Stability of the Classification of Returns to Scale FDH Models in the Presence of Undesirable Data

This paper deals with the estimation of returns to scale (RTS) in free disposal hull (FDH) models for undesirable data and provides some stability intervals for preserving the RTS classification. It has been shown that the proposed stability intervals can be obtained via a polynomial-time algorithm based on the calculation of certain ratios of inputs and outputs, without solving any mathematical programming problem. The results of the study have been proved via some lemmas and theorems for undesirable data and have been illustrated by numerical example.