source("http://192.38.117.59/~linearpredictors/datafiles/readPbc3.R")

pbc3$failure <- ifelse(pbc3$status != 0, 1, 0)
pbc3$tment <- relevel(pbc3$tment, ref = "1")

## ftable() flattens out the layout of the table
ftable(xtabs(~ failure + biligroup + tment, data = pbc3),
       row.vars = 1)

s <- survdiff(Surv(followup, failure) ~ strata(biligroup) + tment, data = pbc3)
## E^s_tment
s$exp

#coxph(Surv(followup, failure) ~ biligroup - 1, data = pbc3)

## 
model <- coxph(Surv(followup, failure) ~ tment:strata(biligroup), data = pbc3)
summary(model)