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Glossary » NOIR


nominal-ordinal-interval-ratio. A mnemonic for remembering common data scales used in empirical measurement.

  • Nominal – a set of items that can be distinguished by name or category.
  • Ordinal – items that can be ordered, such as military rank, or units of government, but whose degree of difference can’t be measured.
  • Interval – items that have a measurable distance between them, but no meaningful (non-arbitrary) zero point, such as Fahrenheit and Celsius temperatures.
  • Ratio – measurements that have a meaningful zero and can be divided meaningfully, such as the Kelvin temperature scale.

Scales are useful to understand in analyzing data from user testing or surveys. They are also helpful in representing data in information visualization.