en تحقیق در عملیات Operations Research پژوهشي Research Data envelopment analysis operates as a tool for appraising the relative efficiency of a set of homogenous decision making units. This methodology is applied widely in different contexts. Regarding to its logic, DEA allows each DMU to take its optimal weight in comparison with other DMUs while a similar condition is considered for other units. This feature is a bilabial characteristic which optimizes the performance of units in one hand. This flexibility on the other hand threats the comparability of different units because different weighting schemes are used for different DMUs. This paper proposes a unified model for determination of a common set of weights to calculate DMUs efficiency. This model is developed based on a multi objective fractional linear programming model that considers the original DEA's results as ideal solution and seeks a set of common weights that rank the DMUs and increase the model's discrimination power. Comparison of the proposed method with some of the previously presented models has shown its advantages as a DMUs ranking model. DEA, Common Set of Weights, Multi Objective Fractional Linear Programming, Membership Function, Ranking. 207 214 http://ijiepr.iust.ac.ir/browse.php?a_code=A-10-672-1&slc_lang=en&sid=1 Seyed Hossein Razavi Hajiagha s.hossein.r@gmail.com 180031947532846003229 180031947532846003229 Yes Institute for Trade Studies and Research Shide Sadat Hashemi shide_hashemi@yahoo.com 180031947532846003230 180031947532846003230 No Department of management, Kashan Branch, Islamic Azad University, Kashan, Iran Hannan Amoozad Mahdiraji h.amoozad@ut.ac.ir 180031947532846003231 180031947532846003231 No Department of management, Kashan Branch, Islamic Azad University, Kashan, Iran