Measurement errors, or errors of measurement, are also referred to measurement deviations. Measurement errors are used in metrology and represent the difference between the measured value indicated minus the correct (true) value as per DIN standard 1319.
The indicated value (measurement result) is skewed by imperfections in the measuring instruments and measuring methods (systematic error (fsys)) and by environmental influences as well as change over time for all measurands (random error (fr)).
The geometric sum (root of the sum of squares) of both measurement errors yields the total error (ftot). This error, which occurs in (acceptance) measurements, is regarded in acceptance standard DIN EN ISO 9906:1999 via specification of permissible total measurement uncertainties that are changed following the current revision of DIN EN ISO 9906:1999 . See Fig. 1 Measurement error
Changed, permissible total measurement uncertainties are described in a revision of this standard that has not yet been published. See Fig. 2 Measurement error