Scales of Measurement

Photo by Kool Kats Photography

Details for measurement scales for data.

In order of desirability: Nominal – ordinal – interval – ratio.

Nominal Scale of Measurement

  • Data that consists of names or categories only.
  • Allows us to classify the object.
    • Ex. Is a famous beach or not.
  • Does not allow rank
    • Ex. Doesn’t rank HOW famous the beach is.
  • Cannot determine the interval.
  • No ordering scheme is possible.
  • Ex. # of M&M colors in a bag.

Ordinal (Ranking) Scale of Measurement

  • Data arranged in order.
  • Differences between the values cannot be determined or are meaningless.
  • A ranking scale.
  • Ex. Likert Customer satisfaction scale.
    • The difference between a 2 rating and a 4 rating does not mean the customer is twice as satisfied when giving a 4.
  • Ex. Software defect categories.
    • 3 UI, 4 data, 1 browser compatibility.
  • Ex. House of Quality roof example.

Interval Scale of Measurement

  • Has an interval.
  • Data is arranged in order and differences can be found.
  • No starting point.
  • Ratios are meaningless.
  • Ex. Temperature of 3 pizzas. if one pizza is 100 degrees, that doesn’t make a 300 degree object 3 times as hot.

Ratio Scale of Measurement

  • Extension of interval level that includes a zero starting point.
  • Data is high level variable data.
  • There is an inherent zero starting point.
  • Both differences and ratio are meaningful.
  • Classify objects
  • Rank objects
  • Has equal intervals
  • Has a true zero point
  • Ex. Watches that cost $200 and $400. The 2nd one is 2 times as expensive as the first.


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