Abstract: In this paper, we introduce the Fisher-Yates’s score function and Van der Waerden’s score function, four nonparametric test statistics are given for detecting changes in laction. "We give tables for the null distributions of the statistics for onesided and two-sided alternatives. We also report on some Monte-Oarlo power comparisons involving another two nonparametric test statistics, proposed by Pettitt and Schechtman.