On constrained balance randomization for clinical trials.

abstract：:A semiparametric estimate of an average regression effect with right-censored failure time data has recently been proposed under the Cox-type model where the regression effect beta(t) is allowed to vary with time. In this article, we derive a simple algebraic relationship between this average regression effect and a m...

journal_title：Biometrics

authors： Xu R,Harrington DP

更新日期：2001-09-01 00:00:00

abstract：:We extend the linear random-effects growth curve model (REGCM) (Laird and Ware, 1982, Biometrics 38, 963-974) to study the effects of population covariates on one or more characteristics of the growth curve when the characteristics are expressed as linear combinations of the growth curve parameters. This definition in...

journal_title：Biometrics

authors： Stukel TA,Demidenko E

更新日期：1997-06-01 00:00:00

abstract：:We propose a generalized linear mixed model to estimate and test marginal effects on titers repeatedly measured by serial dilution assays. The link is log-log and the titer is assumed to follow a gamma distribution. The parameters are estimated by generalized estimating equations. The marginal effects are tested by me...

journal_title：Biometrics

authors： Bloch J,Chavance M

更新日期：1998-06-01 00:00:00

abstract：:A general theory for estimating the size of a closed population from multiple-recapture data is presented. This theory is easily extended to open population models for multiple-recapture data. Estimation is based on a log-linear model developed for modeling dependent capture-recapture data when capture probabilities v...

journal_title：Biometrics

authors： Evans MA,Bonett DG,McDonald LL

更新日期：1994-06-01 00:00:00

abstract：:We extend the Mantel-Haenszel estimating function to estimate both the intra-cluster pairwise correlation and the main effects for sparse clustered binary data. We propose both a composite likelihood approach and an estimating function approach for the analysis of such data. The proposed estimators are consistent and ...

journal_title：Biometrics

authors： Wang M,Williamson JM

更新日期：2005-12-01 00:00:00

abstract：:Many statistical tests have been proposed for case-control data to detect disease association with multiple single nucleotide polymorphisms (SNPs) in linkage disequilibrium. The main reason for the existence of so many tests is that each test aims to detect one or two aspects of many possible distributional difference...

journal_title：Biometrics

authors： Han F,Pan W

更新日期：2012-03-01 00:00:00

abstract：:Despite major methodological developments, Bayesian inference in Gaussian graphical models remains challenging in high dimension due to the tremendous size of the model space. This article proposes a method to infer the marginal and conditional independence structures between variables by multiple testing, which bypas...

journal_title：Biometrics

authors： Leday GGR,Richardson S

更新日期：2019-12-01 00:00:00

abstract：:We propose a similarity-based regression method to detect associations between traits and multimarker genotypes. The model regresses similarity in traits for pairs of "unrelated" individuals on their haplotype similarities, and detects the significance by a score test for which the limiting distribution is derived. Th...

journal_title：Biometrics

authors： Tzeng JY,Zhang D,Chang SM,Thomas DC,Davidian M

更新日期：2009-09-01 00:00:00

abstract：:We propose group sequential tests of the equivalence of two treatments based on ideas related to repeated confidence intervals. These tests adapt readily to unpredictable group sizes, to the possibility of continuing even though a boundary has been crossed, and to nonnormal observations. In comparing two binomial dist...

journal_title：Biometrics

authors： Jennison C,Turnbull BW

更新日期：1993-03-01 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：:The characteristics of deleterious genes have been of great interest in both theory and practice in genetics. Because of the complex genetic mechanism of these deleterious genes, most current studies try to estimate the overall magnitude of mortality effects on a population, which is characterized classically by the n...

journal_title：Biometrics

authors： Lee JK,Lascoux M,Newton MA,Nordheim EV

更新日期：1999-06-01 00:00:00

abstract：:In this article, we develop new methods for estimating average treatment effects in observational studies, in settings with more than two treatment levels, assuming unconfoundedness given pretreatment variables. We emphasize propensity score subclassification and matching methods which have been among the most popular...

journal_title：Biometrics

authors： Yang S,Imbens GW,Cui Z,Faries DE,Kadziola Z

更新日期：2016-12-01 00:00:00

abstract：:In spatial surveys for estimating the density of objects in a survey region, systematic designs will generally yield lower variance than random designs. However, estimating the systematic variance is well known to be a difficult problem. Existing methods tend to overestimate the variance, so although the variance is g...

journal_title：Biometrics

authors： Fewster RM

更新日期：2011-12-01 00:00:00

abstract：:We present a method for individual and integrative analysis of high dimension, low sample size data that capitalizes on the recurring theme in multivariate analysis of projecting higher dimensional data onto a few meaningful directions that are solutions to a generalized eigenvalue problem. We propose a general framew...

journal_title：Biometrics

authors： Safo SE,Ahn J,Jeon Y,Jung S

更新日期：2018-12-01 00:00:00

abstract：:In multivariate recurrent event data regression, observation of recurrent events is usually terminated by other events that are associated with the recurrent event processes, resulting in informative censoring. Additionally, some covariates could be measured with errors. In some applications, an instrumental variable ...

journal_title：Biometrics

authors： Yu H,Cheng YJ,Wang CY

更新日期：2018-09-01 00:00:00

abstract：:In the genetic study of complex traits, especially behavior related ones, such as smoking and alcoholism, usually several phenotypic measurements are obtained for the description of the complex trait, but no single measurement can quantify fully the complicated characteristics of the symptom because of our lack of und...

journal_title：Biometrics

authors： Yu K,Wheeler W,Li Q,Bergen AW,Caporaso N,Chatterjee N,Chen J

更新日期：2010-03-01 00:00:00

abstract：:This article proposes an efficient approach to screening genes associated with a phenotypic variable of interest in genomic studies with subgroups. In order to capture and detect various association profiles across subgroups, we flexibly estimate the underlying effect size distribution across subgroups using a semi-pa...

journal_title：Biometrics

authors： Matsui S,Noma H,Qu P,Sakai Y,Matsui K,Heuck C,Crowley J

更新日期：2018-03-01 00:00:00

abstract：:We estimate how the effect of antiretroviral treatment depends on the time from HIV-infection to initiation of treatment, using observational data. A major challenge in making inferences from such observational data arises from biases associated with the nonrandom assignment of treatment, for example bias induced by d...

journal_title：Biometrics

authors： Lok JJ,DeGruttola V

更新日期：2012-09-01 00:00:00

abstract：:Because the number of patients waiting for organ transplants exceeds the number of organs available, a better understanding of how transplantation affects the distribution of residual lifetime is needed to improve organ allocation. However, there has been little work to assess the survival benefit of transplantation f...

journal_title：Biometrics

authors： Vock DM,Tsiatis AA,Davidian M,Laber EB,Tsuang WM,Finlen Copeland CA,Palmer SM

更新日期：2013-12-01 00:00:00

abstract：:Traditional paradigms for clinical translation are challenged in settings where multiple contemporaneous therapeutic strategies have been identified as potentially beneficial. Platform trials have emerged as an approach for sequentially comparing multiple trials using a single protocol. The Ebola virus disease outbrea...

journal_title：Biometrics

authors： Kaizer AM,Hobbs BP,Koopmeiners JS

更新日期：2018-09-01 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：:We develop locally D-optimal designs for nonlinear models when the variance of the response is a function of its mean. Using the two-parameter Michaelis-Menten model as an example, we show that the optimal design depends on both the type of heteroscedasticity and the magnitude of the variation. In addition, our result...

journal_title：Biometrics

authors： Dette H,Wong WK

更新日期：1999-09-01 00:00:00

abstract：:A study of otitis media that requires a test for the comparison of two clustered samples of censored data is described. A method is proposed taking into account the within-subject correlation in the formation of the log-rank statistic. ...

journal_title：Biometrics

authors： Le CT,Lindgren BR

更新日期：1996-03-01 00:00:00

abstract：:A routine challenge is that of making inference on parameters in a statistical model of interest from longitudinal data subject to dropout, which are a special case of the more general setting of monotonely coarsened data. Considerable recent attention has focused on doubly robust (DR) estimators, which in this contex...

journal_title：Biometrics

authors： Tsiatis AA,Davidian M,Cao W

更新日期：2011-06-01 00:00:00

abstract：:Epidemiologic data for case-control studies are often summarized into K 2 x 2 tables. Given a fixed number of cases and controls, the degree of sparseness in the data depends on the number of strata, K. The effect of increasing stratification on size and power of seven tests of homogeneity of the odds ratio is studied...

journal_title：Biometrics

authors： Jones MP,O'Gorman TW,Lemke JH,Woolson RF

更新日期：1989-03-01 00:00:00

abstract：:We describe a Bayesian quantile regression model that uses a confirmatory factor structure for part of the design matrix. This model is appropriate when the covariates are indicators of scientifically determined latent factors, and it is these latent factors that analysts seek to include as predictors in the quantile ...

journal_title：Biometrics

authors： Burgette LF,Reiter JP

更新日期：2012-03-01 00:00:00

abstract：:We describe an exact, unconditional, non-randomized procedure for producing confidence intervals for the grand mean in a normal-normal random effects meta-analysis. The procedure targets meta-analyses based on too few primary studies, ≤ 7 , say, to ...

journal_title：Biometrics

authors： Michael H,Thornton S,Xie M,Tian L

更新日期：2019-06-01 00:00:00

abstract：:A class of adaptive weighted log-rank statistics is described where the vector of weights is chosen in a data-dependent way from a family of "smooth" weight vectors. A parametric family of weight vectors is identified which includes most shapes of weighting vectors that will be near optimal in many cancer prevention a...

journal_title：Biometrics

authors： Self SG

更新日期：1991-09-01 00:00:00

abstract：:In multivariate matching, fine balance constrains the marginal distributions of a nominal variable in treated and matched control groups to be identical without constraining who is matched to whom. In this way, a fine balance constraint can balance a nominal variable with many levels while focusing efforts on other mo...

journal_title：Biometrics

authors： Yang D,Small DS,Silber JH,Rosenbaum PR

更新日期：2012-06-01 00:00:00

abstract：:A critical component of longitudinal study design involves determining the sampling schedule. Criteria for optimal design often focus on accurate estimation of the mean profile, although capturing the between-subject variance of the longitudinal process is also important since variance patterns may be associated with ...

journal_title：Biometrics

authors： Wu M,Diez-Roux A,Raghunathan TE,Sánchez BN

更新日期：2018-03-01 00:00:00