Table 3.

Prediction performances with Norris derivate filter between valid acidity and second derivate spectra using different gap size (segment length=5 nm)

Model	Gap size	No. of factors	r2	RMSEC	RMSEP
1	1	6	0.793	0.0623	0.0717
2	3	5	0.785	0.0635	0.0697
3	5	5	0.790	0.0627	0.0693
4	7	6	0.815	0.0573	0.0689
5	8	4	0.779	0.0644	0.0703
6	9	6	0.816	0.0588	0.0660
7	10	7	0.831	0.0562	0.0670
8	12	4	0.781	0.0640	0.0705

r ²: Correlation coefficient of determination