Level of measurement defines which summary statistics and graphs should be used. The following table provides definitions, examples, appropriate summary statistics, and graphs for variables based on their level of measurement.
|
Nominal |
Ordinal |
Scale |
|---|
| Definition |
Unordered categories |
Ordered categories |
Both interval and ratio |
| Examples |
Gender, geographic location, job category |
Satisfaction ratings, income groups, ranking of
preferences |
Number of purchases, cholesterol level, age |
| Measures of Central Tendency |
Mode |
Median |
Median or mean |
| Measures of Dispersion |
None |
Min/max/range |
Min/max/range, Standard deviation/ variance |
| Graph |
Pie or bar |
Bar |
Histogram |
