A contingent valuation study was used to value improvements to a coral reef, where, at present, the reef quality, measured in terms of percentage of reef cover, is so poor that the local residents can no longer rely on the reef for their supply of fish. The study sample, which included users (one-third) and non-users, found the following estimates of average WTP.

Mean WTP ($ per annum)

Scenario Whole sample Local users Others 1.Increase reef cover to 50% 25 45 15 2.Increase reef cover to 75% 40 70 25 3.Increase reef cover to 100% 53.5 95 33 i Construct a demand curve for reef quality for: users; others; and the whole sample and discuss the forms of these curves (remember that a demand curve describes willingness to pay for an additional unit of a good or service).

ii Explain how this information could be used in a BCA to compare management options to improve the quality of the reef.