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

## table of treatment and ascites
t1 <- xtabs(~ tment + asc, data = csl)
t1 <- addmargins(t1)

## same table, but on the subset of data where dc = 1
t2 <- xtabs(~ tment + asc, data = subset(csl, dc==1))
t2 <- addmargins(t2)

## now for each cell in the table we find the percentage of
## events
t2/t1*100