Hello all,
I want to use an extended Cox model to allow for the incorporation of a
time-varying covariate (each individual is subjected to several measurements
over time).
I modified my data set adequatly to get as many time intervals as necessary
and use the coxph(Surv(start, stop, event) ~ X1 + X2.+ X3.) function, where X1
and X2 are fixed-time covariates and X3 the time-varying covariate.
I wonder if the cox.zph function can still be used to assess the independence
of the beta coefficients with time?
Thanks
sylvie
Sylvie DALLOT
USDA/ARS/USHRL
2001 South Rock Road
FORT PIERCE, FL 34945
USA
phone: 1 772 462 58 60
FAX: 1 772 462 59 86
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