In agglomerative methods of hierarchical cluster analysis , the clusters obtained at the previous step are fused into larger clusters. Agglomerative methods start with N clusters comprising a single object, then on each step two clusters from the previous step are fused into a bigger cluster. The criterion of such fusion is the minimal distance between the two clusters to be fused, as specified by the chosen linkage function .

A complementary concept is divisive methods .

See also: the chapter in XLMiner help , and the short online courses

Cluster Analysis ,

Data Mining: Unsupervised Techniques .