothesis proposed by Darwin postulates that the relative position of anthers and stigmas in distylous flowers enhances pollen flow between flowers of different morphs (legitimate pollination), in comparison to flow between flowers of the same morph (illegitimate pollination). In order to test this hypothesis, we measured pollen transport, mediated by a trained Copper-rumped Hummingbird (Amazilia tobaci), between flowers of the distylous Palicourea fendleri under laboratory conditions. In individual tests, we offered to the hummingbird a pollen donor flower and two emasculated recipient flowers in a controlled sequence. After each foraging bout, we counted the number of pollen grains transported from the donor flower to the stigmas of both recipient flowers. In agreement with Darwin's hypothesis, we found that hummingbirds transport pollen of "pin" flowers in significantly higher numbers to legitimate "thrum" stigmas, even if previously visiting a "pin" flower. However, "thrum" pollen was deposited in greater numbers on illegitimate "thrum" stigmas. We interpret this asymmetry largely as the consequence of floral morphology; pollen flow was greater between anthers and stigmas that exhibit greater spatial matching. In P. fendleri, the position of floral organs along the corolla tube does not always precisely correspond. In our experimental system, the probability that the pollinator extracts a pollen grain from the anther and the probability of self-pollination were both dependent on the type of floral morph. We discuss the relevance of the latter findings in relation to other studies of pollen flow in heterostylous species.

  14. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone

    Science.gov (United States)

    2016-01-01

    Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures. PMID:26926069

  15. Testing the Hypothesis of Biofilm as a Source for Soft Tissue and Cell-Like Structures Preserved in Dinosaur Bone.

    Directory of Open Access Journals (Sweden)

    Mary Higby Schweitzer

    Full Text Available Recovery of still-soft tissue structures, including blood vessels and osteocytes, from dinosaur bone after demineralization was reported in 2005 and in subsequent publications. Despite multiple lines of evidence supporting an endogenous source, it was proposed that these structures arose from contamination from biofilm-forming organisms. To test the hypothesis that soft tissue structures result from microbial invasion of the fossil bone, we used two different biofilm-forming microorganisms to inoculate modern bone fragments from which organic components had been removed. We show fundamental morphological, chemical and textural differences between the resultant biofilm structures and those derived from dinosaur bone. The data do not support the hypothesis that biofilm-forming microorganisms are the source of these structures.

  16. Testing the associative-link hypothesis in immediate serial recall: Evidence from word frequency and word imageability effects.

    Science.gov (United States)

    Tse, Chi-Shing; Altarriba, Jeanette

    2007-08-01

    Two immediate serial recall experiments were conducted to test the associative-link hypothesis (Stuart & Hulme, 2000). We manipulated interitem association by varying the intralist latent semantic analysis (LSA) cosines in our 7-item study word lists, each of which consists of high- or low-frequency words in Experiment 1 and high- or low-imageability words in Experiment 2. Whether item recall performance was scored by a serial-recall or free-recall criterion, we found main effects of interitem association, word imageability, and word frequency. The effect of interitem association also interacted with the word frequency effect, but not with the word imageability effect. The LSA-cosinexword frequency interaction occurred in the recency, but not primacy, portion of the serial position curve. The present findings set explanatory boundaries for the associative-link hypothesis and we argue that both item- and associative-based mechanisms are necessary to account for the word frequency effect in immediate serial recall.

  17. Do mothers really know best? Complexities in testing the preference-performance hypothesis in polyphagous frugivorous fruit flies.

    Science.gov (United States)

    Birke, A; Aluja, M

    2017-12-04

    The preference-performance hypothesis (PPH) has widely been used to explain host exploitation patterns by phytophagous insects. However, this hypothesis often fails in the case of polyphagous species when compared with specialists. One explanation, validated by the information-processing hypothesis (IPH), considers that polyphagous insects are unable to process a large array of cues, which hinders females from distinguishing between high- and low- quality hosts. Here we analyzed Anastrepha ludens female host preference and offspring performance, and tested if neuronal limitations could possibly play a role in the incapacity of the polyphagous A. ludens to make 'accurate decisions' and therefore partially explain mismatches related to PPH. Results testing the PPH by correlating female preference to six naturally occurring hosts and its offspring outcomes show that A. ludens females oviposited greater proportions of eggs on fruit according to hierarchical preferences. Infestation level was low in white sapote, the preferential and seemingly putative ancestral host, likely due to sapote defence mechanisms. Pupal weight and adult size were lower when A. ludens larvae developed in guava (conditional host that was artificially infested) and peach, a lower ranked host compared with 'Marsh' grapefruit, white sapote, and 'Manila' mango (three preferred hosts). Larvae reared in 'Manzano' pepper, a low-ranked host, performed better than in peach and guava. Results testing the IPH, show that polyphagous A. ludens females were less accurate when discerning between a non natural host (guava) when compared with a preferred, natural host (grapefruit): error rate was significantly higher, number of oviposited fruit in a 6-h period was extremely low, time searching and ovipositing took longer, and pupae recovery was extremely low. Our findings indicate that both hypotheses tested are complementary and help better understand host use by A. ludens. However, we also discuss the

  18. Ocular torsion as a test of the asymmetry hypothesis of space motion sickness

    Science.gov (United States)

    Diamond, Shirley G.; Markham, Charles H.

    Disconjugate eye torsion induced by O G and 1.8 G during parabolic flight was studied in nine former astronauts in 1990 and eight in 1991, four of whom were included in the previous experiment. The astronauts could be divided into two statistically significant groups on the basis of low and high scores of disconjugacy. When their histories of space motion sickness (SMS) were later revealed, all of the low scorers had not been sick on previous space flights; all the high scorers had had SMS. These data give support to the hypothesis that SMS in one-half or two-thirds of astronauts is due to an otolith, probably utricular, asymmetry in those persons. Ocular disconjugacy tended to increase at O G with increasing numbers of parabolas, this being particularly evident in those subjects with prior SMS. One conclusion: 10 to 20 parabolas are necessary to adequately discriminate those who are subject to SMS from those who are not. Tilting the subjects with high disconjugacy values and presumed otolith asymmetry by small amounts in right ear down or left ear down positions for several exposures to hypergravity did not reveal a lessened amount of ocular disconjugacy; there were actually increased amounts of ocular disconjugacy induced in the tipped positions. We suspect the increased disconjugacy caused by multiple parabolas may have masked any "null" point induced at 1.8 G by small head angulations. Space motion sickness (SMS) appears to be a unique form of motion sickness. It occurs within minutes to hours after entering microgravity environment, typically lasts the first 1 to 4 days in space flight, and may occur in abbreviated form on returning to earth. The symptoms are much like other forms of motion sickness except vomiting may occur with little warning. The substrate of SMS appears to be a loss of the constant force of gravity acting on the vestibular otolith system. In certain subjects in this "sensory mismatched" state, motion sickness may be easily triggered by

  19. A test of the hydraulic vulnerability segmentation hypothesis in angiosperm and conifer tree species.

    Science.gov (United States)

    Johnson, Daniel M; Wortemann, Remi; McCulloh, Katherine A; Jordan-Meille, Lionel; Ward, Eric; Warren, Jeffrey M; Palmroth, Sari; Domec, Jean-Christophe

    2016-08-01

    Water transport from soils to the atmosphere is critical for plant growth and survival. However, we have a limited understanding about many portions of the whole-tree hydraulic pathway, because the vast majority of published information is on terminal branches. Our understanding of mature tree trunk hydraulic physiology, in particular, is limited. The hydraulic vulnerability segmentation hypothesis (HVSH) stipulates that distal portions of the plant (leaves, branches and roots) should be more vulnerable to embolism than trunks, which are nonredundant organs that require a massive carbon investment. In the current study, we compared vulnerability to loss of hydraulic function, leaf and xylem water potentials and the resulting hydraulic safety margins (in relation to the water potential causing 50% loss of hydraulic conductivity) in leaves, branches, trunks and roots of four angiosperms and four conifer tree species. Across all species, our results supported strongly the HVSH as leaves and roots were less resistant to embolism than branches or trunks. However, branches were consistently more resistant to embolism than any other portion of the plant, including trunks. Also, calculated whole-tree vulnerability to hydraulic dysfunction was much greater than vulnerability in branches. This was due to hydraulic dysfunction in roots and leaves at less negative water potentials than those causing branch or trunk dysfunction. Leaves and roots had narrow or negative hydraulic safety margins, but trunks and branches maintained positive safety margins. By using branch-based hydraulic information as a proxy for entire plants, much research has potentially overestimated embolism resistance, and possibly drought tolerance, for many species. This study highlights the necessity to reconsider past conclusions made about plant resistance to drought based on branch xylem only. This study also highlights the necessity for more research of whole-plant hydraulic physiology to better

  20. A test of the submentalizing hypothesis: Apes' performance in a false belief task inanimate control

    National Research Council Canada - National Science Library

    Krupenye, Christopher; Kano, Fumihiro; Hirata, Satoshi; Call, Josep; Tomasello, Michael

    2017-01-01

    ... themselves knew that it was no longer there. In response, Heyes proposed that apes' looking behavior was guided not by social cognitive mechanisms but rather domain-general cueing effects, and suggested the use of inanimate controls to test...

  1. Confidence bounds and hypothesis tests for normal distribution coefficients of variation

    Science.gov (United States)

    Steve Verrill; Richard A. Johnson

    2007-01-01

    For normally distributed populations, we obtain confidence bounds on a ratio of two coefficients of variation, provide a test for the equality of k coefficients of variation, and provide confidence bounds on a coefficient of variation shared by k populations.

  2. Testing the thrifty gene hypothesis: the Gly482Ser variant in PPARGC1A is associated with BMI in Tongans

    Directory of Open Access Journals (Sweden)

    Macartney-Coxson Donia P

    2011-01-01

    Full Text Available Abstract Background The thrifty gene hypothesis posits that, in populations that experienced periods of feast and famine, natural selection favoured individuals carrying thrifty alleles that promote the storage of fat and energy. Polynesians likely experienced long periods of cold stress and starvation during their settlement of the Pacific and today have high rates of obesity and type 2 diabetes (T2DM, possibly due to past positive selection for thrifty alleles. Alternatively, T2DM risk alleles may simply have drifted to high frequency in Polynesians. To identify thrifty alleles in Polynesians, we previously examined evidence of positive selection on T2DM-associated SNPs and identified a T2DM risk allele at unusually high frequency in Polynesians. We suggested that the risk allele of the Gly482Ser variant in the PPARGC1A gene was driven to high frequency in Polynesians by positive selection and therefore possibly represented a thrifty allele in the Pacific. Methods Here we examine whether PPARGC1A is a thrifty gene in Pacific populations by testing for an association between Gly482Ser genotypes and BMI in two Pacific populations (Maori and Tongans and by evaluating the frequency of the risk allele of the Gly482Ser variant in a sample of worldwide populations. Results We find that the Gly482Ser variant is associated with BMI in Tongans but not in Maori. In a sample of 58 populations worldwide, we also show that the 482Ser risk allele reaches its highest frequency in the Pacific. Conclusion The association between Gly482Ser genotypes and BMI in Tongans together with the worldwide frequency distribution of the Gly482Ser risk allele suggests that PPARGC1A remains a candidate thrifty gene in Pacific populations.

  3. Nitrogen Exchanges: Testing the Hypothesis of a Country without Agricultural Production

    Directory of Open Access Journals (Sweden)

    M.-F. Slak

    2001-01-01

    Full Text Available Today, finding data on agricultural nitrogen balances is quite easy. Calculations of such balances are carried out by most of the European countries as an indicator of environmental pollution attributable to the agricultural sector. In France, average values of agricultural nitrogen balances show an excess of 1.5 to 2 million tons of nitrogen. This excess is enormous. What would the balance of a country be if agricultural activity were stopped? In the following article, a country (France is used as an example without agriculture is studied in order to assess its nitrogen balance. Using a previously published model describing nitrogen input and output of a given country, nitrogen flows are identified. Inputs include deposition, fixation, and products not intended for agricultural use. Outputs are reduced to zero if agriculture disappears (in France, agriculture is the only sector exporting products containing nitrogen. All flows are calculated considering the hypothesis of disappearance of agriculture. Nitrogen requirements to feed people and pets in France are estimated based on medical and veterinary data (recommended daily amounts for proteins and/or usual average consumption. Indeed, most of the food that nourishes the French population is produced nationally. If agriculture stops, it will be necessary to import food from foreign countries. Results show an unexpectedly high excess (for a country without agriculture having a structure similar to France: number of human beings and pets of 1.5 million tons of nitrogen. An attempt to calculate an agricultural balance with the same data gives a result close to 3 million tons. Differences in French agricultural balances found in the literature can mainly be explained by values taken into account for deposition and fixation (values used here are at least 300,000 tons higher than values used by the Organisation for Economic Co-operation and Development. In conclusion, nitrogen excess in agriculture

  4. Null hypothesis significance tests. A mix-up of two different theories

    DEFF Research Database (Denmark)

    Schneider, Jesper Wiborg

    2015-01-01

    criticisms raised against NHST. As practiced, NHST has been characterized as a ‘null ritual’ that is overused and too often misapplied and misinterpreted. NHST is in fact a patchwork of two fundamentally different classical statistical testing models, often blended with some wishful quasi......-Bayesian interpretations. This is undoubtedly a major reason why NHST is very often misunderstood. But NHST also has intrinsic logical problems and the epistemic range of the information provided by such tests is much more limited than most researchers recognize. In this article we introduce to the scientometric community...

  5. God's punishment and public goods : A test of the supernatural punishment hypothesis in 186 world cultures.

    Science.gov (United States)

    Johnson, Dominic D P

    2005-12-01

    Cooperation towards public goods relies on credible threats of punishment to deter cheats. However, punishing is costly, so it remains unclear who incurred the costs of enforcement in our evolutionary past. Theoretical work suggests that human cooperation may be promoted if people believe in supernatural punishment for moral transgressions. This theory is supported by new work in cognitive psychology and by anecdotal ethnographic evidence, but formal quantitative tests remain to be done. Using data from 186 societies around the globe, I test whether the likelihood of supernatural punishment-indexed by the importance of moralizing "high gods"-is associated with cooperation.

  6. Statistical resolution limit for the multidimensional harmonic retrieval model: hypothesis test and Cramér-Rao Bound approaches

    Directory of Open Access Journals (Sweden)

    El Korso Mohammed

    2011-01-01

    Full Text Available Abstract The statistical resolution limit (SRL, which is defined as the minimal separation between parameters to allow a correct resolvability, is an important statistical tool to quantify the ultimate performance for parametric estimation problems. In this article, we generalize the concept of the SRL to the multidimensional SRL (MSRL applied to the multidimensional harmonic retrieval model. In this article, we derive the SRL for the so-called multidimensional harmonic retrieval model using a generalization of the previously introduced SRL concepts that we call multidimensional SRL (MSRL. We first derive the MSRL using an hypothesis test approach. This statistical test is shown to be asymptotically an uniformly most powerful test which is the strongest optimality statement that one could expect to obtain. Second, we link the proposed asymptotic MSRL based on the hypothesis test approach to a new extension of the SRL based on the Cramér-Rao Bound approach. Thus, a closed-form expression of the asymptotic MSRL is given and analyzed in the framework of the multidimensional harmonic retrieval model. Particularly, it is proved that the optimal MSRL is obtained for equi-powered sources and/or an equi-distributed number of sensors on each multi-way array.

  7. Shrub biomass production following simulated herbivory: A test of the compensatory growth hypothesis

    Science.gov (United States)

    Terri B. Teaschner; Timothy E. Fulbright

    2007-01-01

    The objective of this experiment was to test the hypotheses that 1) simulated herbivory stimulates increased biomass production in spiny hackberry (Celtis pallida), but decreases biomass production in blackbrush acacia (Acacia rigidula) compared to unbrowsed plants and 2) thorn density and length increase in blackbrush acacia to a...

  8. The P-Value Concept in Hypothesis Testing and Its Application on ...

    African Journals Online (AJOL)

    This study is aimed at comparing the probability value (p–value) of various hypotheses tested with the specified level of significance á at 5% level. The study used data obtained from Hajiya Gambo Sawaba Government General Hospital, Kofan Gaya, Zaria and other related examples to achieve this objective. The study ...

  9. What's in a p? : Reassessing best practices for reporting hypothesis- testing research

    NARCIS (Netherlands)

    Meyer, K.; van Witteloostuijn, Arjen; Beugelsdijk, S.

    Social science research has recently been subject to considerable criticism regarding the validity and power of empirical tests published in leading journals, and business scholarship is no exception. Transparency and replicability of empirical findings are essential to build a cumulative body of

  10. The Demand for Higher Education and a Test of the Extreme Screening Hypothesis

    Science.gov (United States)

    Tao, Hung-Lin

    2006-01-01

    This study proposes a model to estimate the demand for higher education. The present model is characterized by an ability-based distribution of high school graduates who choose between entering the labor market and beginning post-secondary schooling. In addition to estimating the demand for higher education, this model also derives a test of the…

  11. Testing the strain hypothesis of the Demand Control Model to explain severe bullying at work

    NARCIS (Netherlands)

    Notelaers, G.; Baillien, E.; de Witte, H.; Einarsen, S.; Vermunt, J.K.

    2013-01-01

    Workplace bullying has often been attributed to work-related stress, and has been linked to the Job Demand Control Model. The current study aims to further these studies by testing the model for bullying in a heterogeneous sample and by using latent class (LC)-analyses to define different demands

  12. Testing the ATI Hypothesis: Should Multimedia Instruction Accommodate Verbalizer-Visualizer Cognitive Style?

    Science.gov (United States)

    Massa, Laura J.; Mayer, Richard E.

    2006-01-01

    College students (Experiment 1) and non-college adults (Experiment 2) studied a computer-based 31-frame lesson on electronics that offered help-screens containing text (text group) or illustrations (pictorial group), and then took a learning test. Participants also took a battery of 14 cognitive measures related to the verbalizer-visualizer…

  13. What's in a p? Reassessing best practices for conducting and reporting hypothesis-testing research

    NARCIS (Netherlands)

    Meyer, Klaus E.; Van Witteloostuijn, Arjen; Beugelsdijk, Sjoerd

    2017-01-01

    Social science research has recently been subject to considerable criticism regarding the validity and power of empirical tests published in leading journals, and business scholarship is no exception. Transparency and replicability of empirical findings are essential to build a cumulative body of

  14. What's in a p? Reassessing best practices for conducting and reporting hypothesis-testing research

    NARCIS (Netherlands)

    Meyer, Klaus E.; van Witteloostuijn, Arjen; Beugelsdijk, Sjoerd

    Social science research has recently been subject to considerable criticism regarding the validity and power of empirical tests published in leading journals, and business scholarship is no exception. Transparency and replicability of empirical findings are essential to build a cumulative body of

  15. Probabilistic biomechanical finite element simulations: whole-model classical hypothesis testing based on upcrossing geometry

    Directory of Open Access Journals (Sweden)

    Todd C. Pataky

    2016-11-01

    Full Text Available Statistical analyses of biomechanical finite element (FE simulations are frequently conducted on scalar metrics extracted from anatomically homologous regions, like maximum von Mises stresses from demarcated bone areas. The advantages of this approach are numerical tabulability and statistical simplicity, but disadvantages include region demarcation subjectivity, spatial resolution reduction, and results interpretation complexity when attempting to mentally map tabulated results to original anatomy. This study proposes a method which abandons the two aforementioned advantages to overcome these three limitations. The method is inspired by parametric random field theory (RFT, but instead uses a non-parametric analogue to RFT which permits flexible model-wide statistical analyses through non-parametrically constructed probability densities regarding volumetric upcrossing geometry. We illustrate method fundamentals using basic 1D and 2D models, then use a public model of hip cartilage compression to highlight how the concepts can extend to practical biomechanical modeling. The ultimate whole-volume results are easy to interpret, and for constant model geometry the method is simple to implement. Moreover, our analyses demonstrate that the method can yield biomechanical insights which are difficult to infer from single simulations or tabulated multi-simulation results. Generalizability to non-constant geometry including subject-specific anatomy is discussed.

  16. Testing the junk-food hypothesis on marine birds: Effects of prey type on growth and development

    Science.gov (United States)

    Romano, Marc D.; Piatt, John F.; Roby, D.D.

    2006-01-01

    The junk-food hypothesis attributes declines in productivity of marine birds and mammals to changes in the species of prey they consume and corresponding differences in nutritional quality of those prey. To test this hypothesis nestling Black-legged Kittiwakes (Rissa tridactyla) and Tufted Puffins (Fratercula cirrhata) were raised in captivity under controlled conditions to determine whether the type and quality of fish consumed by young seabirds constrains their growth and development. Some nestlings were fed rations of Capelin (Mallotus villosus), Herring (Clupea pallasi) or Sand Lance (Ammodytes hexapterus) and their growth was compared with nestlings raised on equal biomass rations of Walleye Pollock (Theragra chalcograma). Nestlings fed rations of herring, sand lance, or capelin experienced higher growth increments than nestlings fed pollock. The energy density of forage fish fed to nestlings had a marked effect on growth increments and could be expected to have an effect on pre- and post-fledging survival of nestlings in the wild. These results provide empirical support for the junk-food hypothesis.

  17. Distinction between fear and surprise: an interpretation-independent test of the perceptual-attentional limitation hypothesis.

    Science.gov (United States)

    Chamberland, Justin; Roy-Charland, Annie; Perron, Melanie; Dickinson, Joël

    2017-12-01

    The perceptual-attentional limitation hypothesis posits that the confusion between emotional facial expressions of fear and surprise may be due to their visual similarity, with shared muscle movements. In Experiment 1 full face images of fear and surprise varying as a function of distinctiveness (mouth index, brow index, or both indices) were displayed in a gender oddball task. Experiment 2, in a similar task, directed attention toward the eye or mouth region with a blurring technique. The current two studies used response time and event-related potentials (ERP) to test the perceptual-attentional limitation hypothesis. While ERP results for Experiment 1 suggested that individuals may not have perceived a difference between the emotional expressions in any of the conditions, response time results suggested that individuals processed a difference between fear and surprise when a distinctive cue was in the mouth. With directed attention in Experiment 2, ERP results indicated that individuals were capable of detecting a difference in all the conditions. In effect, the current two experiments suggest that participants display difficulty in distinguishing the prototypes of fear and surprise with the eye region, which may be due to a lack of attention to that region, providing support for the attentional limitation hypothesis.

  18. Testing The Magmatic Underplating Hypothesis: An Example From The Uk and Ireland

    Science.gov (United States)

    Al-Kindi, S.; White, N.; Sinha, M.; England, R.

    Magmatic underplating associated with mantle plume activity is an important mech- anism for driving regional surface uplift and denudation of large portion of the continents. Here we present quantitative and predictive models linking the surface- measured uplift and denudation with deep crustal structure across the British Isles. The crustal model was derived from re-interpreting the 1982 wide-angle Caledonian Suture Seismic Project and it's Irish extension (CSSP&ICSSP) data sets. A joint CSSP/ICSSP velocity model was obtained for the first time by inverting for six main travel-time phases comprising more than 3000 picks having picking uncertainty ranges of 50-100 ms and average of 82 ms with best picks for first breaks at close offsets. Two indepen- dent tomographic codes namely RAYINVR (Zelt and Smith, 1992) and Jive3D (Ho- bro, 2000) were used to model the picked travel-times adopting 'interpreter-guided' and 'pure tomographic' approaches, respectively. The codes represent natural end- member approaches to travel-time tomography where the former seeks an irregular grid, minimum-parameter velocity model, whereas the later seeks minimum-structure velocity model. The final outcome of the two methods are remarkably similar which has greatly boosted confidence in the interpretation. Complementary resolution and uncertainty tests were preformed. The most striking feature of the outcome of the inversion processes is the emergence of a discrete high-velocity (7.0-7.5 km/s) intermediate layer above the Moho. The top interface of this layer is sampled by lower crustal reflections, whereas the layer velocity is sampled by refracted rays. The base of the layer is bounded by the Moho interface roughly at 33 km, constrained by upper mantle diving rays. Some Moho reflections were observed on some record sections, but the majority are believed to be masked by the early arriving, highly-reflective coda generated by resonance of seismic waves within the intermediate layer. The

  19. [Psychosomatic sterility. Search for a hypothesis for personaity structure using Moretti's graphology method].

    Science.gov (United States)

    Deragna, S; Agostini, R; Coghi, I; Montanino, G; Nicotra, M; Ruozi Berretta, L

    1994-01-01

    Over the past three years the authors have performed a random clinical study on couples who came to the aim of identifying the possible presence, in those cases in which it was not possible to pinpoint an organic or functional etiological factor, of a relationship between personality structure and so-called "sterility sine cause" which according to the recent studies by Pancheri and Zichella on reproductive emotionality, is thought to caused by a factor of psychosomatic origin, The substantiality of the concept of reproductive emotionality, otherwise referred to as sexual instinct, was put forward in 1962 by Padre Gerolamo Moretti, a leading figure of Italian graphology. Research to date, carried out using traditional methods of clinical psychology, interview and tests, in an attempt to determine a particular personality profile, has not produced completely satisfactory results. From the literature it does not appear that graphological analysis has been applied in research of this nature. Graphology, if used by competent and appropriately trained persons, is certainly a powerful and refined diagnostic method which enables an idiographic, holistic and integrated personality profile (intelligence and temperament) tp be obtained for the subject in question. Moretti's temperament classification was used to define the personality structure of patients: assault, resistance, assignment and expectation. Research using graphological techniques has revealed that it is possible to define a personality structure within which suspected "sine cause" patients may be classified. In comparison to the control group, there was a prevalent attitude expressing a tendency to reserve, introversion, diffidence, anxiety, excessive and sometimes unmotivated concern regarding persons and things, attachment to one's own ideas, inflexibility of one's own position, scarce capacity to make oneself available, excessive attention to formal aspects. A number of practical considerations also emerged

  20. General Multidecision Theory: Hypothesis Testing and Changepoint Detection with Applications to Homeland Security

    Science.gov (United States)

    2016-01-19

    case, the solution of this problem is not tractable. For this reason, we address the asymptotic problem of minimizing the average detection delay as α...of likelihood based charting methods. IIE Transactions, 44(9):724–743, Sept. 2012. 34

  1. Model Selection and Hypothesis Testing for Large-Scale Network Models with Overlapping Groups

    Directory of Open Access Journals (Sweden)

    Tiago P. Peixoto

    2015-03-01

    Full Text Available The effort to understand network systems in increasing detail has resulted in a diversity of methods designed to extract their large-scale structure from data. Unfortunately, many of these methods yield diverging descriptions of the same network, making both the comparison and understanding of their results a difficult challenge. A possible solution to this outstanding issue is to shift the focus away from ad hoc methods and move towards more principled approaches based on statistical inference of generative models. As a result, we face instead the more well-defined task of selecting between competing generative processes, which can be done under a unified probabilistic framework. Here, we consider the comparison between a variety of generative models including features such as degree correction, where nodes with arbitrary degrees can belong to the same group, and community overlap, where nodes are allowed to belong to more than one group. Because such model variants possess an increasing number of parameters, they become prone to overfitting. In this work, we present a method of model selection based on the minimum description length criterion and posterior odds ratios that is capable of fully accounting for the increased degrees of freedom of the larger models and selects the best one according to the statistical evidence available in the data. In applying this method to many empirical unweighted networks from different fields, we observe that community overlap is very often not supported by statistical evidence and is selected as a better model only for a minority of them. On the other hand, we find that degree correction tends to be almost universally favored by the available data, implying that intrinsic node proprieties (as opposed to group properties are often an essential ingredient of network formation.

  2. Statistical test of a null hypothesis: Taser shocks have not caused or contributed to subsequent in-custody deaths

    Science.gov (United States)

    Lundquist, Marjorie

    2009-03-01

    Since 1999 over 425 in-custody deaths have occurred in the USA after law enforcement officers (LEOs) used an M26 or X26 Taser, causing Amnesty International and the ACLU to call for a moratorium on Taser use until its physiological effects on people have been better studied. A person's Taser dose is defined as the total duration (in seconds) of all Taser shocks received by that person during a given incident. Utilizing the concept of Taser dose for these deaths, TASER International's claim of Taser safety can be treated as a null hypothesis and its validity scientifically tested. Such a test using chi-square as the test statistic is presented. It shows that the null hypothesis should be rejected; i.e., model M26 and X26 Tasers are capable of producing lethal effects non-electrically and so have played a causal or contributory role in a great many of the in-custody deaths following their use. This implies that the Taser is a lethal weapon, and that LEOs have not been adequately trained in its safe use!

  3. Handling realistic assumptions in hypothesis testing of 3D co-localization of genomic elements

    OpenAIRE

    Paulsen, Jonas; Lien, Tonje G.; Sandve, Geir Kjetil; Holden, Lars; Borgan, Ørnulf; Glad, Ingrid K.; Hovig, Johannes Eivind

    2013-01-01

    The study of chromatin 3D structure has recently gained much focus owing to novel techniques for detecting genome-wide chromatin contacts using next-generation sequencing. A deeper understanding of the architecture of the DNA inside the nucleus is crucial for gaining insight into fundamental processes such as transcriptional regulation, genome dynamics and genome stability. Chromatin conformation capture-based methods, such as Hi-C and ChIA-PET, are now paving the way for routine genome-wide ...

  4. The effect of visual deprivation on the organization of conceptual knowledge: testing the grounded cognition hypothesis.

    Science.gov (United States)

    Marques, J Frederico

    2010-01-01

    The present paper evaluates the effect of visual deprivation on the organization and retrieval of conceptual knowledge. The experimental study used the release from proactive interference (PI-release) paradigm. Early onset blind (EOB) and sighted (S) subjects were tested with this task and additional visual and nonvisual property retrieval cues. PI-release results showed that the visual cue was less effective for EOB individuals than for S individuals, whereas the nonvisual cue was similarly effective for EOB individuals and S individuals. Results support a grounded view of cognition where the organization of conceptual knowledge depends on the role that sensory and motor channels play in its acquisition.

  5. Testing of Frank's hypothesis on a containerless packing of macroscopic soft spheres and comparison with mono-atomic metallic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, K.K., E-mail: kisor.sahu@mat.ethz.ch [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich (Switzerland); Wessels, V. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich (Switzerland); Kelton, K.F. [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States); Loeffler, J.F. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich (Switzerland)

    2011-06-15

    Highlights: > Testing of Frank's hypothesis for Centripetal Packing (CP) has been proposed. > It is shown that CP is an idealized model for Monatomic Supercooled Liquid (MSL). > The CP is fit for comparing with studies on MSL in a containerless environment. > We measure local orders in CP by HA and BOO methods for the first time. > It is shown that icosahedral order is greater in CP than MSL and reasons explored. - Abstract: It is well-known that metallic liquids can exist below their equilibrium melting temperature for a considerable time. To explain this, Frank proposed that icosahedral ordering, incompatible with crystalline long-range order, is prevalent in the atomic structure of these liquids, stabilizing them and enabling them to be supercooled. Some studies of the atomic structures of metallic liquids using Beam-line Electrostatic Levitation (BESL; containerless melting), and other techniques, support this hypothesis . Here we examine Frank's hypothesis in a system of macroscopic, monodisperse deformable spheres obtained by containerless packing under the influence of centripetal force. The local structure of this packing is analyzed and compared with atomic ensembles of liquid transition metals obtained by containerless melting using the BESL method.

  6. Integrating multiple lines of evidence into historical biogeography hypothesis testing: a Bison bison case study.

    Science.gov (United States)

    Metcalf, Jessica L; Prost, Stefan; Nogués-Bravo, David; DeChaine, Eric G; Anderson, Christian; Batra, Persaram; Araújo, Miguel B; Cooper, Alan; Guralnick, Robert P

    2014-02-22

    One of the grand goals of historical biogeography is to understand how and why species' population sizes and distributions change over time. Multiple types of data drawn from disparate fields, combined into a single modelling framework, are necessary to document changes in a species's demography and distribution, and to determine the drivers responsible for change. Yet truly integrated approaches are challenging and rarely performed. Here, we discuss a modelling framework that integrates spatio-temporal fossil data, ancient DNA, palaeoclimatological reconstructions, bioclimatic envelope modelling and coalescence models in order to statistically test alternative hypotheses of demographic and potential distributional changes for the iconic American bison (Bison bison). Using different assumptions about the evolution of the bioclimatic niche, we generate hypothetical distributional and demographic histories of the species. We then test these demographic models by comparing the genetic signature predicted by serial coalescence against sequence data derived from subfossils and modern populations. Our results supported demographic models that include both climate and human-associated drivers of population declines. This synthetic approach, integrating palaeoclimatology, bioclimatic envelopes, serial coalescence, spatio-temporal fossil data and heterochronous DNA sequences, improves understanding of species' historical biogeography by allowing consideration of both abiotic and biotic interactions at the population level.

  7. The hard parts of the Cambrian Explosion: a palaeobiological approach to testing the 'biomineralization toolkit' hypothesis

    Science.gov (United States)

    Murdock, Duncan

    2017-04-01

    The Cambrian Explosion was the most dramatic event in the history of animal life on Earth, yet the processes underlying it are poorly understood not least the role of biomineralization in driving this fundamental evolutionary episode. One explanation for this event, based on observations on the developmental and molecular biology of modern organisms, is that all animals inherited a common 'toolkit' of genes, independently co-opted to similar tasks, including building skeletons. This initially imprecise 'toolkit' was subsequently honed by the acquisition of more and more complex gene regulatory networks. This predicts that animal skeletons, and by inference their organic frameworks, should exhibit a higher degree of morphological plasticity at their origin than later in their evolutionary history - a prediction that is virtually untested. Here I set out a new approach to testing this prediction, by quantifying the phenotypic variation displayed in fossil remains of some of the earliest animal skeletons, over multiple scales from microscopic variations in their component biominerals to how skeletons themselves are put together. This approach will provide direct evidence to test the importance of the genetic basis of the skeleton in the origin of the animals, making a significant contribution to our understanding of this crucial event in the history of life on Earth, including the evolution of our own ancestors.

  8. Motivation towards extracurricular activities and motivation at school: A test of the generalization effect hypothesis.

    Science.gov (United States)

    Denault, Anne-Sophie; Guay, Frédéric

    2017-01-01

    Participation in extracurricular activities is a promising avenue for enhancing students' school motivation. Using self-determination theory (Deci & Ryan, 2000), the goal of this study was to test a serial multiple mediator model. In this model, students' perceptions of autonomy support from their extracurricular activity leader predicted their activity-based intrinsic and identified regulations. In turn, these regulations predicted their school-based intrinsic and identified regulations during the same school year. Finally, these regulations predicted their school-based intrinsic and identified regulations one year later. A total of 276 youths (54% girls) from disadvantaged neighborhoods were surveyed over two waves of data collection. The proposed mediation model was supported for both types of regulation. These results highlight the generalization effects of motivation from the extracurricular activity context to the school context. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

  9. A test of the culture-performance related distress hypothesis among employees in a collectivistic culture

    Directory of Open Access Journals (Sweden)

    Pheko, M.M

    2013-06-01

    Full Text Available To test the notions that people from collectivist cultures may experience more intense Sensitivity Towards being the Target of Upward Comparison (STTUC responses the current study investigated the relationships between traditional gender role orientation and STTUC, and collectivistic cultural orientation and STTUC. Using a quantitative, cross-sectional survey approach, a convenient sample of 464 participants from various organizations in Botswana completed the questionnaire. The participants were mostly female (59.9%, in a dating relationship (67.9%, and between the ages of 20 and 57 (M = 32.69, SD = 7.43. In the main, the hypotheses were not supported as the correlation results indicated that neither collectivistic cultural orientation nor traditional gender role orientation were linked to STTUC experiences. Discussions center on the importance of reporting and suggesting theoretical justifications for the so called ‘”nonsignificant findings.” Implications of the empirical findings and the future research directions are also discussed.

  10. Revisiting Parole Decision Making: Testing for the Punitive Hypothesis in a Large U.S. Jurisdiction.

    Science.gov (United States)

    Vîlcică, E Rely

    2016-09-15

    The decision to grant conditional release from prison (aka the parole decision) has been largely neglected in the contemporary criminological literature, despite its critical implications. The current study, conducted in Pennsylvania, United States, tests for punitive themes in parole decision making by examining the impact of several measures reflective of punishment satisfaction on the decision to grant release to eligible parole candidates. The results indicate that the amount of time served in relation to the original punishment does not predict parole decisions but the nature of the original offense does. Moreover, inmates eligible for parole have to experience at least one parole denial to increase their chances of release, suggesting that parole decision makers use the parole process as a punitive means. The implications of the findings are discussed. © The Author(s) 2016.

  11. Application of Multilevel Models to Morphometric Data. Part 1. Linear Models and Hypothesis Testing

    Directory of Open Access Journals (Sweden)

    O. Tsybrovskyy

    2003-01-01

    Full Text Available Morphometric data usually have a hierarchical structure (i.e., cells are nested within patients, which should be taken into consideration in the analysis. In the recent years, special methods of handling hierarchical data, called multilevel models (MM, as well as corresponding software have received considerable development. However, there has been no application of these methods to morphometric data yet. In this paper we report our first experience of analyzing karyometric data by means of MLwiN – a dedicated program for multilevel modeling. Our data were obtained from 34 follicular adenomas and 44 follicular carcinomas of the thyroid. We show examples of fitting and interpreting MM of different complexity, and draw a number of interesting conclusions about the differences in nuclear morphology between follicular thyroid adenomas and carcinomas. We also demonstrate substantial advantages of multilevel models over conventional, single‐level statistics, which have been adopted previously to analyze karyometric data. In addition, some theoretical issues related to MM as well as major statistical software for MM are briefly reviewed.

  12. Exaggerated sexual swellings and male mate choice in primates: testing the reliable indicator hypothesis in the Amboseli baboons.

    Science.gov (United States)

    Fitzpatrick, Courtney L; Altmann, Jeanne; Alberts, Susan C

    2015-06-01

    The paradigm of competitive males vying to influence female mate choice has been repeatedly upheld, but, increasingly, studies also report competitive females and choosy males. One female trait that is commonly proposed to influence male mate choice is the exaggerated sexual swelling displayed by females of many Old World primate species. The reliable indicator hypothesis posits that females use the exaggerated swellings to compete for access to mates, and that the swellings advertise variation in female fitness. We tested the two main predictions of this hypothesis in a wild population of baboons (Papio cynocephalus). First, we examined the effect of swelling size on the probability of mate-guarding ('consortship') by the highest-ranking male and the behavior of those males that trailed consorshipts ('follower males'). Second, we asked whether a female's swelling size predicted several fitness measures. We found that high-ranking males do not prefer females with larger swellings (when controlling for cycle number and conception) and that females with larger swellings did not have higher reproductive success. Our study-the only complete test of the reliable indicator hypothesis in a primate population-rejects the idea that female baboons compete for mates by advertising heritable fitness differences. Furthermore, we found unambiguous evidence that males biased their mating decisions in favor of females who had experienced more sexual cycles since their most recent pregnancy. Thus, rather than tracking the potential differences in fitness between females, male baboons appear to track and target the potential for a given reproductive opportunity to result in fertilization.

  13. 5-HTTLPR Expression Outside the Skin: An Experimental Test of the Emotional Reactivity Hypothesis in Children.

    Science.gov (United States)

    Weeland, Joyce; Slagt, Meike; Brummelman, Eddie; Matthys, Walter; de Castro, Bram Orobio; Overbeek, Geertjan

    2015-01-01

    There is increasing evidence that variation in the promoter region of the serotonin transporter gene SLC6A4 (i.e., the 5-HTTLPR polymorphism) moderates the impact of environmental stressors on child psychopathology. Emotional reactivity -the intensity of an individual's response to other's emotions- has been put forward as a possible mechanism underlying these gene-by-environment interactions (i.e., G×E). Compared to children homozygous for the L-allele (LL-genotypes), children carrying an S-allele (SS/SL-genotypes), specifically when they have been frequently exposed to negative emotions in the family environment, might be more emotionally reactive and therefore more susceptible to affective environmental stressors. However, the association between 5-HTTLPR and emotional reactivity in children has not yet been empirically tested. Therefore, the goal of this study was to test this association in a large-scale experiment. Children (N = 521, 52.5% boys, Mage = 9.72 years) were genotyped and randomly assigned to happy, angry or neutral dynamic facial expressions and vocalizations. Motor and affective emotional reactivity were assessed through children's self-reported negative and positive affect (n = 460) and facial electromyography activity (i.e., fEMG: the zygomaticus or "smile" muscle and the corrugator or "frown" muscle, n = 403). Parents reported on their negative and positive parenting behaviors. Children mimicked and experienced the emotion they were exposed to. However, neither motor reactivity nor affective reactivity to these emotions depended on children's 5-HTTLPR genotype: SS/SL-genotypes did not manifest any stronger response to emotional stimuli than LL-genotypes. This finding remained the same when taking the broader family environment into account, controlling for kinship, age, gender and genetic ancestry, and when including a tri-allelic factor. We found no evidence for an association between the 5-HTTLPR polymorphism and children's emotional

  14. 5-HTTLPR Expression Outside the Skin: An Experimental Test of the Emotional Reactivity Hypothesis in Children.

    Directory of Open Access Journals (Sweden)

    Joyce Weeland

    Full Text Available There is increasing evidence that variation in the promoter region of the serotonin transporter gene SLC6A4 (i.e., the 5-HTTLPR polymorphism moderates the impact of environmental stressors on child psychopathology. Emotional reactivity -the intensity of an individual's response to other's emotions- has been put forward as a possible mechanism underlying these gene-by-environment interactions (i.e., G×E. Compared to children homozygous for the L-allele (LL-genotypes, children carrying an S-allele (SS/SL-genotypes, specifically when they have been frequently exposed to negative emotions in the family environment, might be more emotionally reactive and therefore more susceptible to affective environmental stressors. However, the association between 5-HTTLPR and emotional reactivity in children has not yet been empirically tested. Therefore, the goal of this study was to test this association in a large-scale experiment.Children (N = 521, 52.5% boys, Mage = 9.72 years were genotyped and randomly assigned to happy, angry or neutral dynamic facial expressions and vocalizations. Motor and affective emotional reactivity were assessed through children's self-reported negative and positive affect (n = 460 and facial electromyography activity (i.e., fEMG: the zygomaticus or "smile" muscle and the corrugator or "frown" muscle, n = 403. Parents reported on their negative and positive parenting behaviors.Children mimicked and experienced the emotion they were exposed to. However, neither motor reactivity nor affective reactivity to these emotions depended on children's 5-HTTLPR genotype: SS/SL-genotypes did not manifest any stronger response to emotional stimuli than LL-genotypes. This finding remained the same when taking the broader family environment into account, controlling for kinship, age, gender and genetic ancestry, and when including a tri-allelic factor.We found no evidence for an association between the 5-HTTLPR polymorphism and children

  15. Testing the risk compensation hypothesis for safety helmets in alpine skiing and snowboarding.

    Science.gov (United States)

    Scott, Michael D; Buller, David B; Andersen, Peter A; Walkosz, Barbara J; Voeks, Jennifer H; Dignan, Mark B; Cutter, Gary R

    2007-06-01

    The prevalence of helmet use by alpine skiers and snowboarders was estimated and self-reports on risk taking were assessed to test for potential risk compensation when using helmets in these sports. Skiers and snowboarders were observed and interviewed at 34 resorts in the western United States and Canada. Respondents were 1779 adult skiers and snowboarders in the 2003 ski season. Observations of helmet use and questions about perceived speed and degree of challenge when not wearing a helmet (helmet wearers) or in previous ski seasons (non-helmet wearers). Helmet wearers reported that they skied/snowboarded at slower speeds (OR = 0.64, p<0.05) and challenged themselves less (OR = 0.76, p<0.05) than non-helmet wearers. Adoption of safety helmets in 2003 (23%) continued to increase over 2002 (OR = 0.46, p<0.05) and 2001 (OR = 0.84, p<0.05). No evidence of risk compensation among helmet wearers was found. Decisions to wear helmets may be part of a risk reduction orientation. Helmet use continues to trend upwards but adoption may be slowing.

  16. Meningococcemia as a model for testing the hypothesis of antisepsis therapies.

    Science.gov (United States)

    Giroir, B P

    2000-09-01

    To critically review the advantages and disadvantages of pediatric meningococcemia as a model for testing antisepsis therapies. Research and review articles on the pathogenesis and treatment of human meningococcemia, as well as editorial commentaries discussing the failure of clinical trials for adult sepsis or Systemic Inflammatory Response Syndrome. Data from these sources are presented in the context of the author's experience as principal investigator in a large, randomized trial on children with invasive meningococcal disease. Studies were selected to include aspects of epidemiology, pathophysiology, outcome prediction, and therapeutic trials. Compared with an adult sepsis population, meningococcemia is a single disease, diagnosed clinically with high reliability. Patients are previously healthy, without underlying medical or surgical conditions. In contrast to sepsis trials, nearly all patients with meningococcal disease receive effective antibiotics. Finally, meningococcemia most closely resembles animal models of endotoxin infusion, in which most antisepsis therapies have been highly effective. However, the meningococcal model carries major disadvantages, among them that meningococcemia is rare and rapidly progressive and patients are widely dispersed geographically. In addition, a wide range of experimental therapies is routinely provided in an attempt to preserve life or limbs. Meningococcemia is an ideal model of a rapidly progressive bacterial infection associated with marked endotoxemia. Problems with the model can be overcome by extensive pretrial logistic planning, as well as close coordination and cooperation with national regulatory agencies.

  17. Testing the mate-choice hypothesis of the female orgasm: disentangling traits and behaviours.

    Science.gov (United States)

    Sherlock, James M; Sidari, Morgan J; Harris, Emily Ann; Barlow, Fiona Kate; Zietsch, Brendan P

    2016-01-01

    The evolution of the female orgasm in humans and its role in romantic relationships is poorly understood. Whereas the male orgasm is inherently linked to reproduction, the female orgasm is not linked to obvious reproductive or survival benefits. It also occurs less consistently during penetrative sex than does the male orgasm. Mate-choice hypotheses posit that the wide variation in female orgasm frequency reflects a discriminatory mechanism designed to select high-quality mates. We aimed to determine (1) whether women report that their orgasm frequency varies between partners, (2) whether this variation reflects mates' personal characteristics, and (3) whether this variation reflects own and partner sexual behaviour during intercourse. We collected survey data from 103 women who rated (1) the extent to which their orgasm frequency varied between partners, (2) the characteristics of previous sexual partners who induced high-orgasm frequency and those who induced low-orgasm frequency, and (3) the specific behaviours during sex with those partners. This is the first study to test within-woman variation in orgasm and partner traits. Overall, women reported variation in their orgasm rates with different partners. Partners who induced high-orgasm rates were rated as more humorous, creative, warm, faithful, and better smelling than partners who induced low-orgasm rates, and also engaged in greater efforts to induce partner orgasm. Some assumptions and predictions of mate-choice hypotheses of female orgasm were supported, while other aspects of our findings provide reasons to remain sceptical.

  18. Testing the face shape hypothesis in twins discordant for nonsyndromic orofacial clefting

    Science.gov (United States)

    Roosenboom, Jasmien; Indencleef, Karlijne; Hens, Greet; Peeters, Hilde; Christensen, Kaare; Marazita, Mary L.; Claes, Peter; Leslie, Elizabeth J.; Weinberg, Seth M.

    2017-01-01

    Nonsyndromic orofacial clefts (OFCs) are complex traits characterized by multifactorial inheritance and wide phenotypic variability. Numerous studies have shown subtle differences in the faces of unaffected relatives from cleft families compared to controls, the implication being that such outward differences are an incomplete expression reflecting an underlying genetic predisposition. Twins discordant for OFCs provide a unique opportunity to further test this idea, as the unaffected co-twin shares on average 50% (for dizygotic twins) and 100% (for monozygotic twins) of the genetic risk factors as the affected twin. We used 3D surface imaging and spatially-dense morphometry to compare facial shape in a sample of 44 unaffected co-twins and age- and sex-matched unaffected controls (n = 241). Unaffected co-twins showed statistically significant differences in the midface, lateral upper face, and forehead regions, compared to controls. Furthermore, co-twins were characterized by a distinct pattern of midfacial retrusion, broader upper faces, and greater protrusion of the mandible and brow ridges. This same general facial pattern was shown in both unaffected monozygotic and dizygotic co-twin subsets. These results provide additional support that altered facial shape is a phenotypic marker for OFC susceptibility. PMID:28884971

  19. Exchange and cohesion in dyads and triads: A test of Simmel's hypothesis.

    Science.gov (United States)

    Yoon, Jeongkoo; Thye, Shane R; Lawler, Edward J

    2013-11-01

    This paper uses social exchange theory to address a classic question posed by Simmel (1964) regarding dyads and triads. The question is whether exchanges in a triad will generate more cohesion at the group level than exchanges in an isolated dyad. The main hypotheses, integrating several ideas from Simmel and social exchange theories, are as follows. First, triads generate less variability of behavior than dyads; that is, there is more uniformity or convergence in triads. Second, in the context of repeated exchange, we predict higher levels of cohesion in triads than in dyads. Third, positive emotion or affect has a stronger impact on cohesion in dyads than in triads, whereas uncertainty reduction has a stronger impact on cohesion in triads. To test these hypotheses, an experiment compared isolated dyads to dyads nested in a triadic exchange network. Subjects engaged in exchanges across a series of distinct episodes, using standard experimental procedures from research on relational cohesion (Lawler and Yoon, 1996) and exchange networks (Molm and Cook, 1995; Willer, 1999). Consistent with the hypotheses, the results reveal more convergence of behavior and higher cohesion in triads than in dyads; moreover, uncertainty reduction is the primary basis for cohesion in the triad, whereas positive affect was the primary basis for cohesion in the dyad. These results are discussed in relation to Simmelian dyad-triad dynamics and the theory of relational cohesion. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Racial Discrimination and Mental Health in the USA: Testing the Reverse Racism Hypothesis.

    Science.gov (United States)

    Woo, Bongki

    2017-08-15

    The present study examined whether the health disadvantages consequent of racial discrimination experienced by four racial/ethnic minority groups are equivalent with that of the dominant racial group. Data was derived from the 2013 National Epidemiologic Survey on Alcohol and Related Conditions. Logistic regression and heterogeneous choice models were used to test the moderating role of race/ethnicity in regards to the associations between racial discrimination and ten DSM-V diagnoses. Non-Hispanic blacks reported the highest levels of experiencing racial discrimination, while Non-Hispanic whites reported the lowest. Exposure to racial discrimination was associated with higher odds of psychiatric disorders for non-Hispanic blacks, non-Hispanic Asian/Pacific Islanders, and Hispanics than it was for non-Hispanic whites, while non-Hispanic American Indians/Alaska Natives had lower odds of psychiatric disorders. Analyses indicated that racial discrimination poses stronger mental health disadvantages on racial/ethnic minorities than it does to non-Hispanic whites. This finding not only refutes the notion of reverse racism, but also calls for more efforts to close the racial/ethnic health gap for those exposed to racial discrimination.

  1. Properties of hypothesis testing techniques and (Bayesian) model selection for exploration-based and theory-based (order-restricted) hypotheses.

    Science.gov (United States)

    Kuiper, Rebecca M; Nederhoff, Tim; Klugkist, Irene

    2015-05-01

    In this paper, the performance of six types of techniques for comparisons of means is examined. These six emerge from the distinction between the method employed (hypothesis testing, model selection using information criteria, or Bayesian model selection) and the set of hypotheses that is investigated (a classical, exploration-based set of hypotheses containing equality constraints on the means, or a theory-based limited set of hypotheses with equality and/or order restrictions). A simulation study is conducted to examine the performance of these techniques. We demonstrate that, if one has specific, a priori specified hypotheses, confirmation (i.e., investigating theory-based hypotheses) has advantages over exploration (i.e., examining all possible equality-constrained hypotheses). Furthermore, examining reasonable order-restricted hypotheses has more power to detect the true effect/non-null hypothesis than evaluating only equality restrictions. Additionally, when investigating more than one theory-based hypothesis, model selection is preferred over hypothesis testing. Because of the first two results, we further examine the techniques that are able to evaluate order restrictions in a confirmatory fashion by examining their performance when the homogeneity of variance assumption is violated. Results show that the techniques are robust to heterogeneity when the sample sizes are equal. When the sample sizes are unequal, the performance is affected by heterogeneity. The size and direction of the deviations from the baseline, where there is no heterogeneity, depend on the effect size (of the means) and on the trend in the group variances with respect to the ordering of the group sizes. Importantly, the deviations are less pronounced when the group variances and sizes exhibit the same trend (e.g., are both increasing with group number). © 2014 The British Psychological Society.

  2. Testing the mate-choice hypothesis of the female orgasm: disentangling traits and behaviours

    Directory of Open Access Journals (Sweden)

    James M. Sherlock

    2016-10-01

    Full Text Available Background: The evolution of the female orgasm in humans and its role in romantic relationships is poorly understood. Whereas the male orgasm is inherently linked to reproduction, the female orgasm is not linked to obvious reproductive or survival benefits. It also occurs less consistently during penetrative sex than does the male orgasm. Mate-choice hypotheses posit that the wide variation in female orgasm frequency reflects a discriminatory mechanism designed to select high-quality mates. Objective: We aimed to determine (1 whether women report that their orgasm frequency varies between partners, (2 whether this variation reflects mates' personal characteristics, and (3 whether this variation reflects own and partner sexual behaviour during intercourse. Design: We collected survey data from 103 women who rated (1 the extent to which their orgasm frequency varied between partners, (2 the characteristics of previous sexual partners who induced high-orgasm frequency and those who induced low-orgasm frequency, and (3 the specific behaviours during sex with those partners. This is the first study to test within-woman variation in orgasm and partner traits. Results: Overall, women reported variation in their orgasm rates with different partners. Partners who induced high-orgasm rates were rated as more humorous, creative, warm, faithful, and better smelling than partners who induced low-orgasm rates, and also engaged in greater efforts to induce partner orgasm. Conclusions: Some assumptions and predictions of mate-choice hypotheses of female orgasm were supported, while other aspects of our findings provide reasons to remain sceptical.

  3. Acorn selection by Mexican jays: a test of a tri-trophic symbiotic relationship hypothesis.

    Science.gov (United States)

    Hubbard, J Andrew; McPherson, Guy R

    1997-03-01

    By caching acorns, jays serve as important dispersal agents for oak (Quercus) species. Yet little is known about which acorn characteristics affect selection by jays. In the traditional model of jay/oak symbiosis, large, brown, ripe acorns free of invertebrate parasites (e.g., Curculio acorn weevils) are selected by jays. Recently, it has been suggested that a tri-trophic relationship between oaks, jays, and weevils may have evolved to counter the negative dietary effects of acorn tannins. Under the tri-trophic model, jays would preferentially select acorns containing weevil larvae. We tested the assumptions that (1) acorns containing curculionid larvae exist in sufficient quantities to support jay populations and (2) jays can detect, and preferentially select, acorns containing weevil larvae, and investigated the cues by which jays select acorns. Captive Mexican jays (Aphelocomaultramarina) were presented Emory oak (Quercusemoryi) acorns in aviary feeding trials. Large, dense, viable acorns free of curculionid larvae were preferentially selected. Contrary to results of previous research, color did not affect selection. Acorn viability increased and curculionid larval occupancy decreased in adjacent savannas and isolated stands relative to existing oak woodland, perhaps favoring oak recruitment into adjacent lower-elevation grasslands. Our results compel us to reject the tri-trophic model for this system, and are consistent with the traditional jay/oak symbiosis model. Relatively long-distance dispersal of viable acorns favors Emory oak replacement, and spatial patterns of acorn viability and curculionid parasitism suggest expansion of Emory oak into adjacent low-elevation semi-arid grasslands.

  4. The Avalanche Hypothesis and Compression of Morbidity: Testing Assumptions through Cohort-Sequential Analysis.

    Directory of Open Access Journals (Sweden)

    Jordan Silberman

    Full Text Available The compression of morbidity model posits a breakpoint in the adult lifespan that separates an initial period of relative health from a subsequent period of ever increasing morbidity. Researchers often assume that such a breakpoint exists; however, this assumption is hitherto untested.To test the assumption that a breakpoint exists--which we term a morbidity tipping point--separating a period of relative health from a subsequent deterioration in health status. An analogous tipping point for healthcare costs was also investigated.Four years of adults' (N = 55,550 morbidity and costs data were retrospectively analyzed. Data were collected in Pittsburgh, PA between 2006 and 2009; analyses were performed in Rochester, NY and Ann Arbor, MI in 2012 and 2013. Cohort-sequential and hockey stick regression models were used to characterize long-term trajectories and tipping points, respectively, for both morbidity and costs.Morbidity increased exponentially with age (P<.001. A morbidity tipping point was observed at age 45.5 (95% CI, 41.3-49.7. An exponential trajectory was also observed for costs (P<.001, with a costs tipping point occurring at age 39.5 (95% CI, 32.4-46.6. Following their respective tipping points, both morbidity and costs increased substantially (Ps<.001.Findings support the existence of a morbidity tipping point, confirming an important but untested assumption. This tipping point, however, may occur earlier in the lifespan than is widely assumed. An "avalanche of morbidity" occurred after the morbidity tipping point-an ever increasing rate of morbidity progression. For costs, an analogous tipping point and "avalanche" were observed. The time point at which costs began to increase substantially occurred approximately 6 years before health status began to deteriorate.

  5. Aerobic power and flight capacity in birds: a phylogenetic test of the heart-size hypothesis.

    Science.gov (United States)

    Nespolo, Roberto F; González-Lagos, César; Solano-Iguaran, Jaiber J; Elfwing, Magnus; Garitano-Zavala, Alvaro; Mañosa, Santiago; Alonso, Juan Carlos; Altimiras, Jordi

    2018-01-09

    Flight capacity is one of the most important innovations in animal evolution; it only evolved in insects, birds, mammals and the extinct pterodactyls. Given that powered flight represents a demanding aerobic activity, an efficient cardiovascular system is essential for the continuous delivery of oxygen to the pectoral muscles during flight. It is well known that the limiting step in the circulation is stroke volume (the volume of blood pumped from the ventricle to the body during each beat), which is determined by the size of the ventricle. Thus, the fresh mass of the heart represents a simple and repeatable anatomical measure of the aerobic power of an animal. Although several authors have compared heart masses across bird species, a phylogenetic comparative analysis is still lacking. By compiling heart sizes for 915 species and applying several statistical procedures controlling for body size and/or testing for adaptive trends in the dataset (e.g. model selection approaches, phylogenetic generalized linear models), we found that (residuals of) heart size is consistently associated with four categories of flight capacity. In general, our results indicate that species exhibiting continuous hovering flight (i.e. hummingbirds) have substantially larger hearts than other groups, species that use flapping flight and gliding show intermediate values, and that species categorized as poor flyers show the smallest values. Our study reveals that on a broad scale, routine flight modes seem to have shaped the energetic requirements of birds sufficiently to be anatomically detected at the comparative level. © 2018. Published by The Company of Biologists Ltd.

  6. Testing the cancer stem cell hypothesis in melanoma: the clinics will tell.

    Science.gov (United States)

    Shakhova, Olga; Sommer, Lukas

    2013-09-10

    Whether tumorigenic cancer stem cells (CSCs) exist in melanoma has been the focus of much controversy in recent years. A number of studies have pointed to the existence of melanoma cell sub-populations that act as CSCs and can be distinguished from other tumor cells based on specific surface marker expression or specific properties such as the capacity for extensive self-renewal. Other studies failed to identify melanoma stem cells and proposed that the potential to initiate tumors is a wide spread feature in melanoma inherent to most if not all cells of the tumor mass. As with normal stem cells, the term CSC is based on an operational definition, indicating not just a tumor-initiating cell, but also a cell with the capacity to sustain long-term tumor propagation. Therefore, the experimental set-up chosen to identify putative CSCs in melanoma is crucial: Both the method of tumor cell preparation and the procedure used to assess CSC properties in vivo influence the experimental outcome and hence its interpretation. In this review, we summarize our current knowledge on CSCs and the role of stem cell properties in melanoma and discuss recent findings with respect to their clinical relevance. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  7. Development of Pelvic Sexual Dimorphism in Hylobatids: Testing the Obstetric Constraints Hypothesis.

    Science.gov (United States)

    Zollikofer, Christoph P E; Scherrer, Marc; Ponce de León, Marcia S

    2017-05-01

    Pelvic sexual dimorphism in primates is typically seen as the result of female-specific adaptations to obstetric constraints, which arise from the tight fit between the neonate head and the maternal pelvis. However, it remains debated to which extent pelvic dimorphism is a correlate of obstetric constraints, of body size dimorphism, and/or of other factors. Also, little is known on how pelvic dimorphism develops. Here we use methods of biomedical imaging and geometric morphometrics to address these questions in two hylobatid species, Hylobates lar and Symphalangus syndactylus. These species differ markedly in body size, but within each species, there is only little body size dimorphism. Results show that the neonates of H. lar are large compared to the maternal pelvis, resulting in high cephalopelvic proportions and substantial obstetric constraints. Pelvic sexual dimorphism is moderate but significant: During puberty, females develop a more capacious pelvic inlet than males, while overall pelvic size is similar in both sexes. S. syndactylus has substantially larger pelves than H. lar, but neonates are similar in size to those of H. lar. Cephalopelvic proportions are thus low, and there are no obstetric constraints. Pelvic sexual dimorphism is absent. Overall, these data indicate that pelvic sexual dimorphism in hylobatids reflects obstetric constraints. Anat Rec, 300:859-869, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Motivation in vigilance - A test of the goal-setting hypothesis of the effectiveness of knowledge of results.

    Science.gov (United States)

    Warm, J. S.; Riechmann, S. W.; Grasha, A. F.; Seibel, B.

    1973-01-01

    This study tested the prediction, derived from the goal-setting hypothesis, that the facilitating effects of knowledge of results (KR) in a simple vigilance task should be related directly to the level of the performance standard used to regulate KR. Two groups of Ss received dichotomous KR in terms of whether Ss response times (RTs) to signal detections exceeded a high or low standard of performance. The aperiodic offset of a visual signal was the critical event for detection. The vigil was divided into a training phase followed by testing, during which KR was withdrawn. Knowledge of results enhanced performance in both phases. However, the two standards used to regulate feedback contributed little to these effects.

  9. The Pacific Northwest Hydrological Observatory (PNW HO): Hypothesis and model testing power through diversity

    Science.gov (United States)

    McDonnell, J. J.; Grant, G.; Hulse, D.

    2004-12-01

    The Pacific Northwest Hydrological Observatory (PNW HO) is a proposed national facility for the examination of the linkages between hydrologic and biogeochemical cycles, sustainability of water resources in the face of increasing human demands and climate change, hydrologic and ecosystem interactions, and hydrologic extremes. The PNW HO infrastructure will support research that examines forcings, feedbacks and couplings across hydro-eco-climatic interfaces, process scaling, and development of new predictive schemes and methods to reduce predictive uncertainty. Much of the data collection infrastructure is already in place, in the form of USGS gauging, local and State data recording. The PNW HO includes a novel experimental design that twins two neighboring watersheds-the humid Willamette and arid Deschutes River Basins-that represent a full range of landscape gradients and societal problems relating to water quantity and quality. Workers at the PNW HO will be able to build upon existing synthesis documents in the form of the Willamette River Basin Planning Atlas and recent AGU Monograph on the Deschutes River Basin. The PNW HO design builds upon the HJ Andrews LTER site in the headwaters and recent listing of the Willamette River Basin as a UNESCO HELP international observatory. The PNW HO has access to one of the richest SNOTEL datasets in North America along the divide between the Willamette and Deschutes Basins. The Willamette is a USGS NAWQA basin and the Deschutes has been the focus of a major USGS groundwater investigation, and is one of five sites nationally in the Fire Learning Network. Finally, and perhaps most importantly for technology transfer of HO science to policy and practice, the PNW HO enjoys a rather unique combination of Oregon's state-based land use planning and doctrine of prior appropriations water law (land use planning and water rights). While there are certainly areas in the West where human populations are growing as fast or faster, none

  10. Automatic Testing with Formal Methods

    NARCIS (Netherlands)

    Tretmans, G.J.; Belinfante, Axel

    1999-01-01

    The use of formal system specifications makes it possible to automate the derivation of test cases from specifications. This allows to automate the whole testing process, not only the test execution part of it. This paper presents the state of the art and future perspectives in testing based on

  11. Combining multiple hypothesis testing and affinity propagation clustering leads to accurate, robust and sample size independent classification on gene expression data

    Directory of Open Access Journals (Sweden)

    Sakellariou Argiris

    2012-10-01

    Full Text Available Abstract Background A feature selection method in microarray gene expression data should be independent of platform, disease and dataset size. Our hypothesis is that among the statistically significant ranked genes in a gene list, there should be clusters of genes that share similar biological functions related to the investigated disease. Thus, instead of keeping N top ranked genes, it would be more appropriate to define and keep a number of gene cluster exemplars. Results We propose a hybrid FS method (mAP-KL, which combines multiple hypothesis testing and affinity propagation (AP-clustering algorithm along with the Krzanowski & Lai cluster quality index, to select a small yet informative subset of genes. We applied mAP-KL on real microarray data, as well as on simulated data, and compared its performance against 13 other feature selection approaches. Across a variety of diseases and number of samples, mAP-KL presents competitive classification results, particularly in neuromuscular diseases, where its overall AUC score was 0.91. Furthermore, mAP-KL generates concise yet biologically relevant and informative N-gene expression signatures, which can serve as a valuable tool for diagnostic and prognostic purposes, as well as a source of potential disease biomarkers in a broad range of diseases. Conclusions mAP-KL is a data-driven and classifier-independent hybrid feature selection method, which applies to any disease classification problem based on microarray data, regardless of the available samples. Combining multiple hypothesis testing and AP leads to subsets of genes, which classify unknown samples from both, small and large patient cohorts with high accuracy.

  12. Coreferentiality: a new method for the hypothesis-based analysis of phenotypes characterized by multivariate data.

    Directory of Open Access Journals (Sweden)

    Constantin Fesel

    Full Text Available Many multifactorial biologic effects, particularly in the context of complex human diseases, are still poorly understood. At the same time, the systematic acquisition of multivariate data has become increasingly easy. The use of such data to analyze and model complex phenotypes, however, remains a challenge. Here, a new analytic approach is described, termed coreferentiality, together with an appropriate statistical test. Coreferentiality is the indirect relation of two variables of functional interest in respect to whether they parallel each other in their respective relatedness to multivariate reference data, which can be informative for a complex effect or phenotype. It is shown that the power of coreferentiality testing is comparable to multiple regression analysis, sufficient even when reference data are informative only to a relatively small extent of 2.5%, and clearly exceeding the power of simple bivariate correlation testing. Thus, coreferentiality testing uses the increased power of multivariate analysis, however, in order to address a more straightforward interpretable bivariate relatedness. Systematic application of this approach could substantially improve the analysis and modeling of complex phenotypes, particularly in the context of human study where addressing functional hypotheses by direct experimentation is often difficult.

  13. Water developments and canids in two North American deserts: a test of the indirect effect of water hypothesis.

    Directory of Open Access Journals (Sweden)

    Lucas K Hall

    Full Text Available Anthropogenic modifications to landscapes intended to benefit wildlife may negatively influence wildlife communities. Anthropogenic provisioning of free water (water developments to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence native species. Water developments may negatively influence arid-adapted species (e.g., kit fox, Vulpes macrotis by enabling water-dependent competitors (e.g., coyote, Canis latrans to expand distribution in arid landscapes (i.e., indirect effect of water hypothesis. We tested the two predictions of the indirect effect of water hypothesis (i.e., coyotes will visit areas with free water more frequently and kit foxes will spatially and temporally avoid coyotes and evaluated relative use of free water by canids in the Great Basin and Mojave Deserts from 2010 to 2012. We established scent stations in areas with (wet and without (dry free water and monitored visitation by canids to these sites and visitation to water sources using infrared-triggered cameras. There was no difference in the proportions of visits to scent stations in wet or dry areas by coyotes or kit foxes at either study area. We did not detect spatial (no negative correlation between visits to scent stations or temporal (no difference between times when stations were visited segregation between coyotes and kit foxes. Visitation to water sources was not different for coyotes between study areas, but kit foxes visited water sources more in Mojave than Great Basin. Our results did not support the indirect effect of water hypothesis in the Great Basin or Mojave Deserts for these two canids.

  14. Water Developments and Canids in Two North American Deserts: A Test of the Indirect Effect of Water Hypothesis

    Science.gov (United States)

    Hall, Lucas K.; Larsen, Randy T.; Knight, Robert N.; Bunnell, Kevin D.; McMillan, Brock R.

    2013-01-01

    Anthropogenic modifications to landscapes intended to benefit wildlife may negatively influence wildlife communities. Anthropogenic provisioning of free water (water developments) to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence native species. Water developments may negatively influence arid-adapted species (e.g., kit fox, Vulpes macrotis) by enabling water-dependent competitors (e.g., coyote, Canis latrans) to expand distribution in arid landscapes (i.e., indirect effect of water hypothesis). We tested the two predictions of the indirect effect of water hypothesis (i.e., coyotes will visit areas with free water more frequently and kit foxes will spatially and temporally avoid coyotes) and evaluated relative use of free water by canids in the Great Basin and Mojave Deserts from 2010 to 2012. We established scent stations in areas with (wet) and without (dry) free water and monitored visitation by canids to these sites and visitation to water sources using infrared-triggered cameras. There was no difference in the proportions of visits to scent stations in wet or dry areas by coyotes or kit foxes at either study area. We did not detect spatial (no negative correlation between visits to scent stations) or temporal (no difference between times when stations were visited) segregation between coyotes and kit foxes. Visitation to water sources was not different for coyotes between study areas, but kit foxes visited water sources more in Mojave than Great Basin. Our results did not support the indirect effect of water hypothesis in the Great Basin or Mojave Deserts for these two canids. PMID:23844097

  15. Biorhythms, deciduous enamel thickness, and primary bone growth: a test of the Havers-Halberg Oscillation hypothesis.

    Science.gov (United States)

    Mahoney, Patrick; Miszkiewicz, Justyna J; Pitfield, Rosie; Schlecht, Stephen H; Deter, Chris; Guatelli-Steinberg, Debbie

    2016-06-01

    Across mammalian species, the periodicity with which enamel layers form (Retzius periodicity) in permanent teeth corresponds with average body mass and the pace of life history. According to the Havers-Halberg Oscillation hypothesis (HHO), Retzius periodicity (RP) is a manifestation of a biorhythm that is also expressed in lamellar bone. Potentially, these links provide a basis for investigating aspects of a species' biology from fossilized teeth. Here, we tested intra-specific predictions of this hypothesis on skeletal samples of human juveniles. We measured daily enamel growth increments to calculate RP in deciduous molars (n = 25). Correlations were sought between RP, molar average and relative enamel thickness (AET, RET), and the average amount of primary bone growth (n = 7) in humeri of age-matched juveniles. Results show a previously undescribed relationship between RP and enamel thickness. Reduced major axis regression reveals RP is significantly and positively correlated with AET and RET, and scales isometrically. The direction of the correlation was opposite to HHO predictions as currently understood for human adults. Juveniles with higher RPs and thicker enamel had increased primary bone formation, which suggests a coordinating biorhythm. However, the direction of the correspondence was, again, opposite to predictions. Next, we compared RP from deciduous molars with new data for permanent molars, and with previously published values. The lowermost RP of 4 and 5 days in deciduous enamel extends below the lowermost RP of 6 days in permanent enamel. A lowered range of RP values in deciduous enamel implies that the underlying biorhythm might change with age. Our results develop the intra-specific HHO hypothesis. © 2016 Anatomical Society.

  16. Why do capuchin monkeys urine wash? An experimental test of the sexual communication hypothesis using fMRI.

    Science.gov (United States)

    Phillips, Kimberley A; Buzzell, Courtney A; Holder, Nicholas; Sherwood, Chet C

    2011-06-01

    Urine washing (UW) consists of depositing urine on the hands and vigorously rubbing the body. As urine contains chemical and pheromonal cues, UW may convey socially relevant information. Although ritualized UW is observed in many New World primates, including capuchin monkeys, the functional significance of UW remains unclear. In this experiment, we investigated the social signaling hypothesis of UW. Specifically, we hypothesized that UW by males conveys socially relevant signals that females can detect. We used functional magnetic resonance imaging (fMRI) to test whether adult female capuchins show differential brain activation in response to adult male and juvenile male capuchin urine. We expected to see changes in activation of structures involved in olfactory processing, including the piriform cortex, medial preoptic and anterior hypothesis, orbitofrontal cortex, hippocampus, and cerebellum. Data were acquired from four adult female capuchin monkeys. Presentations of odor stimuli (obtained from unfamiliar males) were made during fMRI acquisition using a standard ON-OFF design. All fMRI data were spatially normalized to a template and analyzed using the FMRI Expert Analysis Tool Version 5.98, part of the FMRIB's Software Library (www.fmrib.ox.ac.uk/fsl). Whole brain analyses revealed significant activations in the inferior temporal cortex, parahippocampal gyrus, precuneus, hippocampus, pulvinar, and cerebellum when females were presented with the adult male urine. Notably, significantly greater signal activation was observed in several regions associated with olfactory processing, when subjects were presented with adult male urine as compared with urine from juvenile males. Our results indicate that UW serves a social communicative function in capuchins, providing support for the sexual signaling hypothesis. © 2011 Wiley-Liss, Inc.

  17. [Hypothesis and application of bimolecular marking methods in Chinese materia medica].

    Science.gov (United States)

    Huang, Lu-qi; Qian, Dan; Deng, Chao

    2015-01-01

    Based on the current shortage of genuine/false authentication and quality evaluation in the molecular identification, and the weak functional gene research in the establishment of two-dimensional molecular markering methods for Chinese materia medica, the authors proposed a new method, the bimolecular marking methods (BIMM) for Chinese materia medica, combining DNA marker and metabolomics marker, that could simultaneously research the species and quality differences at the molecular level at the present stage. The authors introduced the concept, principle, methods, and technical process of BIMM, and summarized the technical advantages in this paper. Meanwhile, the application of BIMM in the identification of multiple sources of Chinese materia medica, years-identification, different locations, elite germplasm research, discovery of new drugs resources, protection of new varieties was also discussed. As a supplement of two-dimensional molecular markering method for Chinese materia medica, BIMM would not only expand connotation of identification of Chinese materia medica but also provide another effective way for quality evaluating.

  18. A reappraisal of the deconditioning hypothesis in low back pain: review of evidence from a triumvirate of research methods on specific lumbar extensor deconditioning.

    Science.gov (United States)

    Steele, James; Bruce-Low, Stewart; Smith, Dave

    2014-05-01

    'Disuse' and 'Deconditioning' in relation to low back pain (LBP) are terms often used interchangeably. Discussions of 'disuse' refer to general physical inactivity, which evidence suggests does not differ between symptomatic and asymptomatic persons. 'Deconditioning' refers to a decrease in function, commonly both cardiovascular/aerobic fitness and muscular strength/endurance, again noting little difference. However, examination of decreased function relating specifically to lumbar extensor musculature deconditioning has yet to be examined, corroborating all possible methods. Thus, this review attempts to reappraise the deconditioning hypothesis in LBP, specifically considering lumbar extensor deconditioning. A literature review was conducted examining both cross-sectional and prospective data on specific lumbar extensor deconditioning and LBP. A narrative approach and 'snowballing' style literature search was used involving initial use of PubMed and Google Scholar databases searching up to December 2012. Included were studies utilizing the following three research methods, allowing specific induction of the role of such deconditioning; (1) strength/endurance testing of the isolated lumbar extensor musculature, (2) imaging and histochemical examination of the lumbar extensor musculature, and (3) fatigue testing of the lumbar extensor musculature using electromyography. Despite issues interpreting individual studies due to methods, the majority of evidence suggests LBP is associated with decreased strength/endurance, atrophy, and excessive fatigability of the lumbar extensors. Prospective studies also suggest lumbar extensor deconditioning may be a common risk factor predicting acute low back injury and LBP. The hypothesis of specific lumbar extensor deconditioning as being a causal factor in LBP is presently well supported. It is by no means the only causative factor and further research should more rigorously test this hypothesis addressing the methodological

  19. Radiovaccination Hypothesis

    National Research Council Canada - National Science Library

    Eapen Libni

    2017-01-01

    .... We review the relevant immune physiology and radiotherapy particulars and propose the hypothesis that radiovaccination with high fractional dose to skin metastases can stimulate the development...

  20. Testing the stress-gradient hypothesis during the restoration of tropical degraded land using the shrub Rhodomyrtus tomentosa as a nurse plant

    Science.gov (United States)

    Nan Liu; Hai Ren; Sufen Yuan; Qinfeng Guo; Long Yang

    2013-01-01

    The relative importance of facilitation and competition between pairwise plants across abiotic stress gradients as predicted by the stress-gradient hypothesis has been confirmed in arid and temperate ecosystems, but the hypothesis has rarely been tested in tropical systems, particularly across nutrient gradients. The current research examines the interactions between a...

  1. Male Takeovers Are Reproductively Costly to Females in Hamadryas Baboons: A Test of the Sexual Coercion Hypothesis

    Science.gov (United States)

    Polo, Pablo; Hernández-Lloreda, Victoria; Colmenares, Fernando

    2014-01-01

    During male takeovers, in addition to fighting off the female’s current mating partner, males may exhibit intense aggressive mate guarding of the newly acquired females. Recent studies indicate that coercive sexual aggression by males is an important strategy through which sexual conflict is expressed. Previous tests of the sexual coercion hypothesis in primates have focused on assessing if female mate choice is effectively reduced by male aggression, however, only one recent study has tested a critical prediction of this hypothesis, namely, that male coercion is reproductively costly to victim females. The present study uses 15 years of data on inter-birth intervals from a large multilevel colony of baboons, mostly Papio h. hamadryas, with a mating system based on harem-defence polygyny to examine if male takeovers impact the length of the abducted females’ inter-birth intervals. Our analysis of 121 inter-birth intervals from 45 adult females indicates that male takeovers are reproductively costly to abducted females as they are associated with an increase in the time they take to conceive and a lengthening of the inter-birth intervals. We discuss how several factors may contribute to this reproductive cost, including male-female sexual conflict, male-male competition, and female-female competition. Our findings suggest that the male’s aggressive herding is the main contributor to the abducted females’ immediate reproductive cost. We argue that although some of the male’s aggressive herding may be driven by male-male competition, nonetheless, it serves a coercive function as it both constrains the female’s mate choice options and hampers her immediate breeding performance. This conclusion is backed up by results obtained in the only other study that has tested the same prediction and which has been carried out in a wild population of hamadryas baboons. PMID:24621865

  2. Male takeovers are reproductively costly to females in hamadryas baboons: a test of the sexual coercion hypothesis.

    Directory of Open Access Journals (Sweden)

    Pablo Polo

    Full Text Available During male takeovers, in addition to fighting off the female's current mating partner, males may exhibit intense aggressive mate guarding of the newly acquired females. Recent studies indicate that coercive sexual aggression by males is an important strategy through which sexual conflict is expressed. Previous tests of the sexual coercion hypothesis in primates have focused on assessing if female mate choice is effectively reduced by male aggression, however, only one recent study has tested a critical prediction of this hypothesis, namely, that male coercion is reproductively costly to victim females. The present study uses 15 years of data on inter-birth intervals from a large multilevel colony of baboons, mostly Papio h. hamadryas, with a mating system based on harem-defence polygyny to examine if male takeovers impact the length of the abducted females' inter-birth intervals. Our analysis of 121 inter-birth intervals from 45 adult females indicates that male takeovers are reproductively costly to abducted females as they are associated with an increase in the time they take to conceive and a lengthening of the inter-birth intervals. We discuss how several factors may contribute to this reproductive cost, including male-female sexual conflict, male-male competition, and female-female competition. Our findings suggest that the male's aggressive herding is the main contributor to the abducted females' immediate reproductive cost. We argue that although some of the male's aggressive herding may be driven by male-male competition, nonetheless, it serves a coercive function as it both constrains the female's mate choice options and hampers her immediate breeding performance. This conclusion is backed up by results obtained in the only other study that has tested the same prediction and which has been carried out in a wild population of hamadryas baboons.

  3. Conflict of interest between a nematode and a trematode in an amphipod host: Test of the "sabotage" hypothesis

    Science.gov (United States)

    Thomas, Frédéric; Fauchier, Jerome; Lafferty, Kevin D.

    2002-01-01

    Microphallus papillorobustus is a manipulative trematode that induces strong behavioural alterations in the gamaridean amphipod Gammarus insensibilis, making the amphipod more vulnerable to predation by aquatic birds (definitive hosts). Conversely, the sympatric nematodeGammarinema gammari uses Gammarus insensibilis as a habitat and a source of nutrition. We investigated the conflict of interest between these two parasite species by studying the consequences of mixed infection on amphipod behaviour associated with the trematode. In the field, some amphipods infected by the trematode did not display the altered behaviour. These normal amphipods also had more nematodes, suggesting that the nematode overpowered the manipulation of the trematode, a strategy that would prolong the nematode's life. We hypothesize that sabotage of the trematode by the nematode would be an adaptive strategy for the nematode consistent with recent speculation about co-operation and conflict in manipulative parasites. A behavioural test conducted in the laboratory from naturally infected amphipods yielded the same result. However, exposing amphipods to nematodes did not negate or decrease the manipulation exerted by the trematode. Similarly, experimental elimination of nematodes from amphipods did not permit trematodes to manipulate behaviour. These experimental data do not support the hypothesis that the negative association between nematodes and manipulation by the trematode is a result of the "sabotage" hypothesis.

  4. Testing the Sensory Drive Hypothesis: Geographic variation in echolocation frequencies of Geoffroy's horseshoe bat (Rhinolophidae: Rhinolophus clivosus).

    Science.gov (United States)

    Jacobs, David S; Catto, Sarah; Mutumi, Gregory L; Finger, Nikita; Webala, Paul W

    2017-01-01

    Geographic variation in sensory traits is usually influenced by adaptive processes because these traits are involved in crucial life-history aspects including orientation, communication, lineage recognition and mate choice. Studying this variation can therefore provide insights into lineage diversification. According to the Sensory Drive Hypothesis, lineage diversification may be driven by adaptation of sensory systems to local environments. It predicts that acoustic signals vary in association with local climatic conditions so that atmospheric attenuation is minimized and transmission of the signals maximized. To test this prediction, we investigated the influence of climatic factors (specifically relative humidity and temperature) on geographic variation in the resting frequencies of the echolocation pulses of Geoffroy's horseshoe bat, Rhinolophus clivosus. If the evolution of phenotypic variation in this lineage tracks climate variation, human induced climate change may lead to decreases in detection volumes and a reduction in foraging efficiency. A complex non-linear interaction between relative humidity and temperature affects atmospheric attenuation of sound and principal components composed of these correlated variables were, therefore, used in a linear mixed effects model to assess their contribution to observed variation in resting frequencies. A principal component composed predominantly of mean annual temperature (factor loading of -0.8455) significantly explained a proportion of the variation in resting frequency across sites (P Hypothesis. The predicted future increase in temperature due to climate change is likely to decrease the detection volume in echolocating bats and adversely impact their foraging efficiency.

  5. In vitro strain in human metacarpal bones during striking: testing the pugilism hypothesis of hominin hand evolution.

    Science.gov (United States)

    Horns, Joshua; Jung, Rebekah; Carrier, David R

    2015-10-01

    The hands of hominins (i.e. bipedal apes) are distinguished by skeletal proportions that are known to enhance manual dexterity but also allow the formation of a clenched fist. Because male-male physical competition is important in the mating systems of most species of great apes, including humans, we tested the hypothesis that a clenched fist protects the metacarpal bones from injury by reducing the level of strain during striking. We used cadaver arms to measure in vitro strain in metacarpals during forward strikes with buttressed and unbuttressed fist postures and during side slaps with an open palm. If the protective buttressing hypothesis is correct, the clenched fist posture should substantially reduce strain in the metacarpal bones during striking and therefore reduce the risk of fracture. Recorded strains were significantly higher in strikes in which the hand was secured in unbuttressed and slapping postures than in the fully buttressed posture. Our results suggest that humans can safely strike with 55% more force with a fully buttressed fist than with an unbuttressed fist and with twofold more force with a buttressed fist than with an open-hand slap. Thus, the evolutionary significance of the proportions of the hominin hand may be that these are the proportions that improved manual dexterity while at the same time making it possible for the hand to be used as a club during fighting. © 2015. Published by The Company of Biologists Ltd.

  6. Patterns of host specificity among the helminth parasite fauna of freshwater siluriforms: testing the biogeographical core parasite fauna hypothesis.

    Science.gov (United States)

    Rosas-Valdez, Rogelio; de León, Gerardo Pérez-Ponce

    2011-04-01

    Host specificity plays an essential role in shaping the evolutionary history of host-parasite associations. In this study, an index of host specificity recently proposed was used to test, quantitatively, the hypothesis that some groups of parasites are characteristics of some host fish families along their distribution range. A database with all published records on the helminth parasites of freshwater siluriforms of Mexico was used. The host specificity index was used considering its advantage to measure the taxonomic heterogeneity of the host assemblages and its appropriateness for unequal sampling data. The helminth parasite fauna of freshwater siluriforms in Mexico seems to be specific for different host taxonomic categories. However, a relatively high number of species (47% of the total helminth fauna) is specific to their respective host family. This result provides further corroboration for the biogeographic hypothesis of the core helminth fauna proposed previously. The statistical values for host specificity obtained herein seem to be independent of host range. However, the accurate taxonomic identification of the parasites is fundamental for the evaluation of host specificity and the accurate evolutionary interpretation of this phenomenon.

  7. Sex differences in DNA methylation and expression in zebrafish brain: a test of an extended 'male sex drive' hypothesis.

    Science.gov (United States)

    Chatterjee, Aniruddha; Lagisz, Malgorzata; Rodger, Euan J; Zhen, Li; Stockwell, Peter A; Duncan, Elizabeth J; Horsfield, Julia A; Jeyakani, Justin; Mathavan, Sinnakaruppan; Ozaki, Yuichi; Nakagawa, Shinichi

    2016-09-30

    The sex drive hypothesis predicts that stronger selection on male traits has resulted in masculinization of the genome. Here we test whether such masculinizing effects can be detected at the level of the transcriptome and methylome in the adult zebrafish brain. Although methylation is globally similar, we identified 914 specific differentially methylated CpGs (DMCs) between males and females (435 were hypermethylated and 479 were hypomethylated in males compared to females). These DMCs were prevalent in gene body, intergenic regions and CpG island shores. We also discovered 15 distinct CpG clusters with striking sex-specific DNA methylation differences. In contrast, at transcriptome level, more female-biased genes than male-biased genes were expressed, giving little support for the male sex drive hypothesis. Our study provides genome-wide methylome and transcriptome assessment and sheds light on sex-specific epigenetic patterns and in zebrafish for the first time. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Telemetry test methods. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bowers, J.L.; Bullard, D.L.; Schelp, T.R.

    1978-04-01

    A flexible test system is studied and proposed to provide an extensive evaluation and testing capability for telemetry products. A distributed computer controlled, modular unit test system using Computer Automated Measurement and Control (CAMAC) standard hardware and compatible software is selected because of its flexibility of application and long term cost effectiveness.

  9. Comparing a Real-Life WSN Platform Small Network and its OPNET Modeler Model using Hypothesis Testing

    Directory of Open Access Journals (Sweden)

    Gilbert E. Pérez

    2014-12-01

    Full Text Available To avoid the high cost and arduous effort usually associated with field analysis of Wireless Sensor Network (WSN, Modeling and Simulation (M&S is used to predict the behavior and performance of the network. However, the simulation models utilized to imitate real life networks are often used for general purpose. Therefore, they are less likely to provide accurate predictions for different real life networks. In this paper, a comparison methodology based on hypothesis testing is proposed to evaluate and compare simulation output versus real-life network measurements. Performance related parameters such as traffic generation rates and goodput rates for a small WSN are considered. To execute the comparison methodology, a "Comparison Tool", composed of MATLAB scripts is developed and used. The comparison tool demonstrates the need for model verification and the analysis of good agreements between the simulation and empirical measurements.

  10. A test of the "sexy son" hypothesis: sons of polygynous collared flycatchers do not inherit their fathers' mating status.

    Science.gov (United States)

    Gustafsson, Lars; Qvarnström, Anna

    2006-02-01

    According to the original "sexy son" hypothesis, a female may benefit from pairing with an already-mated male despite a reduction in fecundity because her sons inherit their father's attractiveness. We used data from a long-term study of collared flycatchers (Ficedula albicollis) collected during 24 years to test this prediction. Our results show that the sons of polygynously mated females fledged in poor condition and therefore did not inherit their father's large forehead patch (a condition-dependent display trait) or mating status. From the female's perspective, polygynous pairing resulted in fewer recruited grandchildren than did a monogamous pairing. The reproductive value of sons did not outweigh the fecundity costs of polygyny because the low paternal care reduced the attractiveness of sons. When there are long-lasting parental effects on offspring attractiveness, costs of polygyny may include the production of nonsexy sons.

  11. Are implicit motives revealed in mere words? Testing the marker-word hypothesis with computer-based text analysis

    Directory of Open Access Journals (Sweden)

    Oliver C Schultheiss

    2013-10-01

    Full Text Available Traditionally, implicit motives (i.e., nonconscious preferences for specific classes of incentives are assessed through semantic coding of imaginative stories. The present research tested the marker-word hypothesis, which states that implicit motives are reflected in word frequencies. Using Linguistic Inquiry and Word Count (LIWC; Pennebaker, Francis, & Booth, 2001, Study 1 identified word categories that converged with a content-coding measure of the implicit motives for power, achievement, and affiliation in picture stories collected in German and US student samples, showed discriminant validity with self-reported motives, and predicted well-validated criteria of implicit motives (gender difference for the affiliation motive; in interaction with personal-goal progress: emotional well-being. Study 2 demonstrated LIWC-based motive scores’ causal validity by documenting their sensitivity to motive arousal.

  12. Are implicit motives revealed in mere words? Testing the marker-word hypothesis with computer-based text analysis.

    Science.gov (United States)

    Schultheiss, Oliver C

    2013-01-01

    Traditionally, implicit motives (i.e., non-conscious preferences for specific classes of incentives) are assessed through semantic coding of imaginative stories. The present research tested the marker-word hypothesis, which states that implicit motives are reflected in the frequencies of specific words. Using Linguistic Inquiry and Word Count (LIWC; Pennebaker et al., 2001), Study 1 identified word categories that converged with a content-coding measure of the implicit motives for power, achievement, and affiliation in picture stories collected in German and US student samples, showed discriminant validity with self-reported motives, and predicted well-validated criteria of implicit motives (gender difference for the affiliation motive; in interaction with personal-goal progress: emotional well-being). Study 2 demonstrated LIWC-based motive scores' causal validity by documenting their sensitivity to motive arousal.

  13. Classification based hypothesis testing in neuroscience: Below-chance level classification rates and overlooked statistical properties of linear parametric classifiers.

    Science.gov (United States)

    Jamalabadi, Hamidreza; Alizadeh, Sarah; Schönauer, Monika; Leibold, Christian; Gais, Steffen

    2016-05-01

    Multivariate pattern analysis (MVPA) has recently become a popular tool for data analysis. Often, classification accuracy as quantified by correct classification rate (CCR) is used to illustrate the size of the effect under investigation. However, we show that in low sample size (LSS), low effect size (LES) data, which is typical in neuroscience, the distribution of CCRs from cross-validation of linear MVPA is asymmetric and can show classification rates considerably below what would be expected from chance classification. Conversely, the mode of the distribution in these cases is above expected chance levels, leading to a spuriously high number of above chance CCRs. This unexpected distribution has strong implications when using MVPA for hypothesis testing. Our analyses warrant the conclusion that CCRs do not well reflect the size of the effect under investigation. Moreover, the skewness of the null-distribution precludes the use of many standard parametric tests to assess significance of CCRs. We propose that MVPA results should be reported in terms of P values, which are estimated using randomization tests. Also, our results show that cross-validation procedures using a low number of folds, e.g. twofold, are generally more sensitive, even though the average CCRs are often considerably lower than those obtained using a higher number of folds. Hum Brain Mapp 37:1842-1855, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  14. THE FRACTAL MARKET HYPOTHESIS

    Directory of Open Access Journals (Sweden)

    FELICIA RAMONA BIRAU

    2012-05-01

    Full Text Available In this article, the concept of capital market is analysed using Fractal Market Hypothesis which is a modern, complex and unconventional alternative to classical finance methods. Fractal Market Hypothesis is in sharp opposition to Efficient Market Hypothesis and it explores the application of chaos theory and fractal geometry to finance. Fractal Market Hypothesis is based on certain assumption. Thus, it is emphasized that investors did not react immediately to the information they receive and of course, the manner in which they interpret that information may be different. Also, Fractal Market Hypothesis refers to the way that liquidity and investment horizons influence the behaviour of financial investors.

  15. Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

    Science.gov (United States)

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2015-05-01

    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Are all grandmothers equal? A review and a preliminary test of the "grandmother hypothesis" in Tokugawa Japan.

    Science.gov (United States)

    Jamison, Cheryl Sorenson; Cornell, Laurel L; Jamison, Paul L; Nakazato, Hideki

    2002-09-01

    An unresolved question arising from human evolutionary research relates to the function of the postreproductive period in human females. If menopause is not merely an artifact resulting from the benefits of civilization, there must be an adaptive mechanism favoring the offspring of women who continue to thrive well past the time of their last ovulation. The "grandmother hypothesis" was developed on the basis of the original suggestion by Williams (1957 Evolution 11:32-39) that "stopping early" would benefit already-born children. This idea, combined with the concepts of kin selection (Hamilton 1964 J Theor Biol 7:1-52) and parental investment (Trivers 1972 Sexual Selection and the Descent of Man, Chicago: Aldine, p. 136-179), was expanded to suggest that postreproductive women (in contrast to males) contribute to their inclusive fitness by extending support to their grandchildren. We used discrete time event history analysis (Allison [1984] Event History Analysis, Newbury Park: Sage; Allison [1995] Survival Analysis, Cary, NC: SAS Institute) and logistic regression on data provided in population registers (Shūmon Aratame Chō, or SAC) from a village in central Japan, covering the period from 1671-1871, in a preliminary investigation of the effects of household grandparental presence on the probability of a child's death. We found that after accounting for the presence of other household members, the only grandparent whose presence exerted a consistent negative effect on the likelihood of a child's death was the mother's mother. Due to the small sample size of households that contained maternal grandmothers, these results failed to achieve statistical significance. Their importance, however, is in what they suggest about future research, i.e., census data from preindustrial societies can provide a basis for testing evolutionary proposals, including the "grandmother hypothesis." Copyright 2002 Wiley-Liss, Inc.

  17. Thermal preference and performance in a sub-Antarctic caterpillar: A test of the coadaptation hypothesis and its alternatives.

    Science.gov (United States)

    Haupt, Tanya M; Sinclair, Brent J; Chown, Steven L

    2017-04-01

    Physiological ecologists have long assumed that thermoregulatory behaviour will evolve to optimise physiological performance. The coadaptation hypothesis predicts that an animal's preferred body temperature will correspond to the temperature at which its performance is optimal. Here we use a strong inference approach to examine the relationship between thermal preference and locomotor performance in the caterpillars of a wingless sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae). The coadaptation hypothesis and its alternatives (suboptimal is optimal, thermodynamic effect, trait variation) are tested. Compared to the optimal movement temperature (22.5°C for field-fresh caterpillars and 25, 20, 22.5, 25 and 20°C following seven day acclimations to 0, 5, 10, 15 and 5-15°C respectively), caterpillar thermal preference was significantly lower (9.2°C for field-fresh individuals and 9.4, 8.8, 8.1, 5.2 and 4.6°C following acclimation to 0, 5, 10, 15 and 5-15°C, respectively). Together with the low degree of asymmetry observed in the performance curves, and the finding that acclimation to high temperatures did not result in maximal performance, all, but one of the above hypotheses (i.e. 'trait variation') was rejected. The thermal preference of P. marioni caterpillars more closely resembles temperatures at which survival is high (5-10°C), or where feeding is optimal (10°C), than where locomotion speed is maximal, suggesting that thermal preference may be optimised for overall fitness rather than for a given trait. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Variation is function: Are single cell differences functionally important?: Testing the hypothesis that single cell variation is required for aggregate function.

    Science.gov (United States)

    Dueck, Hannah; Eberwine, James; Kim, Junhyong

    2016-02-01

    There is a growing appreciation of the extent of transcriptome variation across individual cells of the same cell type. While expression variation may be a byproduct of, for example, dynamic or homeostatic processes, here we consider whether single-cell molecular variation per se might be crucial for population-level function. Under this hypothesis, molecular variation indicates a diversity of hidden functional capacities within an ensemble of identical cells, and this functional diversity facilitates collective behavior that would be inaccessible to a homogenous population. In reviewing this topic, we explore possible functions that might be carried by a heterogeneous ensemble of cells; however, this question has proven difficult to test, both because methods to manipulate molecular variation are limited and because it is complicated to define, and measure, population-level function. We consider several possible methods to further pursue the hypothesis that variation is function through the use of comparative analysis and novel experimental techniques. © 2015 The Authors. BioEssays published by WILEY Periodicals, Inc.

  19. Electrokinetic remediation prefield test methods

    Science.gov (United States)

    Hodko, Dalibor (Inventor)

    2000-01-01

    Methods for determining the parameters critical in designing an electrokinetic soil remediation process including electrode well spacing, operating current/voltage, electroosmotic flow rate, electrode well wall design, and amount of buffering or neutralizing solution needed in the electrode wells at operating conditions are disclosed These methods are preferably performed prior to initiating a full scale electrokinetic remediation process in order to obtain efficient remediation of the contaminants.

  20. CO2 emissions, real output, energy consumption, trade, urbanization and financial development: testing the EKC hypothesis for the USA.

    Science.gov (United States)

    Dogan, Eyup; Turkekul, Berna

    2016-01-01

    This study aims to investigate the relationship between carbon dioxide (CO2) emissions, energy consumption, real output (GDP), the square of real output (GDP(2)), trade openness, urbanization, and financial development in the USA for the period 1960-2010. The bounds testing for cointegration indicates that the analyzed variables are cointegrated. In the long run, energy consumption and urbanization increase environmental degradation while financial development has no effect on it, and trade leads to environmental improvements. In addition, this study does not support the validity of the environmental Kuznets curve (EKC) hypothesis for the USA because real output leads to environmental improvements while GDP(2) increases the levels of gas emissions. The results from the Granger causality test show that there is bidirectional causality between CO2 and GDP, CO2 and energy consumption, CO2 and urbanization, GDP and urbanization, and GDP and trade openness while no causality is determined between CO2 and trade openness, and gas emissions and financial development. In addition, we have enough evidence to support one-way causality running from GDP to energy consumption, from financial development to output, and from urbanization to financial development. In light of the long-run estimates and the Granger causality analysis, the US government should take into account the importance of trade openness, urbanization, and financial development in controlling for the levels of GDP and pollution. Moreover, it should be noted that the development of efficient energy policies likely contributes to lower CO2 emissions without harming real output.

  1. Gender differences in emotion perception and self-reported emotional intelligence: A test of the emotion sensitivity hypothesis.

    Science.gov (United States)

    Fischer, Agneta H; Kret, Mariska E; Broekens, Joost

    2018-01-01

    Previous meta-analyses and reviews on gender differences in emotion recognition have shown a small to moderate female advantage. However, inconsistent evidence from recent studies has raised questions regarding the implications of different methodologies, stimuli, and samples. In the present research based on a community sample of more than 5000 participants, we tested the emotional sensitivity hypothesis, stating that women are more sensitive to perceive subtle, i.e. low intense or ambiguous, emotion cues. In addition, we included a self-report emotional intelligence test in order to examine any discrepancy between self-perceptions and actual performance for both men and women. We used a wide range of stimuli and models, displaying six different emotions at two different intensity levels. In order to better tap sensitivity for subtle emotion cues, we did not use a forced choice format, but rather intensity measures of different emotions. We found no support for the emotional sensitivity account, as both genders rated the target emotions as similarly intense at both levels of stimulus intensity. Men, however, more strongly perceived non-target emotions to be present than women. In addition, we also found that the lower scores of men in self-reported EI was not related to their actual perception of target emotions, but it was to the perception of non-target emotions.

  2. Gender differences in emotion perception and self-reported emotional intelligence: A test of the emotion sensitivity hypothesis

    Science.gov (United States)

    Kret, Mariska E.; Broekens, Joost

    2018-01-01

    Previous meta-analyses and reviews on gender differences in emotion recognition have shown a small to moderate female advantage. However, inconsistent evidence from recent studies has raised questions regarding the implications of different methodologies, stimuli, and samples. In the present research based on a community sample of more than 5000 participants, we tested the emotional sensitivity hypothesis, stating that women are more sensitive to perceive subtle, i.e. low intense or ambiguous, emotion cues. In addition, we included a self-report emotional intelligence test in order to examine any discrepancy between self-perceptions and actual performance for both men and women. We used a wide range of stimuli and models, displaying six different emotions at two different intensity levels. In order to better tap sensitivity for subtle emotion cues, we did not use a forced choice format, but rather intensity measures of different emotions. We found no support for the emotional sensitivity account, as both genders rated the target emotions as similarly intense at both levels of stimulus intensity. Men, however, more strongly perceived non-target emotions to be present than women. In addition, we also found that the lower scores of men in self-reported EI was not related to their actual perception of target emotions, but it was to the perception of non-target emotions. PMID:29370198

  3. Error response test system and method using test mask variable

    Science.gov (United States)

    Gender, Thomas K. (Inventor)

    2006-01-01

    An error response test system and method with increased functionality and improved performance is provided. The error response test system provides the ability to inject errors into the application under test to test the error response of the application under test in an automated and efficient manner. The error response system injects errors into the application through a test mask variable. The test mask variable is added to the application under test. During normal operation, the test mask variable is set to allow the application under test to operate normally. During testing, the error response test system can change the test mask variable to introduce an error into the application under test. The error response system can then monitor the application under test to determine whether the application has the correct response to the error.

  4. Using a Simple Binomial Model to Assess Improvement in Predictive Capability: Sequential Bayesian Inference, Hypothesis Testing, and Power Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sigeti, David E. [Los Alamos National Laboratory; Pelak, Robert A. [Los Alamos National Laboratory

    2012-09-11

    We present a Bayesian statistical methodology for identifying improvement in predictive simulations, including an analysis of the number of (presumably expensive) simulations that will need to be made in order to establish with a given level of confidence that an improvement has been observed. Our analysis assumes the ability to predict (or postdict) the same experiments with legacy and new simulation codes and uses a simple binomial model for the probability, {theta}, that, in an experiment chosen at random, the new code will provide a better prediction than the old. This model makes it possible to do statistical analysis with an absolute minimum of assumptions about the statistics of the quantities involved, at the price of discarding some potentially important information in the data. In particular, the analysis depends only on whether or not the new code predicts better than the old in any given experiment, and not on the magnitude of the improvement. We show how the posterior distribution for {theta} may be used, in a kind of Bayesian hypothesis testing, both to decide if an improvement has been observed and to quantify our confidence in that decision. We quantify the predictive probability that should be assigned, prior to taking any data, to the possibility of achieving a given level of confidence, as a function of sample size. We show how this predictive probability depends on the true value of {theta} and, in particular, how there will always be a region around {theta} = 1/2 where it is highly improbable that we will be able to identify an improvement in predictive capability, although the width of this region will shrink to zero as the sample size goes to infinity. We show how the posterior standard deviation may be used, as a kind of 'plan B metric' in the case that the analysis shows that {theta} is close to 1/2 and argue that such a plan B should generally be part of hypothesis testing. All the analysis presented in the paper is done with a

  5. Effect of Probability of Forthcoming Success on Sex Differences in Goal Setting: A Test of the Fear of Success Hypothesis

    Science.gov (United States)

    Stake, Jayne Elley

    1976-01-01

    Each of 96 college females and 95 college males were randomly assigned to either a high or a low subjective probability of outstanding performance condition. The findings are contrary to predictions based on the fear of success hypothesis. Implications of the results for the fear of success hypothesis are discussed. (Author)

  6. Hazardous Waste Test Methods / SW-846

    Science.gov (United States)

    The Resource Conservation and Recovery Act Test Methods for Evaluating Solid Waste: Physical/Chemical Methods (SW-846) provide guidance to analytical scientists, enforcement officers and method developers across a variety of sectors.

  7. Testing the shape-similarity hypothesis between particle-size distribution and water retention for Sicilian soils

    Directory of Open Access Journals (Sweden)

    Chiara Antinoro

    2012-12-01

    Full Text Available Application of the Arya and Paris (AP model to estimate the soil water retention curve requires a detailed description of the particlesize distribution (PSD but limited experimental PSD data are generally determined by the conventional sieve-hydrometer (SH method. Detailed PSDs can be obtained by fitting a continuous model to SH data or performing measurements by the laser diffraction (LD method. The AP model was applied to 40 Sicilian soils for which the PSD was measured by both the SH and LD methods. The scale factor was set equal to 1.38 (procedure AP1 or estimated by a logistical model with parameters gathered from literature (procedure AP2. For both SH and LD data, procedure AP2 allowed a more accurate prediction of the water retention than procedure AP1, confirming that it is not convenient to use a unique value of  for soils that are very different in texture. Despite the differences in PSDs obtained by the SH and LD methods, the water retention predicted by a given procedure (AP1 or AP2 using SH or LD data was characterized by the same level of accuracy. Discrepancies in the estimated water retention from the two PSD measurement methods were attributed to underestimation of the finest diameter frequency obtained by the LD method. Analysis also showed that the soil water retention estimated using the SH method was affected by an estimation bias that could be corrected by an optimization procedure (OPT. Comparison of a-distributions and water retention shape indices obtained by the two methods (SH or LD indicated that the shape-similarity hypothesis is better verified if the traditional sieve-hydrometer data are used to apply the AP model. The optimization procedure allowed more accurate predictions of the water retention curves than the traditional AP1 and AP2 procedures. Therefore, OPT can be considered a valid alternative to the more complex logistical model for estimating the water retention curve of Sicilian soils.

  8. Standard test method for creep-fatigue testing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers the determination of mechanical properties pertaining to creep-fatigue deformation or crack formation in nominally homogeneous materials, or both by the use of test specimens subjected to uniaxial forces under isothermal conditions. It concerns fatigue testing at strain rates or with cycles involving sufficiently long hold times to be responsible for the cyclic deformation response and cycles to crack formation to be affected by creep (and oxidation). It is intended as a test method for fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. The cyclic conditions responsible for creep-fatigue deformation and cracking vary with material and with temperature for a given material. 1.2 The use of this test method is limited to specimens and does not cover testing of full-scale components, structures, or consumer products. 1.3 This test method is primarily ...

  9. Appropriate and inappropriate methods for investigating the "gateway" hypothesis, with a review of the evidence linking prior snus use to later cigarette smoking.

    Science.gov (United States)

    Lee, Peter N

    2015-03-20

    The "gateway hypothesis" usually refers to the possibility that the taking up of habit A, which is considered harmless (or less harmful), may lead to the subsequent taking up of another habit, B, which is considered harmful (or more harmful). Possible approaches to designing and analysing studies to test the hypothesis are discussed. Evidence relating to the use of snus (A) as a gateway for smoking (B) is then evaluated in detail. The importance of having appropriate data available on the sequence of use of A and B and on other potential confounding factors that may lead to the taking up of B is emphasised. Where randomised trials are impractical, the preferred designs include the prospective cohort study in which ever use of A and of B is recorded at regular intervals, and the cross-sectional survey in which time of starting to use A and B is recorded. Both approaches allow time-stratified analytical methods to be used, in which, in each time period, risk of initiating B among never users of B at the start of the interval is compared according to prior use of A. Adjustment in analysis for the potential confounding factors is essential. Of 11 studies of possible relevance conducted in Sweden, Finland or Norway, only one seriously addresses potential confounding by those other factors involved in the initiation of smoking. Furthermore, 5 of the 11 studies are of a design that does not allow proper testing of the gateway hypothesis for various reasons, and the analysis is unsatisfactory, sometimes seriously, in all the remaining six. While better analyses could be attempted for some of the six studies identified as having appropriate design, the issues of confounding remain, and more studies are clearly needed. To obtain a rapid answer, a properly designed cross-sectional survey is recommended.

  10. Social foraging and individual consistency in following behaviour: testing the information centre hypothesis in free-ranging vultures.

    Science.gov (United States)

    Harel, Roi; Spiegel, Orr; Getz, Wayne M; Nathan, Ran

    2017-04-12

    Uncertainties regarding food location and quality are among the greatest challenges faced by foragers and communal roosting may facilitate success through social foraging. The information centre hypothesis (ICH) suggests that uninformed individuals at shared roosts benefit from following informed individuals to previously visited resources. We tested several key prerequisites of the ICH in a social obligate scavenger, the Eurasian griffon vulture (Gyps fulvus), by tracking movements and behaviour of sympatric individuals over extended periods and across relatively large spatial scales, thereby precluding alternative explanations such as local enhancement. In agreement with the ICH, we found that 'informed' individuals returning to previously visited carcasses were followed by 'uninformed' vultures that consequently got access to these resources. When a dyad (two individuals that depart from the same roost within 2 min of each other) included an informed individual, they spent a higher proportion of the flight time close to each other at a shorter distance between them than otherwise. Although all individuals occasionally profited from following others, they differed in their tendencies to be informed or uninformed. This study provides evidence for 'following behaviour' in natural conditions and demonstrates differential roles and information states among foragers within a population. Moreover, demonstrating the possible reliance of vultures on following behaviour emphasizes that individuals in declining populations may suffer from reduced foraging efficiency. © 2017 The Author(s).

  11. Testing the sorption hypothesis in olfaction: a limited role for sniff strength in shaping primary odor representations during behavior.

    Science.gov (United States)

    Cenier, Tristan; McGann, John P; Tsuno, Yusuke; Verhagen, Justus V; Wachowiak, Matt

    2013-01-02

    The acquisition of sensory information during behavior shapes the neural representation, central processing, and perception of external stimuli. In mammals, a sniff represents the basic unit of odor sampling, yet how sniffing shapes odor representations remains poorly understood. Perhaps the earliest hypothesis of the role of sniffing in olfaction arises from the fact that odorants with different physicochemical properties exhibit different patterns of deposition across the olfactory epithelium, and that these patterns are differentially affected by flow rate. However, whether sniff flow rates shape odor representations during natural sniffing remains untested, and whether animals make use of odorant sorption-airflow relationships as part of an active odor-sampling strategy remains unclear. We tested these ideas in the intact rat using a threefold approach. First, we asked whether sniff strength shapes odor representations in vivo by imaging from olfactory receptor neuron (ORN) terminals during controlled changes in inhalation flow in the anesthetized rat. Second, we asked whether sniff strength shapes odor representations by imaging from ORNs during natural sniffing in the awake rat. Third, we asked whether rats actively modulate sniff strength during an odor discrimination task. We found that, while artificial changes in flow rate can alter ORN responses, sniff strength has negligible effect on odor representations during natural sniffing, and behaving rats do not modulate flow rate to improve odor discrimination. These data suggest that modulating sniff strength does not shape odor representations sufficiently to be part of a strategy for active odor sensing in the behaving animal.

  12. Maternal play behaviors, child negativity, and preterm or low birthweight toddlers’ visual-spatial outcomes: Testing a differential susceptibility hypothesis

    Science.gov (United States)

    Dilworth-Bart, Janean E.; Miller, Kyle E.; Hane, Amanda

    2012-01-01

    Objective We examined the joint roles of child negative emotionality and parenting in the visual-spatial development of toddlers born preterm or with low birthweights (PTLBW). Method Neonatal risk data were collected at hospital discharge, observer- and parent-rated child negative emotionality was assessed at 9-months postterm, and mother-initiated task changes and flexibility during play were observed during a dyadic play interaction at 16-months postterm. Abbreviated IQ scores, and verbal/nonverbal and visual-spatial processing data were collected at 24-months postterm. Results Hierarchical regression analyses did not support our hypothesis that the visual-spatial processing of PTLBW toddlers with higher negative emotionality would be differentially susceptible to parenting behaviors during play. Instead, observer-rated distress and a negativity composite score were associated with less optimal visual-spatial processing when mothers were more flexible during the 16-month play interaction. Mother-initiated task changes did not interact with any of the negative emotionality variables to predict any of the 24-month neurocognitive outcomes, nor did maternal flexibility interact with mother-rated difficult temperament to predict the visual-spatial processing outcomes. PMID:22209050

  13. Radon barrier: Method of testing airtightness

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn; Buch-Hansen, Thomas Cornelius

    2017-01-01

    The test method NBI 167/02 Radon membrane: Test of airtightness can be used for determining the airtightness of a radon barrier as a system solution. The test determines the air infiltration through the radon barrier for a number of levels of air pressure differences. The airflow through versus...... of the barrier with the low air pressure, through a well-defined opening, as a modification of the test method in general. Results, obtained using the improved test method, are shown for a number of radon barriers tested....

  14. Development of Dissolution Test Method for Drotaverine ...

    African Journals Online (AJOL)

    Methods: Sink conditions, drug stability and specificity in different dissolution media were tested to optimize a dissolution test method using a USP paddle type dissolution test apparatus set at a speed of. 50 rpm. The dissolution medium consisted of 900 ml of phosphate buffer (pH 6.8) containing 0.25% w/v cetrimide at 37 ...

  15. Statistical analysis of water-quality data containing multiple detection limits II: S-language software for nonparametric distribution modeling and hypothesis testing

    Science.gov (United States)

    Lee, L.; Helsel, D.

    2007-01-01

    Analysis of low concentrations of trace contaminants in environmental media often results in left-censored data that are below some limit of analytical precision. Interpretation of values becomes complicated when there are multiple detection limits in the data-perhaps as a result of changing analytical precision over time. Parametric and semi-parametric methods, such as maximum likelihood estimation and robust regression on order statistics, can be employed to model distributions of multiply censored data and provide estimates of summary statistics. However, these methods are based on assumptions about the underlying distribution of data. Nonparametric methods provide an alternative that does not require such assumptions. A standard nonparametric method for estimating summary statistics of multiply-censored data is the Kaplan-Meier (K-M) method. This method has seen widespread usage in the medical sciences within a general framework termed "survival analysis" where it is employed with right-censored time-to-failure data. However, K-M methods are equally valid for the left-censored data common in the geosciences. Our S-language software provides an analytical framework based on K-M methods that is tailored to the needs of the earth and environmental sciences community. This includes routines for the generation of empirical cumulative distribution functions, prediction or exceedance probabilities, and related confidence limits computation. Additionally, our software contains K-M-based routines for nonparametric hypothesis testing among an unlimited number of grouping variables. A primary characteristic of K-M methods is that they do not perform extrapolation and interpolation. Thus, these routines cannot be used to model statistics beyond the observed data range or when linear interpolation is desired. For such applications, the aforementioned parametric and semi-parametric methods must be used.

  16. Spearman's hypothesis tested comparing Libyan secondary school children with various other groups of secondary school children on the items of the Standard Progressive Matrices

    NARCIS (Netherlands)

    te Nijenhuis, J.; Al-Shahomee, A.A.; van den Hoek, M.; Allik, J.; Grigoriev, A.; Dragt, J.

    2015-01-01

    Spearman's hypothesis tested at the level of items states that differences between groups on the items of an IQ test are a function of the g loadings of these items, such that there are small differences between groups on items with low g loadings and large differences between groups on items with

  17. New Graphical Methods and Test Statistics for Testing Composite Normality

    Directory of Open Access Journals (Sweden)

    Marc S. Paolella

    2015-07-01

    Full Text Available Several graphical methods for testing univariate composite normality from an i.i.d. sample are presented. They are endowed with correct simultaneous error bounds and yield size-correct tests. As all are based on the empirical CDF, they are also consistent for all alternatives. For one test, called the modified stabilized probability test, or MSP, a highly simplified computational method is derived, which delivers the test statistic and also a highly accurate p-value approximation, essentially instantaneously. The MSP test is demonstrated to have higher power against asymmetric alternatives than the well-known and powerful Jarque-Bera test. A further size-correct test, based on combining two test statistics, is shown to have yet higher power. The methodology employed is fully general and can be applied to any i.i.d. univariate continuous distribution setting.

  18. Testing the status-legitimacy hypothesis: A multilevel modeling approach to the perception of legitimacy in income distribution in 36 nations.

    Science.gov (United States)

    Caricati, Luca

    2017-01-01

    The status-legitimacy hypothesis was tested by analyzing cross-national data about social inequality. Several indicators were used as indexes of social advantage: social class, personal income, and self-position in the social hierarchy. Moreover, inequality and freedom in nations, as indexed by Gini and by the human freedom index, were considered. Results from 36 nations worldwide showed no support for the status-legitimacy hypothesis. The perception that income distribution was fair tended to increase as social advantage increased. Moreover, national context increased the difference between advantaged and disadvantaged people in the perception of social fairness: Contrary to the status-legitimacy hypothesis, disadvantaged people were more likely than advantaged people to perceive income distribution as too large, and this difference increased in nations with greater freedom and equality. The implications for the status-legitimacy hypothesis are discussed.

  19. Testing the correlated response hypothesis for the evolution and maintenance of male mating preferences in Drosophila serrata.

    Science.gov (United States)

    Gosden, T P; Rundle, H D; Chenoweth, S F

    2014-10-01

    Mate preferences are abundant throughout the animal kingdom with female preferences receiving the most empirical and theoretical attention. Although recent work has acknowledged the existence of male mate preferences, whether they have evolved and are maintained as a direct result of selection on males or indirectly as a genetically correlated response to selection for female choice remains an open question. Using the native Australian species Drosophila serrata in which mutual mate choice occurs for a suite of contact pheromones (cuticular hydrocarbons or CHCs), we empirically test key predictions of the correlated response hypothesis. First, within the context of a quantitative genetic breeding design, we estimated the degree to which the trait values favoured by male and female choice are similar both phenotypically and genetically. The direction of sexual selection on male and female CHCs differed statistically, and the trait combinations that maximized male and female mating success were not genetically correlated, suggesting that male and female preferences target genetically different signals. Second, despite detecting significant genetic variance in female preferences, we found no evidence for genetic variance in male preferences and, as a consequence, no detectable correlation between male and female mating preferences. Combined, these findings are inconsistent with the idea that male mate choice in D. serrata is simply a correlated response to female choice. Our results suggest that male and female preferences are genetically distinct traits in this species and may therefore have arisen via different evolutionary processes. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  20. Implementation of New Test Methods into Practical Testing.

    Science.gov (United States)

    Curren, Rodger D; Poth, Albrecht; Raabe, Hans A

    New toxicology test methods, especially those using in vitro methods, are continually being developed. Some are used by industry for screening purposes; others are eventually validated for regulatory use. However, for a new test method to be firmly adopted by industry it must be readily available, generally through an in-house industry laboratory, an academic laboratory, or a contract research organization. Regardless of the type of laboratory which intends to implement the test method, certain steps must be taken to ascertain that the method that is put into place is reproducible and performs identically to the test method that was published or has undergone validation. This involves developing protocols and standard operating procedures, training staff, developing historic positive and negative control data, establishing acceptable performance with proficiency chemicals, and addressing all the safety concerns that may accompany the assay. From experience within a contract research laboratory, we provide guidance on how to most efficiently accomplish these tasks.

  1. A Test of the Transdiagnostic Dopamine Hypothesis of Psychosis Using Positron Emission Tomographic Imaging in Bipolar Affective Disorder and Schizophrenia.

    Science.gov (United States)

    Jauhar, Sameer; Nour, Matthew M; Veronese, Mattia; Rogdaki, Maria; Bonoldi, Ilaria; Azis, Matilda; Turkheimer, Federico; McGuire, Philip; Young, Allan H; Howes, Oliver D

    2017-12-01

    The dopamine hypothesis suggests that dopamine abnormalities underlie psychosis, irrespective of diagnosis, implicating dopamine dysregulation in bipolar affective disorder and schizophrenia, in line with the research domain criteria approach. However, this hypothesis has not been directly examined in individuals diagnosed with bipolar disorder with psychosis. To test whether dopamine synthesis capacity is elevated in bipolar disorder with psychosis and how this compares with schizophrenia and matched controls and to examine whether dopamine synthesis capacity is associated with psychotic symptom severity, irrespective of diagnostic class. This cross-sectional case-control positron emission tomographic study was performed in the setting of first-episode psychosis services in an inner-city area (London, England). Sixty individuals participated in the study (22 with bipolar psychosis [18 antipsychotic naive or free], 16 with schizophrenia [14 antipsychotic naive or free], and 22 matched controls) and underwent fluorodihydroxyphenyl-l-alanine ([18F]-DOPA) positron emission tomography to examine dopamine synthesis capacity. Standardized clinical measures, including the Positive and Negative Syndrome Scale, Young Mania Rating Scale, and Global Assessment of Functioning, were administered. The study dates were March 2013 to November 2016. Dopamine synthesis capacity (Kicer) and clinical measures (Positive and Negative Syndrome Scale, Young Mania Rating Scale, and Global Assessment of Functioning). The mean (SD) ages of participants were 23.6 (3.6) years in 22 individuals with bipolar psychosis (13 male), 26.3 (4.4) years in 16 individuals with schizophrenia (14 male), and 24.5 (4.5) years in controls (14 male). There was a significant group difference in striatal dopamine synthesis capacity (Kicer) (F2,57 = 6.80, P = .002). Kicer was significantly elevated in both the bipolar group (mean [SD], 13.18 [1.08] × 10-3 min-1; P = .002) and the schizophrenia

  2. [Statistical tests in medical research: traditional methods vs. multivariate NPC permutation tests].

    Science.gov (United States)

    Arboretti, Rosa; Bordignon, Paolo; Corain, Livio; Palermo, Giuseppe; Pesarin, Fortunato; Salmaso, Luigi

    2015-01-01

    Statistical tests in medical research: traditional methods vs. multivariate npc permutation tests.Within medical research, a useful statistical tool is based on hypotheses testing in terms of the so-called null, that is the treatment has no effect, and alternative hypotheses, that is the treatment has some effects. By controlling the risks of wrong decisions, empirical data are used in order to possibly reject the null hypotheses in favour of the alternative, so that demonstrating the efficacy of a treatment of interest. The multivariate permutation tests, based on the nonparametric combination - NPC method, provide an innovative, robust and effective hypotheses testing solution to many real problems that are commonly encountered in medical research when multiple end-points are observed. This paper discusses the various approaches to hypothesis testing and the main advantages of NPC tests, which consist in the fact that they require much less stringent assumptions than traditional statistical tests. Moreover, the related results may be extended to the reference population even in case of selection-bias, that is non-random sampling. In this work, we review and discuss some basic testing procedures along with the theoretical and practical relevance of NPC tests showing their effectiveness in medical research. Within the non-parametric methods, NPC tests represent the current "frontier" of statistical research, but already widely available in the practice of analysis of clinical data.

  3. Test Methods for Robot Agility in Manufacturing.

    Science.gov (United States)

    Downs, Anthony; Harrison, William; Schlenoff, Craig

    2016-01-01

    The paper aims to define and describe test methods and metrics to assess industrial robot system agility in both simulation and in reality. The paper describes test methods and associated quantitative and qualitative metrics for assessing robot system efficiency and effectiveness which can then be used for the assessment of system agility. The paper describes how the test methods were implemented in a simulation environment and real world environment. It also shows how the metrics are measured and assessed as they would be in a future competition. The test methods described in this paper will push forward the state of the art in software agility for manufacturing robots, allowing small and medium manufacturers to better utilize robotic systems. The paper fulfills the identified need for standard test methods to measure and allow for improvement in software agility for manufacturing robots.

  4. Automated Test Methods for XML Metadata

    Science.gov (United States)

    2017-12-28

    defines artifacts and system configurations essential to the collection and management of telemetry data. The RCC has established standards for...Method for Testing Syntax The test method is as follows. 1. Initialize the programming environment. 2. Write test application code to use the...engine. o At the time of this writing , a recommended encoding of these rules does not exist. o Encodings shall be selected that can be interpreted by

  5. Testing the saprobity hypothesis in a Mediterranean lagoon: effects of confinement and organic enrichment on benthic communities.

    Science.gov (United States)

    Foti, A; Fenzi, G A; Di Pippo, F; Gravina, M F; Magni, P

    2014-08-01

    The macrobenthic community was compared at four sites characterized by varying degrees of freshwater input, organic enrichment and confinement in the Cabras lagoon (Sardinia, Italy). Three sites, riverine (C1), confined (C2) and seaward (C3), were studied on two dates of summer 2010 and on two dates of winter 2011. A fourth site (C12), representative of the central sector of the Cabras lagoon, was included in this study using the extensive historical datasets at our disposal from previously published work. We aimed to test the hypothesis that (1) the benthos is distributed according to the recently proposed concept of habitat saprobity for coastal lagoons that unifies the Pearson-Rosenberg (sensu organic enrichment) and Guélorget-Perthuisot (sensu confinement) models, and (2) indicator species of different saprobic levels can be identified among dominant species occurring along the saprobity gradient. Salinity was also considered as an additional agent of selection in brackish environments. Irrespective of significant seasonal changes within each site, our results highlighted major environmental and biotic differences between sites. At the northward riverine site (C1), most affected by freshwater input and with limited organic matter (OM) enrichment, Corophium orientale was the single dominant species. The most confined site (C2) was characterized by the highest levels of sedimentary OM and benthic Chlorophyll-a and by mesohaline conditions; the site was inhabited mainly by the halolimnobic Hediste diversicolor and Hydrobia spp. Site C12, characterized by a high OM load and high residence time, was dominated by the opportunistic detritivorous Alitta succinea and Polydora ciliata. At the southernmost seaward site (C3) the considerable seawater renewal, resulting in high salinity (only in summer) and limited OM load, favored a much more diverse macrobenthic assemblage, essentially composed of both marine species, such as Corophium insidiosum, Gammarus aequicauda

  6. Evidence of compensatory processing in adults with developmental language impairment: testing the predictions of the procedural deficit hypothesis.

    Science.gov (United States)

    Poll, Gerard H; Miller, Carol A; van Hell, Janet G

    2015-01-01

    The Procedural Deficit Hypothesis (PDH) proposes that individuals with primary developmental language impairment (DLI) have a deficient procedural memory, compromising their syntactic abilities. Individuals with DLI may compensate for procedural memory deficits by engaging declarative memory for syntactic tasks. Arguments are part of the lexicon whereas adjuncts rely on syntactic processing. As a result, individuals with DLI may have unusual difficulty processing adjuncts. Alternatively, processing for adjuncts may be typical for individuals with DLI but show frequency effects, indicating compensatory use of declarative memory. Our goal was to test the predictions of the PDH by comparing argument and adjunct processing times for adults with and without DLI, and to seek evidence of compensatory use of declarative memory for adjunct processing. We further evaluated group performance on measures of visual procedural and declarative memory. Forty-four adults, 21 with DLI, completed a self-paced listening task, a procedural memory task, and a declarative memory task. The self-paced listening task tracked the word-by-word processing time for sentences that included prepositional phrases acting as arguments or adjuncts. We used regression analysis to determine effects of group membership and argument or adjunct status on processing times. Correlation analyses evaluated relationships between argument and adjunct frequency on processing times by group. We found no effect of group membership on the processing time for arguments and adjuncts in the self-paced listening task. Argument phrases were processed more easily by both groups. There were frequency effects for adjunct processing for the group with DLI, but not the group with typical language. We did not find the expected frequency effects for argument processing. The group with DLI also performed more poorly in both the procedural and declarative memory tasks. Secondary analyses found that non-verbal intelligence was

  7. Axial focusing of impact energy in the Earth's interior: Proof-of-principle tests of a new hypothesis

    Science.gov (United States)

    Boslough, M. B.; Chael, E. P.; Trucano, T. G.; Kipp, M. E.; Crawford, D. A.

    1994-01-01

    A causal link between major impact events and global processes would probably require a significant change in the thermal state of the Earth's interior, presumably brought about by coupling of impact energy. One possible mechanism for such energy coupling from the surface to the deep interior would be through focusing due to axial symmetry. Antipodal focusing of surface and body waves from earthquakes is a well-known phenomenon which has previously been exploited by seismologists in studies of the Earth's deep interior. Antipodal focusing from impacts on the Moon, Mercury, and icy satellites has also been invoked by planetary scientists to explain unusual surface features opposite some of the large impact structures on these bodies. For example, 'disrupted' terrains have been observed antipodal to the Caloris impact basis on Mercury and Imbrium Basin on the Moon. Very recently there have been speculations that antipodal focusing of impact energy within the mantle may lead to flood basalt and hotspot activity, but there has not yet been an attempt at a rigorous model. A new hypothesis was proposed and preliminary proof-of-principle tests for the coupling of energy from major impacts to the mantle by axial focusing of seismic waves was performed. Because of the axial symmetry of the explosive source, the phases and amplitudes are dependent only on ray parameter (or takeoff angle) and are independent of azimuthal angle. For a symmetric and homogeneous Earth, all the seismic energy radiated by the impact at a given takeoff angle will be refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Mantle material near the axis of symmetry will experience more strain cycles with much greater amplitude than elsewhere and will therefore experience more irreversible heating. The situation is very different than for a giant earthquake, which in addition to having less energy, has an asymmetric focal

  8. On-line Flagging of Anomalies and Adaptive Sequential Hypothesis Testing for Fine-feature Characterization of Geosynchronous Satellites

    Science.gov (United States)

    Chaudhary, A.; Payne, T.; Kinateder, K.; Dao, P.; Beecher, E.; Boone, D.; Elliott, B.

    The objective of on-line flagging in this paper is to perform interactive assessment of geosynchronous satellites anomalies such as cross-tagging of a satellites in a cluster, solar panel offset change, etc. This assessment will utilize a Bayesian belief propagation procedure and will include automated update of baseline signature data for the satellite, while accounting for the seasonal changes. Its purpose is to enable an ongoing, automated assessment of satellite behavior through its life cycle using the photometry data collected during the synoptic search performed by a ground or space-based sensor as a part of its metrics mission. The change in the satellite features will be reported along with the probabilities of Type I and Type II errors. The objective of adaptive sequential hypothesis testing in this paper is to define future sensor tasking for the purpose of characterization of fine features of the satellite. The tasking will be designed in order to maximize new information with the least number of photometry data points to be collected during the synoptic search by a ground or space-based sensor. Its calculation is based on the utilization of information entropy techniques. The tasking is defined by considering a sequence of hypotheses in regard to the fine features of the satellite. The optimal observation conditions are then ordered in order to maximize new information about a chosen fine feature. The combined objective of on-line flagging and adaptive sequential hypothesis testing is to progressively discover new information about the features of a geosynchronous satellites by leveraging the regular but sparse cadence of data collection during the synoptic search performed by a ground or space-based sensor. Automated Algorithm to Detect Changes in Geostationary Satellite's Configuration and Cross-Tagging Phan Dao, Air Force Research Laboratory/RVB By characterizing geostationary satellites based on photometry and color photometry, analysts can

  9. Absorbing Software Testing into the Scrum Method

    Science.gov (United States)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  10. Born to win? Testing the fighting hypothesis in realistic fights: left-handedness in the Ultimate Fighting Championship

    NARCIS (Netherlands)

    Pollet, T.V.; Stulp, G.; Groothuis, T.G.G.

    2013-01-01

    Given the heritability of human left-handedness and its purported associations with fitness-lowering traits, the persistence of the minority of left-handedness in human populations is an evolutionary puzzle. The fighting hypothesis proposes that these negative fitness costs are offset by fitness

  11. K-Ar dating of the cook-austral island chain: A test of the hot-spot hypothesis

    Science.gov (United States)

    Turner, Donald L.; Jarrard, Richard D.

    1982-05-01

    40K- 40Ar dating indicates that the Cook-Austral chain contains the island with the oldest exposed volcanic rocks on the Pacific plate (Mangaia, 19.3 ± 0.6 Ma B.P.). We have also determined ages from the previously undated islands of Atiu, Mitiaro, Mauke, and Rimatara and from Mangaia, Aitutaki and Rarotonga, for which only unlocated samples had been previously dated. Dated volcanism on Aitutaki spans an interval of at least 7 Ma. The ages from Aitutaki, Atiu, Mauke, Mitiaro, Rarotonga, and Rarutu are much younger than ages predicted by the "hot-spot" hypothesis, and ages from Rimatara may be older than predicted by the hot-spot hypothesis. However, both new and previously reported age data from Mangaia are consistent with the predicted age for this island. Virtually all age data from island and seamount chains on the Pacific plate are consistent with a "hot-line" hypothesis, which makes less specific age predictions than does the hotspot hypothesis.

  12. Born to win? Testing the fighting hypothesis in realistic fights : left-handedness in the Ultimate Fighting Championship

    NARCIS (Netherlands)

    Pollet, Thomas V.; Stulp, Gert; Groothuis, Ton G. G.

    2013-01-01

    Given the heritability of human left-handedness and its purported associations with fitness-lowering traits, the persistence of the minority of left-handedness in human populations is an evolutionary puzzle. The fighting hypothesis proposes that these negative fitness costs are offset by fitness

  13. Student Assessment of Teacher Masculinity and Femininity: A Test of the Sex Role Congruency Hypothesis on Student Attitudes toward Learning.

    Science.gov (United States)

    Wheeless, Virginia Eman; Potorti, Paul F.

    1989-01-01

    The impact of teacher and student sex differences and student assessment of teacher sex role orientation on student attitudes toward learning was examined with 252 undergraduate students, each evaluating 1 teacher. Results do not support the sex role congruency hypothesis. Students were more affected by overall teacher qualities. (SLD)

  14. Methods of Testing Thermal Insulation and Associated Test Apparatus

    Science.gov (United States)

    2004-01-01

    The system and method for testing thermal insulation uses a cryostatic insulation tester having a vacuum chamber and a cold mass including a test chamber and upper and lower guard chambers adjacent thereto. The thermal insulation is positioned within the vacuum chamber and adjacent the cold mass. Cryogenic liquid is supplied to the test chamber, upper guard and lower guard to create a first gas layer in an upper portion of the lower guard chamber and a second gas layer in an upper portion of the test chamber. Temperature are sensed within the vacuum chamber to test the thermal insulation.

  15. Testing the Fundamental Difference Hypothesis: L2 Adult, L2 Child, and L1 Child Comparisons in the Acquisition of Korean "Wh"-Constructions with Negative Polarity Items

    Science.gov (United States)

    Song, Hyang Suk; Schwartz, Bonnie D.

    2009-01-01

    The fundamental difference hypothesis (FDH; Bley-Vroman, 1989, 1990) contends that the nature of language in natives is fundamentally different from the nature of language in adult nonnatives. This study tests the FDH in two ways: (a) via second language (L2) poverty-of-the-stimulus (POS) problems (e.g., Schwartz & Sprouse, 2000) and (b) via a…

  16. Tanpopo: Astrobiology Exposure and Micrometeoroid Capture, a Sample Return Experiment to Test Quasi-Panspermia Hypothesis Onboard the ISS-Kibo Exposed Facility

    Science.gov (United States)

    Yano, H.; Yamagishi, A.; Hashimoto, H.; Yokobori, S.; Kobayashi, K.; Yabuta, H.; Mita, H.; Tabata, M.; Kawai, H.; Higashide, M.; Okudaira, K.; Sasaki, S.; Imai, E.; Kawaguchi, Y.; Uchibori, Y.; Kodaira, S.; Tanpopo Project Team

    2013-11-01

    As the first Japanese astrobiology experiment in space, the Tanpopo will test key concepts of the quasi-panspermia hypothesis by sample returns of microbe and bio-orgaincs exposure and micrometeoroid capture onboard ISS-Kibo Exposed Facility ExHAM.

  17. Method and apparatus for testing microfilaments

    Science.gov (United States)

    Schleitweiler, Patrick M.; Merten, Jr., Charles W.

    1995-08-01

    A method and apparatus are disclosed for testing tensile strength of microfilaments. Fibers as small as 0.001 inch in diameter and 0.04 inches in length have been tested, although the method and apparatus of the invention are capable of testing fibers of smaller diameter and length. The invention utilizes a method wherein one or both ends of a microfilament is gripped using resin which is softened sufficiently to accept an end of the microfilament and then allowed to harden. The invention also employs the use of a translation stage capable of controlled three-dimensional movement suited to facilitating gripping of the microfilament.

  18. On the Keyhole Hypothesis

    DEFF Research Database (Denmark)

    Mikkelsen, Kaare B.; Kidmose, Preben; Hansen, Lars Kai

    2017-01-01

    We propose and test the keyhole hypothesis that measurements from low dimensional EEG, such as ear-EEG reflect a broadly distributed set of neural processes. We formulate the keyhole hypothesis in information theoretical terms. The experimental investigation is based on legacy data consisting of 10...... simultaneously recorded scalp EEG. A cross-validation procedure was employed to ensure unbiased estimates. We present several pieces of evidence in support of the keyhole hypothesis: There is a high mutual information between data acquired at scalp electrodes and through the ear-EEG "keyhole," furthermore we...

  19. SAS molecular tests Salmonella detection kit. Performance tested method 021202.

    Science.gov (United States)

    Bapanpally, Chandra; Montier, Laura; Khan, Shah; Kasra, Akif; Brunelle, Sharon L

    2014-01-01

    The SAS Molecular tests Salmonella Detection method, a Loop-mediated Isothermal Amplification method, performed as well as or better than the U.S. Department of Agriculture-Food Safety Inspection Service Microbiology Laboratory Guidebook and the U.S. Food and Drug Administration Bacteriological Analytical Manual reference methods for ground beef, beef trim, ground turkey, chicken carcass rinses, bagged mixed lettuce, and fresh spinach. The ground beef (30% fat, 25 g test portion), poultry matrixes and leafy greens were validated in a 6-7 h enrichment, and ground beef (30% fat, 375 g composite test portion) and beef trim (375 g composite test portion) were validated in a 16-20 h enrichment. The method performance for meat and leafy green matrixes was shown to be acceptable under conditions of co-enrichment with Escherichia coli 0157. Thus, after a short 6-7 h co-enrichment step, ground beef, beef trim, lettuce, and spinach can be tested for both Salmonella and E. coli O157. Inclusivity and exclusivity testing revealed no false negatives and no false positives among the 100 Salmonella serovars and 30 non-Salmonella species examined. The method was shown to be robust when enrichment time, DNA extract hold time, and DNA volume were varied.

  20. Central and peripheral self-conceptions are differentially influenced by mood: tests of the differential sensitivity hypothesis.

    Science.gov (United States)

    Sedikides, C

    1995-10-01

    This article proposes a differential sensitivity hypothesis, according to which central (i.e., relatively high in personal descriptiveness and importance) and peripheral (i.e., relatively low in personal descriptiveness and importance) self-conceptions are differentially influenced by mood: Peripheral self-conceptions are subject to a mood-congruency bias, whereas central self-conceptions are unaffected by mood. In 4 experiments, participants were first placed into a sad, neutral, or happy mood state through a guided imagery task and later completed behavior self-descriptiveness ratings, trait self-descriptiveness ratings, and trait self-descriptiveness judgmental latencies. Strong support for the differential sensitivity hypothesis was obtained. Peripheral self-conceptions were influenced by mood because they were less elaborated and consolidated and were held with lower certainty, thus increasing the likelihood for the occurrence of constructive, affect-infusing processes (J.P. Forgas, 1995a).