Pseudo inefficiency in multi-period systems: a DEA-based approach

Standard Data Envelopment Analysis (DEA) models measures the efficiency of Decision Making Units (DMUs) in a period of time. In real occasions, multi periods are presented. In presence of a multi-period system, overall efficiency depends on the performance of the DMU in all periods. That is to say, periodic efficiencies must be calculated, also, the overall efficiency is depended to periodic efficiencies. In other words, a DMU cannot be overall efficient, but considered as an efficient unit in each separate period. Hence, the question of pseudo inefficiency is raised?

This paper investigates Ratio-based Data Envelopment Analysis (DEA-R) models to detect pseudo inefficiency in multi-period systems.

The proposed algorithm consists of three steps. As the first step, the average of period-efficiencies is calculated, then the overall efficiency is evaluated as a block-box. For the last step, a ratio of two quantities is estimated. If this ratio is close to unity, there is no significant difference between these two quantities. Otherwise, the estimate claims pseudo inefficiency.

Originality/Value:

 In the literature, pseudo inefficiency has been detected through applying the periodic weights, but this paper proposes a three-step algorithm to investigate pseudo inefficiency. To elucidate the details of the proposed approach, a comparison is made between Kao and Liu [8] and the proposed algorithm to measure the efficiency of 22 Taiwanese commercial banks for the period 2009-2011. The results demonstrate the practicality and superiority of the proposed method in comparison with the existing multi-period models.