Three-level multiple membership models in brms

Interfaces brms
1

I have been examining the relationship between teachers’ attitudes and students’ grades using multiple membership models to account for classes cotaught by two teachers. The models look something like this:

grades ~ teacher_attitude + controls + (1 | mm(teacher1ID, teacher2ID, weights = cbind(w1, w2))

I’ve just learned from the school that teachers are grouped into teams that meet daily. Each team has its own norms and culture that may make teacher attitudes and/or grades more similar within teacher teams, so this seems important to account for in the model. Is it possible to nest a multiple membership grouping term in another level in brms? (Both teachers in cotaught classes are always in the same team.) I tried:

grades ~ ... + (1 | team/mm(teacher1ID, teacher2ID, weights = cbind(w1, w2))

but received the following error:

Error: Illegal grouping term 'team:mm(teacher1ID, teacher2ID, weights = cbind(w1, w2))'. It may contain only variable names combined by the symbol ':'

Is there another way to do this?

Thanks,
Kate

2

You could simply use (1 | team) + (1 | mm(teacher1ID, teacher2ID, weights = cbind(w1, w2)). This is equivalent to what you tried as long as the teacher IDs are unique across teams, that is, as long as no two differents teachers have the same ID.

3

Thank you!