title: Units of sampling, observation, and analysis.
authors.affiliation: Institute for Medical and Biomedical Education, St George's, University of London, London, UK p.sedgwick@sgul.ac.uk.
authors.forename: Philip
authors.initials: P
authors.lastname: Sedgwick
mesh_terms: D006801:Humans; D019370:Observation / Q000379:methods*; D013048:Specimen Handling / Q000706:statistics & numerical data*