title: Invited commentary: propensity scores.
abstract: The propensity score is the conditional probability of exposure to a treatment given observed covariates. In a cohort study, matching or stratifying treated and control subjects on a single variable, the propensity score, tends to balance all of the observed covariates; however, unlike random assignment of treatments, the propensity score may not also balance unobserved covariates. The authors review the uses and limitations of propensity scores and provide a brief outline of associated statistical theory. They also present a new result of using propensity scores in case-cohort studies.
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia 19104-6021, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Joffe
authors.forename: P R
authors.initials: PR
authors.lastname: Rosenbaum
mesh_terms: D016022:Case-Control Studies; D015984:Causality; D015986:Confounding Factors, Epidemiologic; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000601:surgery / Q000628:therapy; D006801:Humans; D015233:Models, Statistical