A non-parametric method to compare two or more populations, when the samples are independent and the data are either ordinal or interval but not normal, is the:
A) Kruskal-Wallis test.
B) Friedman test.
C) Wilcoxon rank sum test.
D) Wilcoxon signed rank sum test.

Question

Quizplus · Accepted Answer

The Kruskal-Wallis test is a non-parametric method used to compare two or more independent samples when the data are either ordinal or interval but not normal. It is a good choice for this question because it can handle more than two groups and does not require the assumption of normality. The Friedman test is a non-parametric method to compare three or more matched or repeated measures when the data are not normally distributed, so it is not appropriate for this question. The Wilcoxon rank sum test and the Wilcoxon signed rank sum test are non-parametric tests used to compare two independent or matched samples, respectively, when the data are not normally distributed. However, they are limited to two groups only, so they are not suitable for this question.

A Non-Parametric Method to Compare Two or More Populations, When