Semiparametric estimation of the covariate-specific ROC curve in presence of ignorable verification bias.

abstract：:In an effort to determine whether a particular treatment causes a particular outcome event, data are obtained from a database system that records events when they occur, and for such events, the system records exposure to the treatment. That is, the system records information about cases. The system provides no inform...

journal_title：Biometrics

authors： Rosenbaum PR

更新日期：2005-03-01 00:00:00

abstract：:The problem of regression dilution arising from covariate measurement error is investigated for survival data using the proportional hazards model. The naive approach to parameter estimation is considered whereby observed covariate values are used, inappropriately, in the usual analysis instead of the underlying covar...

journal_title：Biometrics

authors： Hughes MD

更新日期：1993-12-01 00:00:00

abstract：:The basic technical facts of human cytogenetics and the laboratory methods employed in chromosome research are explained in simple terms. The main variables used to describe chromosome images are defined and discussed. Three discriminant analysis models for chromosome classification are developed: one in which each ch...

journal_title：Biometrics

authors： Habbema JD

更新日期：1979-03-01 00:00:00

abstract：:Link et al. (2010, Biometrics 66, 178-185) define a general framework for analyzing capture-recapture data with potential misidentifications. In this framework, the observed vector of counts, y, is considered as a linear function of a vector of latent counts, x, such that y=Ax, with x assumed to follow a multinomial d...

journal_title：Biometrics

authors： Schofield MR,Bonner SJ

更新日期：2015-12-01 00:00:00

abstract：:We introduce a nearly automatic procedure to locate and count the quantum dots in images of kinesin motor assays. Our procedure employs an approximate likelihood estimator based on a two-component mixture model for the image data; the first component has a normal distribution, and the other component is distributed as...

journal_title：Biometrics

authors： Hughes J,Fricks J

更新日期：2011-06-01 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：:Truncation is a well-known phenomenon that may be present in observational studies of time-to-event data. While many methods exist to adjust for either left or right truncation, there are very few methods that adjust for simultaneous left and right truncation, also known as double truncation. We propose a Cox regressi...

journal_title：Biometrics

authors： Rennert L,Xie SX

更新日期：2018-06-01 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：:Mixed longitudinal growth data consists of several observations on a characteristic over a limited age range for each individual in a study. This data is then combined to model growth over the total age range of all individuals in the study. The limited data collected on each individual precludes a subject-specific ap...

journal_title：Biometrics

authors： Huggins RM,Loesch DZ

更新日期：1998-06-01 00:00:00

abstract：:Gene-disease association studies based on case-control designs may often be used to identify candidate polymorphisms (markers) conferring disease risk. If a large number of markers are studied, genotyping all markers on all samples is inefficient in resource utilization. Here, we propose an alternative two-stage metho...

journal_title：Biometrics

authors： Satagopan JM,Venkatraman ES,Begg CB

更新日期：2004-09-01 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：:Whenever inference for variance components is required, the choice between one-sided and two-sided tests is crucial. This choice is usually driven by whether or not negative variance components are permitted. For two-sided tests, classical inferential procedures can be followed, based on likelihood ratios, score stati...

journal_title：Biometrics

authors： Verbeke G,Molenberghs G

更新日期：2003-06-01 00:00:00

abstract：:For the analysis of time trends in incidence and mortality rates, the age-period-cohort (apc) model has became a widely accepted method. The considered data are arranged in a two-way table by age group and calendar period, which are mostly subdivided into 5- or 10-year intervals. The disadvantage of this approach is t...

journal_title：Biometrics

authors： Heuer C

更新日期：1997-03-01 00:00:00

abstract：:Ten parameters extracted from six currently used parametrizations of the four-parameter logistic model, and one new proposal, were examined for their statistical behavior in nonlinear least-squares estimation in combination with ELISA and RIA data. Those which are adequately near-linear on the basis of the Lowry-Morto...

journal_title：Biometrics

authors： Ratkowsky DA,Reedy TJ

更新日期：1986-09-01 00:00:00

abstract：:A method is presented for choosing an additive constant c when transforming data x to y = log(x + c). The method preserves Type I error probability and power in ANOVA under the assumption that the x + c for some c are log-normally distributed. The method has advantages similar to those of rank transformations--namely,...

journal_title：Biometrics

authors： Berry DA

更新日期：1987-06-01 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：SUMMARY:Recently, median regression models have received increasing attention. When continuous responses follow a distribution that is quite different from a normal distribution, usual mean regression models may fail to produce efficient estimators whereas median regression models may perform satisfactorily. In this ar...

journal_title：Biometrics

authors： Yi GY,He W

更新日期：2009-06-01 00:00:00

abstract：:In this article, we describe a Bayesian approach to the calibration of a stochastic computer model of chemical kinetics. As with many applications in the biological sciences, the data available to calibrate the model come from different sources. Furthermore, these data appear to provide somewhat conflicting informatio...

journal_title：Biometrics

authors： Henderson DA,Boys RJ,Wilkinson DJ

更新日期：2010-03-01 00:00:00

abstract：:Exposure to high levels of air pollution during the pregnancy is associated with increased probability of preterm birth (PTB), a major cause of infant morbidity and mortality. New statistical methodology is required to specifically determine when a particular pollutant impacts the PTB outcome, to determine the role of...

journal_title：Biometrics

authors： Warren J,Fuentes M,Herring A,Langlois P

更新日期：2012-12-01 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：:Capture-recapture models were originally developed to account for encounter probabilities that are less than 1 in free-ranging animal populations. Nowadays, these models can deal with the movement of animals between different locations and are also used to study transitions between different states. However, their use...

journal_title：Biometrics

authors： Pradel R

更新日期：2005-06-01 00:00:00

abstract：:Vaccine-induced protection may not be homogeneous across individuals. It is possible that a vaccine gives complete protection for a portion of individuals, while the rest acquire only incomplete (leaky) protection of varying magnitude. If vaccine efficacy is estimated under wrong assumptions about such individual leve...

journal_title：Biometrics

authors： Mehtälä J,Dagan R,Auranen K

更新日期：2016-09-01 00:00:00

abstract：:Unless the true association is very strong, simple large-sample confidence intervals for the odds ratio based on the delta method perform well even for small samples. Such intervals include the Woolf logit interval and the related Gart interval based on adding .5 before computing the log odds ratio estimate and its st...

journal_title：Biometrics

authors： Agresti A

更新日期：1999-06-01 00:00:00

abstract：:In the context of group testing screening, McMahan, Tebbs, and Bilder (2012, Biometrics 68, 287-296) proposed a two-stage procedure in a heterogenous population in the presence of misclassification. In earlier work published in Biometrics, Kim, Hudgens, Dreyfuss, Westreich, and Pilcher (2007, Biometrics 63, 1152-1162)...

journal_title：Biometrics

authors： Malinovsky Y,Albert PS,Roy A

更新日期：2016-03-01 00:00:00

abstract：:When testing the null hypothesis that treatment arm-specific survival-time distributions are equal, the log-rank test is asymptotically valid when the distribution of time to censoring is conditionally independent of randomized treatment group given survival time. We introduce a test of the null hypothesis for use whe...

journal_title：Biometrics

authors： DiRienzo AG

更新日期：2003-09-01 00:00:00

abstract：:Likelihood ratio tests for parameters estimated assuming normally distributed errors are examined under a variety of homoscedastic and heteroscedastic variance assumptions. It is assumed that gamma ij, the jth observation from the ith population, is distributed as N[mu(chi ij, beta i), (sigma i mu(chi ij, beta i)theta...

journal_title：Biometrics

authors： Kimura DK

更新日期：1990-09-01 00:00:00

abstract：:Capture-recapture models are widely used to estimate demographic parameters of marked populations. Recently, this statistical theory has been extended to modeling dispersal of open populations. Multistate models can be used to estimate movement probabilities among subdivided populations if multiple sites are sampled. ...

journal_title：Biometrics

authors： Lindberg MS,Kendall WL,Hines JE,Anderson MG

更新日期：2001-03-01 00:00:00

abstract：:Laska and Meisner (1989, Biometrics 45, 1139-1151) dealt with the problem of testing whether an identified treatment belonging to a set of k + 1 treatments is better than each of the other k treatments. They calculated sample size tables for k = 2 when using multiple t-tests or Wilcoxon-Mann-Whitney tests, both under ...

journal_title：Biometrics

authors： Horn M,Vollandt R,Dunnett CW

更新日期：2000-09-01 00:00:00

abstract：:The objective of this paper is to develop statistical methods for estimating current and future numbers of individuals in different stages of the natural history of the human immunodeficiency (AIDS) virus infection and to evaluate the impact of therapeutic advances on these numbers. The approach is to extend the metho...

journal_title：Biometrics

authors： Brookmeyer R,Liao JG

更新日期：1990-12-01 00:00:00

abstract：:Epidemiological studies involving biomarkers are often hindered by prohibitively expensive laboratory tests. Strategically pooling specimens prior to performing these lab assays has been shown to effectively reduce cost with minimal information loss in a logistic regression setting. When the goal is to perform regress...

journal_title：Biometrics

authors： Mitchell EM,Lyles RH,Manatunga AK,Danaher M,Perkins NJ,Schisterman EF

更新日期：2014-03-01 00:00:00