Scales of Measurement

One of the most influential distinctions made in measurement was Stevens' (1946, 1957) classification of scales of measurement. He made the distinction between nominal, ordinal, interval, and ratio scales of measurement, which are briefly defined below. A more detailed discussion of these scales can be found in Chapter 4 of the text.

The most important reason for making the distinction between these scales of measurement is that it affects the statistical procedures that you will use in describing and analyzing your data.

In this unit, we will be presenting dozens of examples of measures at each of these levels of measurement, along with some exercises to help you to refine your understanding of these distinctions. We recommend that you complete the exercises since the best way to learn anything is to actively process the information by using it to solve real-life problems.

Examples of Each Scale of Measurement

Listed below are several examples of each scale of measurement. We have focused on general categories to help illustrate what each of the scales represent. We have tried to provide a wide variety of examples to help make these distinctions clear for you.

Nominal Scale Examples

Ordinal Scale Examples

Interval Scale Examples

Ratio Scale Examples


Listed below are a number of exercises designed to familiarize students with the classification of measures using Stevens' classification system. For each of the measures listed, determine what scale of measurement most closely approximates the measure as described. Some of the examples are deliberately ambiguous. To find out the correct answer, click on the word answer at the end of the description of the item.

  1. the number of questions asked by a customer during a simulated encounter with a salesperson answer

  2. the religious group that one affiliates with answer

  3. the time it takes to complete a checking task answer

  4. the score on a 35-item scale of ambivalence answer

  5. the rank of a person's salary within the company answer

  6. rank order based on IQ score in the sample answer

  7. the square footage of each participant's house or apartment answer

  8. the size of the cerebellum expressed as a volume answer

  9. the number of frustrated comments made during a laboratory negotiation task answer

  10. the time it takes for a couple to resolve a custody issue during court ordered mediation answer

  11. score on the Beck Depression Inventory (a pencil and paper depression scale) answer

  12. ratings of anger shown by those involved in courtroom testimony answer

  13. the number of pound lost during a six-week diet answer

  14. the proportion of weight lost during a six-week diet answer

  15. the heart rate of the participant answer

  16. the percent shift in heart rate over baseline during an emotionally demanding task answer

  17. the percent of errors made on a classification task answer

  18. the number of false alarm responses in a monitoring task answer

  19. the types of gramatical errors made in a writing sample answer

  20. one's ice cream preference answer

  21. how quickly a person gives up on an impossible task that looks like it should be possible answer

  22. a student's SAT score answer

  23. the percentile rank from an achievement test answer

  24. the type of categorization errors in a sorting task answer

  25. the pattern of scores on the MMPI personality inventory answer

  26. the age at which one went on his or her first date answer

  27. the number of children in your family answer

  28. the score on an anxiety sensitivity scale answer

  29. whether one has a pet answer

  30. the teacher's rankings of cooperativeness in the classroom answer

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Revised: May 29, 1999
URL: /handouts/scales.htm