abstract：SUMMARY:Many hormones are secreted in pulses. The pulsatile relationship between hormones regulates many biological processes. To understand endocrine system regulation, time series of hormone concentrations are collected. The goal is to characterize pulsatile patterns and associations between hormones. Currently each ...

journal_title：Biometrics

authors： Carlson NE,Johnson TD,Brown MB

更新日期：2009-06-01 00:00:00

abstract：:This article introduces an original methodology based on empirical likelihood, which aims at combining different food contamination and consumption surveys to provide risk managers with a risk measure, taking into account all the available information. This risk index is defined as the probability that exposure to a c...

journal_title：Biometrics

authors： Crépet A,Harari-Kermadec H,Tressou J

更新日期：2009-03-01 00:00:00

abstract：:Functional mapping is a useful tool for mapping quantitative trait loci (QTL) that control dynamic traits. It incorporates mathematical aspects of biological processes into the mixture model-based likelihood setting for QTL mapping, thus increasing the power of QTL detection and the precision of parameter estimation. ...

journal_title：Biometrics

authors： Yang J,Wu R,Casella G

更新日期：2009-03-01 00:00:00

abstract：:Geographic information about the levels of toxics in environmental media is commonly used in regional environmental health studies when direct measurements of personal exposure is limited or unavailable. In this article, we propose a statistical framework for analyzing the spatial distribution of topsoil geochemical p...

journal_title：Biometrics

authors： Calder CA,Craigmile PF,Zhang J

更新日期：2009-03-01 00:00:00

abstract：SUMMARY:Nonparametric regression models are proposed in the framework of ecological inference for exploratory modeling of disease prevalence rates adjusted for variables, such as age, ethnicity/race, and socio-economic status. Ecological inference is needed when a response variable and covariate are not available at th...

journal_title：Biometrics

authors： Staniswalis JG

更新日期：2008-12-01 00:00:00

abstract：SUMMARY:In this article we investigate regression calibration methods to jointly model longitudinal and survival data using a semiparametric longitudinal model and a proportional hazards model. In the longitudinal model, a biomarker is assumed to follow a semiparametric mixed model where covariate effects are modeled p...

journal_title：Biometrics

authors： Ye W,Lin X,Taylor JM

更新日期：2008-12-01 00:00:00

abstract：SUMMARY:A trend test is often employed to analyze ordered categorical data, in which a set of increasing scores is assigned a priori. There is a drawback in this approach, because how to choose a set of scores is not clear. There have been debates on which scores should be used (e.g., Graubard and Korn, 1987, Biometric...

journal_title：Biometrics

authors： Zheng G

更新日期：2008-12-01 00:00:00

abstract：:In longitudinal observational studies, repeated measures are often taken at informative observation times. Also, there may exist a dependent terminal event such as death that stops the follow-up. For example, patients in poorer health are more likely to seek medical treatment and their medical cost for each visit tend...

journal_title：Biometrics

authors： Liu L,Huang X,O'Quigley J

更新日期：2008-09-01 00:00:00

abstract：:We consider the problem of testing for a difference in the probability of success from matched binary pairs. Starting with three standard inexact tests, the nuisance parameter is first estimated and then the residual dependence is eliminated by maximization, producing what I call an E+M P-value. The E+M P-value based ...

journal_title：Biometrics

authors： Lloyd CJ

更新日期：2008-09-01 00:00:00

abstract：:The paper here presented was motivated by a case study involving high-dimensional and high-frequency tidal volume traces measured during induced panic attacks. The focus was to develop a procedure to determine the significance of whether a mean curve dominates another one. The key idea of the suggested method relies o...

journal_title：Biometrics

authors： Lee SH,Lim J,Vannucci M,Petkova E,Preter M,Klein DF

更新日期：2008-09-01 00:00:00

abstract：:This article proposes a two-stage simultaneous confidence procedure for the comparisons of k pairs of population means, without using multiplicity adjustment of more than two populations. The proposed procedure can be broadly applied to parametric or nonparametric models. It is robust and versatile because its derivat...

journal_title：Biometrics

authors： Chen JT

更新日期：2008-06-01 00:00:00

abstract：:Prognostic models in survival analysis typically aim to describe the association between patient covariates and future outcomes. More recently, efforts have been made to include covariate information that is updated over time. However, there exists as yet no standard approach to assess the predictive accuracy of such ...

journal_title：Biometrics

authors： Schoop R,Graf E,Schumacher M

更新日期：2008-06-01 00:00:00

abstract：:In a presentation of various methods for assessing the sensitivity of regression results to unmeasured confounding, Lin, Psaty, and Kronmal (1998, Biometrics54, 948-963) use a conditional independence assumption to derive algebraic relationships between the true exposure effect and the apparent exposure effect in a re...

journal_title：Biometrics

authors： Vanderweele TJ

更新日期：2008-06-01 00:00:00

abstract：:We consider the problem of comparing two outcome measures when the pairs are clustered. Using the general principle of within-cluster resampling, we obtain a novel signed-rank test for clustered paired data. We show by a simple informative cluster size simulation model that only our test maintains the correct size und...

journal_title：Biometrics

authors： Datta S,Satten GA

更新日期：2008-06-01 00:00:00

abstract：:In clinical studies, longitudinal biomarkers are often used to monitor disease progression and failure time. Joint modeling of longitudinal and survival data has certain advantages and has emerged as an effective way to mutually enhance information. Typically, a parametric longitudinal model is assumed to facilitate t...

journal_title：Biometrics

authors： Ding J,Wang JL

更新日期：2008-06-01 00:00:00

abstract：:Motivated by the spatial modeling of aberrant crypt foci (ACF) in colon carcinogenesis, we consider binary data with probabilities modeled as the sum of a nonparametric mean plus a latent Gaussian spatial process that accounts for short-range dependencies. The mean is modeled in a general way using regression splines....

journal_title：Biometrics

authors： Apanasovich TV,Ruppert D,Lupton JR,Popovic N,Turner ND,Chapkin RS,Carroll RJ

更新日期：2008-06-01 00:00:00

abstract：:The approach to early termination for efficacy in a trial where events occur over time but the primary question of interest relates to a long-term binary endpoint is not straightforward. This article considers comparison of treatment groups with Kaplan-Meier (KM) proportions evaluated at increasing times from randomiz...

journal_title：Biometrics

authors： Brittain E,Follmann D,Yang S

更新日期：2008-03-01 00:00:00

abstract：:In this article, we present new methods to analyze data from an experiment using rodent models to investigate the role of p27, an important cell-cycle mediator, in early colon carcinogenesis. The responses modeled here are essentially functions nested within a two-stage hierarchy. Standard functional data analysis lit...

journal_title：Biometrics

authors： Baladandayuthapani V,Mallick BK,Young Hong M,Lupton JR,Turner ND,Carroll RJ

更新日期：2008-03-01 00:00:00

abstract：:Estimating the number of clusters in a data set is a crucial step in cluster analysis. In this article, motivated by the gap method (Tibshirani, Walther, and Hastie, 2001, Journal of the Royal Statistical Society B63, 411-423), we propose the weighted gap and the difference of difference-weighted (DD-weighted) gap met...

journal_title：Biometrics

authors： Yan M,Ye K

更新日期：2007-12-01 00:00:00

abstract：:We consider a semiparametric regression model that relates a normal outcome to covariates and a genetic pathway, where the covariate effects are modeled parametrically and the pathway effect of multiple gene expressions is modeled parametrically or nonparametrically using least-squares kernel machines (LSKMs). This un...

journal_title：Biometrics

authors： Liu D,Lin X,Ghosh D

更新日期：2007-12-01 00:00:00

abstract：:Joint models are formulated to investigate the association between a primary endpoint and features of multiple longitudinal processes. In particular, the subject-specific random effects in a multivariate linear random-effects model for multiple longitudinal processes are predictors in a generalized linear model for pr...

journal_title：Biometrics

authors： Li E,Wang N,Wang NY

更新日期：2007-12-01 00:00:00

abstract：:The study of dynamical models of HIV infection, based on a system of nonlinear ordinary differential equations (ODE), has considerably improved the knowledge of its pathogenesis. While the first models used simplified ODE systems and analyzed each patient separately, recent works dealt with inference in non-simplified...

journal_title：Biometrics

authors： Guedj J,Thiébaut R,Commenges D

更新日期：2007-12-01 00:00:00

abstract：:We consider modeling correlated survival data when cluster sizes may be informative to the outcome of interest based on a within-cluster resampling (WCR) approach and a weighted score function (WSF) method. We derive the large sample properties for the WCR estimators under the Cox proportional hazards model. We establ...

journal_title：Biometrics

authors： Cong XJ,Yin G,Shen Y

更新日期：2007-09-01 00:00:00

abstract：:ChIP-chip (or ChIP-on-chip) is a technology for isolation and identification of genomic sites occupied by specific DNA-binding proteins in living cells. The ChIP-chip signals can be obtained over the whole genome by tiling arrays, where a peak shape is generally observed around a protein-binding site. In this article,...

journal_title：Biometrics

authors： Zheng M,Barrera LO,Ren B,Wu YN

更新日期：2007-09-01 00:00:00

abstract：:Multilist capture-recapture methods are commonly used to estimate the size of elusive populations. In many situations, lists are stratified by distinguishing features, such as age or sex. Stratification has often been used to reduce biases caused by heterogeneity in the probability of list membership among members of ...

journal_title：Biometrics

authors： Sutherland JM,Schwarz CJ,Rivest LP

更新日期：2007-09-01 00:00:00

abstract：:In many applications of generalized linear mixed models to multilevel data, it is of interest to test whether a random effects variance component is zero. It is well known that the usual asymptotic chi-square distribution of the likelihood ratio and score statistics under the null does not necessarily hold. In this no...

journal_title：Biometrics

authors： Fitzmaurice GM,Lipsitz SR,Ibrahim JG

更新日期：2007-09-01 00:00:00

abstract：:An individual's health condition can affect the frequency and intensity of episodes that can occur repeatedly and that may be related to an event time of interest. For example, bleeding episodes during pregnancy may indicate problems predictive of preterm delivery. Motivated by this application, we propose a joint mod...

journal_title：Biometrics

authors： Herring AH,Yang J

更新日期：2007-06-01 00:00:00

abstract：:We study publication bias in meta-analysis by supposing there is a population (y, sigma) of studies which give treatment effect estimates y approximately N(theta, sigma(2)). A selection function describes the probability that each study is selected for review. The overall estimate of theta depends on the studies selec...

journal_title：Biometrics

authors： Henmi M,Copas JB,Eguchi S

更新日期：2007-06-01 00:00:00

abstract：:Johnson and Wehrly (1978, Journal of the American Statistical Association 73, 602-606) and Wehrly and Johnson (1980, Biometrika 67, 255-256) show one way to construct the joint distribution of a circular and a linear random variable, or the joint distribution of a pair of circular random variables from their marginal ...

journal_title：Biometrics

authors： Fernández-Durán JJ

更新日期：2007-06-01 00:00:00

abstract：:Development of HIV resistance mutations is a major cause for failure of antiretroviral treatment. This article proposes a method for jointly modeling the processes of viral genetic changes and treatment failure. Because the viral genome is measured with uncertainty, a hidden Markov model is used to fit the viral genet...

journal_title：Biometrics

authors： Hu C,De Gruttola V

更新日期：2007-03-01 00:00:00

abstract：:The receiver operating characteristic (ROC) curve is a prominent tool for characterizing the accuracy of a continuous diagnostic test. To account for factors that might influence the test accuracy, various ROC regression methods have been proposed. However, as in any regression analysis, when the assumed models do not...

journal_title：Biometrics

authors： Cai T,Zheng Y

更新日期：2007-03-01 00:00:00

abstract：:We consider Bayesian methodology for comparing two or more unlabeled point sets. Application of the technique to a set of steroid molecules illustrates its potential utility involving the comparison of molecules in chemoinformatics and bioinformatics. We initially match a pair of molecules, where one molecule is regar...

journal_title：Biometrics

authors： Dryden IL,Hirst JD,Melville JL

更新日期：2007-03-01 00:00:00

abstract：:In biostatistical practice, it is common to use information criteria as a guide for model selection. We propose new versions of the focused information criterion (FIC) for variable selection in logistic regression. The FIC gives, depending on the quantity to be estimated, possibly different sets of selected variables....

journal_title：Biometrics

authors： Claeskens G,Croux C,Van Kerckhoven J

更新日期：2006-12-01 00:00:00

abstract：:Genomic data are often characterized by a moderate to large number of categorical variables observed for relatively few subjects. Some of the variables may be missing or noninformative. An example of such data is loss of heterozygosity (LOH), a dichotomous variable, observed on a moderate number of genetic markers. We...

journal_title：Biometrics

authors： Houseman EA,Coull BA,Betensky RA

更新日期：2006-12-01 00:00:00

abstract：:We consider a semiparametric inference procedure for data from epidemiologic studies conducted with a two-component sampling scheme where both a simple random sample and multiple outcome- or outcome-/auxiliary-dependent samples are observed. This sampling scheme allows the investigators to oversample certain subpopula...

journal_title：Biometrics

authors： Wang X,Zhou H

更新日期：2006-12-01 00:00:00

abstract：:The Wilcoxon rank sum test is widely used for two-group comparisons for nonnormal data. An assumption of this test is independence of sampling units both between and within groups. In ophthalmology, data are often collected on two eyes of an individual, which are highly correlated. In ophthalmological clinical trials,...

journal_title：Biometrics

authors： Rosner B,Glynn RJ,Lee ML

更新日期：2006-12-01 00:00:00

abstract：:Tag loss in mark-recapture experiments is a violation of one of the Jolly-Seber model assumptions. It causes bias in parameter estimates and has only been dealt with in an ad hoc manner. We develop methodology to estimate tag retention and abundance in double-tagging mark-recapture experiments. We apply this methodolo...

journal_title：Biometrics

authors： Cowen L,Schwarz CJ

更新日期：2006-09-01 00:00:00

abstract：:A Bayesian adaptive design is proposed for dose-finding in phase I/II clinical trials to incorporate the bivariate outcomes, toxicity and efficacy, of a new treatment. Without specifying any parametric functional form for the drug dose-response curve, we jointly model the bivariate binary data to account for the corre...

journal_title：Biometrics

authors： Yin G,Li Y,Ji Y

更新日期：2006-09-01 00:00:00

abstract：:Modeling of longitudinal data from agricultural experiments using growth curves helps understand conditions conducive or unconducive to crop growth. Recent advances in Geographical Information Systems (GIS) now allow geocoding of agricultural data that help understand spatial patterns. A particularly common problem is...

journal_title：Biometrics

authors： Banerjee S,Johnson GA

更新日期：2006-09-01 00:00:00

abstract：:We study the issue of identifiability of mixture models in the context of capture-recapture abundance estimation for closed populations. Such models are used to take account of individual heterogeneity in capture probabilities, but their validity was recently questioned by Link (2003, Biometrics 59, 1123-1130) on the ...

journal_title：Biometrics

authors： Holzmann H,Munk A,Zucchini W

更新日期：2006-09-01 00:00:00