BUCHI NIRCal - Manual (Page 67)

Chemometrics
NIRCal 5.5 Manual, Version A 67
CV Plots
It is possible to show the result of each calibration step (e.g. CV Predicted Property) and also the
result of the final calibration (e.g. Predicted Property).
The Overview contains the following plots:
[1] The 1st C-Set property is chosen automatically for the plots.

Pretreated Spectra:
it is suggested to start the first calibration without pretreatment, but try later some
pretreatments and combinations.

CV Property Residuum vs. Original Property:
property residuum = original property -predicted property. This plot shows for each sample
group the property residuum for the calibration, which had this group in the V-Set during the
CV. A small CV Property Residuum and a regression coefficient between original property and
predicted property residuum close to 0 shows a stable calibration. Spectra with big deviations
are possible outliers and removing them from the C-Set can improve the calibration.

Predicted Property vs. Original Property:
This plot shows the result of the final calibration for the spectra which are in the calibration set
(unused spectra are not visible per default: it can be changed by the user under
Visibility ).

CV Regression Coefficients [1] (called the property spectra in NIRCal 4.21)
Shows the coefficients of the linear relationship between the NIR amplitudes (of the pretreated
spectra) and the selected C-property.
[1] refers to the 1st C-property. In general for each application only one C-Set property is
allowed, so for each property a separate calibration is necessary (NIRCal could handle more,
but NIRWare is designed for only one property / calibration for quantitative measurements).

CV SECV; see further details under Matrix CV SECV .
In general the first local minimum of CV SECV for the secondary PC selection will be taken, in