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Contributions of evidence from the major categories of research approaches
| Research Method | Unique contribution to understanding |
|---|---|
| Basic science | Mechanisms of action |
| Intervention studies in humans / RCTs | Reliable attribution; control of bias, confounding |
| Observational epidemiology; large and diverse population-based samples | Effects at scale |
| Observational epidemiology; long time periods | Duration of effects |
