Aviation the subjects in which college students major is what level of measurement

In surveys they often use arbitrary numbers to code variables such as religion, ethnicity, major in college or gender. In fact, with nominal variables measurement.
Determine which of the four levels of measurement is most appropriate: The subjects in which college students major. a) Nominal b) Ordinal c) Interval d) Ratio. Missing: aviation.
63 Aerospace and aircraft (orders, parts, etc.). 112 Age data, see specific subjects. Many abstracts note . College students, major field of study.
Barcodes and social security numbers are two examples. The amount you pay for your plane ticket, the number of miles you fly, or the degree Fahrenheit at your destination, are all quantities. A group can have a single member, as it is the case with SSN. Numbers can be also used to order. In surveys they often use arbitrary numbers to code variables such as religion, ethnicity, major in college or gender.