Some distribution properties of the sample species-diversity indices and their applications.

abstract：:Some new scale estimators for the censored two-sample accelerated life model are introduced. They are zeros of some integrated weighted difference between the two cumulative hazard estimators. These estimators are asymptotically normal. The weight is chosen to result in estimators whose asymptotic variances do not inv...

journal_title：Biometrics

authors： Yang S

更新日期：1998-09-01 00:00:00

abstract：:Genomic data are often characterized by a moderate to large number of categorical variables observed for relatively few subjects. Some of the variables may be missing or noninformative. An example of such data is loss of heterozygosity (LOH), a dichotomous variable, observed on a moderate number of genetic markers. We...

journal_title：Biometrics

authors： Houseman EA,Coull BA,Betensky RA

更新日期：2006-12-01 00:00:00

abstract：:We propose optimal choice of the design parameters for random discontinuation designs (RDD) using a Bayesian decision-theoretic approach. We consider applications of RDDs to oncology phase II studies evaluating activity of cytostatic agents. The design consists of two stages. The preliminary open-label stage treats al...

journal_title：Biometrics

authors： Trippa L,Rosner GL,Müller P

更新日期：2012-03-01 00:00:00

abstract：:Multistage selection with fixed proportions and selection indices based on covariates of the target variable is studied. Assuming a multivariate normal distribution before the selection, expressions are presented for the expectation and the variance of the target variable in the retained subpopulation. As the numerica...

journal_title：Biometrics

authors： Norell L,Arnason T,Hugason K

更新日期：1991-03-01 00:00:00

abstract：:With the internet, a massive amount of information on species abundance can be collected by citizen science programs. However, these data are often difficult to use directly in statistical inference, as their collection is generally opportunistic, and the distribution of the sampling effort is often not known. In this...

journal_title：Biometrics

authors： Giraud C,Calenge C,Coron C,Julliard R

更新日期：2016-06-01 00:00:00

abstract：:Traditional studies of short-term air pollution health effects use time series data, while cohort studies generally focus on long-term effects. There is increasing interest in exploiting individual level cohort data to assess short-term health effects in order to understand the mechanisms and time scales of action. We...

journal_title：Biometrics

authors： Szpiro AA,Sheppard L,Adar SD,Kaufman JD

更新日期：2014-03-01 00:00:00

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 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：:The study of dynamical models of HIV infection, based on a system of nonlinear ordinary differential equations (ODE), has considerably improved the knowledge of its pathogenesis. While the first models used simplified ODE systems and analyzed each patient separately, recent works dealt with inference in non-simplified...

journal_title：Biometrics

authors： Guedj J,Thiébaut R,Commenges D

更新日期：2007-12-01 00:00:00

abstract：:For the same number of observations in a small-sample clinical trial with dichotomous outcome, the statistical power associated with a two-sample design, analyzed by Fisher's exact test, is slightly greater than that associated with a matched design, analyzed by McNemar's test, and hence of the matched design, is mono...

journal_title：Biometrics

authors： Wacholder S,Weinberg CR

更新日期：1982-09-01 00:00:00

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：:Missing values appear very often in many applications, but the problem of missing values has not received much attention in testing order-restricted alternatives. Under the missing at random (MAR) assumption, we impute the missing values nonparametrically using kernel regression. For data with imputation, the classica...

journal_title：Biometrics

authors： Wang H,Zhong PS

更新日期：2017-09-01 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：:Logistic regression is a popular tool for risk analysis in medical and population health science. With continuous response data, it is common to create a dichotomous outcome for logistic regression analysis by specifying a threshold for positivity. Fitting a linear regression to the nondichotomized response variable a...

journal_title：Biometrics

authors： Schörgendorfer A,Branscum AJ,Hanson TE

更新日期：2013-06-01 00:00:00

abstract：:Objective measures of oxygen consumption and carbon dioxide production by mammals are used to predict their energy expenditure. Since energy expenditure is not directly observable, it can be viewed as a latent construct with multiple physical indirect measures such as respiratory quotient, volumetric oxygen consumptio...

journal_title：Biometrics

authors： Tekwe CD,Zoh RS,Bazer FW,Wu G,Carroll RJ

更新日期：2018-03-01 00:00:00

abstract：:Multipoint linkage analysis is being performed routinely in medical genetic studies to localize disease genes. This likelihood-based method is very computationally intensive. Exact computations are thus formidable for problems with large number of genetic markers and complex pedigrees. This paper proposes a Monte Carl...

journal_title：Biometrics

authors： Lin S

更新日期：1996-12-01 00:00:00

abstract：:At any age the mean residual life function gives the expected remaining life at that age. Reliabilists and biometricians have found it useful to categorize failure distributions by the monotonicity properties of the mean residual life function. Hollander and Proschan (1975, Biometrika 62, 585-593) have derived tests o...

journal_title：Biometrics

authors： Chen YY,Hollander M,Langberg NA

更新日期：1983-03-01 00:00:00

abstract：:In this article, we consider two-phase sampling in the situation in which all covariates are categorical. Two-phase designs are appealing from an efficiency perspective since they allow sampling to be concentrated in informative cells. A number of likelihood-based methods have been developed for the analysis of two-ph...

journal_title：Biometrics

authors： Ross M,Wakefield J

更新日期：2013-06-01 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：: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：: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 clinical trial design in which the endpoint is measured both at baseline and at the end of the study is used in a variety of situations. For two-group designs, test such as the t test or analysis of covariance are commonly used to evaluate treatment efficacy. Often such pretest-posttest trials restrict participati...

journal_title：Biometrics

authors： Follmann DA

更新日期：1991-06-01 00:00:00

abstract：:A life table estimates probabilities of surviving and of dying as well as death rates, as these would apply in a stationary population with the same underlying continuous mortality curve as the observed population. We have derived approximations to the probability of surviving that require no iteration, do not depend ...

journal_title：Biometrics

authors： Keyfitz N,Frauenthal J

更新日期：1975-12-01 00:00:00

abstract：:Functional mapping is a useful tool for mapping quantitative trait loci (QTL) that control dynamic traits. It incorporates mathematical aspects of biological processes into the mixture model-based likelihood setting for QTL mapping, thus increasing the power of QTL detection and the precision of parameter estimation. ...

journal_title：Biometrics

authors： Yang J,Wu R,Casella G

更新日期：2009-03-01 00:00:00

abstract：:A broad approach to the design of Phase I clinical trials for the efficient estimation of the maximum tolerated dose is presented. The method is rooted in formal optimal design theory and involves the construction of constrained Bayesian c- and D-optimal designs. The imposed constraint incorporates the optimal design ...

journal_title：Biometrics

authors： Haines LM,Perevozskaya I,Rosenberger WF

更新日期：2003-09-01 00:00:00

abstract：:Consider case control analysis with a dichotomous exposure variable that is subject to misclassification. If the classification probabilities are known, then methods are available to adjust odds-ratio estimates in light of the misclassification. We study the realistic scenario where reasonable guesses, but not exact v...

journal_title：Biometrics

authors： Gustafson P,Le ND,Saskin R

更新日期：2001-06-01 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：:Matched case-control designs are commonly used in epidemiologic studies for increased efficiency. These designs have recently been introduced to the setting of modern imaging and genomic studies, which are characterized by high-dimensional covariates. However, appropriate statistical analyses that adjust for the match...

journal_title：Biometrics

authors： Qian J,Payabvash S,Kemmling A,Lev MH,Schwamm LH,Betensky RA

更新日期：2014-03-01 00:00:00

abstract：:It is not, in general, possible to include all relevant risk factors in a model of survival or disease incidence. This heterogeneity must be accounted for in the interpretation, as it can imply otherwise unexpected results. This is illustrated by diabetic nephropathy, a serious complication experienced by some diabeti...

journal_title：Biometrics

authors： Hougaard P,Myglegaard P,Borch-Johnsen K

更新日期：1994-12-01 00:00:00

abstract：:In studying the relationship between an ordered categorical predictor and an event time, it is standard practice to include dichotomous indicators of the different levels of the predictor in a Cox model. One can then use a multiple degree-of-freedom score or partial likelihood ratio test for hypothesis testing. Often,...

journal_title：Biometrics

authors： Dunson DB,Herring AH

更新日期：2003-12-01 00:00:00