What are the four levels of measurement?

Levels of measurement tell you how precisely variables are recorded. There are 4 levels of measurement, which can be ranked from low to high:

• Nominal: the data can only be categorized.
• Ordinal: the data can be categorized and ranked.
• Interval: the data can be categorized and ranked, and evenly spaced.
• Ratio: the data can be categorized, ranked, evenly spaced and has a natural zero.