Type A evaluation of standard uncertainty may be based on any valid statistical method for analyzing data. The analysis of variance (ANOVA) is particularly useful since it considers both random and systematic effects between groups relative to the random effects within groups.
In Type B evaluation cases, a target is to have the uncertainty correspond to similar coverage. Type-B estimates are difficult to defend as quantitative measures and can't be assigned rigorous confidence limits.
A Type B evaluation of standard uncertainty is usually based on scientific judgment using all the relevant information available about the measurand and the instrument, such as:
The combined standard uncertainty of a measurement result uC is obtained by combining the individual standard uncertainties whether arising from Type A or Type B evaluations.
Select the type of uncertainty (Type A or Type B) referred to by the statement.
The correct answers are shown above.