BUCHI NIRCal - Manual (Page 52)

NIRCal 5.5 Software Manual
52 NIRCal 5.5 Manual, Version A
PC (Factor) Selection Wizard
Primary PC selection:
Test 1.5 : C-Set X-PRESS Slope Ratio Highest test
w(i+1) = ( y(i) - y(i+1) ) / ( y(i+1) - y(i+2) )
Limit = 2
PC i for highest i where w(i) > Limit Precise
Secondary PC selection:
Test 2.2 : Q-Value maxima (limited) test
PC i for Max ( QValue(i) ) I < NumPrimaryPCs
NIRCal calculates the allowed residual using the primary principal components for reconstruction.
Default parameter for residual
Residual Blow Up = 2.5
Allowed residual for calibration is 2.5 x max. C-Set Residual.
For each C-Set spectrum NIRCal creates a tolerance sphere using the Formula 3 for radii calculation
according to the Mahalanobis distances with the secondary PCs. This calibration sphere "inner"
space defines the area for a substance.
Default parameters for scores and radii:
Scores Blow Up = 1.05

Radii Formula = 3
Radii Blow Up = 2.5
SIMCA Q-Value
The Q-Value for SIMCA calibrations can not take into account the "Property Interference" value,
because there is only one cluster type in each calibration. This value is always Zero. This causes a
slightly higher Q-Value against the Cluster calibrations, in case no outliers are in the SIMCA
calibration.
SIMCA Method Validation
SIMCA allows that the principal component spaces cover each other or can partially overlap
another spaces. To check possible overlapping the "Prediction Protocols" can be used, as it is also
suggested for the Cluster calibrations.
The number “Total not identified, Cluster BAD (&)” and „Total not identified, Cluster OK (%)“ can
indicate the correct adjustment of the Blow up (Radii and Residual).
SIMCA tolerance spheres normally lie close to the PC center, other spectra can lie also here, which
causes losts of "Total not identified, Cluster BAD (&)" cases. This can be reduced by reducing the