In DEA we are often puzzled by the big difference in CRS and VRS scores, and by the convex production possibility set syndrome in spite of the S-shaped curve often observed in many real data. In this paper we perform a challenge to these subjects.

It has been pointed out that DEA scores may be influenced by several external environmental factors, which are uncontrollable for DMUs. It implies that the DEA efficiency score without data adjustment might be biased and impractical for measuring genuine management efficiency. Therefore it is...

In data envelopment analysis, there are several methods for measuring efficiency change over time, e.g. the window analysis and the Malmquist index. However, they usually neglect carry-over activities between consecutive two terms. These carry-overs play an important role in measuring the...

This study introduces a new scheme of data envelopment analysis (DEA) named cost gradient measure (CGM) to evaluate technical efficiency. In this model, we can obtain more cost conscious technical efficiency than those by other traditional DEA models such as CCR[7] and slacks-based measure (SBM)...

Firstly, we discuss differences between Farrell and Pareto-Koopmans efficiency measures in DEA, and propose a composite method for discriminating them. Then, we extend the method to so-called “epsilon based-measure (EBM).” The EBM can examine the robustness and stability of efficiency...

In DEA, we have two measures of technical efficiency with different characteristics: radial and non-radial. In this paper we compile them into a composite model called “epsilon-based measure (EBM).” For this purpose we introduce two parameters which connect radial and non-radial models....

Traditional DEA models deal with measurements of relative efficiency of DMUs regarding multiple-inputs vs. multiple-outputs. One of the drawbacks of these models is the neglect of intermediate products or linking activities. After pointing out needs for inclusion of them in DEA models, we...

Liberalization of the electric power industry has been underway in various countries. Under this situation, it is necessary for electric power companies to improve their management efficiency in order to survive in a competitive market. This study examines management efficiency of vertically...

The measure proposed in this paper is a new nonparametric data envelopment analysis (DEA) scheme, the hybrid measure, for determining efficiency in the presence of radial and nonradial inputs or outputs. Further extension of the scheme occurred to address nonseparable desirable and undesirable...