Levels of measurement - what you can and can't do arithmetically

4. Interval scales of measurement

Because the size between intervals is equal within any one scale, you can add and subtract these values. Multiplication and division is not permitted because there is no absolute zero, and, for instance, a temperature of 40°C is not twice as hot as a temperature of 20°C.

Comparisons across different scales (for example centigrade to fahrenheit) should be handled with care, because they’re not starting from the same zero point and although the intervals within a scale are equal, the size of the intervals on different scales will vary.

  • Content author: Heather Wharrad
  • Developer: Al Leeder
  • HTML5 Conversion: Aaron Fecowycz
  • Contact: helm@nottingham.ac.uk

RLO released: 1st January, 2004

Page last updated: Wednesday 11th January 2017

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