Levels of measurement

Brief description of nominal, ordinal, interval, and ratio measurement level


  • Nominal: categorical, with no ranking in the categories. For instance, religion.
  • Ordinal: categorical, with ranked categories. For instance, socio-economic status.
  • Interval: quantitative, where the difference between scores is meaningful. For instance, temperature, measured in celcius degrees. Also, sometimes Likert scales are considered interval scales.
  • Ratio: quantitative, where the difference between scores is meaningful, as well as the zero value. For instance, body length.