Conference Agenda

This study investigates convergent validity between elicitation formats within contingent valuation methodology, with a particular focus on theory-driven formats that are designed to align with incentive compatibility. While earlier literature endorsed the single binary choice elicitation format as the only incentive-compatible format, Vossler and Holladay (2018) identified theoretical conditions under which payment card and open-ended elicitation formats may also satisfy incentive-compatibility, thereby encouraging truthful preference revelation. Nevertheless, empirical findings have revealed a lack of convergent validity across these formats, with behavioral biases proposed as a possible explanation. This study seeks to deepen understanding of this issue by comparing these three theory-driven (and arguably incentive-compatible) formats. Specifically, we assess whether single binary choice and payment card demonstrate robustness against bid-vector effects, and to what extent biases – such as anchoring, yea-saying, and strategic misinterpretation – influence responses in those formats. To explore this, we conducted a large-scale, multi-country survey with 12,343 respondents across Poland, Sweden, Hungary, Spain, Germany, and the Netherlands, examining consumers’ willingness to pay (WTP) for an EU-wide biodiversity enhancing programme. Our analysis reveals significant discrepancies in WTP estimates across formats, with Wald tests consistently rejecting convergent validity. However, analysis of choice frequencies suggests that convergent validity holds for lower bid levels, whereas higher bids introduce more pronounced divergences. We argue that these discrepancies stem from both behavioral biases and methodological factors, including bid vector design and econometric assumptions. Our results underscore the critical influence of bid structure on WTP estimates and highlight the need for further research to refine elicitation formats in contingent valuation studies.