How to do pairwise comparisons within groups after mixed

[Peter Thompson]

Hi all.
I am trying to do contrasts after the following mixed model in Stata 18:

mixed y group##time || id:

There are six groups and three time points.

I want to do all pairwise comparisons of group only within each time point, and all pairwise comparisons of time points only within each group.

contrast r.time@group

and

contrast r.group@time

only do comparisons vs the reference level in each case.

pwcompare time#group

does all pairwise comparisons for all combinations of group and time. How do I restrict the pairwise comparisons between time points to only within the same group, and comparisons between groups to only within the same time points?

Thanks, and apologies for what must be an elementary question.

[Clyde Schechter]

There may be a way to do it in a single command that I'm not thinking of. But you can do this:

forvalues g = 1/6 {
    margins time, at(group = `g') pwcompare
}

Note: Assumes the group variable takes on the values 1 through 6. Modify the -forvalues- command accordingly if this is not the case.

[Peter Thompson]

Thank you so much Clyde, that works perfectly!