library(survival)
data(ex1_delayed_effect)
km1 <- with(ex1_delayed_effect, survfit(Surv(month, evntd) ~ trt))
km1
plot(km1)
with(subset(ex1_delayed_effect, trt == 1), survfit(Surv(month, evntd) ~ trt))
with(subset(ex1_delayed_effect, trt == 0), survfit(Surv(month, evntd) ~ trt))
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