title: On the nature and analysis of clustered data.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Zyzanski
authors.forename: Susan A
authors.initials: SA
authors.lastname: Flocke
authors.forename: L Miriam
authors.initials: LM
authors.lastname: Dickinson
mesh_terms: D016000:Cluster Analysis; D005194:Family Practice / Q000458:organization & administration*; D006801:Humans; D012106:Research