Thank you very much that's perfect.
Rajen
2009/8/4 Terry Therneau <thern...@mayo.edu>
> > Does anyone know if there is a function like survdiff which can also
> handle
> > left-truncated and right-censored data? When I use it on left-truncated
> and
> > right-censored data I get an error message saying Right censored data
> only.
>
> coxph(Surv(time1, time2, status) ~ factor(group), data=mydata)
>
> The 'score' test from a Cox model is identical to the logrank test.
>
> (Well, almost identical - if there are two deaths on the same day the LR
> calculation uses an n-1 at one point where the Cox uses an n. Neither is
> right/wrong, just the choice of the authors of the two different papers.
> The
> difference is never of any consequence, usually several digits out in the
> test
> statistic: just enough to force addendums like this one.)
>
> To recreate the observed -expected columns
>
> fit0 <- coxph(Surv(time1, time2, status) ~ factor(group), data=mydata,
> iter=0, na.action=na.exclude)
> o.minus.e <- tapply(resid(fit0), mydata$group, sum)
> obs <- tapply(mydata$status, mdata$group, sum)
> cbind(observed=obs, expected= obs- o.minus.e, "o-e"=o.minus.e)
>
>
> Terry Therneau
>
>
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