21 lines
694 B
R
21 lines
694 B
R
#
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# New tests 4/2010 to validate strata by covariate interactions
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#
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library(survival)
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options(na.action=na.exclude) # preserve missings
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options(contrasts=c('contr.treatment', 'contr.poly')) #ensure constrast type
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aeq <- function(x,y) all.equal(as.vector(x), as.vector(y))
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tdata <- lung
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tdata$sex <- lung$sex +3
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# Both of these should produce warning messages about singular X, since there
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# are ph.ecog=3 subjects in only 1 of the strata.
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# Does not affect the test
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fit1 <- coxph(Surv(time, status) ~ age + sex:strata(ph.ecog), lung)
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fit2 <- coxph(Surv(time, status) ~ age + sex:strata(ph.ecog), tdata)
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aeq(fit1$coef, fit2$coef)
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aeq(fit1$var, fit2$var)
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aeq(predict(fit1), predict(fit2))
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