Schematic of aggregation procedure in hierarchical cluster analysis.

<p><b>Left column</b>: The position of single units in the n-dimensional space. In each step (A–D) units or groups of units with the smallest distance to each other are grouped together. <b>Right column</b>: The resulting developing dendrogram of the cluster analysis. The linkage distance indicates the similarity of the units. The higher the linkage distance the more differ the units in their properties.