Cancer Institute A national cancer institute
designated cancer center

Philip W. Lavori

Publication Details

  • Sample-size calculations for the Cox proportional hazards regression model with nonbinary covariates CONTROLLED CLINICAL TRIALS Hsieh, F. Y., Lavori, P. W. 2000; 21 (6): 552-560


    This paper derives a formula to calculate the number of deaths required for a proportional hazards regression model with a nonbinary covariate. The method does not require assumptions about the distributions of survival time and predictor variables other than proportional hazards. Simulations show that the censored observations do not contribute to the power of the test in the proportional hazards model, a fact that is well known for a binary covariate. This paper also provides a variance inflation factor together with simulations for adjustment of sample size when additional covariates are included in the model. Control Clin Trials 2000;21:552-560

    View details for Web of Science ID 000165940800003

    View details for PubMedID 11146149

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