• Environmental and Resource Economics Review
• /
• v.25 no.1
• /
• pp.1-25
• /
• 2016

This study investigated the variability of WTP estimates(i.e. mean or median) with ad hoc assumptions of specific parametric probability distributions(i.e. normal, logistic, lognormal, and exponential distribution) to estimate WTP function using dichotomous choice CV data on mortality risk reduction. From the perspective of policy decision, the variability of these WTP estimates are intolerable in comparison with those of Turnbull nonparametric estimation method which is free from ad hoc distribution assumptions. The Turnbull nonparametric estimation can avoid a kind of misspecification bias due to ad hoc assumption of specific parametric distributions. Furthermore, the WTP estimates by Turnbull nonparametric estimation are robust because the similar estimates are elicited from a dichotomous choice or double dichotomous choice CV data, and the statistically significant WTP estimates can be obtained even though it is not possible by parametric estimation methods. If there are considerable variability among those WTP estimates by parametric estimation methods in condition with no criteria of model adequacy, the mean WTPs from Turnbull nonparametric estimation can be the robust estimates without ad hoc assumptions, which can avoid controversial issues in the perspective of policy decisions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.11
• /
• pp.479-485
• /
• 2017

This study estimated the non-use values of the Gum river estuary which are not related to the direct or indirect use of the Gum river estuary using the contingent valuation method (CVM). The non-use values of the Gum river estuary were explained and asked to be evaluated in the CVM questionnaire and estimates of the WTPs(willingness-to-pay) were elicited using the Turnbull nonparametric estimation methods on the dichotomous choice CV data. Results found the Turnbull lower bounded mean WTP per year for non-use value of the Gum river estuary was estimated at 5,822 won (95% C.I. 5,295 ~ 6,349 won) from single dichotomous CV data, and 6,205 won (95% C.I. 5,701 ~ 6,710 won) from double dichotomous CV data. The mean of two WTP estimates, 6,014 won (95% C.I. 5,498 ~ 6,529 won), was used to calculate the annual total non-use value of the Gum river estuary. Therefore, the non-use value of the Gum river estuary was estimated at 220.3 billion won (95% C.I. 201.4 - 239.2 billion won) annually. This non-use value of the Gum river estuary was composed of the bequest value totaling 68.3 billion won (95% C.I. 62.5 - 74.2 billion won), the existence value of 58.0 billion won (95% C.I. 53.0 - 63.0 billion won), the option value of 57.7 billion won (95% C.I. 52.7 - 62.6 billion won), and the vicarious consumption value totaling 36.3 billion won (95% C.I. 33.1 - 39.4 billion won).