3.1, 3.3, 3.4, 3.7, 3.9, 3.13
## Data for 3.9 credit <- read.table("https://raw.githubusercontent.com/alanagresti/categorical-data/refs/heads/master/Credit.dat", header = TRUE) credit$any_card <- 1L*(credit$cards > 0)
4.5, 4.9, 4.13