What is a nominal scale?

Answer 1

A nominal scale is the most basic form of measurement. Notice that the word nominal comes from the same root as the word name. So to use a nominal scale is essentially to name. For instance, I can 'measure' the religion of each person in a sample by assigning a broad religious category from the set {Muslim, Christian, Jewish, Hindu, Animalist, ...} to each person. This would be the use of a nominal scale.

For more, you might visit the wikipedia page about level of measurement.