ABSTRACT
A very typical example of a hierarchical data structure is the scenario in which individual students are clustered within middle schools. Table 16.1 contains a very small data set used to demonstrate the clustering of students within middle schools. Each letter (A through V) represents a student. Each student only appears once in Table 16.1. The table represents each student’s affiliation with only a single middle school although there are multiple students within each middle school. Thus middle school is a clustering variable. Figure 16.1 also depicts the pure clustering of students within middle schools for students in Table 16.1 in a network graph.
