windows xp R 2.8.1 I am trying to plot the -log(log(survival)) to visually test the proportional hazards assumption of a Cox regression. The plot, which should give two lines (one for each treatment) gives only one line and a warning message. I would appreciate help getting two lines, and an explanation of the warning message. My problem may the that I have very few events in one of my strata, but I don't know. Thanks, John
fit0<-coxph(Surv(Time30,Died)~strata(Rx)+Age,data=GVHDdata) plot(survfit(fit0),fun="cloglog") WARNING: Warning in xy.coords (x, y, xlabel, ylabel, log) : 2 x values <=0 omitted from logarithmic plot > print(survfit(fit0),fun="cloglog") Call: survfit.coxph(object = fit0) n events median 0.95LCL 0.95UCL Rx=0 31 5 Inf Inf Inf Rx=1 32 15 Inf 1.17 Inf John David Sorkin M.D., Ph.D. Chief, Biostatistics and Informatics University of Maryland School of Medicine Division of Gerontology Baltimore VA Medical Center 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 (Phone) 410-605-7119 (Fax) 410-605-7913 (Please call phone number above prior to faxing) Confidentiality Statement: This email message, including any attachments, is for th...{{dropped:6}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.