期刊名称：Journal of Modern Applied Statistical Methods
出版年度：2006
卷号：5
期号：1
页码：2
出版社：Wayne State University
摘要：Confidence intervals must be robust in having nominal and actual probability coverage in close agreement. This article examined two ways of computing an effect size in a two-group problem: (a) the classic approach which divides the mean difference by a single standard deviation and (b) a variant of a method which replaces least squares values with robust trimmed means and a Winsorized variance. Confidence intervals were determined with theoretical and bootstrap critical values. Only the method that used robust estimators and a bootstrap critical value provided generally accurate probability coverage under conditions of nonnormality and variance heterogeneity in balanced as well as unbalanced designs.
关键词：Effect size; confidence interval; trimmed means; Winsorized variance; noncentral distribution
