title: Neither within-region nor cross-regional independence of exposure and covariates prevents ecological bias.
authors.forename: S
authors.initials: S
authors.lastname: Greenland
authors.forename: H
authors.initials: H
authors.lastname: Morgenstern
mesh_terms: D015982:Bias; D004812:Epidemiologic Methods; D006801:Humans; D016014:Linear Models