Johannes Huesing <johan...@huesing.name> [Mon, Jan 10, 2011 at 09:26:37PM CET]: > I am trying to model survival data with a Weibull distribution > > using survreg. Units are clustered two apiece, sometimes receiving > > the same treatment and sometimes opposing treatment. > > > > Residual and predict methods are not carried out on the survreg > > object, although the component linear.predictors exists for the > > survreg object. Looking at the code I see that the residual method > > refuses to run if any of the components of the pterms vector is > > equal to 2. > > > > When taking the logarithm of the data and trying a linear mixed > > model, residuals and predicted values are produced just fine. > > > > So what is pterms and why is it that, when any component of it > > is 2, residuals are not allowed to be displayed?
I am using R 2.10.1, and here is some example code: anzpat <- 32 device <- rep(unlist(expand.grid(list(c("C", "Z"), c("C", "Z")))), anzpat / 4) bleedtimes <- exp(rnorm(anzpat * 2, 0, .3) + as.numeric(device) * log(3)) pat <- as.factor(rep(1:anzpat, each=2)) library(survival) survmod <- survreg(Surv(sapply(bleedtimes, min, 10), bleedtimes < 10) ~ device + frailty.gaussian(pat)) residuals(survmod) ### Fehler in residuals.survreg.penal(survmod) : ### Residualss not available for sparse models survmod$pterms ### (Intercept) device frailty.gaussian(pat) ### 0 0 2 -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, "Life on the Mississippi") ______________________________________________ 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.