Table 7. Collective PLS-DA Models for All SERS and FT-IR Spectra, Calibrated by the Age Group for PBA (A), PBU (B), SBA (C), and SBU (D).

		SERS	actual age group			FT-IR	actual age group
	predicted age groups	accuracy, %	20–25 (n = 300)	30–36 (n = 150)	43 (n = 50)	accuracy, %	20–25 (n = 18)	30–36 (n = 9)	43 (n = 3)
A	20–25	100	300	2	0	66.7	12	1	1
	30–36	98.0	0	147	0	88.9	2	8	0
	43	100	0	1	50	66.7	4	0	2
B	20–25	95.3	286	2	0	66.7	12	1	0
	30–36	98.7	14	148	0	88.9	5	8	0
	43	100	0	0	50	100	1	0	3
C	20–25	96.0	288	5	0	61.1	11	3	1
	30–36	96.7	12	145	1	44.4	3	4	0
	43	98.0	0	0	49	66.7	4	2	2
D	20–25	96.3	289	5	0	55.6	10	1	0
	30–36	96.7	11	145	1	88.9	7	8	0
	43	98.0	0	0	49	100	1	0	3