The payment scale format has been widely used in willingness-to-pay studies in health care. Concerns have been expressed that the format is, in theory, prone to range bias, although this proposition has not been tested directly. We report the findings of a contingent valuation questionnaire...

An examination of the willingness to pay values elicited from more than 3000 persons involved in three independent studies revealed that the majority had offered one of a limited number of values from the ranges available to them. These values were 'prominent numbers', the use of which has been...