In 1944, Marschak and Andrews published a seminal paper on how to obtain consistent estimates of a production technology. The original formulation of the econometric model regarded the joint estimation of the production function together with the first-order nec-essary conditions for profit-maximizing behavior. In the seventies, with the advent of econometric duality, the preference seemed to have shifted to a dual approach. Recently, however, Mundlak resurrected the primal-versus-dual debate with a provocative paper ti-tled “Production Function Estimation: Reviving the Primal. ” In that paper, the author as-serts that the dual estimator, unlike the primal approach, is not efficient because it fails to utilize all the available information....