Re: [R] Apparently Conflicting Results with coxph

2007-10-03 Thread Terry Therneau
I thought about this some more, and I'm not sure that possibility is to blame. In my time-dependent model, I don't think I'm doing anything different than is done for transplant in the Stanford Heart Study (the often used example for this kind of time-dependent covariate). As in my case,

Re: [R] Apparently Conflicting Results with coxph

2007-10-02 Thread Kevin E. Thorpe
Kevin E. Thorpe wrote: Peter Dalgaard wrote: Kevin E. Thorpe wrote: Dear List: I have a data frame prepared in the couting process style for including a binary time-dependent covariate. The first few rows look like this. PtNo StartEnd Status Imp 1 1 0 608.0 0 0

Re: [R] Apparently Conflicting Results with coxph

2007-10-02 Thread Terry Therneau
From my experience, what you are seeing is almost certainly a patient selection effect. (The number 1 reason for puzzling results is incorrect coding of a time-dependent covariate, but you appear to have been quite careful). Assigning the implant as a non-time dependent covariate

Re: [R] Apparently Conflicting Results with coxph

2007-10-02 Thread Charles C. Berry
On Tue, 2 Oct 2007, Kevin E. Thorpe wrote: Kevin E. Thorpe wrote: Peter Dalgaard wrote: Kevin E. Thorpe wrote: Dear List: I have a data frame prepared in the couting process style for including a binary time-dependent covariate. The first few rows look like this. PtNo StartEnd

[R] Apparently Conflicting Results with coxph

2007-10-01 Thread Kevin E. Thorpe
Dear List: I have a data frame prepared in the couting process style for including a binary time-dependent covariate. The first few rows look like this. PtNo StartEnd Status Imp 1 1 0 608.0 0 0 2 2 0 513.0 0 0 3 2 513 887.0 0 1 4 3