absolute error

(mathematics) In an approximate number, the numerical difference between the number and a number considered exact.
(ordnance) Shortest distance between the center of impact or the center of burst of a group of shots and the point of impact or burst of a single shot within the group. Error of a sight consisting of its error in relation to a master service sight with which it is tested and of the known error of the master service sight.

The average deviation of a set of scores from a target value. Absolute error is a measure of overall error and does not take into account the direction of the deviation.