ALT Good data is not cheap to collect — but it is good value, especially when thoughtfully commissioned or built into policymaking by default. One promising avenue is support for systematic research summaries such as those produced by the Cochrane Collaboration for medicine and the Campbell Collaboration for social science and policy. If you want to understand how to promote literacy in primary schools, or whether neighbourhood policing is effective, a good research synthesis will tell you what the evidence says. Just as important, by revealing the gaps in our knowledge it provides a basis for funding new research.