关键词: 环境服务企业, 全要素生产率, 三阶段DEA, Malmquist模型

Abstract: As an important part of the environmental protection industry, the level of development of the environmental services industry is an important sign of the maturity of the country’s environmental protection industry. In developed countries, the market share of environmental services is close to 70% as their environmental protection equipment market has become saturated. According to calculations by the China Environmental Protection Industry Association, China’s environmental services revenue accounted for 53% of the environmental protection industry in 2016, which is still a gap with developed countries. Despite the rapid development of China’s environmental service industry, environmental service companies are still facing some problems due to their late start, single service model, and lack of innovation ability. As an emerging strategic industry, does the high growth of environmental service enterprises mean high quality growth? At present, there is a relative lack of research literature on environmental service enterprises, especially on the productivity of environmental service enterprises from a micro perspective, which lacks systematic research and objective empirical evidence to support it. This paper aims to answer the following questions: What is the current productivity of environmental service firms? What factors drive the productivity levels of firms? What are the barriers to efficiency growth of firms? What are the productivity levels of environmental service firms in different segments?
The main methods for measuring total factor productivity (TFP) are the traditional Solow residual method, Solow extended model, stochastic frontier model, and DEA-Malmquist model. Compared with other methods, the DEA-Malmquist model does not need to consider the functional forms of inputs and outputs, which is less constrained in the study and the measurement results are more scientific and objective. In addition, it can decompose and analyze the total factor productivity and deeply explore the reasons behind the productivity changes. However, the efficiency values measured by the traditional DEA method are susceptible to the influence of environmental and stochastic factors. In this paper, we use the three-stage DEA-Malmquist model to eliminate the influence of environmental and random factors on productivity. The specific research ideas are as follows: Firstly, the DEA-Malmquist model is used to measure the total factor productivity of environmental service firms. Secondly, the SFA model is constructed to estimate the effects of environmental variables on input slack variables using each input slack variable measured in the first stage as the explanatory variable and environmental variables as the explanatory variables. Finally, based on the regression results in the second stage, the environmental and random factors are removed from the input indicators. The DEA-Malmquist model is applied again to measure the total factor productivity of enterprises using the adjusted input data.
Based on the data of 63 listed environmental service enterprises in China from 2015 to 2018,this paper uses the three-stage DEA-Malmquist model to eliminate the influences of environmental factors and random factors, and conduct an empirical analysis of these enterprises’ TFP. The results show that the enterprises’ TFP is sensitive to the external environment, which verifies the necessity of considering environmental and random factors. In recent years, there is an improving trend in the TFP of the environmental service industry, wherein the sub-sector with the fastest growth is the environmental monitoring industry. The TFP of environmental service enterprises is dominated by technical efficiency. Compared with technological innovation, the decision-making ability of management plays a greater role in improving productivity. Among the sub-sectors, the wastewater treatment industry is obviously driven by management and technical factors, while both driving forces are weak for the soil remediation industry.

Key words: environmental service enterprises, TFP, three-stage DEA approach, Malmquist index