Dear Signe,
I know (and I've already used) that for stata 7 and 8 exhist an extension of ivreg command called ivreg2 that allows for GMM and, in its more recent version for Stata 8, also other types of estimators for dynamic panel, such as Limeted Information maximum likeliohood. Ivreg2 is an extension of ivreg, so it's useful also for that panel that are not dynamic but that are affected from enogeneity problems.
Best Regards,
Andrea Sisto
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