title: Controversy over "contradiction": Should randomized trials always trump observational studies?
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Fletcher
mesh_terms: D015982:Bias; D016021:Epidemiologic Studies; D019317:Evidence-Based Medicine; D006801:Humans; D019370:Observation / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D012107:Research Design