A comparison of responses to single and repeated discrete choice questions

According to neoclassical economic theory, a stated preference elicitationformat comprising a single binary choice between the status quo and one alternative isincentive compatible under certain conditions. Formats typically used in choiceexperiments comprising a sequence of discrete choice questions do not hold this property.In this paper, the effect on stated preferences of expanding the number of binary choicetasks per respondent from one to four is tested using a split sample treatment in anattribute-based survey relating to the undergrounding of overhead electricity andtelecommunications wires. We find evidence to suggest that presenting multiple choicetasks per respondent decreases estimates of expected willingness to pay. Preferencesstated in the first of a sequence of choice tasks are not significantly different from thosestated in the incentive compatible single binary choice task, but, in subsequent choicetasks, responses are influenced by cost levels observed in past questions. Threebehavioural explanations can be advanced – weak strategic misrepresentation, referencepoint revision and cost-driven value learning. The evidence is contrary to the standard assumption of truthful response with stable preferences.