A measurement is not only a number. It should be accompanied by information describing how far the reported value may reasonably be from the value attributed to the measurand. VA places particular emphasis on uncertainty evaluation, including real-time calculations.
Error and uncertainty
Random effects produce dispersion between repeated observations; systematic effects shift results consistently. Uncertainty is not an error correction but a quantitative evaluation of the doubt associated with the result.
Type A and Type B
Type A evaluation
Derived from statistical analysis of repeated observations, such as mean and standard deviation.
Type B evaluation
Uses specifications, certificates, resolution, experience, tolerances and other available information.
Combination
Components are expressed as standard uncertainties and combined according to the mathematical relationship between input quantities. Indirect measurements use uncertainty propagation.
VA and uncertainty
When the necessary data are available, VA associates readings with an estimate consistent with the chosen method. This does not turn an audio interface into a certified instrument, but it makes assumptions and limitations explicit.
Read more in the Visual Analyser Handbook
This page is an operational introduction. Chapter 2 — Measurement and uncertainty of the forthcoming book covers theory, controls, algorithms, examples and measurement notes in much greater depth.