Table 2.

Comparison results of preprocessing methods.

	Rc	Rp	SEC	SEP	Offset	RPD	RMSEC	RMSEP
Raw spectrum	0.40	0.27	0.00007	0.00011	−0.0459	14.39	0.00173	0.00183
1D + SG	0.51	0.64	0.00009	0.00013	0.0210	14.34	0.00162	0.00139
1D + NO	0.74	0.74	0.00015	0.00013	−0.0209	14.51	0.00126	0.00124
2D + SG	0.57	0.71	0.00011	0.00011	0.0227	14.34	0.00155	0.00130
2D + NO	0.74	0.77	0.00013	0.00018	−0.0013	14.49	0.00126	0.00125

Note: SEC, calibration set standard error; SEP, prediction set standard error; RPD, relative percentage difference.