Public Opinion and Policy-making
'Evidence-based policy' often uses systematic reviews of existing research on the effectiveness of interventions to provide guidance for policymakers. When applied to gauging public support for interventions, there are two stumbling blocks - opinion data on contentious issues are volatile and prone to measurement error, and the barometer of public opinion should be set for the present rather than reflecting sentiments of other times. Despite these impediments, systematic reviews are a useful tool. Authoritative evidence to support policy is not a matter of taking contemporary, error-free snapshots of public opinion but derives from building and testing explanation of how public attitudes arise. We make this case via a review of public support for legislation banning smoking in cars carrying children. © 2013 John Wiley & Sons Ltd.