the estimation of piecewise linear cost efficiency in integer-valued data envelopment analysis

One of the efficiency concepts that is evaluated in data envelopment analysis(dea) is cost efficiency. in all studied done in the field of cost efficiency, the costs have been applied in the model in a linear form. it is while in some cases, especially when savings and observance of consumption patterns are important, the costs are usually considered as stepwise. in this article, considering the costs in the piecewise linear form, we first present a model to evaluate cost efficiency and then this model is developed for the state that the inputs and outputs are integer, in order to be able to evaluate the efficiency of units with integer inputs and piecewise linear costs. at the end, the results of the model are explained using a numerical example.