Wilcoxon-type rank-sum statistics for selecting the best population: Some advances

Abstract

In this article, we introduce three new nonparametric procedures for testing the equality of two lifetime distributions. The proposed testing processes are based on appropriately modified Wilcoxon-type rank-sum statistics. The exact null distribution of these statistics is studied and closed formulae for the corresponding exact probability of correct selection of the best population are derived for the class of Lehmann alternatives. A detailed numerical study is carried out to elucidate the performance of the proposed testing schemes. For illustration purposes, a real data application is presented in some detail. © 2020 John Wiley & Sons, Ltd.