Validity of open-ended and payment scale approaches to eliciting willingness to pay

The open-ended and payment scale approaches to eliciting willingness to pay (WTP) valuations are compared. Use of the payment scale led to a higher response rate, a higher rate of completion of the WTP question, higher mean and median WTP values, a stronger association between WTP and ability to pay and a higher R(2) in regression analysis of WTP on several independent variables. Taking these results in combination, it can be inferred that the payment scale technique leads to more valid WTP values than use of the open-ended approach.