BUCHI NIRCal - Manual (Page 189)

Chemometrics
NIRCal 5.5 Manual, Version A 189
3.18.54 Property Box Center
Description The center position (expressed as score) of the smallest possible box in the
score space that contains each C-Set spectra of a property.
Use Shows the distribution of the properties in the score space.
Method Cluster (CLU) / SIMCA
Matrices ID 46
Tip In higher PC dimensions the property box center falls together. These higher
PCs are useless for property separation, so remove them from the secondary
PC selection. See also the Property Box Radii matrix.
Details Only C-Set spectra and C-Set property are used for calculations.
Related Topic Property Box Radii
3.18.55 Property Box Center Uniformity
Description Uniformity of the distribution of the Property Box Centers.
Use Additional information for PCs selection.
Method Cluster (CLU) / SIMCA
Matrices ID 51
Tip
Details Estimates the place consumption of all properties per PC.
If several properties lay near each other in a PC, the PC becomes a low
uniformity value. A uniformity value of 1.0 is ideal.
Related Topic Property Box Radi i, Property Box Center , Scores
3.18.56 Property Box Radii
Description The distance from the Property Box Center to each wall of the smallest
property box.
Use Shows the score distribution of the properties versus PCs. One of the best
matrix to select the secondary PCs for the cluster method.
Method Cluster (CLU) / SIMCA
Matrices ID 47
Tip Small values (normally bellow 0.1) indicate good reproducibility. To get good
separation of the properties select these PCs for the secondary PCs.
Details
Related Topic Property Box Center
3.18.57 Property F-Test backward
Description Significance of PCs starting at the minimum of the SEP function.
Use For secondary principal component selection.
Method PCR / PLS
Matrices ID 37
Tip
Details Starting at the PCs they set the SEP value to the minimum, take PCs away
as long as no significant change for the worse of the SEP value occurs. This
process is called backward search operation.
Related Topic Property F-Test forward