Data envelopment analysis was introduced as a nonparametric linear programming estimator to estimate the production frontier and technical efficiency of observed production units. Allowing multiple inputs and multiple outputs, the approach can be considered a nonparametric quantile regression...

It is well known in the Data Envelopment Analysis literature that proper variable selection is necessary for the reliable measurement of efficiency. Omitting production relevant variables and/or including irrelevant variables will lead to biased measurement. It is also known that the sample size...