Do contingent valuation estimates pass a 'scope' test? A meta-analysis

This paper considers the scope test proposed to judge the internal consistency of contingent valuation estimates. The test is shown to be quite sensitive to the maintained hypotheses required to derive fairly precise expectations for the properties of WTP functions, and, therefore, a different approach may be needed in gauging the reliability of CV. This paper describes an approach that relies on a weight-of-the-evidence criterion and uses meta- analysis to develop a systematic appraisal of what the economic values of changes in amenity resources are. The approach is illustrated for the case of estimating people's willingness to pay for improving (or maintaining) visibility at the national parks.