a directional distance function approach to efficiency evaluation in the presence of undesirable factors

Traditional data envelopment analysis (dea) approaches rely on the assumption that inputs are minimized and outputs are maximized. however, some production processes consumed widely used inputs which should be increased to improve the performance measure of a decision making unit (dmu). in this paper, a new definition of weak disposability of inputs is represented. then a production technology is designed based on five axioms as inclusion, free disposability, weak disposability of inputs, convexity and minimum extrapolation. since the production technology is non-linear, hence a linearization method is proposed and then a directional distance function is applied to calculate the efficiency measure of the dmus. the proposed approach is tested to 17 azad university departments in mobarake.