Hi,
Please, help me understand what is happening with the means of a Cox model?
I have:
R version 4.0.2 (2020-06-22) -- "Taking Off Again"
Copyright (C) 2020 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64 (64-bit)
getOption("contrasts")
unordered ordered
"contr.treatment" "contr.poly"
According to the help coxph.object has a component holding the means of the X
(model.matrix). This does not hold any more.
```
library(survival)
test1 <- list(time=c(4,3,1,1,2,2,3),
status=c(1,1,1,0,1,1,0),
x=c(0,2,1,1,1,0,0),
sex=factor(c(0,0,0,0,1,1,1)))
m1 <- coxph(Surv(time, status) ~ x + sex, test1)
m1$means
## x sex1
## 0.7142857 0.0000000
colMeans(model.matrix(m1))
## x sex1
## 0.7142857 0.4285714
```
Will new observations be scored using the zero mean from the object?? Is this
just a reporting change where $means shows the reference level and no longer
the mean of the model matrix??
Thanks everybody
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