Empirical Study on "Content-dependency" of WTP for Ecological Service in CVM Research:A Case Study of CVM in Water Environmental Restoration of Urban Rivers in Shanghai

The validity and reliability of CVM have been questioned by many economists for quite a long time for its survey nature in spite of its wide application.One of the main issues raised is the 'content-dependency' of WTP estimates in that they are not invariant to the inclusion of other goods in the survey questionnaire.This paper investigates the context-dependent effects of WTP for ecosystem restoration of the urban river in Shanghai,China.Four schemes and parallel questionnaire investigations are designed and conducted aiming at how the same policy change is valued in different contexts,such as the diffterent scale,the different order,and the amount of goods.Based on 720 sample,employing the t-test and comparing the WTP estimates,the results show that:(a) the WTP is not sensible to the dimension of surface water environment valuated;(b) the sum of WTP for different parts of the surface water environment is larger than the valuation placed on it as a whole;(c) WTP is higher when the change in water services is valued earlier in the survey instrument than later;and(d) WTP for a river is smaller when it is valued as apart of regional river than that valued on its own.The exsistence of scope insensitivity,embedding eflect,sequencing effects and part-whole effect of WTP was proved in this study which is consistent with the report in literatures.In this case income effect and substitute effect are the main reasonable explanation to the phenomenon above.These findings are consistent with underlying economic theory,so deviation caused by the phenomenon should be considered when results from a CVM study are adopted in policy analysis.