R version 2.7.1 (2008-06-23)
Copyright (C) 2008 The R Foundation for Statistical Computing
ISBN 3-900051-07-0

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> options(na.action=na.exclude) # preserve missings
> options(contrasts=c('contr.treatment', 'contr.poly')) #ensure constrast type
> library(survival)
Loading required package: splines
> 
> #
> # A test of  NULL models
> #
> fit1 <- coxph(Surv(stop, event) ~ rx + strata(number), bladder, iter=0)
> fit2 <- coxph(Surv(stop, event) ~ strata(number), bladder)
> 
> all.equal(fit1$loglik[2], fit2$loglik)
[1] TRUE
> all.equal(fit1$resid, fit2$resid)
[1] TRUE
> 
> 
> fit1 <- coxph(Surv(start, stop, event) ~ rx + strata(number), bladder2, iter=0)
> fit2 <- coxph(Surv(start, stop, event) ~ strata(number), bladder2)
> 
> all.equal(fit1$loglik[2], fit2$loglik)
[1] TRUE
> all.equal(fit1$resid, fit2$resid)
[1] TRUE
>