BUCHI NIRCal - Manual (Page 48)

NIRCal 5.5 Software Manual
48 NIRCal 5.5 Manual, Version A
Formula 2
If generally small tolerances are required, Formula 2 can be used:
min. of r = R1*0.499 (0.499: to avoid overlapping)
or r = R3 * Pre Blow Up * f
or r = R4*0.5*Pre Blow Up * f
The smallest of the three possible values for the radius “r” is used.
The pre Blow Up factor is 5, this is an empirically evaluated value. The default Radii Blow Up f = 1,
this value can be adapted by the user. In general it should be increased to get connected spheres.
Formula 3
It is used only for SIMCA calibration, where only one substance is calculated (there is no R1).
Min. of r = R2 * 0.5
or r = R3 * Pre Blow Up * f
or r = R4 * 0.5 * Pre Blow Up * f
The smallest of the three possible values for the radius “r” is used.
The tolerance circles can now be plotted for all calibration spectra:
These tolerance ranges will show if the sum of the radii of one property generates only one cluster:
cluster / property should be one. In this case the number of the secondary PC selection is OK. If more
than one cluster is generated, the number of the secondary PCs is not optimal or other calculation
(e.g. pretreatment) should be tried.
Assessing the calibration
Cluster per Property
The Cluster per Property plot shows if all tolerance circles build one connected cluster for each
property.
Here only a value of 1 is acceptable.
All spectra in the C- and V-Set should be identified correctly
The identification is made according to the distance in the scores plot and residual: