A Note on Parameterizing Input Distance Functions: Does the Choice of a Functional Form Matter?

We use a Monte Carlo experiment to compare the quadratic and translog functional forms in terms of their ability to approximate known frontiers that possess convex curvature. Unlike some of the existing simulation studies that have studied this topic, we find that both functional forms provide a reliable approximation to a true frontier. Our results lend support to existing explanations concerning the translog form’s innate propensity to yield convex, rather than concave, frontier estimates.