BUCHI NIRCal - Manual (Page 252)

NIRCal 5.5 Software Manual
252 NIRCal 5.5 Manual, Version A
Spectra Nearest Neighbor Select
The Matrix "Spectrum Nearest Neighbor Index": (NIRExplorer / Matrices / "Spectrum Nearest Neighbor
Index") contains the spectrum index of the nearest spectrum to each spectrum in the project. The best
is to show it as 1D-Scatter-Plot for selected spectra. This matrix is related to "Spectrum Nearest
Neighbor" which contains the Mahalanobis Distance between nearest spectra pairs. As referred in the
ASTM E1655-05 "16.4.8 Nearest Neighbor Distance". Note: "Spectrum Nearest Neighbor Index" and
"Spectrum Nearest Neighbor" depends on the secondary PC-selection.
Note: In most cases, the project has multiple repetitive measurements. Then the picture shows a
nearly upward diagonal with some spikes. The reason is that repetitive measurements are the most
similar and successively stay together.
Note: pair-wise distances are not always symmetric. A can be nearest to B and B can be nearest to C
(and to A).
Spectra Select by QL Property
All spectra belonging to the marked qualitative property will be selected.
NOTE
These modules are installed but not added to the Modules menu.
Average spectrum
Average Spectra can be calculated and saved to file (nsf). The project is not affected, it is only the
data source.
To define which spectra will be averaged they can be defined as so called Groups:

Sequence block wise sequences

Spectra Name same spectra name

Property Values same property values
The stored Average Spectra contains the following additional information:

Comment i.e. Average of 12 Spectra

Description contains all the spectra GUID's of the averaged Spectra

Instrument Serial -1 as marking of a Average Spectrum