Ranking Efficient Decision Making Units in Data Envelopment Analysis based on Reference Set and coefficient of variation

One of the drawbacks of Data Envelopment Analysis (DEA) is the problem of lack of discrimination among efficient Decision Making Units (DMUs). A method for removing this difficulty is called changing reference set proposed by Jahanshahloo and et.al (2007). The method has some drawbacks. In this paper a method to remove this difficulty is suggested. Numerical example for illustration are given. section 3 Jahanshahloo and et.al (2007) method will be disscused. Section 4 contains the proposed method. Numerical example for comparing the methods and illustration are given in Section 5. The last section summaries and concludes.