title: Commentary: Assessing the quality of observational studies--or a lesson from Mars.
authors.affiliation: Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland. vonelm@ispm.unibe.ch
authors.forename: Erik
authors.initials: E
authors.lastname: von Elm
mesh_terms: D004812:Epidemiologic Methods; D006801:Humans; D019370:Observation; D011785:Quality Assurance, Health Care / Q000379:methods*