Good intentions and received wisdom are not enough.

There is a common view among social and public health scientists that there is an evidence-based medicine (EBM) juggernaut, a powerful, naive, and overweening attempt to impose an inappropriately narrow and medical model of experimentation onto a complex social world. We have both frequently come across hostility among social scientists, and public health or health promotion practitioners or theorists, to attempts to apply EBM principles (for example, systematic reviews or experimental designs) in social or public health settings (for example, sex education in schools, health promotion campaigns, or community development 1). We believe such hostility to be misplaced, and to be based on a number of misconceptions. The first misconception is that systematic reviews and experimental designs have a wholly biomedical prov-enance. As Ann Oakley has pointed out, the use of experimental designs was well established in United States by the 1930s, and from the early 1960s to early 1980s there were many randomised experiments for evaluating public policy interventions in United States, these being considered the optimum design. Much of the early literature on experimental designs (including blinding) came from the social sciences, as a response to the perceived need to be able to make valid causal inferences. 2 The second misconception is that the " real world " is too complex, messy, or culturally/historically specific for the appropriate application of EBM principles. Objections on the grounds that experimentation is often unethical or impractical in real life are common; however, experimental evaluation is more common in social settings than is often realised, 3 4 and many apparent practical or ethical diYcul-ties can be overcome. For example, a review by Berk, Boruch and colleagues describes RCTs of the eVects of prison rehabilitation programmes, " welfare-to-work " type income supplements, electricity pricing as means of managing demand, and of the educational eVects of the children's programme " Sesame Street ". 5 The third misconception is that social and public health interventions do not have the capacity to do harm, and that having good intentions is therefore a suYcient basis for policy making. There are enough examples of well meaning interventions with adverse eVects to suggest that this is not the case. A weekly exercise programme among nursing staV, expected to have beneficial eVects on fitness and musculoskeletal problems, had only one significant eVect: it interfered with their ability to plan their work. 6 A bicycle safety education programme (" Bike Ed …