We consider questions of efficiency and redundancy in the GMM estimation problem in which we have two sets of moment conditions, where two sets of parameters enter into one set of moment conditions, while only one set of parameters enters into the other. We then apply these results to a...

The traditional predictor of technical inefficiency proposed by Jondrow et al. (1982) is a conditional expectation. We study whether, and by how much, the predictor can be improved by using auxiliary information in the conditioning set. To do so, we use simulations to study two types of...