variable and the disturbances, the estimated standard error of the two-step GMM
estimator was found to be downward biased.Meanwhile, Arellano and Bover (1995) used
a unifying GMM framework that looks at the efficient instrumental variable estimators
for dynamic panel data models, and they have proved that the three stage least squares
(3SLS) estimator is asymptotically equivalent to the limited information maximum
likelihood procedure (Baltagi, 2001). Therefore, the more reliable estimator among these
columns of Table 4 would be the two-step estimator of Arellano and Bover (1995) since
they use the extra moment conditions when certain stationary conditions of the initial
observation are satisfied.