If a Kruskal-Wallis test is used, what is the minimum number of independent samples?

If a Kruskal-Wallis test is used, what is the minimum number of independent samples?

• A. Two
• B. Four
• C. Five
• D. Three

Answer: (D)

Kruskal-Wallis is a nonparametric method used to compare multiple independent samples by ranking all observations together and testing whether the median ranks are the same across the groups. It’s designed for three or more groups; with only two independent samples, the appropriate test is the Mann-Whitney U test. Because Kruskal-Wallis analyzes differences across three or more groups, the minimum number of independent samples is three. When you have three or more groups, you compute the H statistic from the average ranks of each group and compare it to a chi-square distribution with degrees of freedom equal to the number of groups minus one. So the smallest scenario where this test applies is three independent samples.

Kruskal-Wallis is a nonparametric method used to compare multiple independent samples by ranking all observations together and testing whether the median ranks are the same across the groups. It’s designed for three or more groups; with only two independent samples, the appropriate test is the Mann-Whitney U test. Because Kruskal-Wallis analyzes differences across three or more groups, the minimum number of independent samples is three. When you have three or more groups, you compute the H statistic from the average ranks of each group and compare it to a chi-square distribution with degrees of freedom equal to the number of groups minus one. So the smallest scenario where this test applies is three independent samples.