Some more words and phrases to add to your NIR vocabulary....
Standardisation - this process happens to an instrument (or instruments) whereby adjustments are made such that the machines predict similar values when operating the same calibration model. A number of techniques can be used; broadly speaking you can choose between pre-prediction methods or post-prediction methods.
Pre-prediction standardisation - where the spectra of samples are adjusted to minimise the differences between the response of a 'master' instrument and each instrument in the group.
Post-prediction standardisation - where linear regression is used to adjust the predicted values produced by each instrument to make them as similar as possible to those from a 'master' instrument.