Congestion measurement in data envelopment analyses under weak disposability of desirable and undesirable outputs in a Two-phase Network

Congestion is one of the main issues in data envelopment analyses which have particular importance. Recently researches about congestion, whether in economic articles or in Operations Research articles in had grown increasingly. Congestion is a wasteful stage of the production process where outputs are reduced due to excessive amount of inputs. In economics, congestion is very important because elimination of it results in decrease in costs as well as increase in outputs. Therefore the benefits of recognition of density and decreasing of it are high. In this paper, we will be introduced a method for definition and calculation of congestion degree under weak disposability of desirable and undesirable outputs in a Two-phase Network. And we will present a model for definition and calculation of congestion value considering desirable and undesirable final outputs.