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：:With the prevalence of gene expression studies and the relatively low reproducibility caused by insufficient sample sizes, it is natural to consider joint analysis that could combine data from different experiments effectively to achieve improved accuracy. We present in this article a model-based approach for better i...

journal_title：Biometrics

authors： Ruan L,Yuan M

更新日期：2011-12-01 00:00:00

abstract：:We present a natural generalization of the Buckley-James-type estimator for traditional survival data to right-censored length-biased data under the accelerated failure time (AFT) model. Length-biased data are often encountered in prevalent cohort studies and cancer screening trials. Informative right censoring induce...

journal_title：Biometrics

authors： Ning J,Qin J,Shen Y

更新日期：2011-12-01 00:00:00

abstract：:Petersen-type mark-recapture experiments are often used to estimate the number of fish or other animals in a population moving along a set migration route. A first sample of individuals is captured at one location, marked, and returned to the population. A second sample is then captured farther along the route, and in...

journal_title：Biometrics

authors： Bonner SJ,Schwarz CJ

更新日期：2011-12-01 00:00:00

abstract：:In practice, when analyzing data from a capture-recapture experiment it is tempting to apply modern advanced statistical methods to the observed capture histories. However, unless the analysis takes into account that the data have only been collected from individuals who have been captured at least once, the results m...

journal_title：Biometrics

authors： Stoklosa J,Hwang WH,Wu SH,Huggins R

更新日期：2011-12-01 00:00:00

abstract：:Covariate-specific receiver operating characteristic (ROC) curves are often used to evaluate the classification accuracy of a medical diagnostic test or a biomarker, when the accuracy of the test is associated with certain covariates. In many large-scale screening tests, the gold standard is subject to missingness due...

journal_title：Biometrics

authors： Liu D,Zhou XH

更新日期：2011-09-01 00:00:00

abstract：:In most research on smoothing splines the focus has been on estimation, while inference, especially hypothesis testing, has received less attention. By defining design matrices for fixed and random effects and the structure of the covariance matrices of random errors in an appropriate way, the cubic smoothing spline a...

journal_title：Biometrics

authors： Nummi T,Pan J,Siren T,Liu K

更新日期：2011-09-01 00:00:00

abstract：:In epidemiologic studies of time to an event, mean lifetime is often of direct interest. We propose methods to estimate group- (e.g., treatment-) specific differences in restricted mean lifetime for studies where treatment is not randomized and lifetimes are subject to both dependent and independent censoring. The pro...

journal_title：Biometrics

authors： Zhang M,Schaubel DE

更新日期：2011-09-01 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：: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 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：: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：: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：:Population admixture can be a confounding factor in genetic association studies. Family-based methods (Rabinowitz and Larid, 2000, Human Heredity 50, 211-223) have been proposed in both testing and estimation settings to adjust for this confounding, especially in case-only association studies. The family-based methods...

journal_title：Biometrics

authors： Wang Y,Yang Q,Rabinowitz D

更新日期：2011-06-01 00:00:00

abstract：:Most existing methods for identifying aberrant regions with array CGH data are confined to a single target sample. Focusing on the comparison of multiple samples from two different groups, we develop a new penalized regression approach with a fused adaptive lasso penalty to accommodate the spatial dependence of the cl...

journal_title：Biometrics

authors： Wang HJ,Hu J

更新日期：2011-06-01 00:00:00

abstract：:Statistical models that include random effects are commonly used to analyze longitudinal and correlated data, often with the assumption that the random effects follow a Gaussian distribution. Via theoretical and numerical calculations and simulation, we investigate the impact of misspecification of this distribution o...

journal_title：Biometrics

authors： McCulloch CE,Neuhaus JM

更新日期：2011-03-01 00:00:00

abstract：:In family studies, canonical discriminant analysis can be used to find linear combinations of phenotypes that exhibit high ratios of between-family to within-family variabilities. But with large numbers of phenotypes, canonical discriminant analysis may overfit. To estimate the predicted ratios associated with the coe...

journal_title：Biometrics

authors： Jin M,Fang Y

更新日期：2011-03-01 00:00:00

abstract：:In this article, we propose a Bayesian approach to dose-response assessment and the assessment of synergy between two combined agents. We consider the case of an in vitro ovarian cancer research study aimed at investigating the antiproliferative activities of four agents, alone and paired, in two human ovarian cancer ...

journal_title：Biometrics

authors： Hennessey VG,Rosner GL,Bast RC Jr,Chen MY

更新日期：2010-12-01 00:00:00

abstract：:In genetic family studies, ages at onset of diseases are routinely collected. Often one is interested in assessing the familial association of ages at the onset of a certain disease type. However, when a competing risk is present and is related to the disease of interest, the usual measure of association by treating t...

journal_title：Biometrics

authors： Shih JH,Albert PS

更新日期：2010-12-01 00:00:00

abstract：:Calibration, the statistical consistency of forecast distributions and the observations, is a central requirement for probabilistic predictions. Calibration of continuous forecasts is typically assessed using the probability integral transform histogram. In this article, we propose significance tests based on scoring ...

journal_title：Biometrics

authors： Held L,Rufibach K,Balabdaoui F

更新日期：2010-12-01 00:00:00

abstract：:Spatial cluster detection is an important methodology for identifying regions with excessive numbers of adverse health events without making strong model assumptions on the underlying spatial dependence structure. Previous work has focused on point or individual-level outcome data and few advances have been made when ...

journal_title：Biometrics

authors： Cook AJ,Li Y,Arterburn D,Tiwari RC

更新日期：2010-09-01 00:00:00

abstract：:Variable selection for clustering is an important and challenging problem in high-dimensional data analysis. Existing variable selection methods for model-based clustering select informative variables in a "one-in-all-out" manner; that is, a variable is selected if at least one pair of clusters is separable by this va...

journal_title：Biometrics

authors： Guo J,Levina E,Michailidis G,Zhu J

更新日期：2010-09-01 00:00:00

abstract：:With increasing frequency, epidemiologic studies are addressing hypotheses regarding gene-environment interaction. In many well-studied candidate genes and for standard dietary and behavioral epidemiologic exposures, there is often substantial prior information available that may be used to analyze current data as wel...

journal_title：Biometrics

authors： Mukherjee B,Ahn J,Gruber SB,Ghosh M,Chatterjee N

更新日期：2010-09-01 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：:Asbestos exposure is a well-known risk factor for various lung diseases, and when they occur, workmen's compensation boards need to make decisions concerning the probability the cause is work related. In the absence of a definitive work history, measures of short and long asbestos fibers as well as counts of asbestos ...

journal_title：Biometrics

authors： Weichenthal S,Joseph L,Bélisle P,Dufresne A

更新日期：2010-06-01 00:00:00

abstract：:In large cohort studies, it often happens that some covariates are expensive to measure and hence only measured on a validation set. On the other hand, relatively cheap but error-prone measurements of the covariates are available for all subjects. Regression calibration (RC) estimation method (Prentice, 1982, Biometri...

journal_title：Biometrics

authors： Yu M,Nan B

更新日期：2010-06-01 00:00:00

abstract：:Reversible jump Markov chain Monte Carlo (RJMCMC) methods are used to fit Bayesian capture-recapture models incorporating heterogeneity in individuals and samples. Heterogeneity in capture probabilities comes from finite mixtures and/or fixed sample effects allowing for interactions. Estimation by RJMCMC allows automa...

journal_title：Biometrics

authors： Arnold R,Hayakawa Y,Yip P

更新日期：2010-06-01 00:00:00

abstract：:We propose a new estimation method for multivariate failure time data using the quadratic inference function (QIF) approach. The proposed method efficiently incorporates within-cluster correlations. Therefore, it is more efficient than those that ignore within-cluster correlation. Furthermore, the proposed method is e...

journal_title：Biometrics

authors： Xue L,Wang L,Qu A

更新日期：2010-06-01 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：: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：:Pharmacovigilance systems aim at early detection of adverse effects of marketed drugs. They maintain large spontaneous reporting databases for which several automatic signaling methods have been developed. One limit of those methods is that the decision rules for the signal generation are based on arbitrary thresholds...

journal_title：Biometrics

authors： Ahmed I,Dalmasso C,Haramburu F,Thiessard F,Broët P,Tubert-Bitter P

更新日期：2010-03-01 00:00:00

abstract：:We consider a fully model-based approach for the analysis of distance sampling data. Distance sampling has been widely used to estimate abundance (or density) of animals or plants in a spatially explicit study area. There is, however, no readily available method of making statistical inference on the relationships bet...

journal_title：Biometrics

authors： Johnson DS,Laake JL,Ver Hoef JM

更新日期：2010-03-01 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：:Methods for modeling and mapping spatial variation in disease risk continue to motivate much research. In particular, spatial analyses provide a useful tool for exploring geographical heterogeneity in health outcomes, and consequently can yield clues as to disease etiology, direct public health management, and generat...

journal_title：Biometrics

authors： Costain DA

更新日期：2009-12-01 00:00:00

abstract：:Bayesian experimental design for a clinical trial involves specifying a utility function that models the purpose of the trial, in this case the selection of patients for a diagnostic test. The best sample of patients is selected by maximizing expected utility. This optimization task poses difficulties due to a high-di...

journal_title：Biometrics

authors： Buzoianu M,Kadane JB

更新日期：2009-09-01 00:00:00

abstract：:In many longitudinal clinical studies, the level and progression rate of repeatedly measured biomarkers on each subject quantify the severity of the disease and that subject's susceptibility to progression of the disease. It is of scientific and clinical interest to relate such quantities to a later time-to-event clin...

journal_title：Biometrics

authors： Li L,Hu B,Greene T

更新日期：2009-09-01 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：SUMMARY:We consider the analysis of clinical trials that involve randomization to an active treatment (T = 1) or a control treatment (T = 0), when the active treatment is subject to all-or-nothing compliance. We compare three approaches to estimating treatment efficacy in this situation: as-treated analysis, per-protoc...

journal_title：Biometrics

authors： Little RJ,Long Q,Lin X

更新日期：2009-06-01 00:00:00

abstract：SUMMARY:We develop sample size formulas for studies aiming to test mean differences between a treatment and control group when all-or-none nonadherence (noncompliance) and selection bias are expected. Recent work by Fay, Halloran, and Follmann (2007, Biometrics 63, 465-474) addressed the increased variances within grou...

journal_title：Biometrics

authors： Shardell MD,El-Kamary SS

更新日期：2009-06-01 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