Agglomerative Methods (of Cluster Analysis):
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 .