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A Set of Measures of Centrality Based on Betweenness

Why this mattered

Freeman’s paper mattered because it turned an intuitive sociological idea, that some actors are powerful because information must pass through them, into a general, computable measure. Earlier centrality measures emphasized local prominence, such as many direct ties, or closeness to all others. Betweenness centrality instead defined importance by a node’s position on shortest paths between other nodes, making “brokerage,” “gatekeeping,” and potential control of communication measurable across networks of different sizes and structures. This shifted centrality from a single notion of being well connected to a family of structurally distinct roles.

The paper also made centrality usable as a comparative network concept. By defining point centrality and graph centralization, Freeman provided tools not only to rank actors within a network but also to describe how concentrated a whole network’s communication structure was. Its applicability to connected and unconnected symmetric networks helped make the measure practical for real social data, where networks are often fragmented or incomplete.

After this paper, later work could treat shortest-path mediation as a standard structural signal rather than a qualitative interpretation. Betweenness centrality became foundational in social network analysis and later network science, influencing studies of organizational control, political brokerage, epidemiological transmission, infrastructure vulnerability, and community structure. Subsequent breakthroughs, including algorithmic improvements for computing betweenness at scale and methods such as edge-betweenness community detection, depended on Freeman’s formulation as a common mathematical language for identifying nodes and ties that hold networks together.

Abstract

A family of new measures of point and graph centrality based on early intuitions of Bavelas (1948) is introduced. These measures define centrality in terms of the degree to which a point falls on the shortest path between others and there fore has a potential for control of communication. They may be used to index centrality in any large or small network of symmetrical relations, whether connected or unconnected.

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