HOW CERTAIN ARE VISITORS OF THEIR ECONOMIC VALUES OF RIVER RECREATION- AN EVALUATION USING REPEATED QUESTIONING AND REVEALED PREFERENCE

We test the robustness of visitor dichotomous choice willingness to pa y (WTP) for maintaining instream flow by challenging respondent's affi rmative answers. This is followed by rephrasing the per trip WTP quest ion into an annual dichotomous choice WTP question and reasking the qu estion. About 5% of visitors revised their ''yes'' answer to ''no.'' E stimated WTP changed from $12.81 per trip to $11.96 per trip. Using th e method of convolutions, this is an insignificant difference. To furt her evaluate the robustness of contingent valuation method estimated W TP, these values are compared to WTP derived from the revealed prefere nce travel cost model of the same visitors. No statistical difference was found.