This paper analyzes the possible advantages of the trichotomous choice elicitation question format in contingent valuation studies over the traditional dichotomous choice format. In the past, contingent valuation studies showed that mean stated willingness to pay (WTP) for a public project was...

In Stated Preference studies for the appraisal of environmental projects in poor countries or regions it often turns out that the stated willingness to pay of people for environmental improvements, which is used as measure of individual welfare changes, is very low. This is often interpreted as...