search for: coxenv

...als= ?strata?). The code runs, and gives the wrong answer (group is treated as an ordinary covariate). The solution 1. Add code very early that rewrites the formula without the offendinge survival:: string 2. Before calling model.frame(), insert my copy of strata into the calling chain coxenv <- new.env(parent= environment(formula)) assign("strata", survival::strata, envir= coxenv) environment(formula) <- coxenv The second part of this deals with those who want to use survival functions but not use library(survival). Now to the question. I had always (naively)...