UPGMA

UPGMA stands for Unweighted Pair-Group Method with Arithmetic mean.

Assume that there are three clusters called C1, C2 and C3 including n1, n2 and n3 number of rows or columns. Clusters C2 and C3 are aggregated to form a new single cluster called C4.

The distance between cluster C1 and the new cluster C4 is calculated as:

hc_upgma_eq_1.png

where

hc_upgma_eq_2.png

hc_upgma_eq_3.png

See also:

Clustering Methods Overview