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2008 Nov 10
1
coxph diagnostics plot for shape of hazard function?
Hi,
I've been banging my head against the following problem for a while
and thought the fine people on r-help might be able to help. I'm
using the survival package.
I'm studying the survival rate of a population with a preexisting
linear-like event rate (there are theoretical reasons to believe
it's linear, but of course it's subject to the usual sampling noise)
Some of the
2009 Mar 16
0
hazard function in a Cox model
...es, to
better understand what is occurring in the log plots.
--- end inclusion ----
The best tool for understanding what is happening is cox.zph.
cox.V <- coxph(Surv(intDaysUntilFVPO, Event_v) ~ intAgeAtMHCIndex +
PRE + group + MHC + strGender, data = recidivismv)
zpfit <- cox.zph(cox.V, transform='identity')
plot( zpfitp[1]) #plot for the first variable
plot( zpfitp[2]) #plot for the second
You will get a plot of beta(t) versus time, a horizontal line corresponds to a
constant hazard ratio. The Cox model coefficient is an "average&quo...