摘要:

We introduce new rank tests for testing independence. The new testing procedures are sensitive not only for grade linear correlation, but also for grade correlations of higher-order polynomials. The number of polynomials involved is determined by the data. Model selection is combined with application of the score test in the selected model. Whereas well-known tests as Spearman's test or Hoeffding's test may completely break down for alternatives that are dependent but have low grade linear correlation, the new tests have greater power stability. Monte Carlo results clearly show this behavior. Theoretical support is obtained by proving consistency of the new tests.

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473844

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We consider the one-way layout for comparingktreatment effects μi, 1 ≤i≤k.Hayter earlier proposed a one-sided studentized range test (OSRT) for testing the null hypothesisHμO: μ1= μ2= ··· = μkagainst the simple ordered alternativeHA: μ1≤ μ2≤ ··· ≤ μkwith at least one strict inequality. The OSRT gives a set of simultaneous confidence intervals for all ordered pairwise differences μj- μi,i<j. These intervals are one-sided and have infinite upper bounds. The confidence interval procedure proposed in this article maintains the sensitivity of the OSRT in detecting the ordered differences μj- μi> 0, but provides two-sided finite confidence intervals if the sample averages are all far apart.

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473845

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Tests of homogeneity are being increasingly used for the analysis of event time data, but relatively little attention has been paid to their distributional properties in settings with small to moderate sample sizes. Here we consider tests of homogeneity for recurrent event data in which the null model is a Poisson process and the alternative is a mixed Poisson process. We examine score and adjusted score statistics in the context of parametric and semiparametric regression models, where the adjustments correct for the bias induced by substituting the maximum likelihood estimates of the parameters into the test statistic. We report the results of simulation studies suggesting that the adjusted score statistics are superior in terms of size and power. We also find that the adjusted score test in the semiparametric regression model does not perform particularly well in small samples, but the adjusted score test based on a piecewise exponential model has satisfactory performance. The latter thus provides an attractive alternative in terms of robustness and frequency properties, and we recommend using this test statistic for datasets of small to moderate size. We illustrate and contrast the methods by application to a clinical trial.

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473846

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Two-sample weighted log-rank statistics are used in the presence of right censoring to test whether failure times from two populations have different survival distributions. Kosorok has showed that large families of these statistics form stochastic processes indexed by weight functions, and that these function-indexed statistics can be used to construct versatile test procedures simultaneously sensitive to a wide array of both ordered hazards and stochastic ordering alternatives. The complexity of the asymptotic distribution of these statistics precludes obtainingpvalues through analytical means. In this article we develop a Monte Carlo method for accurately obtaining thesepvalues, and we evaluate the moderate sample size properties of this method and compare the power of function-indexed statistics with previously developed weighted log-rank tests. These statistics are also examined in a data analysis of the Beta-Blocker Heart Attack Trial (BHAT). The results of this article demonstrate that the proposed function-indexed procedures can be more powerful for a variety of clinically relevant alternatives than previously described weighted log-rank tests.

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473847

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Bootstrap Methods and Their Application.A. C. Davison and D. V. Hinkley. New York: Cambridge University Press, 1996. ISBN 0–521–57391–2. x + 582 pp. $100. Reviewed by Thomas M. Loughin

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473848

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473849

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This article has no abstract

ISSN:0162-1459    

DOI:10.1080/01621459.1999.10473813

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor