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NeuroRx. 2004 July; 1(3): 341–347.
PMCID: PMC534936
Observational Versus Experimental Studies: What’s the Evidence for a Hierarchy?
John Concato
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, and the Clinical Epidemiology Research Center, West Haven Veterans Affairs Medical Center, West Haven, Connecticut 06516
Address correspondence and reprint requests to John Concato, M.D., M.P.H., Yale University School of Medicine, Department of Internal Medicine, Sterling Hall of Medicine IE-61, New Haven, CT 06510. E-mail: john.concato/at/yale.edu
Abstract
Summary: The tenets of evidence-based medicine include an emphasis on hierarchies of research design (i.e., study architecture). Often, a single randomized, controlled trial is considered to provide “truth,” whereas results from any observational study are viewed with suspicion. This paper describes information that contradicts and discourages such a rigid approach to evaluating the quality of research design. Unless a more balanced strategy evolves, new claims of methodological authority may be just as problematic as the traditional claims of medical authority that have been criticized by proponents of evidence-based medicine.
Keywords: Cohort studies, case control studies, clinical trials, evidence-based medicine, bias