title: Is there a hierarchy of methods in clinical research?
authors.affiliation: University Hospital, Leiden, The Netherlands.
authors.forename: J P
authors.initials: JP
authors.lastname: Vandenbroucke
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods; D015331:Cohort Studies / Q000379:methods; D005069:Evaluation Studies as Topic / Q000379:methods*; D006801:Humans; D011446:Prospective Studies / Q000379:methods; D011897:Random Allocation; D012189:Retrospective Studies / Q000379:methods