The aim of the paper is to present a statistical methodology allowing the estimation of technical performances of production units within a particular sector of activities. The approach is such that it allows the introduction of exogenous environmental factors explaining a part of the apparent inefficiency. The statistical procedure will be based on the observation of production activities of a set of firms. The method is illustrated through the analysis of technical efficiencies of railway companies.
Deprins, D., & Simar, L. (1989). Estimating technical inefficiencies with corrections for environmental conditions. Annals of Public and Cooperative Economics, 60(1), 81-102. https://doi.org/10.1111/j.1467-8292.1989.tb02010.x (Original work published 1989)