Measurement errors in a measurement process consist of known and unknown systematic errors from a number of different sources and causes.
In German, the traditional term “measuring error” has been replaced by the term “measurement deviation” since the publication of DIN 1319:1995. In case of measuring instruments or measuring systems, the permissible systematic errors prescribed by different standards and guidelines (e.g. VDI/VDE/DGQ 2618 ff [28]) are referred to as maximum permissible error or error limit.
Different types of measurement errors (see Figure 6) show up in measurement results:
random measurement errors
Random errors are caused by non-controlled random influence factors. They may be characterized by the standard deviation and the type of distribution (see Dispersion 1 and 2 in Figure 6).
systematic measurement errors (known, unknown)
Systematic errors may be characterized by size and sign (+ or –):
Bi = yi– true value
The difference between the reference value of a measurement standard and the mean of the measured values often form the basis for calculating the systematic measurement error:
x arithmetic mean of the measured values
xm reference value of the measurement standard
Where measurement errors are not regarded as systematic, the cause of the measurement error has not been sought for economic and complexity reason or the resolution is inadequate (e.g. %RE greater 5% of the specification;
reference:VDA
