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Obtaining Unbiased Contingent Values: Further Tests of Entreaties to Avoid Hypothetical Bias. Thomas C. Brown, Icek Ajzen, and Daniel Hrubes. The Hypothetical Bias may comes from:.
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Obtaining Unbiased Contingent Values: Further Tests of Entreaties to Avoid Hypothetical Bias Thomas C. Brown, Icek Ajzen, and Daniel Hrubes
The Hypothetical Bias may comes from: • First, some participants in hypothetical referenda may try to estimate their real willingness to pay but may over-estimate. • Second, some may ignore their budget constraint, thereby responding as if they faced none. • Third, some may use their vote to indicate whether or not they think the cause is worthy of support. • Fourth, some may use their vote to indicate whether or not they think such a referendum should be held for real.
Introduction • Test method, similar to budget constrain reminder, to correct hypothetical bias • Generally the method instructs respondents that when responding WTP, they respond it as if were real payment.
Method to correct hypothetical bias • “reminder” remind respondent clearly that please response as if you are really paying • “cheap talk” Instruct respondent that there is the hypothetical bias and they should self-correct for it
Discussion • The Cummings and Taylor script is long and difficult to use on the phone or in the mail • The Loomis script is short and did not educate about the hypothetical bias • The testing has been conducted with the students at the University of Massachusets
Discussion (con’t) • Only further research will determine whether the script can be shortened without loss of impact. • If further tests continue to show that the cheap talk script helps remove bias at all but insignificant small (e.g., $1) payment amounts, but works extremely well at higher payment amounts • If additional research shows that the script can be shortened in length without loss of effect, it would not appropriate to delay its application to dichotomous choice contingent valuation.
Conclusion • The script worked well whether the vote was open or secret at higher payment levels, but inadequately corrected the bias at a lower payment level
Group members • Mr. Pornpoj Roger Sangsuchat • Ms. Saranporn Rungreangsri • Ms. Tanyathon Phetmanee