Social Networks

A social network may be defined as a set of actors (generally individuals or organizations) linked by social relations or ties of a specified type, such as friendship, kinship, flow of resources, shared interests, or group membership, to name but a few. Research carried out in various fields has shown that social networks play a central role in determining the way problems are solved, innovations are diffused, and organizations are run; social networks also play a role in the degree to which individuals succeed in achieving their goals.

A social network may be represented as a map of all of the relevant social relationships linking a group of actors. Nodes and ties are often displayed in a social network diagram, in which nodes represent the actors and ties are the lines representing a particular social relation. To study any social network, it is essential to examine the structure of the relationships between the nodes analyzed. The measurement of relationships between actors is called social network analysis (SNA).

SNA has been used to describe networks of relationships and to trace the flow of information between individuals and groups. This approach stands in sharp contrast to other areas of social sciences, which, in order to study attitudes, opinions, and behaviors, have tended to focus on actors' attributes—that is, the characteristics of people, groups, and organizations—rather than on actors' relations.

Those interested in social networks have developed several tools and concepts—many adapted from graph theory—to help reveal and characterize network linkages. Through sociograms, researchers are able to visualize structures, identify leaders, and isolate individuals in groups to show asymmetry and reciprocity. When looking at the map of relations between nodes (or actors), the focus is usually on (a) the overall network properties, (b) the nature of links, and (c) actors' positions.

Research has demonstrated the importance of bridging contacts between groups. In this regard, many studies have demonstrated that whereas strong ties may be central to maintaining or reproducing a group's position and identity, weaker or bridging ties have in fact proved more significant for spreading information across group boundaries by facilitating the linking of actors that would otherwise be isolated from each other. As has frequently been shown by [Page 1330]Mark Granovetter and Nan Lin, without weak ties, information does not flow to outside the single group or network. Network analysis can also be used to study change within a group or among groups over time. For example, economic transactions between nations or specific economic groups could be measured at several points in time, thereby using the network perspective to study longitudinal changes.

The historical roots of SNA are to be found in the work of German sociologist Georg Simmel, who, at the turn of the twentieth century, sought to construct a theory that explained how various social phenomena come about. Simmel's famous writing on the fundamental difference between the interactions in dyads (two people) and triads (three people), as well as his notion of urban systems being composed of intersecting networks and circles, was the basis for his “formal sociology,” which is often considered a precursor to SNA.

...