Laserfiche WebLink
<br />. <br /> <br />Of course one concern with the hypothetical market approach is whether individuals would <br /> <br />actually pay the dollar amount they state in the survey. This issue of validity can be tested <br /> <br />for recreation visitors by comparison of stated WTP to WTP calculated from travel cost <br /> <br />models for the same site. In over a hundred such comparisons for activities as diverse as <br /> <br />hunting, fishing, camping, swimming and boating, Carson, et ,al. found no statistical <br /> <br />difference in values from the two techniques. On net, Carson et al., found that the stated <br /> <br />values in the surveys slightly underestimated the WTP from the travel cost models. <br /> <br />When non-visiting households are asked to pay for instream flows to protect endangered <br />species, the validity is less than for recreation. In a series of cash experiments, the actual <br />cash WTP ranged from one-half to one-eighth of the stated WTP. Recent innovations have <br />suggested a "certainty of response" question to calibrate stated WTP to increase its <br />correspondence with actual WTP (Champ, et al., 1997). This technique shows promise for <br />improving the accuracy of stated WTP in constructed markets and simulated referenda. <br />Nonetheless, if the true WTP for preservation of instream flows is one-half the stated WTP, <br />the fact that millions of households throughout the U.S. would pay to maintain instream flow <br />for fish and wildlife (Loomis, 1996; Welsh, et al.), suggests even the calibrated magnitude of <br />benefits would be in the hundreds of millions of dollars. <br /> <br />While use of surveys to monetize public values is not without controversy, the techniques <br /> <br />involved have been recommended by a blue ribbon panel chaired by two Nobel Laurets in <br /> <br />economics (Arrow, et al., 1993) and used by several federal agencies (U.S. Department of <br /> <br />10 <br />