dendrogram
n. a type of treelike diagram used in hierarchical clustering. It lists all of the participants at one end and then directs branches out from those participants who are similar and connects them with a node that represents a cluster. A dendrogram could be used, for example, to cluster individuals into various categories of HIV risk, depending on their number of sexual partners, their frequency of unprotected sex, and the perceived risk of their partners. Individuals who had few sexual partners with little or no unprotected sex and who perceived little or no partner risk of HIV infection would be branched into a cluster that could be labeled low risk, whereas individuals with high values on these three variables would branch into a high-risk cluster, with other individuals presumably clustering into a medium-risk group.