A Wilcoxon rank sum test for comparing two populations involves two independent samples of sizes 15 and 20. The value of the unstandardised test statistic is T = 225. The value of the standardised test statistic is z = -1.50.

Question

Quizplus · Accepted Answer

The Wilcoxon rank sum test involves ranking all observations from both samples together and then summing the ranks for one of the samples. The standardised test statistic z is calculated based on the rank sum, sample sizes, and expected mean and variance under the null hypothesis. Given the unstandardised test statistic T and sample sizes, a z value of -1.50 is plausible.

A Wilcoxon Rank Sum Test for Comparing Two Populations Involves