Primarily because of the hypothetical character of interview situations, respondents are often unable to state their true willingness to pay (WTP). This inability results in the so-called hypothetical bias. To address this bias, incentive-compatible methods have been proposed, but such methods...

The somewhat ad-hoc method of certainty calibration, based on self-stated preference certainty follow-up questions, has been found to be a successful method of eliminating or reducing hypothetical bias in stated preference studies. But is the preference certainty really context dependent, or do...