1. Phase 0: problem and contextual assessment, and development of the theoretical basis for an intervention;
2. Phase 1: definition of components of the intervention (using modeling or simulated techniques and qualitative methods);
3. Phase 2: exploratory studies to further develop the intervention and plan a definitive evaluative study
(using a variety of methods);
4. Phase 3: definitive evaluative studies (using quantitative evaluative methods, predominantly randomized designs); and,
5. Phase 4: studies evaluating the sustainability of complex interventions.