In case this time-dependent covariate is an internal time-dependent covariate (aka endogenous time-dependent covariate), you can use the jointModel() function from package JM, with the option "weibull-AFT-GH" for the 'method' argument.

For more information you may have a look at: http://rwiki.sciviews.org/doku.php?id=packages:cran:jm


I hope it helps.

Best,
Dimitris


Philipp Rappold wrote:
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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Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

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