Two methods for calibrating discrete choice contingent valuation responses – the dichotomous choice with followup certainty question method of Champ et al. (1997) and the multiple bounded method of Welsh and Poe (1998) – are evaluated using data from a field validity comparison of hypothetical and actual participation decisions in a green electricity pricing program. Both calibration methods can produce hypothetical participation levels that closely correspond with actual program participation rates. However, the two methods demonstrate procedural variance as they yield significantly different underlying distributions of willingness to pay.