Table 1.

Statistical measures for variability of the methods.

Measure	Definition
Technical Error of Measurement (TEM)	$TEM=\frac{{\sum }_1^N[{\sum }_1^{K}M{\left(n\right)}^2-\frac{{\left({\sum }_1^{K}M\left(n\right)\right)}^2}{K}]}{N\left(K-1\right)}$
Standard Deviation (SD)	$SD=\sqrt{\frac{1}{N}{\displaystyle {\displaystyle \sum }_{i=1}^N}\left(m_i-\overline{m}\right)}$
Average Reliability Coefficient (R)	$R=1-\left[{\left(TEM\right)}^2/{\left(SD\right)}^2\right]$
Intra- or Inter-class Correlation Co-efficient (ICC)	$ICC=\frac{S{D}_{\left\{intra or inter\right\}}^2}{S{D}_{intra}^2+S{D}_{inter}^2}$
Mean Absolute Difference (MAD)	$MAD=\frac{1}{N}{\displaystyle {\displaystyle \sum }_{i=1}^N}\left|m_i-{\widehat{m}}_i\right|$
Mean Square Error (MSE)	$MSE=\frac{{\sum }_{i=1}^n{\left(m_i-\overline{m}\right)}^2}{N}$