研究成果概要：The technique ofdata envelopment analysis (DEA) introduced by Charnes, Cooper and Rhodes (CCR)in 1978 has been wide...The technique ofdata envelopment analysis (DEA) introduced by Charnes, Cooper and Rhodes (CCR)in 1978 has been widely applied to evaluating the relative efficiency ofdecision making units (DMUs). DEA provides not only efficient performance ofeach assessed DMU but also a target that improves efficiency of the DMU. Theefficient targets provided by the classical DEA models are always very far fromthe assessed DMU. However, the closest efficient target is often moreappropriate because it needs less effort to make the DMU efficient from theperspective of managers of DMUs. The difficulties of computing the closestefficient target are: (a) the definition of the efficient frontier is given inan implicit fashion, that is hard to be exploited in an algorithm; (b) theefficient frontier is nonconvex. In our research, in order to overcome thesedifficulties, we use the optimization tool (Karush-Kuhn-Tucker conditions) totransform the definition of the efficient frontier and make the definitioncomputation-friendly. The main works we have done can be summarized as follows.(1) We proposed anew approach that can provide an efficient target that is closer to theassessed DMU than that provided by the existing studies;(2) We used theproposed approach in (1) to assess the bankruptcy-based performance of Japanesebanks. Then, an early warning of the firm's financial performance and an easy-to-achieveimprovement plan for the default firm can be provided.