Data Envelopment Analysis (DEA) with integer and negative inputs and outputs

Selecting an appropriate model in DEA to calculate the efficiency of DMUs has always been considered by science researchers. Original models of DEA have been implemented only for some technologies which have positive inputs and outputs feature. In this paper, first we examine semi-oriented radial measure (SORM) model to calculate the efficiency of units based on negative data. After providing a review of the disadvantages to the mentioned model, we present its modified model. Then a new model is offered to evaluate the main units in the presence of negative integer data. Finally, a numerical example is provided in which the efficiency of the units is calculated by using the mentioned models.