The information contained in the matrix is used to create both and networks. Figure 1 displays an organizational network based on the overlapping members in Table 1. It shows that organization A is at the "center" of the network due to the largest number of connections among these individuals. Figure 2 shows the interpersonal network that emerges from Table 1. Note that no one person is at the center of this interpersonal network, even though the organizational network had a center. That may seem counterintuitive, but it is a good example of the fact that these are two different networks, not just some mirror image of each other. Note also that one person is an "isolate," with no connections. That's the situation for 99% of Americans when it comes to the schools, clubs, policy groups, and companies of the upper class and the power elite in the United States.
The empirical study of power begins with a search for connections among the people and organizations that are thought to constitute the powerful group or class. This procedure is called It starts with a study of people and all the organizations they belong to. Or conversely, you could say the study starts with a list of organizations that includes all of their members. It leads to the same result -- that's why it's called membership network analysis. The results of a membership network analysis are usually presented in the form of a matrix, as shown in Table 1. The people are listed from the top to bottom and the organizations are arrayed from left to right. The "cells" or boxes created by the intersection of a person and organization are filled with "relational" information such as "member," "director," "owner," or "financial donor." The attitudes the person has toward any given organization in the matrix also can be included, such as "supporter" or "opponent." Maybe think of attitudinal information as a "psychological" relation to the organization. The information used in filling the cells of the matrix is obtained in a variety of ways described later in this document.
Before I begin, I want to stress that the methodological approach outlined in this document makes it possible to discover any concentration or configuration of power. Researchers of any theoretical persuasion can use it because it is not biased for or against any given theory. It contains only one assumption: there is a power structure of some kind or another, no matter how weak or fragmented, in any large-scale society or social group. The method can discover that power is highly concentrated or more dispersed, depending on the degree of difference between rival networks on the power indicators. It can show that some groups or classes have power in one arena, some in another arena. It can reveal changes in a power structure over time by changes in the power indicators. In the United States it usually has led to corporate power structures at the national level and landowner/developer/real estate power structures at the local level, but the results could be different for other countries and they are sometimes different for cities in the United States.
The reputational method works best at the community or city level, where it is less expensive and time-consuming to apply than at the state or national level. It is especially valuable for small towns where very little printed information is available. However, the method has been used with good results in two studies of national power in the United States, and in studies of Australia and Norway. The two American studies are by Floyd Hunter, (Chapel Hill: University of North Carolina Press, 1957) and Gwen Moore, "The Structure of a National Elite Network," 44 (1979): 673-92. The Australian study is by John Higley, Desley Deacon, and Don Smart, (London: Routledge and Kegan Paul, 1979). The Norwegian study is by John Higley, G. Lowell Field, and Knut Groholt, (New York: Columbia University Press, 1976). For a summary of reputational studies at the local level in the United States, see G. William Domhoff, and (New Brunswick, NJ: Transaction Books, 1978). That final book may seem out of date, but the sad truth is that there haven't been many detailed studies of local power structures in the past few decades. For one recent exception that includes new references, see Richard Gendron and G. William Domhoff, (Westview, 2009). See also the section on on this site.