Several studies were presented regarding ego-networks in the scope of social network analysis. The areas are varied between biology, sociology to criminal networks. In this section, the authors introduce related work in a wider scope by mentioning publications regarding social networks, which include information about ego-networks.
Ego-Networks
In (Hanneman & Riddle, 2005), a throughout exposition about social networks is made, and a full chapter is dedicated to ego-networks. Hanneman et al. define “ego” as an individual “focal” node in a network. “neighborhood” sets the boundaries of ego networks and includes all the direct connections and egos that tie with an ego. Dejordy et al. (Dejordy & Halgin, 2009), introduce the network perspective and the differences between socio-centric and ego-centric analysis. The ego-centric approach fits studies about phenomena or entities across different networks. The socio-centric approach is more suitable for studying interaction within a defined network.
Wasserman et al. provide a complete study of social networks with several models in (Wasserman & Faust, 1994). Some relevant studies address the social structure of competition.
For Burt et al. (Burt, 1992), the social structure of competition addresses the consequences of voids in relational and resource networks. Competitive behavior can be understood regarding player access to “holes” in the social structure of the competitive arena. Those “structural holes” create entrepreneurial opportunities for information access, timing, referrals, and control. Ego-networks analysis provides an answer to this sensible information or properties that are also studied in the Case Study section of this document.
Figure 1 represents two ego-networks with connections to the 4th and 2nd order, respectively for node 1 and 5. This example shows how the same network change in terms of visualization, depending on the selected ego node.
Figure 1. Ego-Network visualization: (a) selected ego node 1 and (b) Ego-Network centered in node 1; (c) same network but with ego node 5 and (d) Ego-Network centered in node 5.