What is the appropriate panel data model when you have time dependent Y, but the X's are time-invariant (apart from the implicit time variable itself of course)?
My desired model is analogous to the following - my Y is income (which varies over time), but I want to see how growth in income is affected by gender (which is time-invariant). Thus, I have a model like:
Yit = ait + bit*gender + errors
Random effects seems to allow time-invariant X's, but doesn't quite seem appropriate and is not working in Stata either.