Hi everybody,
I am a new user of R, design package.
I am trying to plot the estimated hazard ratio's of my cox regression
model with the confidence intervals. But I keep getting the
message:Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") :
contrasts can be applied only to factors with 2 or more levels
I have dichotomous, categorical as well as continuous variables in the
model, but I can only plot the dichotomous variable.
I started with the following syntax:
dd <- datadist(x1, x2, x3)
options(datadist='dd')
fit<-cph(S~ x1 +x2 +x3, x=T,y=T)
plothr<- summary(fit)
plot(plothr, log=T)
Because the levels defined by datadist didn't seem to work I tried to
adjust the levels after fitting the model:
dd$limits["Adjust to","x1"] <- 1
dd$limits["Adjust to","x2"] <- 30
fit <- update(fit)
plothr<- summary(fit)
plot(plothr, log=T)
Finally I have tried: summary(fit, x1=1, x2=30, x3=3)
But this option didn't work either. Can anybody tell me what goes wrong
and why?
Thanks for your help,
Cary
Cary Dehing-Oberije
Researcher CAT project
p/a MAASTRO clinic
Dr. Tanslaan 12
6229 ET Maastricht
The Netherlands
phone: 088 - 4455666 / 088 - 4455767
email: cary.dehing@maastro.nl
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