F. Hosseinzadeh Lotfi - Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran.
M. Rostamy mal khalifeh - Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran.
M. Heydari Alvar - Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran.

In this paper, a method for ranking efficient DMUs based on TOPSIS has been proposed. The difference between the distance of the center of gravity of all efficient DMUs to the ideal point and the anti-ideal point after and before deleting efficient DMUs one by one is the criteria of ranking efficient DMUs. In this paper, the proposed method is compared with AP (input oriented), MAJ (input oriented), AP(output oriented), MAJ (output oriented) models and norm l۱ method. This comparison shows that the proposed method is better than the above-mentioned models. The proposed method is also always feasible and simpler in comparison with other methods.

Data Envelopment Analysis, Decision making unit (DMU), Ranking models, TOPSIS