Research designs for studies evaluating the effectiveness of change and improvement strategies
- 1Centre for Health Services Research, University of Newcastle upon Tyne, Newcastle upon Tyne, UK
- 2Clinical Epidemiology Programme, Ottawa Health Research Institute, Ottawa, Canada
- 3Health Services Research Unit, University of Aberdeen, Aberdeen, UK
- Correspondence to: Professor M Eccles, Professor of Clinical Effectiveness, Centre for Health Services Research, 21 Claremont Place, Newcastle upon Tyne NE2 4AA, UK;
- Accepted 29 October 2002
The methods of evaluating change and improvement strategies are not well described. The design and conduct of a range of experimental and non-experimental quantitative designs are considered. Such study designs should usually be used in a context where they build on appropriate theoretical, qualitative and modelling work, particularly in the development of appropriate interventions. A range of experimental designs are discussed including single and multiple arm randomised controlled trials and the use of more complex factorial and block designs. The impact of randomisation at both group and individual levels and three non-experimental designs (uncontrolled before and after, controlled before and after, and time series analysis) are also considered. The design chosen will reflect both the needs (and resources) in any particular circumstances and also the purpose of the evaluation. The general principle underlying the choice of evaluative design is, however, simple—those conducting such evaluations should use the most robust design possible to minimise bias and maximise generalisability.