Purpose, Intent, and Elements of Traditional Efficacy Studies and Practical Effectiveness Trials
| Issue | Traditional Efficacy Study | Practical Effectiveness Trial |
|---|---|---|
| I. Purpose and intent | ||
| Study goal | Isolate treatment mechanism; unique approach | Replicable treatment |
| Key criteria | Internal validity | External validity |
| Purpose/world view | Isolate cause | Understand program in context |
| Decisions regarding | Theory | Practice and policy |
| II. Study elements | ||
| Participants | Homogeneous, motivated | Heterogeneous, representative |
| Settings | Homogeneous, single or few under control of investigator | Heterogeneous, multiple to evaluate generalization across settings |
| Intervention | Intensive, highly structured, complex | Less intensive, moderate structure, and flexible to permit options |
| Intervention staff | Research staff or highly trained experts | Regular staff in representative settings |