Ranking DMUs by ideal points with interval data in DEA

An original DEA model is to evaluate each DMU optimistically, but the interval DEA model proposed in this paper has been formulated to obtain an efficiency interval consisting of evaluations from both the optimistic and the pessimistic viewpoints.DMUs are improved so that their lower bounds become so large as to attain the maximum value one. The points obtained by this method are called ideal points. In order to improve the lower bound of the efficiency interval, different ideal points are defined for different DMUs.The purpose of this paper is to rank DMUs by these ideal points for each DMU. Finally we extend the proposed ranking model to interval data.