Shabnam Razavyan - Department of mathematics, South Tehran Branch, Islamic Azad University, Tehran, Iran
Ali Ebrahimnejad - Department of Mathematics, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran
Elham Mirzaie Fard - Department of Mathematics, South Tehran Branch, Islamic Azad University, Tehran, Iran

Data envelopment analysis (DEA) is a widely used mathematical programmingtechnique that compares the inputs and outputs of a set of homogenous decision making units(DMUs) by evaluating their relative efficiency. In the conventional DEA model, all the data areknown precisely or given as crisp values. However, the observed values of the input and outputdata in real-world problems are sometimes imprecise or vague. In addition, performancemeasurement in the conventional DEA method is based on the assumption that inputs should beminimized and outputs should be maximized. In this study, we first classify the solution methodsfor solving fuzzy data envelopment analysis into several groups and then explore the weaknessand strength of each group in details. Finally, we give some new results leading to a newapproach for measuring of efficiencies of DMUs with fuzzy inputs and outputs.

Data Envelopment Analysis, Fuzzy Efficiencies, Ranking