Accuracy of Measurement

the characteristic of a measurement that indicates the degree to which the results of measurement approach the true value of the measured quantity. The smaller the deviation of the result of measurement from the true value of the quantity—that is, the smaller the error—the higher the measurement accuracy, regardless of whether the error is systematic or random, or contains components of both (seeERROR OF MEASUREMENT).

Error is sometimes used as a quantitative evaluation of the accuracy of measurement; however, error is a concept that is the converse of accuracy, and it is more logical to evaluate the accuracy by specifying the inverse of the relative error, without regard to sign. For example, if the relative error is ± 10 ^–5, then the accuracy is 10 ⁵.