multi-period efficiency of two–stage systems with a slacks-based measure method: the case of mellat bank branches

Recently, evaluating the efficiency and the performance of decision makingunits (dmus) with two-stage structure is one of the most critical and important issuesof managers. hence, two-stage data envelopment analysis models have been proposed in order to measure the efficiency of these systems. these models are focused over measuring the efficiency of systems in a single time point. therefore, in this paper a slacks-based measure (sbm) model is proposed to measure the efficiency of multi- period two-stage systems. also, we shall decompose the overall efficiency of the system over a number of time periods as a weighted average of the efficiency in each period. the efficiency of the stages, in respect to the entire periods shall be decomposed interms of the weighted average efficiency of the stages in each period. finally, the realdata of mellat bank branches is used to illustrate the proposed approach.