\(\delta_{\text{ij}}=\frac{(\text{ETa}_{\text{ij}}-\ {\overset{\overline{}}{\text{ETa}}}_{j})}{{\overset{\overline{}}{\text{ETa}}}_{j}}\) (16)
\(\sigma_{\text{ij}}=\sqrt{\frac{{(\text{ETa}_{\text{ij}}-\ {\overset{\overline{}}{\text{ETa}}}_{j})}^{2}}{np-1}}\) (17)
\(\text{TSI}=\sqrt{{\delta_{\text{ij}}}^{2}+\sigma_{\text{ij}}{\delta_{\text{ij}}}^{2}}\) (18)