I am running one-way ANOVA to determine whether several groups have differing means. I also run post-hoc multiple comparison to determine which means are different. The problem is that I need to have it showed which sets of groups are not different (like REGWQ test does). The problem is that Levene's test shows that the data I use do not have equal variances, thus, I cannot run REGWQ test.
Is there any alternative to REGWQ for cases when equal variances are not assumed (except for non-parametric K-W test)?
I use SPSS but can also try R.
Best Answer
If I understand your question correctly, then yes SPSS has Unequal Sample Sizes and Unequal Variances (Post Hoc Tests algorithms): Games-Howell, Tamhane's T2, Dunnett's T3, and Dunnett's C. You would have to figure out yourself which one to use given your data, design and research objectives.
As for R, you can run the Games-Howell test in the
userfriendlyscienceR package (see also here for an example) and Dunnett's T3. For the other tests there don't seem to be packages/functions available for R.