The Role of Use and Non-use Values in Environmental Valuation: Do they matter in Scope Tests?

Scope insensitivity has been a common result in many contingent valuation studies applied to high non-use value resources. Previous studies have explained these results with different arguments, such as the theory of diminishing marginal existence values or even going as far as questioning the validity of contingent valuation method (CVM). In this paper, we conduct a meta-analysis on contingent valuation studies of biodiversity and ecosystems valuation, underlining the differential role played by use and non-use values. Our results show that WTP is positively related to the size of resources which provide mainly use values, and on the opposite, negatively related to the good size when non-use values are predominant. Moreover, we assess the differential effect of each type of good valued, finding that the size of some resources such as wetlands, rivers and valleys increases significantly the WTP estimates, while on the other hand, in wildlife valuation studies larger sizes lead to lower welfare estimates. Results are commented and discussed in order to shed some light on previous scope test failures surrounding non-use values.