Clinical Research: Thinking it through
Part 1: The research question, literature review, and appraisal of the relevance of results
3. Different types of study designs
3.3 Conclusion
The level of evidence is often determined with respect to the type of study design, the strongest level being from the randomized controlled clinical trial.
The type of study design chosen depends mainly on the question being asked, and thus should correspond to it (Figure 1).
In conclusion, once the question is asked, the hypothesis is raised, and the type of study design chosen, the research protocol can be precisely formulated.
| Question asked | Study Design |
|---|---|
| Diagnostic test | Cross-sectional study, randomized trial |
| Prevalence | Cross-sectional study |
| Incidence | Cohort Study |
| Pronostic | Cohort Study |
| Treatment/ Intervention | Randomized clinical trial |
| Etiology and causality | Cohort Study |