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Dear R-users, I am checking the proportional hazard assumption of a cox model for a given covariate, let say Z1, after adjusting for other relavent covariates in the model. To this end, I fitted cox model stratified on the discrete values of Z1 and try to get beslow estimator for the baseline cumulative hazard function (H(t)) in each stratum. As far as i know, if the proportionality assumption holds, the plot of ln[H(t)] of each stratum versus time should be approximately parallel. i.e fit<-coxph(Surv(start,end,status)~sx+rated+AGLEVEL+strata(Z1),data=AL...

...il.com> Content-Type: text/plain Dear R-users, I am checking the proportional hazard assumption of a cox model for a given covariate, let say Z1, after adjusting for other relavent covariates in the model. To this end, I fitted cox model stratified on the discrete values of Z1 and try to get beslow estimator for the baseline cumulative hazard function (H(t)) in each stratum. As far as i know, if the proportionality assumption holds, the plot of ln[H(t)] of each stratum versus time should be approximately parallel. i.e fit<-coxph(Surv(start,end,status)~sx+rated+AGLEVEL+strata(Z1),data=AL...