title: A simplified method of calculating an overall goodness-of-fit test for the Cox proportional hazards model.
abstract: Grønnesby and Borgan (1996) propose an overall goodness-of-fit test for the Cox proportional hazards model. The basis of their test is a grouping of subjects by their estimated risk score. We show that the Grønnesby and Borgan test is algebraically identical to one obtained from adding group indicator variables to the model and testing the hypothesis the coefficients of the group indicator variables are zero via the score test. Thus showing that the test can be calculated using existing software. We demonstrate that the table of observed and estimated expected number of events within each group of the risk score is a useful adjunct to the test to help identify potential problems in fit.
authors.affiliation: Department of Biostatistics and Epidemiology, University of Massachusetts at Amherst, USA.
authors.forename: S
authors.initials: S
authors.lastname: May
authors.forename: D W
authors.initials: DW
authors.lastname: Hosmer
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods; D003627:Data Interpretation, Statistical; D006801:Humans; D016013:Likelihood Functions; D008105:Liver Cirrhosis, Biliary / Q000401:mortality; D008910:Minnesota / Q000453:epidemiology; D009101:Multiple Myeloma / Q000401:mortality; D016016:Proportional Hazards Models; D018570:Risk Assessment; D015996:Survival Rate; D014903:West Virginia / Q000453:epidemiology