title: A simple correction for ties when censoring times depend on covariates.
abstract: We point out that the conventional methods for ties correction may be seriously biased when censoring times depend on covariates. A simple modification to the Efron correction method is suggested which works remarkably well in simulation studies. The method corresponds closely to breaking ties by random ordering. The modified correction method is easy to implement and computationally no more demanding than the Efron correction.
authors.affiliation: Department of Mathematics, University of Oslo, P.O. Box 1053 Blindern, 0316 Oslo, Norway. osamuels@math.uio.no
authors.forename: S O
authors.initials: SO
authors.lastname: Samuelsen
authors.forename: T F
authors.initials: TF
authors.lastname: Wisløff
authors.forename: A
authors.initials: A
authors.lastname: Skrondal
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003075:Coitus; D003198:Computer Simulation; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008875:Middle Aged; D016016:Proportional Hazards Models