Appendix: Measurement Levels & Summary Statistics
| Statistic / Parameter |
Categorical Nominal |
Ranked Ordinal |
Discrete/Counts Interval/Ratio |
Continuous Interval/Ratio |
|---|---|---|---|---|
| Data set size (n) Percent / Frequency Count or rate Categories (levels) Mode Median Interquartile range Median absolute deviation Range Minimum/maximum value Quantiles Mean (average) Standard deviation Coefficient of variation |
Y Y Y Y Y No No No No No No No No No |
Y Y Y Y Y Y Y Y Y Y Y No No No |
Y Y Y Y Y Y Y Y Y Y Y Y Y* Y* |
Y Y Y Y Y Y Y Y Y Y Y Y Y* Y* |
* You must use the correct distribution (proper mean-variance relationship) to ensure you get the correct standard deviation; most software defaults to calculating the standard deviation for a normally-distributed sample, which could be incorrect for certain kinds of count, rate, or proportion data, for example.