BUCHI NIRCal - Manual (Page 208)

NIRCal 5.5 Software Manual
208 NIRCal 5.5 Manual, Version A
Interpretation: difference between pretreated spectrum and reconstructed spectrum will be summed up
and squared. It is with the:
1. PC: X-PRESS 1= [pretreated spectrum-(mean spectrum + score 1 x PC 1)]2
2. PC: X-PRESS 2= [pretreated spectrum-(m.s. + score 1 x PC 1+ score 2 x PC 2)]2
3. PC: X-PRESS 3= [pretreated spectrum-(m.s. + score 1 x PC 1+ score 2 x PC 2 + score 3
x PC 3)]2 etc.
The primary principal components should be set at the point where no significant changes in the X-
PRESS value can be determined. The PC, which has no effect on the X-PRESS, normally has very
small or only noisy information (see:
Loadings ).
Here: 1-3 PCs are important.
3.18.101 Y-Scores
Description Each spectra is placed in the n-dimensional y-score space. The position of
the spectra is given by the n-dimensional coordinate of the y-scores.
Use For PLS2 (multi property calibration).
Method PLS
Matrices ID 111
Tip Compare with the Scores.
Details Calculated for the C-Set (V-Set Y-Scores are 0).
Related Topic Scores , Y-Loadings
Matrices of the final PLS calculation:

Spectra are decomposed to Scores and Loadings.

Properties are decomposed to Y-Scores and Y-Loadings.

Y-Scores are predicted from the Scores and Properties are predicted from the Y-Scores.
3.18.102 y-loadings
Description Y-Loadings build up the base for reconstructing the property together with
the Y-Scores.
Use For PLS2 (multi property calibration).
Method PLS
Matrices ID 112
Tip
Details For one C-Set property (PLS1) the Y-Loadings are constant 1.