From BIPM:
- “type of quantity” (i.e. length and diameter both behave like “length” and could be used in an equation expecting a length, whereas “roughness” - which like the other two could be expressed in nanometres – is something very different
- “type of scale” (i.e. ratio, interval, ordinal, nominal)
For example roughness would be “ordinal” – you can’t do maths with the values.
- “Thermodynamic temperature” (ISO 80000 5.1, in kelvin) would be “ratio”
- “Temperature difference” (undefined in ISO 80000? in K or °C) would be “ratio”
- “Celsius temperature” (5.2, in °C) would be “interval”
From BIPM:
For example roughness would be “ordinal” – you can’t do maths with the values.