[Carlo Lazzaro]

Nitin:
what is weird is that Stata does not offer an iv version of -nbreg-, not to to say -xtnbreg-.
When this happens, the usual reason is the lack of a sufficient statistic; therefore, Stata avoids to propose methodologically flawed tools.

[Nitin Jain]

Nitin:
what is weird is that Stata does not offer an iv version of -nbreg-, not to to say -xtnbreg-.
When this happens, the usual reason is the lack of a sufficient statistic; therefore, Stata avoids to propose methodologically flawed tools.

Fine, Carlo. Thanks for the help.