Given a number of things, xi where i=1..n,
each thing having a number of attributes, xi1,...,xim,
which are variously discrete or continuous values,
how many classes (clusters, groups, species, types, ...)
do the things belong to?
Note that the number of classes and
the specifications of the classes have not been given;
they are part of the problem too.
This problem is variously known as
numerical taxonomy, and
in different disciplines.
The Model Class
- factor Snob,
- mixture modelling,