Experimentation at the interface of science and policy: a multi-case analysis of how policy experiments influence political decision-makers.

For decades now, scholars have grappled with questions about how knowledge producers can enhance the influence of their knowledge on users and improve policy making. However, little attention has been paid to how policy experiments, a flexible and ex ante method of policy appraisal, obtain influence over political decision-making. To address this gap, an exploratory framework has been developed that facilitates systematic analysis of multiple experiments, allowing hypotheses to be tested regarding how an experiment's institutional design can influence the views of political decision-makers. Cash's categories of effectiveness are used to describe an experiment's conceptual influence; being how credible, salient, and legitimate decision-makers perceive an experiment to be. The hypotheses are tested using 14 experiment cases found relevant to climate adaptation in the Netherlands, with complete survey responses from over 70 respondents. The results show that although, in general, the experiments had medium to high influence on decision-makers, institutional design does have a noticeable impact. Organisers should make choices carefully when designing an experiment, particularly in order to maintain relevance during an experiment's implementation and to build community acceptance. Suggestions for future research include a comparison of experiment effects with the effects of non-experimental forms of appraisal, such as piloting or ex ante impact assessment.