A qualitative examination of how respondents in a contingent valuation study rationalise their WTP responses to an increase in the quantity of the environmental good

The issue of how bidders respond to an increase in the quantity or quality of an environmental good is of central importance to the economic validity of the contingent valuation method (CVM). This paper undertakes both a quantitative and qualitative examination of individual bidder response in respect of a particular case study. Using an open ended multiple bid design with follow up verbal reports, we explore respondent motivations behind scope-sensitive and non-scope sensitive responses. An exact statistical test is used to show a clear relationship between the scope sensitivity of WTP and the motivational explanations used to explain scope sensitive or insensitive behaviour. We find that motivational explanations reported can be placed into three major categories, only one of which is consistent with the conventional underlying theory. The implications of this mixed type of individual motivations for the validity of aggregate CVM values remains unresolved. (C) 2003 Elsevier Science B.V. All rights reserved.