title: Ecological analysis of intended treatment effects: caveat emptor.
authors.affiliation: Department of Medicine, University of Toronto, Sunnybrook Health Science Centre, Ontario, Canada.
authors.forename: C D
authors.initials: CD
authors.lastname: Naylor
mesh_terms: D015982:Bias; D015986:Confounding Factors, Epidemiologic; D003627:Data Interpretation, Statistical; D015987:Effect Modifier, Epidemiologic; D006801:Humans; D015233:Models, Statistical; D015203:Reproducibility of Results; D016896:Treatment Outcome