In statistics, one usually differentiates between - nominal scales (e.g. man/woman), - ordinal scales (elementary school/middle school/high school), - interv

In statistics, one usually differentiates between - nominal scales (e.g. man/woman), - ordinal scales (elementary school/middle school/high school), - interval scales (degrees Celsius) and - ratio scales (human height, degrees Kelvin). Only ratio scales may be multiplied and divided. Interval scales may be subtracted and added. Ordinal scales may only be compared (less/greater/equal). Nominal scales may only be compared in terms of (in)equality. https://en.wikipedia.org/wiki/Level_of_measurement https://en.wikipedia.org/wiki/Level_of_measurement