Contingent valuation of global environmental resources:: Test of perfect and regular embedding

The present study examines the internal consistency of willingness to pay (WTP) assessed for four environmental amenities in a hypothetical market scenario. Particularly, the occurrence of embedding is investigated by performing external tests of part-whole effects and insensitivity to scope. Moreover, four different measures or intensifiers of scope (i.e., absolute magnitudes, percentages, number of events, and verbal cues) are applied in order to evaluate their influence on scope sensitivity. The responsiveness of WTP is also compared with categorical rating (CR) as an alternative measure of environmental priorities. Our results indicate that neither instrument, as utilised here, is capable of making the respondents responsive to scope. The weak relation between expressed economic value and instrumental considerations are also supported by small variations in mean WTP across the four issues. A part-whole effect is finally demonstrated for global warming, where respondents are willing to pay more when global warming is valued on its own than respondents who consider this amenity in conjunction with three other environmental issues. (C) 2000 Published by Elsevier Science B.V. All rights reserved. PsycINFO classification. 3920; 4070 JEL classification: H41.