Hi - I am fitting various Cox PH models with spline predictors. After fitting the model, I would like to use termplot() to examine the functional form of the fitted model (e.g., to obtain a plot of the relative risk (or log r.r.) versus the predictors).
When there is only 1 predictor in the model, termplot returns a "?". In this case, I have not been able to figure out how to create the desired plot. Otherwise,termplot is easy to use. Example: library(survival) library(splines) data(pbc) fit1<-coxph(Surv(time,status)~ns(bili,4)+ns(age,4), data=pbc) fit2<-coxph(Surv(time,status)~ns(bili,4), data=pbc) par(mfrow=c(2,2)) termplot(fit1) # returns two plots (one for bili and one for age) termplot(fit2) # returns a "?" prompt Does anyone have any suggestions for obtaining a plot of the log relative risk as a function of bili in the second example (or for this type of model in general)? On a similar note, I would like to be able to obtain predicted values for "new" subjects. I tried using: temp<-data.frame(bili=0.8) predict(fit2,newdata=temp, safe=T) This gives the following error message: Error in qr(t(const)) : NA/NaN/Inf in foreign function call (arg 1) Is there a simple method available for obtaining predicted values for new subjects when using these types of models? I have encountered similar problems when trying to use smoothing splines w/ the above examples (i.e., 'pspline' in the survival package). I am currently using R version 1.8.1 for windows. Any help would be greatly appreciated! John John Fieberg, Ph.D. Wildlife Biometrician, MN DNR 5463-C W. Broadway Forest Lake, MN 55434 Phone: (651) 296-2704 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
