title: How do observational studies expand the evidence base for therapy?
authors.forename: M J
authors.initials: MJ
authors.lastname: Radford
authors.forename: J M
authors.initials: JM
authors.lastname: Foody
mesh_terms: D015331:Cohort Studies; D019317:Evidence-Based Medicine; D006801:Humans; D019370:Observation; D016032:Randomized Controlled Trials as Topic