Whether in hospital, in economic consulting or in the design of learning environments, the people involved must constantly make decisions that have a considerable impact on the individual, institutional or social level of interaction. The concept of "evidence based practice" builds upon the notion that important decisions should not be made exclusively on the basis of personal experience and subjective assessments or needs. The best scientific evidence currently available should be considered. |Martin W. Bauer is professor of Social Psychology and Science Methodology at the LSE.