The measurement error is the deviation of the outcome of a measurement from the true value. For example, if electronic scales are loaded with a 1 kilogram standard weight and the reading is 1002 grams, the measurement error is +2 gram (1002 - 1000).
Measurement error is usually considered as consisting of a systematic error and a random error . According to the type of relationship between measurement error and the true value, errors are subdivided into additive errors and multiplicative errors .
See also the short courses