the existence of flexible data in evaluating cost and revenue efficiency and malmquist productivity index

Data envelopment analysis (dea) is a powerful tool for assessing the efficiency of decision making units (dmus). in the traditional dea models, it has been assumed that the input and output data in the homogeneous dmus are well-defined, but according to the circumstances and changes in some management issues, there may be data that does not indicate the status of the input or output, which is called flexible data, to this type of data. the current paper develops a cost model dea when there is a flexible data and examines the productivity at different times. using the malmquist productivity index, the efficiency of the dmus was evaluated over two different periods, and their progress and regress were examined.also, with an example of an application that includes data from iranian banks in 2005 and 2009, we will examine the proposed models in the paper.