Nominal variable

The values of a nominal variable are pure labels, so you can count them and name the most common one, but ranking or averaging them means nothing. For example, blood types A, B, and O among 100 donors with counts 20, 15, and 65 give a mode of O at $65 / 100 = 0.65$, and there is no such thing as a median blood type. The AP Statistics course framework does not use the words nominal or ordinal; it groups both under categorical variables, also called qualitative variables. Treat the split as useful college vocabulary rather than tested AP content.