title: Lack of standards in direct standardization.
authors.forename: J B
authors.initials: JB
authors.lastname: Reitsma
authors.forename: G J
authors.initials: GJ
authors.lastname: Bonsel
authors.forename: L J
authors.initials: LJ
authors.lastname: Gunning-Schepers
authors.forename: J G
authors.initials: JG
authors.lastname: Tijssen
mesh_terms: D015986:Confounding Factors, Epidemiologic; D003627:Data Interpretation, Statistical; D006801:Humans; D012015:Reference Standards