I have a 2x2 study design to test the interaction between two drugs, with a single variable outcome. The data are very much non-parametric and it seems that a good alternative to the traditional two-way ANOVA is to use a permutation ANOVA, e.g. aovp(outcome ~ drugA * drugB)
from the lmperm
package.
My question is what is the most appropriate way to run a post-hoc test on the resulting aovp
object, to make adjusted comparisons between specific drug combinations? Any advice is appreciated.