Variables

The Nominal Scale

The Team variable is an example of a variable measured on a nominal scale. For any variable measured on a nominal scale:

• We can tell whether two individuals are different or not (with respect to that variable).

• We can't say anything about the direction and the size of the difference.

• We know that it can only describe qualities.

When a qualitative variable is described with numbers, the principles of the nominal scale still hold. We can tell whether there's a difference or not between individuals, but we still can't say anything about the size and the direction of the difference.

If basketball player A has the number 5 on her shirt, and player B has 8, we can tell they're different with respect to shirt numbers, but it doesn't make any sense to subtract the two values and quantify the difference as a 3. Nor it makes sense to say that B is greater than A. The numbers on the shirts are just identifiers here, they don't quantify anything.