title: Observational studies identify associations, not causality.
authors.affiliation: Department of Anesthesiology; Emory University School of Medicine; Atlanta, GA; arnold_berry@emoryhealthcare.org.
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Berry
mesh_terms: D000758:Anesthesia / Q000401:mortality*; D004569:Electroencephalography; D006801:Humans; D013514:Surgical Procedures, Operative / Q000401:mortality*; D013997:Time Factors