Analyzing the concept of super-efficiency in data envelopment analysis:   A directional distance function approach
  Based on the framework of the directional distance function, we conduct a systematic analysis on the measurement of super-efficiency in order to achieve two main objectives. Our primary purpose is developing two generalized directional measures of super-efficiency that completely resolve the crucial infeasibility issue, commonly arisen in the traditional super-efficiency measures. The secondary goal is to demonstrate that our directional super-efficiency models encompass the conventional ones as special cases. The proposed measures are advantageous because they circumvent biases in super-efficiency estimation due to input and output slacks. They are general, and satisfy several desirable properties, such as always feasibility, monotonicity, unit independence, and translation invariance. 
Mahmood Mehdiloozad, Israfil Roshdi
math.OC