Probable error

(Mensuration)

See under Probable.

of an observation, or of the mean of a number), that within which, taken positively and negatively, there is an even chance that the real error shall lie. Thus, if 3 is the probable error in a given case, the chances that the real error is greater than 3 are equal to the chances that it is less. The probable error is computed from the observations made, and is used to express their degree of accuracy.

See also: Error Probable