efficiency security margin of decision making units in data envelopment analysis model – case study: departments in university of science and culture

one of the most applicable methods to measure efficiency is using data envelopment analysis (dea) models. dea measures efficiency for some homogenous units (units with the same inputs and outputs) and determines efficient and non-efficient units. since the evaluated efficiency for each unit is a relative value, it is clear that each unit tries to improve its performance and preserve (or even improve) its ranking in comparison with others. the distance between efficiency values of the units makes a security margin for them. this concept is first introduced by the authors and named efficiency security margin (esm). in this paper, in addition to illustrating the concept and the motivation for it, an algorithm is proposed to measure the esm of departments in university of science and culture (usc).