I'm trying to create a linear mixed effect model where I have three fixed effects (X1, X2, X3) and one random effect (Z1) using fitlmematrix.m.
The issue I'm having is that I'm not sure how to get results for "mixed" terms, i.e. X1*X2, X2*X3, X1*X2*X3. When I look up the help for the linear mixed model class I can see the "Formula" member, but I'm not sure how to specify it when calling fitlmematrix.m.
I'm under the impression that LMMs handle mixed terms differently to including them directly in the system matrix (i.e. creating X4 = X1*X2 etc).
Any help on how to get the mixed terms into the model would be greatly appreciated, Andrew