Two-mode networks: the measurement of efficiency in the profiles of actors’ participation in the occasions

Abstract

In two-mode networks, the analysis of centrality aims at identifying the actors that reach predominant roles and positions by participating in the observed occasions, without investigating how they do it. In this paper, we focus on the identification of the actors who reach a significant level of connection with the others on the basis of an unsteady, but efficient, profile of participation. The concept of efficiency will be formally introduced using an axiomatic system, and extended to the network of occasions, leading to the concept of power center. We will then propose two approaches to the measurement of efficiency and power centers, based on a confrontation, namely a ratio, between actors’ and occasions’ level of social proximity and number of occasions attended (for actors), or number of participants (for occasions). The level of actors’ and occasions’ social proximity will be measured using a centrality approach. Finally, we will present an empirical application to a real two-mode network, in order to practically analyze the features and properties of the proposed indexes, and to compare them with the main centrality measures.