ABSTRACT
Cluster analysis encompasses many diverse techniques for discovering structure within complex bodies of data. In a typical situation, one has a sample of data units each described by scores on selected variables, such as achievement test scores. The objective is to group either the data units or the variables into clusters such that the elements within a cluster have a high degree of ‘natural association’ among themselves while the clusters are ‘relatively distinct’ from one another. The term classification may refer to an end product or to a process. As an end product, a classification is a systematic scheme or arrangement of classes already known or established. As a process, classification consists of sorting individual objects into well-known classes. For a variety of research goals, researchers need to find out which objects in a set are similar and which objects are dissimilar. The best known of these research goals is the making of classifications.
