Biostatistics & Research · single question
Which type of study provides the HIGHEST level of clinical evidence?
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Correct answer: C. Randomized Controlled Trial (RCT)
In the hierarchy of evidence (pyramid), systematic reviews/meta-analyses of RCTs sit at the top. Among individual study designs, the Randomized Controlled Trial (RCT) provides the highest level of evidence because randomization minimizes confounding bias and allows causal inference. The hierarchy: RCT > Cohort > Case-control > Cross-sectional > Case report/series > Expert opinion.
- A. CORRECT. RCTs provide the highest level of individual study evidence due to randomization, which controls for confounding variables and allows causation to be established.
- B. Incorrect. Cohort studies are observational and cannot establish causation as definitively as RCTs — they rank below RCTs in the evidence hierarchy.
- C. Incorrect. Case-control studies are retrospective and more prone to bias than RCTs or cohort studies.
- D. Incorrect. Case reports represent the lowest level of evidence — they describe individual patients and cannot be generalized to populations.
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