title: Diminishing returns to aggregate level studies.
authors.affiliation: National Primary Care Research and Development Centre, University of York, York Y010 5DD. hg8@york.ac.uk
authors.forename: H
authors.initials: H
authors.lastname: Gravelle
mesh_terms: D004522:Educational Status; D006304:Health Status; D006801:Humans; D007182:Income / Q000706:statistics & numerical data*; D009026:Mortality; D012923:Social Class