运用Spike模型分析CVM中零响应对价值评估的影响——以南京市居民对长江流域生态补偿的支付意愿为例  

Using Spike Model to Evaluate the Effect of Zero Responseon Welfare Measurement——Evidence from the Willingness to Pay for the Ecological Compensation of the Yangtze River Basin in Nanjing Section

作　　者：杜丽永[1,2] 蔡志坚[1,3] 杨加猛[1] 蒋瞻[1] 

机构地区：[1]南京林业大学经济管理学院,南京210037 [2]江阴职业技术学院管理系,江苏无锡214400 [3]江苏高校哲学社会科学重点研究基地生态经济研究中心,南京210037

出　　处：《自然资源学报》2013年第6期1007-1018,共12页Journal of Natural Resources

基　　金：中国博士后科学基金特别资助项目(201104534);中国博士后科学基金面上资助项目(20100471344);江苏高校哲学社会科学重点研究基地重大项目(2010JDXM017);江苏省普通高校研究生科研创新计划项目(CXZZ12_0555)

摘　　要：条件价值法调查中会有相当比例的受访者不愿意支付费用,对这部分群体如果处理不当会影响到价值评估的可靠性和有效性。以南京市居民对长江流域生态补偿的支付意愿为例,采用双边界两分式问卷调查获取1 403份有效样本。分析了忽略零响应问题的传统模型所造成的支付意愿(Willingness to Pay,WTP)估算偏差,并采用Spike模型对WTP估算进行了校正。结果显示:若直接删除零响应样本,中位数WTP在359～396元/(户.a)之间;而将零响应的实际支付用接近零的正数进行替代,得到的中位数WTP在154～208元/(户.a)之间。根据Spike模型,将真实零响应样本纳入分析后,得到的WTP估算结果在259～288元/(户.a)之间。表明直接删除零响应会明显高估WTP,而用零或接近零的正数替代零响应又会低估WTP。未来5 a内长江南京段的生态补偿总价值至少为24.4×108元。将决策过程划分为"加入决策"和"支付决策"两个阶段后,论文还发现,"加入决策"和"支付决策"是两种不同的机制,二者在影响因素上存在差异。此外,不同收入家庭的WTP存在明显异质性。In contingent valuation surveys, data is often complicated by zero willingness to pay （WTP） responses in the sample. Without properly dealing with, zero responses would deeply re duce the reliability and validity of welfare valuation. Based on a case study on the WTP for eco logical compensation of the Yangtze River Basin in Nanjing city, 1403 individual questionnaires in closedended double bounded dichotomous choice format were collected. Given conventional methods dealing with zero responses will result in estimation bias in terms of WTP, special atten tion was paid to the issue of zero response in the survey, and a Spike model that allows for a non zero probability of zero response was applied. Because different types of zero responses have dif ferent economic implications, without distinguishing between true zero response and protest re sponses will result in nonneglecting measure bias. The conventional methods to deal with zero re sponse have been known as dropping it from the analysis, or substituting it with either zero or a near zero positive number. When dropping zero responses, it yielded a WTP between 359 and 396 yuan per household per year. While replacing zero responses with a near zero positive number, it yielded a WTP between 154 and 208 yuan per household per year. However, dropping zero re sponses will run the risk of sample selection bias, while replacing it with near zero number seems somewhat too subjective. Thus, a Spike model that allows for a nonzero probability of zero WTP in referendumstyle was brought into practice. It includes many of the often used models as spe cial cases and allows various analyses that are not possible in standard applications. Under the Spike model, the zero response samples were further divided into protest response and true zero response according to their behind motivations. Then the value of WTP was estimated between 259 and 288 yuan per household per year, which is significantly smaller than the dropping method but larger than the replacing method. The tot

关 键 词：生态补偿 条件价值法 双边界 零响应 Spike模型 长江流域 

分 类 号：X2[环境科学与工程—环境科学]