# Zad 2
View(cancer)
object <- with(na.omit(cancer), Surv(time, status))
model <- survfit(object ~ sex, data = na.omit(cancer))
print(model, rmean="common")

dif <- survdiff(object ~sex, data = na.omit(cancer))
print(dif, rmean="common")


ggsurvplot(model,
           data = na.omit(cancer),
           risk.table = TRUE,
           pval = TRUE,
           conf.int = TRUE,
           fun = 'pct',
           legend.labs = c('Male', 'Female'),
           legend.title = 'Sex')

model4 <- coxph(object ~ sex + age + meal.cal, data = na.omit(cancer))
summary(model4)

step(model4)