On Oct 6, 2011, at 7:00 AM, koshihaku wrote:
Dear all,
Is there a way to calculate the non-cumulative hazard (instantaneous
hazard), which is the product of baseline hazard and
exp{beta*covariate} ?
I knew in survfit, we can get the estimator of cumulative baseline
hazard,
but how can we get the non-cumulative one?
The instantaneous hazard is just (dS/dt)/ S. It should be fairly easy
to calculate that value at each event from the estimated baseline
survival, S_0(t). I don't know if there is an intermediate result in
the coxph or survfit internals that could be exported as the "baseline
hazard function". Most of the presentation of the theory in Therneau
and Grambsch uses the cumulative hazard function.
Therneau suggests: "Users are strongly advised to use the newdata
argument. Note that this data set needs to contain values for the main
effects but not for any interaction terms." The "baseline survival"
has the same problems in interpretation that are discussed on the
opening paragraph for the Details section in help(survfit.coxph).
--
David Winsemius, MD
West Hartford, CT
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