Table 8 External validation

Slope of the plot of observed Activity versus calculated activity (k)

\(\frac{{\Delta Y_{{{\text{cal}}}} }}{{\Delta Y_{{{\text{obs}}}} }}\)

0.85 < k < 1.15

Passed

Slope of the plot of calculated versus observed activity values (k’)

\(\frac{{\Delta Y_{{{\text{obs}}}} }}{{\Delta Y_{{{\text{cal}}}} }}\)

0.85 < k < 1.15

Passed

\(/r_{{\text{o}}}^{2} - r_{{\text{o}}}^{{{\prime }2}} /\)

 < 0.3

Passed

\(\frac{{r^{2} - r_{{\text{o}}}^{{{\prime }2}} }}{{r^{2} }}\)

 < 0.1

Passed

\(\frac{{r^{2} - r_{{\text{o}}}^{{{\prime }2}} }}{{r^{2} }}\)

 < 0.1

Passed

\(R_{{{\text{test}}}}^{2}\)

\(1 - \frac{{\sum \left( {Y_{{{\text{ext}}}} - \overline{Y}_{{{\text{ext}}}} } \right)^{2} }}{{\sum \left( {Y_{{{\text{ext}}}} - \overline{Y}} \right)^{2} }}\)

\(R_{{{\text{pred}}}}^{{2}}\) > 0.6

Passed