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Combined standard uncertainty

Definition

The overall standard uncertainty of a result, obtained by combining all Type A and Type B component uncertainties in quadrature (square root of the sum of squared components weighted by sensitivity coefficients). Denoted u_c.

Related terms

Expanded uncertainty
The combined standard uncertainty multiplied by a coverage factor k, chosen to achieve a stated coverage probability. For a normal distribution, k...
GUM
Guide to the Expression of Uncertainty in Measurement. The international standard, maintained by eight metrology and standardisation bodies, that defines Type A...
Type A uncertainty
Uncertainty evaluated by statistical analysis of a series of observations. The standard uncertainty is the standard deviation of the mean (standard error)...
Type B uncertainty
Uncertainty evaluated by means other than statistical analysis of repeated measurements. Sources include calibration certificates, instrument specifications, reference data, and expert scientific...
z-score (proficiency testing)
A performance statistic in PT defined as z = (x - X) / s_PT, where x is the laboratory's result, X is...

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