Contingent values for New Mexico instream flows: With tests of scope, group-size reminder and temporal reliability

The protection of instream flows, the flow of wafer in natural river channe ls, is a controversial environmental issue throughout the US West This is e specially the case in New Mexico, which is unique in that no legal avenue f or protection exists. This contingent valuation study investigates the non- market benefits of protecting minimum instream flows in New Mexico; the eli cited values are expected to have a significant non-use component. The orig inal dichotomous choice contingent valuation telephone survey was conducted in February 1995, and used a voluntary contribution trust fund format. Usi ng the same 2 x 2 experimental design, computer-assisted telephone intervie w system and sampling frame of New Mexico residents, the survey was then re plicated in February 1996. As a measure of theoretical validity, we test th e sensitivity in valuation responses to a change in the scope of the good ( nested geographical components). Split-sample statistical tests of scope re main relatively rare in contingent valuation studies involving nonuse value s, especially when combined with other tests of validity and reliability us ing the same sampling frame and survey instrument. Thus, corollary tests of sensitivity in valuation responses to information about the collective nat ure of providing the good (a group-size reminder) and the temporal reliabil ity of results are also conducted. Despite the explicit 'contributions fram e: there is no evidence to support the simple contribution model for interp reting valuation responses. (C) 2000 Academic Press.