I have three questions.
I want to conduct a planned comparison in ANCOVA which compares three groups (n=2, n=7 and n=5) with two groups (n=11 and n=25). Is it ok to include the group with n=2 if I am only conducting a planned comparison as described above?
Is it ok to conduct an ANCOVA when I am only comparing two groups? E.g. if I wanted to compare left and right hemisphere groups, controlling for another variable.
If the DV in an ANCOVA has been transformed (because it was non-normal) does the covariate have to undergo the same transformation? E.g. If the DV is (log transformed) heart rate during an experimental condition, and the covariate is heart rate measured at baseline (which is normally distributed), does the baseline HR need to be transformed as well?