Table 7.

Determination accuracies of Cr, and Ni concentrations based on spectral bands associated with SOM and Vis–NIR.

Dataset	Statistical Method	Elements	Calibration (n = 27)		Validation (n = 10)
			RMSEC	RC2	RMSEV	RV2
Vis–NIR	PLSR	Cr	0.46	0.99	1.56	0.66
		Ni	0.38	0.97	1.28	0.55
	PCR	Cr	3.75	0.12	2.06	0.42
		Ni	1.76	0.35	1.99	0.33
	SVMR	Cr	3.81	0.68	4.27	0.38
		Ni	2.27	0.61	2.52	0.17
SOM	PLSR	Cr	0.67	0.97	1.69	0.61
		Ni	0.33	0.98	1.44	0.43
	PCR	Cr	3.88	0.06	2.57	0.09
		Ni	2.34	0.05	1.42	0.45
	SVMR	Cr	3.85	0.53	4.22	0.36
		Ni	2.31	0.59	2.52	0.25