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Test post-hoc Kruskal Wallis

Sarah666
Level I

Hello,
I'm running a Kruskal Wallis test on JMP. I want to observe whether the score obtained in paragraph comprehension differs between 3 groups. The samples are small and unpaired: a group of 5, a group of 5, and a group of 11.
The Kruskal-Wallis test is significant. I want to carry out post-hoc tests to see which group differs from the central tendency.
Is the Wilcoxon pairwise test appropriate? I've also heard of the Dunn or Steel-Dwass tests, which give insignificant results...
What's more, Wilcoxon concerns two paired samples, which is not my case. A Mann-Whitney would be more appropriate, but I can't do it on JMP.
Thank you for your help,
Yours sincerely

3 REPLIES 3
MRB3855
Super User


Re: Test post-hoc Kruskal Wallis

Hi @Sarah666 , and welcome: You may be confusing Wilcoxon signed-rank test with Wilcoxon rank-sum test. The former is for paired samples, the latter is not. You can choose the "Wilcoxon Each Pair" (Wilcoxon rank-sum) option to do multiple comparisons you are looking for.

 

 

Sarah666
Level I

Re: Test post-hoc Kruskal Wallis

Good morning,

Thank you very much for your help.

So I conclude that the "Wilcoxon each pair" option in JMP does not require matching? In your opinion, is this a good method or should I do a Dunn or Steel-Dwass test?


THANKS

This post originally written in French and has been translated for your convenience. When you reply, it will also be translated back to French .

MRB3855
Super User


Re: Test post-hoc Kruskal Wallis

Hi @Sarah666 : Yes, you are correct. The language can be confusing. "Wilcoxon each pair" does not require matching; and what they mean by "each pair" is "each two group combination".