${\mathit{x}}_{\mathit{i}},{{\stackrel{-}{\mathit{x}}}_{\mathit{m}},\stackrel{-}{\mathit{x}}}_{\mathit{M}}$	Single range sample, sample mean, overall mean value for entire test	mm
${\mathit{\sigma }}_{\mathit{m}},{\stackrel{-}{\mathit{\sigma }}}_{\mathit{M}}$	Standard deviation of samples, overall mean value of standard deviation for entire test	mm
${\mathit{\eta }}_{\mathit{m}},{\stackrel{-}{\mathit{\eta }}}_{\mathit{M}}$	Relative error of samples, overall mean value of relative error for entire test	%
RMSE	Root mean square error	mm
Xm, Xn	Predicted mean value, current estimated mean value	mm
Pm, Pn	Predicted variance value, current estimated variance value	mm2
R, Q	Constant measurement variance, constant process variance	mm2