R help - Apr 2006 - testing proportional hazard in a Cox model including a time-varying covariate

I am using a syntax like coxph(Surv(start, stop, event) ~ X, data) to estimate
the effect of X, which may change at each measurement (every 6 months). Is there
anyone who knows a way to test the proportional hazard assumption in that case?

 

Thank you in advance

 

Jean-François Boudreau

Sherbrooke University

 


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See 

?cox.zph 

in library 'survival' 

-Christos

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Boudreau
Jean-Francois
Sent: Monday, April 03, 2006 2:58 PM
To: r-help at stat.math.ethz.ch
Subject: [R] testing proportional hazard in a Cox model including
atime-varying covariate

I am using a syntax like coxph(Surv(start, stop, event) ~ X, data) to
estimate the effect of X, which may change at each measurement (every 6
months). Is there anyone who knows a way to test the proportional hazard
assumption in that case?

 

Thank you in advance

 

Jean-Frangois Boudreau

Sherbrooke University

 


	[[alternative HTML version deleted]]

On Mon, 3 Apr 2006, Boudreau Jean-Francois wrote:
> I am using a syntax like coxph(Surv(start, stop, event) ~ X, data) to 
> estimate the effect of X, which may change at each measurement (every 6 
> months). Is there anyone who knows a way to test the proportional hazard 
> assumption in that case?
You can use cox.zph(), or you can just put in interactions between X and 
start.

 	-thomas

>
>
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> Thank you in advance
>
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>
> Jean-Fran?ois Boudreau
>
> Sherbrooke University
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>
> 	[[alternative HTML version deleted]]
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>
Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle