Compared to the past, ever larger amounts of data are being collected in astronomy, and the rate will continue to accelerate in the next decades. It is therefore necessary to work on bigger samples if full advantage is to be taken of all accessible information. It is also necessary to derive as much information as possible from the diversity of the data, rather than restricting attention to subsets of it. One way to work effectively on large samples is to apply, and if necessary to develop, suitable statistical methods.
Physical analysis is necessary subsequently to refine and interpret the results.
Hierarchical Cluster Analysis 3. Non-Hierarchical Clustering, or Partitioning 4. We will look briefly at each of these in turn. In the following sections we will concentrate on various practical aspects of the methods.