Published online by Cambridge University Press: 01 November 1999
In his book ‘Effectiveness and Efficiency’ Cochrane drew attention to the need to evaluate the effectiveness of health service intervention. Despite his plea for more evaluative research in health services, it has been suggested that only 20% of health care interventions have been rigorously evaluated. Changes in the structure and philosophy of the NHS in the past decade have stimulated interest in the evaluation of health services interventions at both local and national levels.