search for: imputati

...vious post. Assuming i'm doing well, i'd prefer to use cph because of the rms bootstrap validation facilities. Unfortunately cph doesn't wanto to model an interaction term without the both corresponding main effects: > fit.cph <- cph(TACE.Surv~PS+PS:TIME.start,data=DatasetTACE.imputati) Error in if (!length(fname) || !any(fname == zname)) { : missing value where TRUE/FALSE needed coxph runs without complaining. I could make the design matrix columns by hand, but this is generally not recommended, isn't it? Any sort of comment will be appreciated. Thank you very much....