Table 2.

Summary of external validation parameters for CoMFA and CoMSIA.

Condition	Parameters	Threshold Value	CoMFA	CoMSIA
1	$q^2$	>0.5	0.537	0.669
2	$r^2$	>0.6	0.865	0.918
3a	$r_0^2$	Close to value of $r^2$	0.864	0.911
3b	${r^{\prime }}_0^2$	Close to value of $r^2$	0.834	0.885
4a	$k$	0.85 < $k$ < 1.15	1.002	0.996
4b	$k\prime$	0.85 < k$\prime$ < 1.15	0.937	1.004
5a	$\left(r^2-r_0^2\right)/r^2$	<0.1	0.001	0.007
5b	$\left(r^2-{r^{\prime }}_0^2\right)/r^2$	<0.1	0.036	0.034
6	$\left|r_0^2-{r^{\prime }}_0^2\right|$	<0.3	0.031	0.027
7	$r_m^2$	>0.5	0.793	0.843

q² and r² are the same parameters as listed in Table 1; $r_0^2$ and k are the correlation coefficient between the experimental (x) versus predicted activities (y) for test set through the origin and the respective slope of regression; and $r_0^{\prime 2}$ and k$\prime$ are the correlation coefficient between the predicted (y) versus experimental activities (x) for test set through the origin and the respective slope of regression. $r_m^2$ was defined in Equation (6).