title: External Validity of Contingent Valuation: Comparing Hypothetical and Actual Payments.
abstract: Whilst contingent valuation is increasingly used in economics to value benefits, questions remain concerning its external validity that is do hypothetical responses match actual responses? We present results from the first within sample field test. Whilst Hypothetical No is always an Actual No, Hypothetical Yes exceed Actual Yes responses. A constant rate of response reversals across bids/prices could suggest theoretically consistent option value responses. Certainty calibrations (verbal and numerical response scales) minimise hypothetical-actual discrepancies offering a useful solution. Helping respondents resolve uncertainty may reduce the discrepancy between hypothetical and actual payments and thus lead to more accurate policy recommendations. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Health Economics Research Unit, Institute of Applied Health, Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: Mandy
authors.initials: M
authors.lastname: Ryan
authors.affiliation: Economics Department, School of Social Sciences, University of Southampton, Southampton, UK.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Mentzakis
authors.affiliation: Department of Epidemiology, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
authors.forename: Suthi
authors.initials: S
authors.lastname: Jareinpituk
authors.affiliation: Health Services Research & Policy, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Cairns
mesh_terms: D003132:Commerce; D005382:Financing, Personal / Q000191:economics; D005102:Health Expenditures; D006801:Humans; D018803:Models, Economic; D011795:Surveys and Questionnaires; D035501:Uncertainty
keywords: certainty; contingent valuation; external validity