search for: hermaphrodite

...a long discussion of the differences between these, and the various pitfalls. By default, survfit produces the curve for a hypothetical "average" subject whose covariate values are the respective means of the data set. I'm not very keen on this estimate --- what is sex=.453, a hermaphrodite? But it is the historical default. Terry Therenau ---- begin included message ------------- I am confused when trying the function survfit. my question is: what does the survival curve given by plot.survfit mean? is it the survival curve with different covariates at different points?...

...g what the default reference levels should be, and building the data frame with those levels. It's the first part that is hard. For survival curves from a Cox model the historical default has been to use the mean of each covariate, which can be awful (sex coded as 0/1 leads to prediction for a hermaphrodite?). Nevertheless, I've not been able to think of a strategy that would give sensible answers for most of the data I use and coxph retains the flawed default for lack of a better idea. When teaching a class on this, I tell listeners "bite the bullet" and build the newdata that makes c...

Dear all, I am confused with the output of survfit.coxph. Someone said that the survival given by summary(survfit.coxph) is the baseline survival S_0, but some said that is the survival S=S_0^exp{beta*x}. Which one is correct? By the way, if I use "newdata=" in the survfit, does that mean the survival is estimated by the value of covariates in the new data frame? Thank you very much!