摘要:

AbstractMany epidemiologic investigations are designed to study the effects of multiple exposures. Most of these studies are analysed either by fitting a risk‐regression model with all exposures forced in the model, or by using a preliminary‐testing algorithm, such as stepwise regression, to produce a smaller model. Research indicates that hierarchical modelling methods can outperform these conventional approaches. I here review these methods and compare two hierarchical methods, empirical‐Bayes regression and a variant I call ‘semi‐Bayes’ regression, to full‐model maximum likelihood and to model reduction by preliminary testing. I then present a simulation study of logistic‐regression analysis of weak exposure effects to illustrate the type of accuracy gains one may expect from hierarchical methods. Finally, I compare the performance of the methods in a problem of predicting neonatal mortality rates. Based on the literature to date, I suggest that hierarchical methods should become part of the standard approaches to multiple

ISSN:0277-6715    

DOI:10.1002/sim.4780120802

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn the context of competing risks the Kaplan—Meier estimator is often unsuitable for summarizing failure time data. We discuss some alternative descriptive methods including marginal probability and conditional probability estimators. Two‐sample test statistics are also presen

ISSN:0277-6715    

DOI:10.1002/sim.4780120803

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

年代:1993

数据来源: WILEY

摘要:

AbstractSequential monitoring has been a topic of major interest in clinical trials methodology over the past two decades. This paper presents a unified conceptual framework for sequential monitoring that covers a wide variety of monitoring procedures in a wide variety of clinical trial settings. The central elements of this framework consist of a suitable concept of statistical information and a scheme for using this concept as a basis for summarizing the accumulating results of a trial in a standardized form, through a stochastic process that can be shown to approximate classical Brownian motion. The ideas are developed in a simple step‐by‐step fashion and illustrated by several practical examp

ISSN:0277-6715    

DOI:10.1002/sim.4780120804

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe identify two types of random loss that may afflict registries which use ‘passive follow‐up’. The effects of these errors on estimates related to survival are examined mathematically and numerically. A procedure for correcting the attendant biases is suggested, and its strengths and limitations are exp

ISSN:0277-6715    

DOI:10.1002/sim.4780120805

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn planning experiments having two groups of equal but small size, investigators face the uncertainty of power calculations that rely on asymptotic methods. This paper presents a method for determining power for two‐sided tests. I compare two randomization tests, Fisher's exact test (FET), and the mid‐P(MID), with the uncorrected chi‐square test (CHI). Results show power as a function of relative risk for these methods, and assesses their relative power and type I error rates. MID is shown to have intermediate power between CHI, which is the most powerful, and FET, the least powerful. Situations are shown in which CHI and MID occasionally exceed the nominal level

ISSN:0277-6715    

DOI:10.1002/sim.4780120806

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

年代:1993

数据来源: WILEY

摘要:

AbstractReport of a workshop held on 18 July 1991 at the National Institutes of Health in Bethesda, MD. Workshop participants were: William J. Blot, National Cancer Institute, Bethesda, MD; Ronald S. Brookmeyer, Johns Hopkins University, Baltimore, MD; Theodore Colton, Boston University, Boston, MA; Genrose D. Copley, National Cancer Institute, Rockville, MD; Mitchell Gail, National Cancer Institute, Rockville, MD; Nancy L. Geller, National Heart, Lung and Blood Institute, Bethesda, MD; Frank E. Harrell, Jr., Duke University, Durham, NC; Marthana Hjortland, National Cancer Institute, Rockville, MD; Elizabeth Holly, Northern California Cancer Center, Belmont, CA; Michel Ibrahim, University of North Carolina, Chapel Hill, NC; Stephen W. Lagakos, Dana‐Farber Cancer Institute, Boston, MA (written report only); G. Iris Obrams, National Cancer Institute, Rockville, MD; Wasema Rida, National Institute of Allergy and Infectious Diseases, Rockville, MD; Jonathan Samet, New Mexico Tumor Registry, Albuquerque, NM; Robert F. Woolson, University of Iowa, Iowa City, IA; and Mimi C. Yu, University of Southern California, Los Angeles, CA (Chair

ISSN:0277-6715    

DOI:10.1002/sim.4780120807

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

年代:1993

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780120808

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

年代:1993

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780120801

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

年代:1993

数据来源: WILEY