Questioning the Presumed Level of Expertise of Respondents in Evaluating Complex Environmental Projects: Insights from Coastal Protection

In the face of accelerating coastal risks driven by climate change, the economic valuation of protection measures has become a crucial issue for public decision-makers However, this valuation, often based on stated preference approaches, is complex, and its relevance depends on the level of expertise implicitly attributed to respondents. This article challenges this presumed respondents' expertise by proposing a typology of Discrete Choice Experiments (DCE): Expert, Enduser, and Hybrid. An Enduser approach, focused on the final consequences of protection measures, allows for a broader and more accessible valuation of protection strategies, provided that a prior mapping between measures and their effects is established, either through expert assessments or respondents' perceptions. A survey conducted among residents of the French Atlantic coast reveals first their limited level of expertise, questioning the feasibility of an Expert DCE and highlighting the challenges of decision-making based on non-expert perceptions. At the same time, this survey implemented an Enduser DCE, allowing for the valuation of a wide range of alternative protection measures.