Bayesian enrichment strategies for randomized discontinuation trials.

abstract：:Cohort case-control design is an efficient and economical design to study risk factors for disease incidence or mortality in a large cohort. In the last few decades, a variety of cohort case-control designs have been developed and theoretically justified. These designs have been exclusively applied to the analysis of ...

journal_title：Biometrics

authors： Lu SE,Wang MC

更新日期：2002-12-01 00:00:00

abstract：:Statistical inference based on right-censored data for the proportional hazards (PH) model with missing covariates has received considerable attention, but interval-censored or current status data with missing covariates has not yet been investigated. Our study is partly motivated by the analysis of fracture data from...

journal_title：Biometrics

authors： Wen CC,Lin CT

更新日期：2011-09-01 00:00:00

abstract：:We investigate two-stage parametric and two-stage semi-parametric estimation procedures for the association parameter in copula models for bivariate survival data where censoring in either or both components is allowed. We derive asymptotic properties of the estimators and compare their performance by simulations. Bot...

journal_title：Biometrics

authors： Shih JH,Louis TA

更新日期：1995-12-01 00:00:00

abstract：:It has become increasingly common in epidemiological studies to pool specimens across subjects to achieve accurate quantitation of biomarkers and certain environmental chemicals. In this article, we consider the problem of fitting a binary regression model when an important exposure is subject to pooling. We take a re...

journal_title：Biometrics

authors： Zhang Z,Albert PS

更新日期：2011-06-01 00:00:00

abstract：:A multiple toxicity model for the quantal response of organisms is constructed based on an existing bivariate theory. The main assumption is that the tolerances follow a multivariate normal distribution function. However, any monotone tolerance distribution can be applied by mapping the integration region in the n-dim...

journal_title：Biometrics

authors： Christensen ER,Chen CY

更新日期：1985-09-01 00:00:00

abstract：:The first part of the article reviews the Data Augmentation algorithm and presents two approximations to the Data Augmentation algorithm for the analysis of missing-data problems: the Poor Man's Data Augmentation algorithm and the Asymptotic Data Augmentation algorithm. These two algorithms are then implemented in the...

journal_title：Biometrics

authors： Wei GC,Tanner MA

更新日期：1991-12-01 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：:Geographic disease surveillance methods identify regions that have higher disease rates than expected. These approaches are generally applied to incident or prevalent cases of disease. In some contexts, disease-related events rather than individuals are the appropriate units of analysis for geographic surveillance. We...

journal_title：Biometrics

authors： Rosychuk RJ,Huston C,Prasad NG

更新日期：2006-06-01 00:00:00

abstract：:An important objective in biomedical and environmental risk assessment is estimation of minimum exposure levels that induce a pre-specified adverse response in a target population. The exposure points in such settings are typically referred to as benchmark doses (BMDs). Parametric Bayesian estimation for finding BMDs ...

journal_title：Biometrics

authors： Fang Q,Piegorsch WW,Simmons SJ,Li X,Chen C,Wang Y

更新日期：2015-12-01 00:00:00

abstract：:We consider Bayesian inference and model selection for prevalence estimation using a longitudinal two-phase design in which subjects initially receive a low-cost screening test followed by an expensive diagnostic test conducted on several occasions. The change in the subject's diagnostic probability over time is descr...

journal_title：Biometrics

authors： Erkanli A,Soyer R,Costello EJ

更新日期：1999-12-01 00:00:00

abstract：:In principle, G-estimation is an attractive approach for dealing with confounding by variables affected by treatment. It has rarely been applied for estimation of the effects of treatment on failure-time outcomes. Part of this is due to artificial censoring, an analytic device which considers some subjects who actuall...

journal_title：Biometrics

authors： Joffe MM,Yang WP,Feldman H

更新日期：2012-03-01 00:00:00

abstract：:We propose a response-adaptive model for functional linear regression, which is adapted to sparsely sampled longitudinal responses. Our method aims at predicting response trajectories and models the regression relationship by directly conditioning the sparse and irregular observations of the response on the predictor,...

journal_title：Biometrics

authors： Wu S,Müller HG

更新日期：2011-09-01 00:00:00

abstract：:The distribution of ventilation-perfusion ratio over the lung is a useful indicator of the efficiency of lung function. Information about this distribution can be obtained by observing the retention in blood of inert gases passed through the lung. These retentions are related to the ventilation-perfusion distribution ...

journal_title：Biometrics

authors： Lim LL,Whitehead J

更新日期：1992-03-01 00:00:00

abstract：:Conventional statistical determinations of sample size in phase II studies typically lead to sample sizes of the order of 25 (Schoenfeld, 1980, International Journal of Radiation Oncology, Biology and Physics 6, 371-374). When the development of new treatments is proceeding rapidly relative to the recruitment of suita...

journal_title：Biometrics

authors： Whitehead J

更新日期：1985-06-01 00:00:00

abstract：:Motivated by the particular problem of predicting defoliation based on a measure of gypsy moth egg mass density, prediction in the presence of measurement error is discussed. The measurement error variances and covariances are allowed to vary from unit to unit and are estimated by some type of within unit sampling. A ...

journal_title：Biometrics

authors： Buonaccorsi JP

更新日期：1995-12-01 00:00:00

abstract：:Drawing inferences for high-dimensional models is challenging as regular asymptotic theories are not applicable. This article proposes a new framework of simultaneous estimation and inferences for high-dimensional linear models. By smoothing over partial regression estimates based on a given variable selection scheme,...

journal_title：Biometrics

authors： Fei Z,Zhu J,Banerjee M,Li Y

更新日期：2019-06-01 00:00:00

abstract：:In this article, we consider two-phase sampling in the situation in which all covariates are categorical. Two-phase designs are appealing from an efficiency perspective since they allow sampling to be concentrated in informative cells. A number of likelihood-based methods have been developed for the analysis of two-ph...

journal_title：Biometrics

authors： Ross M,Wakefield J

更新日期：2013-06-01 00:00:00

abstract：:A mean residual life function is the average remaining life of a surviving subject, as it varies with time. The proportional mean residual life model was proposed by Oakes and Dasu (1990, Biometrika77, 409-410) in regression analysis to study its association with related covariates in absence of censoring. In this art...

journal_title：Biometrics

authors： Chen YQ,Jewell NP,Lei X,Cheng SC

更新日期：2005-03-01 00:00:00

abstract：:In biomedical cohort studies for assessing the association between an outcome variable and a set of covariates, usually, some covariates can only be measured on a subgroup of study subjects. An important design question is-which subjects to select into the subgroup to increase statistical efficiency. When the outcome ...

journal_title：Biometrics

authors： Wang L,Williams ML,Chen Y,Chen J

更新日期：2020-03-01 00:00:00

abstract：:This paper studies randomization model methods for analyzing data from a multicenter study comparing the effectiveness of two treatments. The Mantel-Haenszel mean score statistic, which can be used for continuous or ordered categorical response variables, is shown to be a useful nonparametric alternative to standard l...

journal_title：Biometrics

authors： Davis CS,Chung Y

更新日期：1995-09-01 00:00:00

abstract：:Mixed latent Markov (MLM) models represent an important tool of analysis of longitudinal data when response variables are affected by time-fixed and time-varying unobserved heterogeneity, in which the latter is accounted for by a hidden Markov chain. In order to avoid bias when using a model of this type in the presen...

journal_title：Biometrics

authors： Bartolucci F,Farcomeni A

更新日期：2015-03-01 00:00:00

abstract：:Suppose that a heterogeneous group of individuals is followed over time and that each individual can be in state 0 or state 1 at each time point. The sequence of states is assumed to follow a binary Markov chain. In this paper we model the transition probabilities for the 0 to 0 and 1 to 0 transitions by two logistic ...

journal_title：Biometrics

authors： Muenz LR,Rubinstein LV

更新日期：1985-03-01 00:00:00

abstract：:We present a class of simple designs that can be used in early dose-finding studies in HIV. Such designs, in contrast with Phase I designs in cancer, have a lot of the Phase II flavor about them. Information on efficacy is obtained during the trial and is as important as that relating to toxicity. The designs proposed...

journal_title：Biometrics

authors： O'Quigley J,Hughes MD,Fenton T

更新日期：2001-12-01 00:00:00

abstract：:Neuroendocrine ensembles communicate with their remote and proximal target cells via an intermittent pattern of chemical signaling. The identification of episodic releases of hormonal pulse signals constitutes a major emphasis of endocrine investigation. Estimating the number, temporal locations, secretion rate, and e...

journal_title：Biometrics

authors： Yang YC,Liu A,Wang Y

更新日期：2006-03-01 00:00:00

abstract：:Let Yi be an ni X 1 vector of observations, Xi an ni X p matrix of known values, and beta an unknown p X 1 with the structure Yi = Xi beta + epsilon i, where the covariance matrix of epsilon i is of intra-class form, that is Cov (epsilon i) = sigma2[(1 - rho) Ii + rho e i e i'] where Ii is the ni X ni identity matrix ...

journal_title：Biometrics

authors： Wiorkowski JJ

更新日期：1975-09-01 00:00:00

abstract：:We propose a Bayesian latent Ornstein-Uhlenbeck (OU) model to analyze unbalanced longitudinal data of binary and ordinal variables, which are manifestations of fewer continuous latent variables. We focus on the evolution of such latent variables when they continuously change over time. Existing approaches are limited ...

journal_title：Biometrics

authors： Tran TD,Lesaffre E,Verbeke G,Duyck J

更新日期：2020-05-11 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：:In Western countries where food supply is satisfactory, consumers organize their diets around a large combination of foods. It is the purpose of this article to examine how recent nonnegative matrix factorization (NMF) techniques can be applied to food consumption data to understand these combinations. Such data are n...

journal_title：Biometrics

authors： Zetlaoui M,Feinberg M,Verger P,Clémençon S

更新日期：2011-12-01 00:00:00

abstract：:Normality of random effects is a routine assumption for the linear mixed model, but it may be unrealistic, obscuring important features of among-individual variation. We relax this assumption by approximating the random effects density by the seminonparameteric (SNP) representation of Gallant and Nychka (1987, Econome...

journal_title：Biometrics

authors： Zhang D,Davidian M

更新日期：2001-09-01 00:00:00

abstract：:Some new scale estimators for the censored two-sample accelerated life model are introduced. They are zeros of some integrated weighted difference between the two cumulative hazard estimators. These estimators are asymptotically normal. The weight is chosen to result in estimators whose asymptotic variances do not inv...

journal_title：Biometrics

authors： Yang S

更新日期：1998-09-01 00:00:00