Missed opportunities in the evaluation of public health interventions: a case study of physical activity programmes.

Our study of the evaluations demonstrated a missed opportunity to confidently establish what worked and what did not work in walking programmes with particular populations. This limited the potential for evidence synthesis and to highlight innovative practice warranting further investigation. Our findings suggest a mandate for evaluability assessment. Used at the planning stage this may have ensured the development of realistic objectives and crucially may have identified innovative practice to implement and evaluate. Logic models may also have helped in the development of the intervention and its means of capturing evidence prior to implementation. It may be that research-practice partnerships between universities and practitioners could enhance this process. A lack of conceptual clarity means that replicability and scaling-up of effective interventions is difficult and the opportunity to learn from failure lost.