Semiparametric methods for mapping quantitative trait loci with censored data.

abstract：:Long-term follow-up is common in many medical investigations where the interest lies in predicting patients' risks for a future adverse outcome using repeatedly measured predictors over time. A key quantity is the likelihood of developing an adverse outcome among individuals who survived up to time s given their covar...

journal_title：Biometrics

authors： Maziarz M,Heagerty P,Cai T,Zheng Y

更新日期：2017-03-01 00:00:00

abstract：:In this article, we present an estimation approach for solving nonlinear constrained generalized estimating equations that can be implemented using object-oriented software for nonlinear programming, such as nlminb in Splus or fmincon and lsqnonlin in Matlab. We show how standard estimating equation theory includes th...

journal_title：Biometrics

authors： Contreras M,Ryan LM

更新日期：2000-12-01 00:00:00

abstract：:Using genetic recombination data to make inferences about chiasmata on the tetrad during meiosis is a classic problem dating back to Weinstein's paper in 1936 (Genetics 21, 155-199). In the last few years, Weinstein's methods have been revived and applied to new problems, but a number of important statistical issues r...

journal_title：Biometrics

authors： Yu K,Feingold E

更新日期：2002-06-01 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：: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：:Adaptive line transect sampling offers the potential of improved population density estimation efficiency over conventional line transect sampling when populations are spatially clustered. In adaptive sampling, survey effort is increased when areas of high animal density are located, thereby increasing the number of o...

journal_title：Biometrics

authors： Pollard JH,Palka D,Buckland ST

更新日期：2002-12-01 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：:Linear multivariate theory is applied to the problem of combining several multivariate bioassays. Results are an asymptotic test of the hypothesis of a common log relative potency; the maximum likelihood estimator of the common log relative potency; and an exact and asymptotic confidence interval estimator for log rel...

journal_title：Biometrics

authors： Meisner M,Kushner HB,Laska EM

更新日期：1986-06-01 00:00:00

abstract：:In this article, we propose a Bayesian approach to phase I/II dose-finding oncology trials by jointly modeling a binary toxicity outcome and a continuous biomarker expression outcome. We apply our method to a clinical trial of a new gene therapy for bladder cancer patients. In this trial, the biomarker expression indi...

journal_title：Biometrics

authors： Bekele BN,Shen Y

更新日期：2005-06-01 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：:The fitting of finite mixture models via the EM algorithm is considered for data which are available only in grouped form and which may also be truncated. A practical example is presented where a mixture of two doubly truncated log-normal distributions is adopted to model the distribution of the volume of red blood ce...

journal_title：Biometrics

authors： McLachlan GJ,Jones PN

更新日期：1988-06-01 00:00:00

abstract：:The Wilcoxon rank sum test is widely used for two-group comparisons for nonnormal data. An assumption of this test is independence of sampling units both between and within groups. In ophthalmology, data are often collected on two eyes of an individual, which are highly correlated. In ophthalmological clinical trials,...

journal_title：Biometrics

authors： Rosner B,Glynn RJ,Lee ML

更新日期：2006-12-01 00:00:00

abstract：:Often with data from immunoassays, the concentration-response relationship is nonlinear and intra-assay response variance is heterogeneous. Estimation of the standard curve is usually based on a nonlinear heteroscedastic regression model for concentration-response, where variance is modeled as a function of mean respo...

journal_title：Biometrics

authors： Belanger BA,Davidian M,Giltinan DM

更新日期：1996-03-01 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：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：:In sampling certain types of materials, such as bags of fertilizer, or subsampling large quantities of water, as might be done in investigating the density of plankton in certain environmental situations, it is customary to composite the samples. That is, several samples are drawn, mixed into a composite sample, and a...

journal_title：Biometrics

authors： Rohde CA

更新日期：1976-06-01 00:00:00

abstract：:Alterations in DNA methylation have been linked to the development and progression of many diseases. The bisulfite sequencing technique presents methylation profiles at base resolution. Count data on methylated and unmethylated reads provide information on the methylation level at each CpG site. As more bisulfite sequ...

journal_title：Biometrics

authors： Ji T

更新日期：2019-06-01 00:00:00

abstract：:In this article, we propose a graphical technique for assessing the goodness-of-fit of a stationary hidden Markov model (HMM). We show that plots of the estimated distribution against the empirical distribution detect lack of fit with high probability for large sample sizes. By considering plots of the univariate and ...

journal_title：Biometrics

authors： MacKay Altman R

更新日期：2004-06-01 00:00:00

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：:A log-linear model for estimating the size of a closed population is defined for inverse multiple-recapture sampling with dependent samples. Efficient estimators of the log-linear model parameters and the population size are obtained by the method of minimum chi-square. A chi-square test of the general linear hypothes...

journal_title：Biometrics

authors： Bonett DG,Woodward JA,Bentler PM

更新日期：1987-12-01 00:00:00

abstract：:In diagnostic medicine, estimating the diagnostic accuracy of a group of raters or medical tests relative to the gold standard is often the primary goal. When a gold standard is absent, latent class models where the unknown gold standard test is treated as a latent variable are often used. However, these models have b...

journal_title：Biometrics

authors： Zhang B,Chen Z,Albert PS

更新日期：2012-12-01 00:00:00

abstract：:Spatial data have become increasingly common in epidemiology and public health research thanks to advances in GIS (Geographic Information Systems) technology. In health research, for example, it is common for epidemiologists to incorporate geographically indexed data into their studies. In practice, however, the spati...

journal_title：Biometrics

authors： Huque MH,Bondell HD,Carroll RJ,Ryan LM

更新日期：2016-09-01 00:00:00

abstract：:Heart rate oscillates in synchrony with respiration. Several methods have been employed to assess this 'sinus arrhythmia', as an index of autonomic nervous system function. This paper proposes a new, easily computed measure, R, which is relatively resistant to the major nonrespiratory sources of variation, including p...

journal_title：Biometrics

authors： Weinberg CR,Pfeifer MA

更新日期：1984-09-01 00:00:00

abstract：:Epidemiolgic studies have strongly suggested that a vast majority (80-90%) of cancers are caused by radiation, chemical and biologic agents; the remainder result from endogenous or genetic factors. Biologically, cancer is most probably the end result of a complex multistage process and therefore may be due to a sequen...

journal_title：Biometrics

authors： Lilienfeld AM

更新日期：1982-03-01 00:00:00

abstract：:The data set presented relates a binomial response to ordered levels of an explanatory variable, representing doses of a drug, with data collected at several centers. A study goal is to test independence of the response and the ordinal factor, assuming under the alternative only that the binomial parameter is a monoto...

journal_title：Biometrics

authors： Agresti A,Coull BA

更新日期：1996-09-01 00:00:00

abstract：:Inference regarding the inclusion or exclusion of random effects in linear mixed models is challenging because the variance components are located on the boundary of their parameter space under the usual null hypothesis. As a result, the asymptotic null distribution of the Wald, score, and likelihood ratio tests will ...

journal_title：Biometrics

authors： Lee OE,Braun TM

更新日期：2012-06-01 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 consider methods for estimating the treatment effect and/or the covariate by treatment interaction effect in a randomized clinical trial under noncompliance with time-to-event outcome. As in Cuzick et al. (2007), assuming that the patient population consists of three (possibly latent) subgroups based on treatment p...

journal_title：Biometrics

authors： Li S,Gray RJ

更新日期：2016-09-01 00:00:00

abstract：:Increasingly, genetic studies of tumors of the same histologic diagnosis are elucidating subtypes that are distinct with respect to clinical endpoints such as response to treatment and survival. This raises concerns about the efficiency of using the simple log-rank test for analysis of treatment effect on survival in ...

journal_title：Biometrics

authors： Li Y,Betensky RA,Louis DN,Cairncross JG

更新日期：2002-03-01 00:00:00

abstract：:If the regulatory requirements are symmetrical, the use of symmetrical confidence intervals as a decision rule for bioequivalence assessment leads, as shown by simulations, to better level properties and an inferior power compared to a rule based on shortest confidence intervals. A choice between these two approaches ...

journal_title：Biometrics

authors： Mandallaz D,Mau J

更新日期：1981-06-01 00:00:00