Tore Opsahl

Thesis: 3.4 Contribution to the literature

This project contributes to the literature by providing a method for assessing the extent to which prominent nodes direct their efforts towards each other. This is a feature of complex networks that was not detected previously. This project lies within the context of the rich-club perspective, which studies the properties of a subset of prominent or rich nodes. Much emphasis has been placed on the extent to which highly connected nodes of a network interact with one another, and to a lesser extent on the nature and strength of their interactions. The explanatory power of the rich-club perspective has so far been hindered by its assumption that only one class of nodes, namely the highly connected ones, are likely to play a crucial role in a network. In this chapter, we relaxed this assumption, and developed a novel framework for examining the tendency of prominent nodes to attract and secure control of resources. By exploring different definitions of prominence in a network, we are able to identify novel organising principles that help us deepen our understanding of the network’s organisation and functioning.

The wide applicability of our method to a variety of empirical settings makes it a particularly suitable methodological tool for scientific investigations across multiple disciplinary fields. Results uncover mechanisms governing the distribution of air travel, the selection and intensity of scientific collaborations, and the way people commit themselves to one another in a virtual setting. The implications of our analysis for these three domains only represent a small fraction of the potential of the proposed method. In fact, this method can be applied to network data from a variety of fields, including biological sciences, social and political sciences, computer and information sciences, environmental sciences, spatial economy, and ecology, among others.