All the below categories are implemented by using multiple different algorithms and formulas which leads to many different calibrations.
Steps in modeling
Data Cleaning – (bad data, missing values, duplicate elimination, spectral quality / intensity / noise, input value typing errors, …)
Initial Calibration set up – selection of calibration, validation and test samples
Data preprocessing, pretreatments
Choosing the number of Principal Components / Latent Variables
Validation of calibration model / Statistics of performance – (accuracy, precision, linearity, repeatability, range, distribution, robustness / stability, sensitivity, simplicity, etc.)
Outlier examination and removal
The problem of choosing the optimal number of factors to find the optimum betweenunderfitting and overfitting is solvedby having multiple methods and protocols implemented leading to multiple calibrations.
The evaluation and the selection of the best calibration is based on many individual statistical values including the most popular RMSEP, SEP, Bias, SEC, R2 and PCs etc.
Results and Reporting
A detailedcalibration report is provided detailing the best available calibration containing all calibration parameter settings and statistics of prediction performance of the calibration set, the validation set and the test set. A visual expression of the calibration is provided with the most importance plots.
Our service works with any quantitative NIR spectra data set in the standard JCAMP-DX format and uses mainly PLS and PCR to be compatible with other chemometric calibration software.
Summary of the NIR Chemometric survey polls (as of end of Sept. 2013)
The interesting finding is that most of the answers fit the following pattern. The most companies that use NIR have one NIR Instrument and only one employee that is able to develop NIR calibrations. For that the most common off-the-shelf chemometrics program is used and spent 2 hours or over a month and therefore gets no calibration training about the complex topics like Chemometrics and NIR Spectroscopy or only once (introduction). The calibration maintenance ranges from never to 3 times a year. Interestingly, there was no one who uses portable NIR instruments. We continue our surveys, for the discovery of new trends. Conclusion Seeing this picture, we think that there is huge potential to improve the calibrations. Advanced knowledge can help individuals to build the calibrations with best practices and improve their models accuracy and reliability. Once the decision and investment in NIR technology is done, you should get the best out of your data, because this extra NIR performance can be given by calibration optimization. We offer this as an easy to use and independent service.
The majority of NIR calibrations are generated using a small number of different parameter settings and all too often are restricted to the time a user has available, their spectroscopic and chemometric knowledge and their ability (tedious use of the software) to choose and combine all the possible parameter settings required for good calibrations.
There are manypublished standards and guidelines (protocols) available for developing NIR calibrations from Standards Consortium such as ASTM, EMEA, ICH, IUPAC, ISO, USP, PASG etc. as well as many good recommendations and guidelines found in various textbooks and papers.
The difficulty with so many ‘Protocols’ for the NIR user is to have them all available and in their thought processes during calibration work and in addition to execute, check and challenge all calibrations generated manually. This is time consuming and sometimes boring repetitive work.
To simplify this for the person generating the NIR Calibrations, we have collected the good practices protocols and integrated them into our service that automates the calibration building and evaluation procedures.
We develop the NIR calibration models with a manufacturer independent chemometrics software mainly with the widely used and proven methods of PLS and PCR, and supports all common data pretreatments. So with every manufacturer specific chemometric software the model can be used.
This are lists of compatible chemometric software packages:
Services and software for data analysis and analytical modeling for spectroscopy.
This NIR calibration service provides the custom development of optimal quantitative NIR calibration models based on your collected NIR and reference data for vendor independent full range NIR spectrometer analyzers (NIR = Near Infra Red spectroscopy) based on chemometric multivariate methods like Partial Least Square Regression (PLS, PLSR) and Principal Component Regression (PCR).
The key points
The NIR calibration model is decisive for the analysis accuracy.
Did you find the time for the right to designate to read, to study, to incorporate them into practice?
Do you have all this knowledge at your calibration developments always present, that you consider anything important, the statistical results, interpret them correctly, analyze the graphs accurately and apply all the tips & tricks of optimizing correctly?
We have the solution for you!
We’ll help you to create and optimize your calibrations. You retain complete control. You have your calibration, with our help, himself under control.
You can view the complete calibration of all the settings down to the smallest detail precisely documented and visualized.
You can also make any changes in the settings. This means you remain independent and have the control in your hand.
We will help you for the time-consuming and knowledge-intensive part.
You get the best calibration solution and decide for yourself