Investigating Insensitivity to Scope: A Split-Sample Test of Perceived Scheme Realism

This paper considers the use of contingent valuation to estimate non-market benefits from separately valued nested goods. Survey respondents were asked referendum WTP questions regarding either a scheme to protect the “whole” area of a wetland or a scheme to protect some nested “part” sub-area. The survey design permitted firstresponse testing and comparison of part and whole values revealed mixed evidence of scope sensitivity. However, allowing for variation in the degree to which differing schemes are considered to be realistic revealed highly significant scope sensitivity. These results illustrate the need for a detailed understanding of the preferences and beliefs of respondents when performing scope sensitivity tests.