Reliable and relevant modelling of real world data: a personal account of the development of PLS Regression

Why and how the Partial Least Squares Regression (PLSR) was developed, is here described from the authorʹs perspective. The paper outlines my frustrating experiences in the 70ʹies with two conflicting and equally over-ambitious and over-simplified modelling cultures - in traditional chemistry and in traditional statistics. It describes my mental progress of first learning to combine them into least squares “unmixing” of known chemical mixtures, and later extending this into the “unscrambling” of partially unknown structures as well. The bi-linear regression framework is summarised in terms of the development from Principal Component Regression into the PLSR. Finally, the versatility of the PLSR is discussed in light of the urgent need for better eduacation in scientific data analysis.