The average group linkage is a method of calculating distance between clusters in hierarchical cluster analysis . The linkage function specifying the distance between two clusters is computed as the distance between the average values (the mean vectors or centroids ) of the two clusters.

Mathematically the linkage function - the distance between clusters and - is described by the following expressions:

• and are two sets of objects (clusters);

• and are the numbers of objects in clusters and respectively;

• and are the mean vectors of the first and the second clusters, respectively;

• is the distance between vectors and .

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

Cluster Analysis ,

Data Mining: Unsupervised Techniques ,

Introduction to Data Mining .