Identifying the scope effect on a meta-analysis of biodiversity valuation studies

Insensitivity to scope is an issue of much debate in contingent valuation (CV) even today. Although the literature about insensitivity to scope is abundant, the reasons for it are not yet well known. Through a meta-analysis of CV studies of biodiversity, the treatment of the different possible measures of the quantity of the good is explored in relation to scope sensitivity. Overall, the findings suggest that CV results are sensitive to the amount of the good being valued, although the result depends on how the environmental change is measured. Results support the use of absolute sizes when conducting CV studies.

► First study investigating the impact of the size variable format on scope effects.
► Sensitivity to scope in a meta-analysis varies with the size variable format.
► CV biodiversity studies pass the scope test with absolute changes in size.
► We explore novel explanatory variables in meta-analysis (between-subjects variable).
► Biodiversity nonuse values are more likely to derive in lower WTP.