Simulated Likelihood Estimation of the Normal-Gamma Stochastic Frontier Function.

The normal-gamma stochastic forntier model was proposed in Greene and Beckers and Hammond as an extension of the normal-exponential proposed in the original derivations of the stochastic frontier by Aigner, Lovell, and Schmidt. The normal-gamma model has the virtue of providing a richer and more flexible parameterization of the inefficiency distribution in the stochastic frontier model than either of the canonical forms, normal-half norma and normal-exponential.