Wireless contacts, Facebook friendships and interests: Analysis of a multi-layer social network in an academic environment

Human mobility traces have drawn increasing attention in recent years due to their usefulness for constructing mobility models and evaluating mobile opportunistic communication systems. Even if human mobility provides us insights into the social behavior of mobile users, there is a growing awareness that human sociality is expressed simultaneously on multiple layers. The multilayered complex network composed by the social network constructed on wireless contacts and other types of social network layers needs still to be analyzed and understood in depth. In this paper, we describe the experiment we performed in a campus environment to trace the wireless contacts in terms of Bluetooth encounters, occurring between nodes inside and outside the group of experimenters carrying smartphones, and to gather the profiles, Facebook friendships, and interests of the participants. By analyzing the multilayer social network constructed on this dataset, we contribute to novel understanding of human behavior at different social dimensions. We study the relationship between offline encounters detected through mobile devices, Facebook friendships and shared interests in terms of closeness between the corresponding social graphs, matching between strong offline ties and the other social ties, and similarity between communities. We show that Bluetooth contacts network layer and Facebook friendships network layer are similar.