GLM with non-parametric post hoc testing?


New Member
Hi guys,
I have a question regarding the appropriate use of comparisons for independent samples (3 factor levels), please.
Overall sample size is N=546, subsamples: 218 or 228 or 100), convenience sampling, stratified.
I use ANOVA with post hoc Tukey, if Levene indicates variance homogeneity.
My question:
If there no equal variance: What do do?
a) Using Kruskal-Wallis?
> For post hoc: Do I use Mann-Whitney for pairwise comparisons (if so: what about the alpha inflation?)?
b) Still using GLM but with non-parametric post hocs?
> If so: which one? Tamhane? Dunnett or Games-Howelll?
> What about F, can I still use it? isn’t H then the more appropriate statistic?
> Why gives GLM anyway the option of running on-parametric tests of homoscedasticity is an assumption (am confused ;-( )

Thanks for any input on this one ☺


Less is more. Stay pure. Stay poor.
So in your overall GLM model, do you have homoscedasticity of residuals? If not, on options may be using Kruskal Wallis followed by Mann-Whitney.