Value of Marine Turtle Conservation
Attributes
Medium: Animals, Plants and/or Others
Country: Thailand
Analytical Framework(s): Contingent Valuation
Unit(s): Mean WTP
Study Date: 2006
Publication Date: 2008
Major Result(s)
| Resource/Environmental Good | THB (2006) |
THB (2014)1 |
USD (2014)2 |
|---|---|---|---|
| Mean WTP - single model | 12.51 | 15.17 | 0.46 |
| Mean WTP - linear model | 13.34 | 16.18 | 0.49 |
| Mean WTP - random utility model with a log linear in income | 2.50 | 3.03 | 0.09 |
About the Inflation Adjustment: Prices in Thailand (THB) changed by 21.26% from 2006 to 2014 (aggregated from annual CPI data), so the study values were multiplied by 1.21 to express them in 2014 prices. The study values could be expressed in any desired year (for example, to 2025) by following the same inflation calculation and being sensitive to directional (forward/backward) aggregations using your own CPI/inflation data.
Study Note: Comparing the performance of the two main approaches of benefit transfers, unit value transfers are outperformed functional transfers in terms of transfer errors. Our range of transfer errors is closed to results found in the literature. In an attempt to see whether different conservation programs have any effect on the reliability and validity of benefit transfer exercises, we examine five assessments using different combinations of split survey subsamples. An interesting finding is arising in assessment 3 (mandatory WTP) with unit value transfers where the validity tests show a high degree of transferability compared to other assessments while the reliability tests are reverse. This suggests that high valid transfer of WTP values from a statistical point of view does not necessarily result in low transfer errors. For function transfers (both country to country and pooled countries to country approaches), we find that assessment 3 (mandatory WTP) provides lower average transfer errors than other assessments. With other assessments, results of validity tests show that the choice of assessments is not very important, in the sense that WTP values and functions are similar (or different) across country transfer pairs. Transfer errors are cluster around the same value from a country to others, or different depending on the income elasticity used.
Study Details
Summary: This report presents and compares results from a large research project - Local WTP for the conservation of sea turtles across China, the Philippines, Thailand, and Vietnam using the same contingent valuation (CV) instrument. Studies involved in this study are available elsewhere, and have described the survey themselves, thus these will not be described in this study. This benefit transfer study tests the validity and reliability of WTP values for the sea turtles across countries using both unit value transfer and functional transfer. For both unit value and functional transfer, we compare them country by country and from multiple (pooled) countries to a country as a policy site. The study attempts to investigate if any of the benefit transfer approaches could provide reasonably low transfer errors between pairs of countries and between a group of countries and country. In regression analysis, we use binary logit models for four individual countries. Results show that the bid variable is significantly and negatively influenced the probability of saying yes to pay in all models, as expected. Education is positive and significant in the Vietnam. Income is positively and significantly affected the probability of saying yes in all models except Thailand. Married respondents are willing to pay less in the case of Vietnam. To be a member of an environmental organization is positively and significantly increased the probability of saying yes in the Philippines sample. We then pool the data from all countries in order to estimate a single regression while capturing country-specific effects with dummy variables. The regression results show that income, education, and member variables have country-specific effects affecting the WTP. Thus, it is important to control for differences in the valuation of sea turtle protection across countries. The implications such differences are investigated in benefit transfer exercises.
Site Characteristics: The original surveys use stratified samples to see whether different conservation programs for sea turtles (including regional conservation program with mandatory payment and voluntary payment, and national program) have the same WTP estimates in all individual countries. We investigate the effect of using subsamples of mandatory and regional conservation programs in all country surveys. Results show that mandatory and regional subsamples are not significantly different in all individual models but Vietnam. We then test the validity and reliability of benefit transfers using five assessments: (1) full samples in all countries; (2) regional subsamples in all countries; (3) mandatory subsamples in all countries; (4) regional subsample for Vietnam & full samples in other countries; and (5) mandatory subsample for Vietnam & full samples in other countries.
Comments: Our average transfer errors are 3-217% for unit value transfers and 5-69% for functional transfers. This range of transfer errors is similar to results of previous studies. For examples, compared to studies testing the validity and reliability of cross-country benefit transfer, Alberini et al. (1997) transferred U.S. WTP estimates to avoid an episode of ill health to Taiwan, and found an average transfer error across four different possible transfers of 34%. Chestnut et al. (1998) transferred the U.S. estimates of median WTP to Bangkok, Thailand, and found transfer errors ranging from 18% to 35%, depending on the ill-health episode valued. Barton and Mourato (2003) found transfer errors of 87% to 130% when comparing WTP values to avoid ill health episodes from Portugal to Costa Rica. Abou-Ali and Belhaj (2006) transferred WTP for air quality improvements between Morocco and Egypt and found transfer errors of 60 to 220%. Ready and Navrud (2006) reviewed cross-country benefit transfer studies conducted to date and found that the average transfer error for cross-country benefit transfers was in the range of 20% to 40%, but individual transfer error was as high as 100-200%.