I did not see an attached figure to compare against, perhaps it was removed by the server. I suspect that: plot(survfit(fit0,newdata=GVHDdata) will produce the plot you're looking for. It will generate survival curves for the data in GVHDdata using the estimates from the fit0 coxph model. At least, that's what I gather from the documentation..
Cheers, On 10/05/09 5:43 PM, "John Sorkin" <jsor...@grecc.umaryland.edu> wrote: R 2.8.1 Windows XP I am trying to plot the results of a coxph using plot(survfit()). The plot should, I believe, show two lines one for survival in each of two treatment (Drug) groups, however my plot shows only one line. What am I doing wrong? My code is reproduced below, my figure is attached to this EMail message. John > #Create simple survival object > GVHDdata<-list(Time=GVHD$Time,Time30=(GVHD$Time)/30, + Age=GVHD$Age,Drug=GVHD$Drug,Died=GVHD$Died, + AgeGrp=cut(GVHD$Age,breaks=c(0,15,25,45))) > > summary(GVHD$Drug) MTX MXT+CSP 32 32 > > > > fit0<-coxph(Surv(Time30,Died)~Drug,data=GVHDdata) > summary(fit0) Call: coxph(formula = Surv(Time30, Died) ~ Drug, data = GVHDdata) n= 64 coef exp(coef) se(coef) z p Drug[T.MXT+CSP] -1.15 0.316 0.518 -2.23 0.026 exp(coef) exp(-coef) lower .95 upper .95 Drug[T.MXT+CSP] 0.316 3.16 0.115 0.871 Rsquare= 0.086 (max possible= 0.915 ) Likelihood ratio test= 5.75 on 1 df, p=0.0165 Wald test = 4.96 on 1 df, p=0.026 Score (logrank) test = 5.52 on 1 df, p=0.0188 > > > plot(survfit(fit0)) 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.