xthtaylor: Instrument variables for Hausman Taylor estimator

[Tracy Yang]

According to the manual, it looks like Hausman Taylor is using time invariant (TI) exogeneous variables as instrument variables (IV) for TI endogeneous variables. Is it possible that I only use one of the TI exogeneous variables as the IV instead of using all? How to do it in xthtaylor?

[Sebastian Kripfganz]

The Hausman-Taylor estimator is using time-varying exogenous variables as instruments for time-invariant endogenous variables. If there are are time-varying variables which you do not want to use as instruments for time-invariant regressors, then simply specify them as endogenous.