kruskall-wallis analysis problem

Comments

• mcp

  January 2020

  datasets+error.pdf

  
  
• mcp

  January 2020

  ?this morning I have the doubt I need to run a Mann Whitney... what do you think ?
• EJ

  February 2020

  Hi mcp,

  Sorry for the tardy reply. In JASP, when you select "independent samples t-test" you will be offered the option of doing the Mann-Whitney, so indeed, that's the one you need. This may also explain the error you got when you were trying to run Kruskal (but I'll forward this to the team anyway; perhaps the error message can be made more informative).

  Cheers,

  E.J.
• JohnnyB

  February 2020

  Hi mcp,

  I think that error is not just concerning the Kruskal Wallis test, but the overall ANOVA. It seems that you only have a single observation per cell of the interaction effect, so when you include that effect, there is no way of calculating the variance per cell. The error message is not very informative, and I think it will be changed in the new release of JASP.

  
  

  As for your tests: Running the Kruskal Wallis only holds in one-way setups, so with only a single factor. In order to compare levels within a factor to each other (i.e., post hoc tests), you can check the boxes for the appropriate post hoc tests. In your case, I would recommend the Dun post hoc test - from the help file:

  • Dunn: This is a non-parametric test that can be used for testing small subsets of pairs. This post hoc test is a follow up for the Kruskal-Wallis test. The p-values are corrected with the Bonferroni and Holm methods

  
  

  I hope this helps, please let me know if you have additional questions or if anything is unclear =)

  Johnny