Notes on the gap between payment-card and closed-ended CVM questions

This paper presents contingent valuation (CV) estimates of benefits provided by a proposed Kalkalpen National Park in Austria. We provide evidence as regards to the difference between payment card (PC) answers and closed-ended question formats. Based on different estimation models for CV questions we get the result of substantial differences between closed-ended and payment card welfare measures. On average PC-WTP measures are below the closed-ended figures. Since the evaluation models are based on different premises in the calculation of WTP figures we plead for a more precise disclosure of the underlying evaluation methods if different question formats are compared to one another. Identical assumptions on the probability distributions have to be assumed whenever open- and closed-ended CV welfare measures are compared. Taking theoretical arguments into account we argue for the application of the closed-ended double-bounded Spike model that provides an average welfare measure.