On the Theory of Scales of Measurement
Stanley Smith Stevens
Science 103, no. 2684 (1946): 677–80.
DOI: 10.1126/science.103.2684.67.
Nominal
| Smokes | | Yes | No |
|---|
| Gender | Male | 20 | 30 |
| Female | 10 | 70 |
- Category with no obvious ordering.
- Count the number of observations.
- Test for membership.
- Test for equality.
- Most common observation: mode.
- No mean or median.
- Contingency table.
- Contingency correlation.
Ordinal
| Pineapple on pizza |
|---|
| Strongly Agree | 100 |
| Agree | 50 |
| Neutral | 2 |
| Disagree | 20 |
| Strongly Disagree | 40 |
- Like nominal, with an ordering.
- Greater or less than.
- Spacing might vary between values.
- Not necessarily centred on any value.
- Can take median as well as mode.
- No mean and standard deviation.
Interval
| ℃ |
|---|
| Water Boils | 100 |
| Normal Body | 37 |
| Triple Point | 0.01 |
| Water Freezes | 0 |
| Strongly Disagree | 40 |
- Numerical values.
- Gaps between values are comparable.
- Calculate means, standard deviations.
- Comparison of magnitude not appropriate.
- Percentages not appropriate.
Ratio
| Speed (km/h) |
|---|
| Cheetah | 120 |
| Pronghorn | 96 |
| Tiger | 60 |
| Human | 40 |
| Sloth | 1 |
- Can compare distances between values.
- Includes fundamental, physical quantities.
- Anchored at a zero point.