存在非期望产出的决策单元阻塞问题研究

阻塞是指企业的过量投入引起生产效益下降的经济现象，近年来已经受到实业界与学术界的广泛关注。现有的决策单元阻塞问题研究普遍假设产出均是期望指标，然而，在实际生产中很多产出属于非期望指标。本文构建了同时存在期望产出和非期望产出决策单元的阻塞度量模型，该模型不仅可以判别决策单元是否存在阻塞，而且可以测算各项投入的阻塞程度，并给出了决策单元阻塞和技术无效之间的关系。最后，运用所提出的模型对我国上市商业银行的效率和阻塞情况进行了测算与分析，验证了本文模型的实用性与可行性。

Research on the Congestion of Decision Making Units with Undesirable Outputs

Congestion is an unfavorable economic phenomenon where the production efficiency is damaged by excessive increase of inputs. As a main source of inefficiency, congestion has been widely explored in both academia and industry. A common assumption in existing studies is that all inputs and outputs of decision making units (DMUs) are desirable. However, bunches of situations where output indices are undesirable exist in real applications. In this paper, the congestion measurement for DMUs with undesirable outputs is explored. First, the definition of congestion for DMUs with undesirable outputs is developed. Then, based on the input relaxation model, a one-model approach is established to measure the congestion in the presence of both desirable and undesirable outputs. By applying the proposed model, not only the existence of congestion is determined, but also the amount of congestion in each input is measured. Furthermore, the relationship between congestion and technical inefficiency is demonstrated. Finally, an empirical study of listed commercial banks in China is employed to test the congestion performance via the proposed approach. The results show that a high degree of congestion is detected for most commercial banks and the congestion varies among state-owned banks, stock banks and urban commercial banks. Some practical policy suggestions are provided to relieve bank congestions. To some extent, the proposed approach enriches the theoretical research on the congestion of DMUs with undesirable outputs. Empirically, feasible improvement strategies are provided for decision makers who face congestion problems.