NIR Spectroscopy Calibration Report for quantitative predictive models

When you send your quantitative NIR spectra data to our NIR Calibration Model Service, you get a detailed calibration report (calibration protocol) of the found optimal calibration settings, so you are able to see all insights and easily re-build the model in your NIR/Chemometric software.

Here is a part of our calibration report, that exactly describes the data used in the calibration set (CSet), the validation set (VSet) and the test set (TSet). The numbers are the number ids of the spectra in your delivered NIR data file.


The calibration method settings and parameters are
Waveselection : the variable selection or wavenumber selection or wavelength selection
Pretreatments : the spectral data pre-processing
PCs : the number of  Principal Components (PC) or Latent Variables (LV)
Method : the modeling method algorithm used, e.g. PLS

Then the statistical analysis of the PLS model by the different sets (CSet, VSet, Tset).

Calibration Report

Statistical analysis of calibration, validation and test results : 1 Name, 2 Unit, 3 N : number of spectra, 4 N : number of samples, 5 Average spectra count per sample, 6 Reference values, 7 Min, 8 Mean, 9 Median, 10 Max, 11 Standard deviation, 12 Skewness : left (-) or right (+) lack of symmetry, 13 Kurtosis : flat (-) or peaked (+) shape, 14 Model statistics, 15 RPD, 16 R², 17 RMSEC, RMSEP, RMSET : root mean square of prediction errors, 18 SEC, SEP, SET : standard error (bias corrected), 19 Bias, 20 Skewness of prediction errors, 21 Kurtosis of prediction errors, 22 Intercept, 23 Slope, 24 Intercept (reverse), 25 Slope (reverse), 26 Sample Prediction Repeatability Error, 27 Sample Prediction Repeatability Error (of Missing data MSet)

This shows how we deliver the optimal settings. With the statistical values, the NIR model predicted values of all spectra and additional plots you are able to compare with your re-built model to verify that the models perform nearly equally.

What is JCAMP-DX ?

JCAMP-DX is a Electronic Data Standards for long-term storage and transfer of chemometric information. The standard is development by the International Union of Pure and Applied Chemistry (IUPAC).

JCAMP-DX is an abreviation for the Joint Committee on Atomic and Molecular Physical data – Data eXchange.

It is an human readable file format that is used to store near infrared spectrometry data (and others like Raman, UV, NMR, mass, x-ray, chromatograms, thermograms) and related chemical and physical information and is used since the late 80s.

Almost all NIR-software packages can export the spectra including the reference values as JCAMP-DX. A single file can contain multiple spectra and reference values. A JCAMP file name looks like “sample.dx“, “sample.jdx” or “sample.jcm“.

All data are stored as labeled fields of variable length using printable ASCII characters. Such files can be loaded in an text editor to check the content:


##TITLE= Indene (FILE: AFIR2.DX)
$$ FILE AFIR2.DX ( derived from TFIR2.DX)
$$ ABSORBANCE
$$ FIXED FORM
$$ INCREASING ABSCISSA
$$ RATIONAL ABSCISSA SPACING
##JCAMP-DX= 4.24 $$ Encoded by INTTODX 1.04 (RS McDonald)
##DATA TYPE= INFRARED SPECTRUM
##ORIGIN= JCAMP-DX Test Disk 1.04
R.S.McDonald, 9 Woodside Dr., Burnt Hills, NY 12027, 518-399-5145
##OWNER= Public Domain
##RESOLUTION= 2.0
##DELTAX=1.00000000
##XUNITS= 1/CM
##YUNITS= ABSORBANCE
##XFACTOR= 1.000000000
##YFACTOR= 0.000100000
##FIRSTX= 400.000
##LASTX= 4.000E+03
##NPOINTS= 3601
##FIRSTY= 3.487E-1
##XYDATA= (X++(Y..Y))
400 3487 3355 3264 3198 3153 3143 3182 3298 3520 3845 4262
411 4783 5449 6304 7383 8684 10209 12041 14123 16003 16162 14191
422 11791 9674 7943 6540 5406 4528 3874 3397 3045 2780 2584
433 2446 2354 2290 2246 2212 2187 2165 2135 2087 2022 1945
444 1865 1786 1713 1649 1596 1550 1512 1478 1448 1422 1401
:

The standard can be downloaded here: “JCAMP-DX: A Standard Form for the Exchange of Infrared Spectra in Computer Readable Form“, ROBERT S. McDONALD and PAUL A. WILKS, JR., Appl. Spectrosc. 42(1), pp151-162, 1988