Gh Tohidi - Department of Mathematics, Islamic Azad University, Central Tehran Branch, Tehran, Iran
Z Shiri Daryani - Faculty of science, Islamic Azad University, South Tehran Branch, Tehran, Iran

Inverse DEA model is a useful tool for estimating inputs/outputs level of decisionmaking units (DMU)s. It can be integrated to estimate inputs/outputs level of a two-stage network.To this end, assume that among a group of comparable two-stage DMUs, we increase outputs levelof a DMU. The question is that how much should be inputs level change in order to the efficiencylevel of all DMUs stay unchanged. This paper discuses the above mentioned question.

Inverse DEA, Network DEA, Two-stage DMU, Input/output level estimation