That exists too: https://en.wikipedia.org/wiki/Average_absolute_deviation https://en.wikipedia.org/wiki/Average_absolute_deviation Standard deviation is mathem

That exists too: https://en.wikipedia.org/wiki/Average_absolute_deviation https://en.wikipedia.org/wiki/Average_absolute_deviation Standard deviation is mathematically easier to work with though and has nice properties e.g. you can compute the standard deviation of combining a bunch of independent things by combining their individual standard deviations.