Table 3 The validation results of PLSR models in the three time periods.
Time since deposition | Cross-validation | External validation | Expanding test | |||||
|---|---|---|---|---|---|---|---|---|
RMSECV | R2 | RMSEP | R2 | RPD | RMSEP | R2 | RPD | |
Indoor model | ||||||||
0.25–7 d | 1.20 | 0.72 | 1.18 | 0.72 | 1.90 | 1.53 | 0.53 | 1.19 |
7–85 d | 5.88 | 0.94 | 5.83 | 0.94 | 4.08 | 12.93 | 0.71 | 1.73 |
0.25–107 d | 7.51 | 0.94 | 7.24 | 0.94 | 4.20 | 13.34 | 0.80 | 2.24 |
Outdoor model | ||||||||
0.25–7 d | 0.91 | 0.84 | 1.10 | 0.76 | 2.09 | 2.15 | 0.08 | 0.99 |
7–85 d | 6.35 | 0.93 | 4.77 | 0.96 | 5.14 | 19.99 | 0.31 | 0.70 |
0.25–107 d | 6.31 | 0.96 | 6.43 | 0.95 | 4.42 | 23.61 | 0.38 | 0.77 |
