Facencounter: bridging the gap between offline and online social networks

Human beings are involved in a broad range of social relationships spanning from real life experiences to online media and social networks. This is leading people to act in a multilayered complex network whose relationships among different layers have still to be analyzed and understood in depth. In this paper, we focus on this problem by comparing and overlapping the online sociality (Facebook network) and the offline sociality (encounter network) of a group of students. First we describe the experiment we performed to trace the encounters, occurring with people both inside and outside the group of experimenters, and to gather information about their online friendships. On the basis of the obtained dataset, we obtain the relevant complex networks, whose separated analysis lead us to observe significant structural differences. Moreover, we study the correlations and overlap between the two interrelated networks, showing how users' centralities change in the two networks. Finally, the information transfer across layers of the unified complex network enables us to obtain results about the effects on paths and centrality.