I have a panel data with about 300 units observed over a period of 4 weeks. In each week, I recorded a response that is a binary variable, y, for each unit of that week. For about 50% of the units, the response y is zero in all four weeks.
I want to fit a mixed model with time trends and individual random effects for the unit (using
Stan). But it seems odd to assume normal individual random effects given most of the units have only zeros. Do you have any suggestions on how to proceed? Should I instead use a compound model (fitting the non-zeros separately)? Any help would be greatly appreciated.