环境价值评估中的WTP值和WTA值测算与非对称性——以广西北部湾经济区滨海生态环境保护为例

Measurement and analysis of asymmetry between WTP and WTA values in the evaluation of environmental value: the case of coastal environmental protection in the Guangxi Beibu Gulf Economic Zone

基于广西北部湾经济区4城市940位受访者的问卷调查结果,采用logit模型对这些受访者保护滨海优良生态环境的最大支付意愿(WTP)和接受的最小赔偿意愿(WTA)进行了测算,其结果显示:5年内的WTP期望值为450.17元a-1户-1,WTA期望值为5772.71元a-1户-1,WTA/WTP比值为12.8倍,表现出非常明显的非对称性特征,但基本符合国内外在该领域的实证结果。通过对同一受访者支付意愿和接受赔偿意愿的交叉分析,可知WTP和WTA同时不为0的受访者有276人,占总抽样人次的29.4%,其WTA/WTP比值为12.54,与logit模型测算的WTA/WTP比值非常接近,从一侧面更准确地反映了这一群体对环境物品估值的差异性,同时也可反映logit模型测算的可靠性。基于行为经济学的前景理论分析,发现研究中的受访者存在厌恶损失效应、框架效应和对预期不确定风险的规避行为,同时受访者还存在明显的搭便车行为。通过对受访者的情境因素分析,发现其中2个情境因素对受访者选择WTP和WTA具有较大影响,主要表现为惩罚效应,尤其是经济收入满意度情境因素对受访者的经济行为影响显著,而另3个情境因素未表现出有规律性的影响。

There have been some discussions in China and elsewhere about the asymmetry between WTP and WTA values; however, so far no consistent conclusions have been reached. This is now a highly topical matter in relation to environmental impact assessment. Research on the subject is especially lacking in China, and is therefore, particularly necessary in this context. In view of this, a survey of 940 respondents was conducted in four cities of the Guangxi Beibu Gulf Economic Zone, in order to estimate individuals＇ maximum willingness to pay （WTP） for good coastal environmental conservation as well as their minimum willingness to accept （WTA） compensation through application of the logit mode. The purpose was to probe impact factors and mechanisms of difference between WTP and WTA, so as to render valuation methods more scientifically applicable and more reliable. The resultant improved methods will be suitable for use in the practice of environmental science in China. The results obtained showed the following. First, over five years, the expectancy values of WTP and WTA were 450.17 Yuan and 5772.71 Yuan per household per year, respectively, with WTA/WTP value of 12.8. This indicates obvious asymmetry but basically accords with empirical results of research in this field conducted both domestically and overseas. Second, through cross-analysis of WTP and WTA, it was found that in 29.4% of the sample （276 respondents）, WTP and WTA were not both zero. The ratio of WTA to WTP was 12.54, with this very close to the estimation result of the logit model. This to some extent reflects differences of this group in estimating environmental products, while also proving the reliability of the logit model. Third, based on prospect theory analysis of behavioral economics, it was found that informants in the survey showed loss aversion and framing effects, and avoidance behavior of uncertain risk and expected ambiguity. At the same time, they also exhibited free-riding behavior. Finally, through analysis of situational factors, the group was divided into five grading levels （ 1-5）, based on the five Richter scales used in the questionnaire. The average that of WTA. Of all situational factors, two had the greatest influence on respondents＇ choice of WTP and WTA, manifesting themselves through a punishing effect. The situational factor of economic income satisfaction had a significant impact on respondents＇ economic behavior, with the ratio of WTA to WTP showing the most obvious asymmetry in this case. The lowest and highest ratios both appeared with this situational factor. The ratio of WTA to WTP for those having the lowest level of satisfaction with their economic income was up to 32.5, far higher than the ratio for those who are basically satisfied and the ratio estimated from the logit model. This shows the loss aversion and punishing effects described in behavioral economics theory. However, the other three situational factors considered did not appear to exert influence to the same degree. In conclusion, the measurement of environmental value is complex, because it refers to hypothetical market valuation of public goods or quasi-public goods where there is no real actual market for reference ; thus, people show more obvious irrational behavior. Local government should therefore pay good attention to local people＇s moods and attitudes when implementing environmental policy.