Cluster Analysis - Tree Clustering Tab

Select the Tree clustering tab of the Cluster Analysis dialog box to access these options. This tab is displayed when Tree Clustering is selected as the algorithm.

Method. In this group box, select a hierarchical clustering method. At this time, the only available option is Ward.

Ward

This method is distinct from all other methods because it uses an analysis of variance approach to evaluate the distances between clusters. This method attempts to minimize the Sum of Squares (SS) of any two (hypothetical) clusters that can be formed at each step. NOTE: Refer to Ward (1963) for details concerning this method. Although this method is regarded as very efficient,  it tends to create clusters of small size.

Single linkage

In this method the distance of the two closest objects (nearest neighbors) in the different clusters determine the distance between two clusters. This rule strings objects together to form clusters, and the resulting clusters tend to represent long chains.

Standardize data. Select this check box to standardize the data. Standardization refers to converting all data into a Z-score, that is, a data point is converted into a Z-score by subtracting the mean and dividing by the standard deviation.