[R] A question about external time-dependent covariates in co x model

Thomas Lumley tlumley at u.washington.edu
Thu Aug 19 17:19:49 CEST 2004

On Thu, 19 Aug 2004, Göran Broström wrote:

> On Thu, Aug 19, 2004 at 09:36:22AM -0300, Hanke, Alex wrote:
> > Dear Rui,
> > >From my understanding of time-dependent covariates (not an expert but have
> > been working on a similar problem), it would appear that the coding of the
> > status column is not correct. Unless you have observed an event at each
> > interval you should only have status=1 for the last interval. In your
> > example I see 3 in total. Also, I think that if "end" is proportional to
> > your "covariate" you are incorporating a redundant time effect into the
> > model. The time effect is in the baseline hazard.
> Right, the 'splitting' was made incorrectly, but 'coxph' shouldn't
> segfault anyway. The error seems to be (caught) in 'coxph_wtest.c',
> line 29, which may be of interest to the R maintainer of 'survival',
> Thomas L.

It's already fixed.  coxph_wtest segfaulted on  covariance matrices of rank 0.


More information about the R-help mailing list