Biased and unbiased estimation in longitudinal studies with informative visit processes.

abstract：:This paper considers the impact of bias in the estimation of the association parameters for longitudinal binary responses when there are drop-outs. A number of different estimating equation approaches are considered for the case where drop-out cannot be assumed to be a completely random process. In particular, standar...

journal_title：Biometrics

authors： Fitzmaurice GM,Lipsitz SR,Molenberghs G,Ibrahim JG

更新日期：2001-03-01 00:00:00

abstract：:In multivariate survival analysis, investigators are often interested in testing for heterogeneity among clusters, both overall and within specific classes. We represent different hypotheses about the heterogeneity structure using a sequence of gamma frailty models, ranging from a null model with no random effects to ...

journal_title：Biometrics

authors： Dunson DB,Chen Z

更新日期：2004-06-01 00:00:00

abstract：:We propose methods for Bayesian inference for a new class of semiparametric survival models with a cure fraction. Specifically, we propose a semiparametric cure rate model with a smoothing parameter that controls the degree of parametricity in the right tail of the survival distribution. We show that such a parameter ...

journal_title：Biometrics

authors： Ibrahim JG,Chen MH,Sinha D

更新日期：2001-06-01 00:00:00

abstract：:With advancements in technology, the collection of multiple types of measurements on a common set of subjects is becoming routine in science. Some notable examples include multimodal neuroimaging studies for the simultaneous investigation of brain structure and function and multi-omics studies for combining genetic an...

journal_title：Biometrics

authors： Zhao Y,Li L,Caffo BS

更新日期：2020-08-13 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：: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：:Spatial weed count data are modeled and predicted using a generalized linear mixed model combined with a Bayesian approach and Markov chain Monte Carlo. Informative priors for a data set with sparse sampling are elicited using a previously collected data set with extensive sampling. Furthermore, we demonstrate that so...

journal_title：Biometrics

authors： Christensen OF,Waagepetersen R

更新日期：2002-06-01 00:00:00

abstract：:The classical concordance correlation coefficient (CCC) to measure agreement among a set of observers assumes data to be distributed as normal and a linear relationship between the mean and the subject and observer effects. Here, the CCC is generalized to afford any distribution from the exponential family by means of...

journal_title：Biometrics

authors： Carrasco JL

更新日期：2010-09-01 00:00:00

abstract：:Some failure time data come from a population that consists of some subjects who are susceptible to and others who are nonsusceptible to the event of interest. The data typically have heavy censoring at the end of the follow-up period, and a standard survival analysis would not always be appropriate. In such situation...

journal_title：Biometrics

authors： Sy JP,Taylor JM

更新日期：2000-03-01 00:00:00

abstract：:For many long-lived animal species, individuals do not breed every year, and are often not accessible during non-breeding periods. Individuals exhibit site fidelity if they return to the same breeding colony or spawning ground when they breed. If capture and recapture is only possible at the breeding site, temporary e...

journal_title：Biometrics

authors： Pledger S,Baker E,Scribner K

更新日期：2013-12-01 00:00:00

abstract：:The use of summary rates of reporting health data is discussed. Directly and indirectly adjusted rates are compared under two models of no interaction. A method of analysis is described whereby a model is first fitted to data in order to investigate assumptions, and subsequently the smoothed rates based on the model a...

journal_title：Biometrics

authors： Freeman DH Jr,Holford TR

更新日期：1980-06-01 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 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：:Training data in a supervised learning problem consist of the class label and its potential predictors for a set of observations. Constructing effective classifiers from training data is the goal of supervised learning. In biomedical sciences and other scientific applications, class labels may be subject to errors. We...

journal_title：Biometrics

authors： Yasui Y,Pepe M,Hsu L,Adam BL,Feng Z

更新日期：2004-03-01 00:00:00

abstract：:We consider the problem of estimating a population size from successive catches taken during a removal experiment and propose two estimating functions approaches, the traditional quasi-likelihood (TQL) approach for dependent observations and the conditional quasi-likelihood (CQL) approach using the conditional mean an...

journal_title：Biometrics

authors： Wang YG

更新日期：1999-12-01 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：: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：:Three properties of interest in bioavailability studies using compartmental models are the area under the concentration curve, the maximum concentration, and the time to maximum concentration. Methods are described for finding designs that minimize the variance of the estimates of these quantities in such a model. The...

journal_title：Biometrics

authors： Atkinson AC,Chaloner K,Herzberg AM,Juritz J

更新日期：1993-06-01 00:00:00

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：: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：:This paper presents an approach to handling missing covariates in the generalized estimating equation (GEE) model for binary outcomes when the probability of missingness depends on the observed outcomes and covariates. The proposed method is to replace the missing quantities in the estimating function with consistent ...

journal_title：Biometrics

authors： Xie F,Paik MC

更新日期：1997-12-01 00:00:00

abstract：:In controlled clinical trials there are usually several prognostic factors known or thought to influence the patient's ability to respond to treatment. Therefore, the method of sequential treatment assignment needs to be designed so that treatment balance is simultaneously achieved across all such patients factor. Tra...

journal_title：Biometrics

authors： Pocock SJ,Simon R

更新日期：1975-03-01 00:00:00

abstract：:Brain connectivity analysis is now at the foreground of neuroscience research. A connectivity network is characterized by a graph, where nodes represent neural elements such as neurons and brain regions, and links represent statistical dependence that is often encoded in terms of partial correlation. Such a graph is i...

journal_title：Biometrics

authors： Xia Y,Li L

更新日期：2017-09-01 00:00:00

abstract：:The situation considered is the prediction of a future observation from a simple exponential survival distribution in a hierarchical Bayes context. It is shown that when the hyperparameters need to be estimated from the data, a sample reuse approach is superior to maximum likelihood and method of moments estimation pr...

journal_title：Biometrics

authors： Geisser S

更新日期：1990-03-01 00:00:00

abstract：:This article develops a latent model and likelihood-based inference to detect temporal clustering of events. The model mimics typical processes generating the observed data. We apply model selection techniques to determine the number of clusters, and develop likelihood inference and a Monte Carlo expectation-maximizat...

journal_title：Biometrics

authors： Xie M,Sun Q,Naus J

更新日期：2009-12-01 00:00:00

abstract：:Identifying disease-associated changes in DNA methylation can help us gain a better understanding of disease etiology. Bisulfite sequencing allows the generation of high-throughput methylation profiles at single-base resolution of DNA. However, optimally modeling and analyzing these sparse and discrete sequencing data...

journal_title：Biometrics

authors： Zhao K,Oualkacha K,Lakhal-Chaieb L,Labbe A,Klein K,Ciampi A,Hudson M,Colmegna I,Pastinen T,Zhang T,Daley D,Greenwood CMT

更新日期：2020-05-21 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：:We explore the use of a posterior predictive loss criterion for model selection for incomplete longitudinal data. We begin by identifying a property that most model selection criteria for incomplete data should consider. We then show that a straightforward extension of the Gelfand and Ghosh (1998, Biometrika, 85, 1-11...

journal_title：Biometrics

authors： Daniels MJ,Chatterjee AS,Wang C

更新日期：2012-12-01 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：:Recent advances in human genetics have led to a renewed interest in statistical methods for the detection of linkage from family data--for example, between marker loci and disease traits. Statistical analysis of linkage between two loci is carried out almost exclusively by means of the lod (log-odds) score test, equiv...

journal_title：Biometrics

authors： Shoukri MM,Lathrop GM

更新日期：1993-03-01 00:00:00