BUCHI NIRCal - Manual (Page 193)

Chemometrics
NIRCal 5.5 Manual, Version A 193
3.18.68 Q-Values
Description Value between 0 and 1. 0 means a bad 1 would be a good calibration. But 1
cannot be reached.
Q-Values depending on the number of PCs.
There is a warning limit for the stored calibration:

0.8 for qualitative

0.6 for quantitative
Use Select the number of secondary PC according the highest Q-Value.
Method PCR / PLS / Cluster (CLU) / SIMCA
Matrices ID 64
Tip In generell: the highest the Q-Value the better the calibration.
Details The Q-Value is in the calibration protocol, see explanation: LINK: Calibration
Protocol Qualitative
It is used for selection of the best calibrations for the automatic Calibration
wizard.
Related Topic Quant Calib. Statistics , Cluster per Property , Spectra Residuals too big
Explanation of the Q-Value calculation of quantitative calibration:
Value
Weights Formula for value General term Aspects of a
good
calibration Detail
wNum
NotC 10 Number of C-Set spectra
with Residual too big Rejection of
known Rejection
count of known
should be 0
wNum
NotV 1 Number of V-Set spectra
with Residual too big Rejection of
unknown Rejection
count of
unknown
should be 0
wQa 2 Abs (SEE-SEP)/
(Abs(SEP)+1.0) Relative
Consistency C-Set and V-
Set should
have similar
low standard
error of
prediction BIAS
corrected
wQb 2 Abs (VsetBIAS)/
Abs(Range) Weighted
BIAS The absolute
V-Set BIAS
should be low
wQc 1 1-VsetRegr Validity The V-Set
regression
coefficient
should be near
1
wQd 1 Abs( CsetRegr-VsetRegr) Comparability C-Set and V-
Set should
have similar
high
regression
wQe 1 SEP / Abs(Range) Precision The V-Set
standard error
of prediction
should be low BIAS
corrected
wQf 1 Abs(RSS)/Abs(Range) Weighted
Accuracy The V-Set
Residual Sum
of squares=
RSS should be
low not BIAS
corrected