You may be wondering: what's the difference between a character vector and a factor? After all, as you saw in the previous exercise, the
phone_factor variables basically look the same. Why would you want to use a factor, anyway? A factor only lets you store values that belong to one of its categories, which are called levels.
You can display these levels with the
levels() function, like so:
R then returns the possible categories that
phone_factor values can belong to:
 "N" "Y"
Note that the categories/levels are displayed in ascending order. In this case, N is alphabetically less than Y, so it's displayed first.