BUCHI NIRCal - Manual (Page 122)

NIRCal 5.5 Software Manual
122 NIRCal 5.5 Manual, Version A

If too many primary PCs are selected, a calibration is overfitted. In this case only the
calibration spectra will be identified correctly but not necessarily the validation samples in the
project.
Example of overfitting:
The residuals of the C-Set are much lower, as for the V-Set.

If too few primary PCs are selected, the spectra are underfitted, the calibration might not be
selective enough for the products.
Example of underfitting: