Weak and strong disposability vs. natural and managerial disposability in DEA environmental assessment: Comparison between Japanese electric power industry and manufacturing industries

The economic concept of weak and strong disposability has long dominated studies on DEA (Data Envelopment Analysis) environmental assessment. This study reviews the two disposability concepts from their conceptual and methodological implications. In particular, this study is interested in the concept of weak disposability because the concept is believed to have an analytical capability to measure an occurrence of “congestion”. The two economic concepts on disposability, accepted by production economists, are replaced by natural and managerial disposability in this study. The natural disposability implies an environmental strategy by which a firm attempts to decrease an input vector to reduce a vector of undesirable outputs. Given the decreased input vector, a firm attempts to increase a vector of desirable outputs as much as possible. This type of strategy indicates negative adaptation. In contrast, the managerial disposability indicates an opposite strategy by increasing the input vector. This disposability expresses an environmental strategy by which a firm considers a regulation change as a new business opportunity. A firm attempts to improve its unified performance by utilizing new clean air technology and/or new management. The strategy indicates positive adaptation. Considering the two groups of disposability, this study compares between weak/strong disposability and natural/managerial disposability in terms of their conceptual and methodological differences, focusing upon the concept of congestion and technology innovation. Furthermore, using the concept of natural and managerial disposability, this study compares Japanese electric power firms with manufacturing firms. This study finds that the manufacturing firms outperform the electric power firms under natural disposability. An opposite result is found under managerial disposability. This empirical study also finds that the two groups of Japanese firms have attained desirable (good) congestion due to technology innovation. Based upon such empirical results, this study identifies two policy implications. One of the two implications is that the two groups of Japanese industries have attained a high level of technology innovation by a result of environmental regulation. The other is that the electric power industry operates more efficiently to reduce the CO2 emission than the manufacturing industries.