Table 2.

Valuation parameters for performance model assessing.

Parameters	Formula	References
Coefficient of determination	$R^2=1-\frac{{\sum }_n^{i=1}{(y_i^{\prime }-y_i)}^2}{{\sum }_n^{i=1}{(y_i^{\prime }-\overline{y})}^2}$	Kotz et al. (2006)
Root Mean Square Errors	$RMS{E}_p=\sqrt{\frac{{\sum }_{i=1}^N{({\hat{y}}_i-y_i)}^2}{\text{N}}}$	Douglas et al. (2018); Rossel et al. (2006); Chang et al. (2001)
Ratio of Performance to Deviation	$RPD=\frac{\text{STD}}{RMS{E}_p}$	Olarewaju et al. (2016); Davey et al. (2009)
Ratio of the Performance to Interquartile	$RPIQ=\frac{\text{IQ}}{RMS{E}_p}=\frac{\text{Q}3-\text{Q}1}{RMS{E}_p}$	Bellon-Maurel et al. (2010)

$y_i$ is the measured value of sample i; $y_i^{\prime }$ is the predicted value of sample i; $\overline{y}$ is the average of measured value; N is the number of samples; $Q1$ is the first quartile; $Q3$ is the third quartile.