18 lines
487 B
R
18 lines
487 B
R
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library(survival)
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# the way a +cluster() term is handled in coxph has implications for update.
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fit1 <- coxph(Surv(time, status) ~ age, cluster= inst, lung)
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fit2 <- coxph(Surv(time, status) ~ age + cluster(inst), lung)
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all.equal(fit1, fit2)
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fit3 <- coxph(Surv(time, status) ~ age + sex + cluster(inst), lung)
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test1 <- update(fit1, .~ .+ sex)
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all.equal(test1, fit3)
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# Gives a spurious warning message
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test2 <- update(fit1, . ~ age + sex + cluster(inst), lung)
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all.equal(test2, fit3)
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