Thanks for the clarification Brian.
I have an additional question why is the cluster option available for
ivtobit but not for tobit? I know that if there is heteroskedasticity tobit
will produce estimators that are inconsistent and cluster only takes care of
the problem in the standard errors. But what if I have say a panel of two
years and I am doing pooled tobit and I want to use cluster to account for
the fact that the observations are repeated twice? I think that will be an
instance where cluster in tobit is valid. So far I have been using intreg
which allows for cluster but it will be easier if tobit had that option.
Anyway, I was wondering why the option is not available for tobit but it is
for ivtobit.
Alejandro,
