Reducing the anchoring bias in multiple question CV surveys

International audienceThe elicitation format is a crucial aspect of Contingent Valuation (CV) surveys and can impact their reliability. This paper contributes to the extensive debate on WTP (Willingness To Pay) elicitation formats by assessing whether the Circular Payment Card (CPC) can reduce anchoring on respondents' previous answers under multiple elicitation questions. This new format uses a visual pie-chart representation without start or end points: respondents spin the circular card in any direction until they find the section that best matches their WTP. We used a CV survey based on two ways of reducing risks associated with flooding, each randomly presented first to half of the respondents, to test the absolute performance of CPC. We presented a second survey on two social insurance schemes for subjects currently uninsured to respondents randomly split into three subgroups. Each group's WTP was elicited using one of three formats: Open-Ended (OE), standard Payment Card (PC) and the new CPC. The two insurance schemes were always proposed in the same order, and we assessed the relative performance of CPC by comparing anchoring across respondents. Our results provide evidence that CPC is likely to reduce anchoring in multiple elicitation questions and that respondents may rely on different heuristic decisions when giving WTP in the OE and in the two PC formats