<Dl> <Dd> r i = X i − X _̄ . (\ displaystyle r_ (i) = X_ (i) - (\ overline (X)).) </Dd> </Dl> <Dd> r i = X i − X _̄ . (\ displaystyle r_ (i) = X_ (i) - (\ overline (X)).) </Dd> <P> The sum of squares of the statistical errors, divided by σ, has a chi - squared distribution with n degrees of freedom: </P> <Dl> <Dd> 1 σ 2 ∑ i = 1 n e i 2 ∼ χ n 2 . (\ displaystyle (\ frac (1) (\ sigma ^ (2))) \ sum _ (i = 1) ^ (n) e_ (i) ^ (2) \ sim \ chi _ (n) ^ (2).) </Dd> </Dl>

Currently the best substitute for the word errors in statistics is