title: The study of group-level factors in epidemiology: rethinking variables, study designs, and analytical approaches.
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI 48101-2548, USA. adiezrou@umich.edu
authors.forename: Ana V
authors.initials: AV
authors.lastname: Diez Roux
mesh_terms: D015331:Cohort Studies; D003625:Data Collection / Q000379:methods; D004812:Epidemiologic Methods; D015340:Epidemiologic Research Design; D006801:Humans; D012307:Risk Factors; D018401:Sample Size