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Measurement uncertainty

Project Item ImageISO definition
"A parameter associated with the result of a measurement, that characterises the dispersion of the values that could reasonably be attributed to the measurand".
Basically, the measurement uncertainty defines a range around the experimentally determined result, which contains the "true value". In the case of biological measurement, uncertainty may arise from a number of possible sources, not necessarily independent of one another. These include poor sampling, incomplete extraction of the analyte, variability in the measurement of incubation time or temperature, etc. The key difference between measurement uncertainty and other quality measures is that it includes both random and systematic effects on results.

Estimate of measurement uncertainty

Measurement uncertainty calculation can be a long and cumbersome process, but it can be approximated using:
1) The results obtained from repeated measurements, as long as they cover a large range of known significant effects (long term precision across analysts, time etc.)
2) Estimation based on knowledge of the equipment, experience of the measurement or previous data.
3) Reference materials to measure bias.

Reliable determination of measurement uncertainty requires specific training.

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