Assessing electrical measurement uncertainties

Taking a measurement involves a process in which several elements are involved. Each of these elements has its own imperfections or influences on the measurement result. These elements are, of course, the measuring instrument and the operator – except, perhaps, in the case of automatic measurement – but also the environment and the measurand. The result obtained is therefore never the true value of the measurement; the measurement result is therefore said to be subject to uncertainty.

Orders of magnitude are, for example, ± 10% in dosimetry and ± 0, 000 000 001% (or 10 - ⁹ ) in frequency measurement. In electricity, measurement uncertainties are around a few % to a few 10 - ⁶ for example.