title: Commentary: exegesis of effect modification - biological or spurious?
authors.affiliation: Department of Obstetrics and Gynaecology, Dalhousie University and the IWK Health Centre, Halifax, Nova Scotia, Canada. ksjoseph@cfri.ca
authors.forename: K S
authors.initials: KS
authors.lastname: Joseph
mesh_terms: D015986:Confounding Factors, Epidemiologic; D015987:Effect Modifier, Epidemiologic; D005260:Female; D006801:Humans; D007226:Infant Mortality / Q000639:trends*; D007231:Infant, Newborn; D008954:Models, Biological; D015233:Models, Statistical; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology