ISSN:0277-6715    

DOI:10.1002/sim.4780141502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780141503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractWe address the problem of testing for independence betweenXandYin two situations. In the first we assume that the joint distribution ofXandYis unknown but the observations onXandYare identifiable. In the second case we assume that the distribution of(X, Y)is exchangeable. Here we consider both when(X, Y)are identifiable and when they are not. We illustrate applications to the testing of independence in DNA databases and in twin studies.

ISSN:0277-6715    

DOI:10.1002/sim.4780141504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBiostatistical concepts and methods apply to various problems arising in actual U.S. legal cases. These involve: measures of association, assessing the potential effect of omitted variables and the Peters—Belson approach to regression. In particular, we present the inapplicability of Fisher's exact test in the case where the process determining the marginal sample sizes is not independent of the hypothesis under study by the 2 × 2 table. We adapt Cornfield's procedure to assess whether the omission of another factor could have contributed to a non‐significant finding of the effect of the major factor under investigation. Finally, we demonstrate the relevance and utility of the Peters—Belson regression methodology to equal pay and promotion

ISSN:0277-6715    

DOI:10.1002/sim.4780141505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780141506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780141507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBiostatisticians in research juggle many responsibilities: short‐term consulting; long‐term collaboration; teaching/training, and statistical research. In an institutionally‐supported service group, the biostatistician frequently faces allocation of limited resources (time and effort) over multiple projects, none of which individually supports the biostatistician. In addition to the level of support provided by a specific project, there are several major issues with resource allocation: the quality of the science and data in the project; the possibility that long‐term support develops from the work; personal and institutional considerations that involve the specific investigator or project.In this paper, we discuss these considerations along with some examples. We present guidelines for making decisions about allocation of time and effort and the possible implications of setting such pri

ISSN:0277-6715    

DOI:10.1002/sim.4780141508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractPaired data occur in many experimental situations. When one views the subjects as a random sample from some large population, it may seem reasonable to model the data according to the typical one‐way random effects analysis of variance (ANOVA). It is then usually of interest to estimate variance components and intraclass correlation. These estimators can be biased if key assumptions are violated, leading to erroneous interpretations and conclusions. We focus upon assumptions about the equality or inequality of means and/or variances of the two measures on each subject. In the framework of the one‐way random effects ANOVA model, and three generalizations of it, we document estimators obtained as solutions to the likelihood equations. We consider the potentially serious effects of mistaken assumptions. Our findings suggest that the most general model considered is most desirable if consistent and efficient estimation of the between‐subject variance component and intraclass correlation is the main goal. We also briefly connect our exposition to the study of reliability or agre

ISSN:0277-6715    

DOI:10.1002/sim.4780141509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA major assumption of the Cox proportional hazards model is that the effect of a given covariate does not change over time. If this assumption is violated, the simple Cox model is invalid, and more sophisticated analyses are required. This paper describes eight graphical methods for detecting violations of the proportional hazards assumption and demonstrates each on three published datasets with a single binary covariate. I discuss the relative merits of these methods. Smoothed plots of the scaled Schoenfeld residuals are recommended for assessing PH violations because they provide precise usable information about the time dependence of the covariate effects.

ISSN:0277-6715    

DOI:10.1002/sim.4780141510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780141511

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY