You would like to ensure that your sample is representative of the racial mix seen in your population of interest. The population is 50% Asian, 20% African American, 20% Caucasian, and 10% other. You need a sample of 500 subjects. You program SPSS to select randomly 250 Asian subjects from your population, 100 African American subjects, 100 Caucasian subjects, and 50 subjects identified as other.

You are interested in how race may affect total cholesterol. Your study classifies race in the categories described above. What level of measurement is this variable?