A nonparametric method to compare more than two populations,when the samples are independent and the data are either ranked or quantitative but not normal,is:
A) Kruskal-Wallis test.
B) Friedman test.
C) Wilcoxon rank sum test.
D) Wilcoxon signed rank test.
E) Sign test for comparing paired samples.

Question

Quizplus · Accepted Answer

The Kruskal-Wallis test is a nonparametric method used to compare more than two independent populations when data are either ranked or quantitative but not normally distributed. It is an extension of the Wilcoxon rank-sum test (also known as the Mann-Whitney U test) for two populations. The Friedman test and the Wilcoxon signed-rank test are both used for paired data, and the sign test is used for comparing paired samples where the data are ordinal or continuous but not necessarily normally distributed. Therefore, the Kruskal-Wallis test is the best choice for comparing more than two independent populations with non-normal data.

A Nonparametric Method to Compare More Than Two Populations,when the Samples