Differences between continuous and discrete contingent value estimates

In a split-sample contingent valuation study of willingness to pay (WTP) for food safety improvements, the dichotomous choice (DC) elicitation method consistently generated much larger estimates of WTP than did a continuous method. Little or none of these differences was due to bias introduced by the statistical techniques used with the DC data. Most or all of the difference was due to differences in respondent behavior. In addition, the continuous WTP responses showed a significant scope effect while the DC responses did not. The observed difference in behavior may be attributable in part to yea-saying by DC respondents.