Do Policymakers Distinguish Correlation from Causation? Evidence from an international Survey Experiment

This study examines whether policymakers distinguish between correlational and causally identified evidence when evaluating policy-relevant research. Policymakers recruited through the Warwick Policymaker Lab complete an online experimental vignette survey in which they evaluate four summaries of evidence on the same healthcare intervention. The vignettes vary experimentally along two dimensions: the inferential basis of the evidence (correlational versus random assignment) and the geographical context (the respondent's own country versus a similar foreign country). The primary outcome is respondents' assessment of the causal credibility of the evidence, while the secondary outcome is their stated willingness to rely on the evidence for policymaking. The primary analysis exploits the randomisation of the first vignette to estimate between-subject treatment effects. Secondary analyses use all four vignette evaluations in respondent fixed-effects models and examine heterogeneity by methodological training, policymaking experience, policy sector, and country where sample sizes permit.