Ranking all of efficient units using the proposed SBM model

One of the important issues discussed in DEA literature is ranking efficient units. This paper presents a new method based on slack based measure SBM with free variables in sign for ranking efficient units. The new method also can rank the efficient units non-extreme. It also does not have the problem of instability and infeasibility. The proposed model specifies the largest MPSS and after that other unit’s portraits to this unit. Then, using examples will be compared with the approaches.