In this note we show, by means of several examples, that a directional distance function model cannot be matched with an additive model. Specifically, we show the difference between the directional slacks-based measure and the corresponding directional distance function.

This book surveys the state-of-the-art in efficiency and productivity analysis, examining advances in the analytical foundations and empirical applications. The analytical techniques developed in this book for efficiency provide alternative ways of defining optimum outcome sets, typically as a...