Stated preference methods using surveys to elicit willingness to pay have been shown to suffer from hypothetical bias and scope/scale bias. Hypothetical bias usually means that willingness to pay is exaggerated in the hypothetical scenario and scope/scale bias means that there is an...

Hypothetical bias is a serious problem of stated preference techniques. The certainty approach calibrates answers by assessing different weights to remedy respondents’ valuation. However, very little research has been done to find a link between economic theory and empirical treatment of...