The relative efficiency evaluation for productivity of each electric power company after electric power deregulation in Japan using the DEA/Window Analysis and the Inverted DEA/Window Analysis

This study evaluates the relative efficiencies for productivity of each electric power company in Japan, using the DEA/Window Analysis (Data Envelopment Analysis/Window Analysis) and the Inverted DEA/Window Analysis (Inverted Data Envelopment Analysis/Window Analysis). The first stage of this evaluation described the trends of the relative efficiencies and inefficiencies of each electric power company for a total of 21 years before and after electric power deregulation. In the second stage of this evaluation, this paper analyzes trends of the relative efficiencies and inefficiencies of each electric power company for a total of 20 years after electric power deregulation. In this paper, trends of the relative efficiencies and inefficiencies of each electric power company became clear by various illustrations. The detailed trends of the productivity of each electric power company were also identified.