Combining designed experiments with several blocks of spectroscopic data

Two varieties of a new method of analysis are introduced and tested against a standard PLS method. The method is developed for situations where experimental design is combined with spectroscopic measurements at several points in an industrial process. The method is a combination of ordinary least squares (OLS) and PLS and is called LS–PLS. The purpose of the methodology is to extract relevant information from spectroscopic measurements without having to calibrate the instrument against external reference measurements first. We compare the LS–PLS variants with a straight forward PLS modeling of all the available variables and demonstrate that the LS–PLS method give results that are easier to interpret. The methods are compared by computer simulations based on real data from a cheese making experiment.