Hello everyone, I am a new user of R. Does anybody know how hazard ratios are extracted for each factor level in a stratified Cox proportional hazard regression model? I have a cancer data set where the variable ?differentiation? is a factor with three levels: poor, intermediate and good. I would like to extract the hazard ratio for each grade level and relate it to another prognostic factor. I?ll appreciate very much if somebody helps me sort out this. Sincerely, Dora
You will have to be more clear about what exactly you are trying to do. I, at least, am quite unsure about what you want. fit <- coxph(Surv(time, status) ~ x1 + strata(x2)) The hazard ratio(s) wrt x1 have the same meaning for a stratified or an unstratified model. If you are asking about hazard ratios for x2 --- there are none. That is the point of a strata; you are declaring a variable to NOT be proportional hazards, and thus there is no single "hazard ratio" that describes it. Terry Therneau