title: Validity versus generalizability in clinical trial design and conduct.
authors.forename: C H
authors.initials: CH
authors.lastname: Hennekens
authors.forename: J E
authors.initials: JE
authors.lastname: Buring
mesh_terms: D000328:Adult; D017677:Age Distribution; D002318:Cardiovascular Diseases / Q000145:classification*; D002986:Clinical Trials as Topic / Q000379:methods / Q000592:standards*; D004608:Eligibility Determination / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D018579:Patient Selection; D016032:Randomized Controlled Trials as Topic / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D012107:Research Design; D015983:Selection Bias; D017678:Sex Distribution