应用两阶段二分式虚拟市场评价法消除环境价值货币评估的偏差

Eliminating Errors in Evaluating Environmental Monetary Value through Application of Two-Bounded Dichotomous Choice Model of Contingent Valuation Method

虚拟市场评价法(CVM)是目前环境经济价值货币评估中最为广泛应用的方法。经过几十年的发展,经济理论基础已日趋完善,但受可能发生的偏差的影响较大,其准确性受到一些学者的质疑。当前国际上最为推崇的两阶段二分式选择法可以最大限度地减少偏差。本文讨论了虚拟市场评价法以及两阶段二分式选择法的原理,推演了应用两阶段二分式选择法计算支付意愿金额(WTP)的数学模型,并应用京津风沙源治理工程环境价值评价案例,详细说明如何应用两阶段二分式虚拟市场评价模型设计调查问卷,并据此估算支付意愿金额。

Contingent Valuation Method （CVM） is the most universal approach used in evaluating environmental monetary value. Despite CVM has already developed its economic theoretical framework over the past decades the concomitant problem is the result of CVM is impressionable to the possible errors. Thus the reliability of CVM is often in debate. In recent years, a two-bounded dichotomous choice model has been developed and has become the most widely adopted model in CVM as it may eliminate possible errors to the utmost. This paper discussed economic theoretical framework of CVM and deduced mathematical model of calculating willingness to pay （WTP） by using the two-bounded dichotomous choice model, and explained the details of questionnaire design and WTP estimation through a case study of the Project for Combating Sandstorm affecting Beijing-Tianjin Metropolitan Region. To improve atmospheric quality influenced by sandstorm in Beijing-Tianjin metropolitan region, a project to combat sandstorm in Inner Mongolia was initiated since March 2000 with ten-year duration. The environmental monitoring data indicate that the number of days in which atmospheric quality is better than second-class has increased from 177 in 2000 to 229 in 2004. It shows that restoration of ecological system in windward areas has positive contributions to improvement of atmospheric quality in leeward areas. This paper estimates the monetary value of environmental benefits of improving atmospheric quality during spring （from March to May） in leeward areas, which is brought by the project of combating sandstorm in windward areas. Based on analysis of field survey of 723 respondents from 6 sub-districts in Beijing in April 2005, the results show that the median of residents＇ WTP is 95 RMB per household per year if an environmental tax was introduced as ecological compensation to windward areas for environmental benefits from improvement of atmospheric quality in leeward areas. The annual environmental tax amounts for 3.9 million RMB as the number of households is 4.1 million in Beijing area, and the total environmental tax in the period is 19. 5 million RMB. The study in this paper indicates that the two-bounded dichotomous choice model may eliminate errors from monetary evaluation of environmental benefits to the utmost and it is possible to introduce ecological compensation for environmental benefits, which is brought by other regions.