
9: Ego Networks


In the previous chapter we looked at the idea of the amount of "embedding" in whole networks - loosely. The main theme was to understand and index the extent and nature of the pattern of "constraint" on actors that results from the way that they are connected to others. These approaches may tell us some interesting things about the entire population and its sub-populations; but, they don't tell us very much about the opportunities and constraints facing individuals.

• 9.1: Introduction to Ego Networks
If we want to understand variation in the behavior of individuals, we need to take a closer look at their local circumstances. Describing and indexing the variation across individuals in the way they are embedded in "local" social structures is the goal of the analysis of ego networks.
• 9.2: Ego Network Data
Ego network data commonly arise in two ways: Surveys may be used to collect information on ego networks. We can ask each research subject to identify all of the actors to whom they have a connection, and to report to us (as an informant) what the ties are among these other actors. Alternatively, we could use a two-stage snowball method; first, ask ego to identify others to whom ego has a tie, then ask each of those identified about their ties to each of the others identified.
• 9.3: Ego Network Density
There are quite a few characteristics of the ego neighborhoods of actors that may be of interest.
• 9.4: Structural Holes
Ronald Burt coined and popularized the term "structural holes" to refer to some very important aspects of positional advantage/disadvantage of individuals that result from how they are embedded in neighborhoods. Burt's formalization of these ideas, and his development of a number of measures has facilitated a great deal of further thinking about how and why the ways that an actor is connected affect their constraints and opportunities, and hence their behavior.
• 9.5: Brokerage
Fernandez and Gould also examined the ways in which actor's embedding might constrain their behavior. These authors, though, took a quite different approach; they focus on the roles that ego plays in connecting groups. That is, Fernandez and Gould's "brokerage" notions examine ego's relations with its neighborhood from the perspective of ego acting as an agent in relations among groups (though, as a practical matter, the groups in brokerage analysis can be individuals).
• 9.S: Ego Networks (Summary)