Multi-period efficiency analysis in the presence of flexible measures

In conventional data envelopment analysis (DEA) models, the efficiency of decision making units (DMUs) is usually evaluated in a special period of time while the input and output status of measures has been specified. However, in real-world applications, there are occasions that the performance of firms must be evaluated over several periods of time while the status of a factor from input and/or output viewpoint is uncertain. Factors with uncertain input/output status are called flexible measures in the literature. In this study, the purpose is to propose a method for evaluating the efficiency of the multi-period systems when flexible measures present. For this reason, an approach based on DEA is suggested to measure the overall and period efficiency of multi-period systems with flexible measures. An example is used to illustrate the proposed method.