A family of techniques which use individual respondents statements about their preferences to estimate change in utility associated with a proposed increase in quality or quantity of an ecosystem service or bundle of services. Respondents are presented with one or more hypothetical policy or project scenarios that lead to a specified environmental change compared to a baseline situation. The answers respondents give, in the form of monetary amounts, ratings, or other indications of preference, are scaled following an appropriate model of preferences to yield a measure of value of the proposed ecosystem service change. This value is often monetary expressed as peoples willingness to pay.
