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