Randomized, Controlled Trials, Observational Studies, and the Hierarchy of Research Designs
Concato J, Shah N, Horwitz R. Randomized, Controlled Trials, Observational Studies, and the Hierarchy of Research Designs. New England Journal Of Medicine 2000, 342: 1887-1892. PMID: 10861325, PMCID: PMC1557642, DOI: 10.1056/nejm200006223422507.Peer-Reviewed Original ResearchConceptsCase-control studyObservational studyBacille Calmette-Guérin (BCG) vaccineCalmette-Guérin vaccineRandomized clinical trialsClinical topicsIndividual observational studiesEffect of vaccinationEffect of treatmentMEDLINE data baseActive tuberculosisControlled TrialsPercent confidence intervalsClinical trialsOdds ratioRelative riskSummary estimatesMajor medical journalsSame interventionTrialsResearch designConfidence intervalsHigh gradeTreatment effectsOriginal report