Do Ordering Effects Matter in Willingness-to-pay Studies of Health Care?

Willingness-to-pay studies are increasingly being used in the evaluation of health care programmes. There are, however, methodological issues that need to be resolved before the potential of willingness-to-pay can be fully exploited as a tool for the economic evaluation of health care programmes. Of particular methodological interest are the consequences of varying the order in which willingness-to-pay questions are presented to respondents in contingent valuation studies. This paper examines the possibility of ordering effects in willingness-to-pay studies in health care. That is, when simultaneously asking willingness-to-pay questions about three health care programmes, does the order the programmes are presented have an impact on the reported willingness-to-pay? We present the results from a survey which allowed us to test for ordering effects and examine, in particular, if the respondent?s past experience with the health care service interacted with the ordering effects.