Factor basics

• A variable that records month:

x1 <- c("Dec", "Apr", "Jan", "Mar")

Problems with using a string: - Only 12 possible values - No way of accounting for typos

x2 <- c("Dec", "Apr", "Jam", "Mar")

• Doesn’t sort in a useful way but alphabetically

sort(x1)

## [1] "Apr" "Dec" "Jan" "Mar"