# Level of measurement

> Categories proposed by S. S. Stevens

Categories proposed by <S. S. Stevens>

## Levels

### Nominal

- Operations: $=$, $\neq$
- <Central tendency>: <Mode (statistics)>
- Variability: <Qualitative variation>

### Ordinal

- Operations: $>$, $<$
- <Central tendency>: <Median>
- Variability: <Range>, <Interquartile range>

### Interval

- Operations: $+$, $-$
- <Central tendency>: <Arithmetic mean>
- Variability: <Deviation>

### Ratio

- Operations: $\times$, $\div$
- <Central tendency>: <Geometric mean>, [Harmonic mean](https://wiki.g15e.com/pages/Harmonic%20mean.txt)
- Variability: <Coefficient of variation>, <Studentized range>

## See also

- [Nominal, ordinal, interval, and ratio typologies are misleading](https://wiki.g15e.com/pages/Nominal,%20ordinal,%20interval,%20and%20ratio%20typologies%20are%20misleading.txt)