6.2 CLUSTER ANALYSIS
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Cluster analysis is a technique for highlighting the relationships in a grid so
that they become visible at a glance. You would normally use one of the many
software packages accessed through the websites I’ve mentioned in the
introduction to this chapter to do the hard work for you (though if you want to
know how to do cluster analysis by hand, for those moments in life when the
electricity supply fails, Jankowicz & Thomas (1982/1983) provide a detailed
step-by-step manual procedure). My purpose in this section is to
(a) give you a simple rationale by which you can understand how cluster
analysis works, without going into all the detail
(b) provide a procedure for interpreting a cluster-analysed printout.