The type of question will often dictate the best study design to address the question:
Key: best - to - adequate, or what is available on topic
Question: Study:
Clinical Examination Prospective, blind comparison to the Gold Standard
Diagnostic Testing Prospective, blind comparison to the Gold Standard
Prognosis Cohort Study - Case Control- Case Series
Therapy RCT- Cohort Study- Case Control - Case Series
Etiology/Harm RCT - Cohort Study - Case Control - Case Series
Prevention RCT- Cohort Study - Case Control - Case Series