Abstract
This research employed contingent valuation method (CVM) to estimate the willingness to pay (WTP) of the respondents to improve the air quality in Klang Valley. The samples were divided according to different question formats i.e. open ended(OE), dichotomous choice(DC) and payment card(PC). The objective of this study is to investigate the convergent validity of contingent valuation estimates by comparing the WTP values of different question formats. The comparison of responses to different question formats in terms of positive response rate, valid zero, rejection of contingent market was carried out using the z-tests. Paired t-tests of equivalent means were also conducted to test the equality of the mean value of the WTP of the respondents for different question formats. The results of the study suggested that the WTP values of the respondents do not differ significantly across different question formats and the WTP values of the respondents using the DC format were the highest. However due to the nature of the question format, the mean WTP values using the DC method would normally be higher than those of OE and PC. The aggregate WTP value of the respondents was RM0.91 billion for air quality improvement in Klang Valley.
Highlights
In Malaysia the ambient atmospheric conditions have progressively deteriorated due to urbanization and industrial development.Transport vehicles and industrial emissions are the major sources of pollutants in the Klang Valley atmosphere, a problem that has been aggravated by the tremendous increase in the number of mobile sources
The comparison of positive response rate is certainly important and this is mostly reported in the literature, but comparisons of other responses such as valid zero willingness to pay (WTP) and rejection of contingent market are important when comparing the values given by the respondents using different question formats
Response Rate of Respondents by Different Question Formats: Table 1 summarizes the WTP values of the respondents according to positive WTP, valid zero and rejection of contingent market across different question formats for the whole survey samples
Summary
In Malaysia the ambient atmospheric conditions have progressively deteriorated due to urbanization and industrial development.Transport vehicles and industrial emissions are the major sources of pollutants in the Klang Valley atmosphere, a problem that has been aggravated by the tremendous increase in the number of mobile sources. It was found that the WTP values of the respondents varies across different question formats and one is confused about the validity of contingent valuation estimates. Many studies compare the WTP values of different question formats to test the convergent validity of the contingent valuation estimates. The comparison of positive response rate is certainly important and this is mostly reported in the literature, but comparisons of other responses such as valid zero WTP and rejection of contingent market are important when comparing the values given by the respondents using different question formats. This study investigates the convergent validity of contingent valuation estimates by comparing the WTP values of different question formats. The comparison of responses to different question formats in terms of positive response rate, valid zero and rejection of contingent market was carried out using the z-tests. Theoretical Framework of Contingent Valuation Method for Air Quality Improvement: The
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