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