title: Study designs in epidemiology and levels of evidence.
authors.affiliation: Centre for Vision Research, Westmead Millennium Institute, University of Sydney, Sydney, Australia. jiejin_wang@wmi.usyd.edu.au
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: John
authors.initials: J
authors.lastname: Attia
mesh_terms: D056808:Biostatistics; D004812:Epidemiologic Methods; D016021:Epidemiologic Studies; D004813:Epidemiology; D019317:Evidence-Based Medicine; D006801:Humans; D012107:Research Design / Q000592:standards*