Dear all,
I have some trouble using the "id"-argument with aftreg (accelerated
failure time regression analysis from the eha library).
As far as I understand it, the id argument is used to group
individuals together if there are time-varying covariates and the
data is arranged in counting process style.
Unfortunately, i cannot figure out how to use the "id"-argument. The
most straight-forward way would be to simply state the grouping
variable, but it throws an error. I've included an example below:
the dataframe for regression is called "test", with the grouping
variable "person".
> test
start end censor person var1
1 0 1 0 1 0.5
2 1 2 0 1 0.4
3 2 3 0 1 0.6
4 3 4 1 1 -0.3
5 0 1 0 2 0.6
6 1 2 0 2 0.7
7 2 3 0 2 0.6
> fit <- aftreg(Surv(start, end, censor)~var1, data=test, id=person)
Error in order(id, Y[, 1]) : argument 1 is not a vector
> fit <- aftreg(Surv(start, end, censor)~var1, data=test,
id=test["person"])
Error in `[.data.frame`(id, ord) : undefined columns selected
What would be the correct way to fit this example model?
Thanks + all the best
Philipp
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