Type B evaluation of uncertainty

A Type B evaluation of uncertainty uses information other than a statistical analysis of repeated observations of the current quantity. Examples include calibration certificates, manufacturer specifications and knowledge of resolution. It describes the evaluation method, not whether an effect is systematic or random.

If a rounding error is reasonably modeled as uniform on $[-a,a]$, its standard uncertainty is $a/\sqrt{3}$. The distribution assumption is part of the evaluation and should be justified by the available information.^[ref]