is ssn nominal
We cannot order Social Security numbers in any meaningful way. Some people have Social Security numbers that start with a higher number than others but there is no meaningful difference signified by this. So the Social Security number is a nominal level variable. Any time that you arbitrarily assign a person or another entity an identification number, the resulting variable will be nominal because the numbers d4o not signify anything important or meaningful. On the other hand, interval level variables are ordered.