PR was part of chemometrics at the start, and indeed for a decade
or more, chemical pattern recognition was almost synonymous with
chemometrics. Yet from the 1980s onwards PR became an increasingly
smaller part of the recognised discipline as demonstrated by
textbooks and conferences. Whereas there have always been and
will always be some very competent and knowledgeable advances
in the theoretical literature, the majority of users are from outside
the core practitioners. These users are mainly hooked on a small
number of approaches such as PLS-DA and SIMCA that are incorporated
into packages whose origins were several decades back, and
may well be inappropriate for the current types of problem. Trying
to educate the users is very hard with the enormous explosion in
usage of PR techniques. There are many dangerous misunderstandings
which the casual user must be aware of. With the increased
usage of chemometric techniques especially for PR, it is useful to
have an insight into its history.