PAUL CAIRNEY, a political scientist at the University of Stirling in the United Kingdom, has a message for those who want facts and research findings to guide policy. “‘Evidence based policy making’ is a good political slogan, but not a good description of the policy process,” he writes on his blog, which has become a popular read for policy wonks (paulcairney. wordpress.com). “If you expect to see it, you will be disappointed.” It's a typically frank assessment from Cairney, who last year published a well-received book entitled The Politics of Evidence-Based Policy Making. But his goal isn't to discourage efforts to inject evidence into statecraft; rather, he aims to arm scientists with some practical advice about the policymaking world that might help them do better. In a recent interview, Cairney offered some do's and don'ts for getting involved.