Multilayer Brokerage in Geo-Social Networks

Open network structures and brokerage positions have long been seen as playing a crucial role in sustaining social capital and competitive advantage. The degree to which individuals intermediate between otherwise disconnected others can differ across online and offline social networks. For example, users may broker online between two others who then exchange offline the information received through social media. Yet network studies of social capital have often neglected the interplay between online and offline interactions, and have concentrated primarily on a single layer. Here, we propose a geo-social multilayer approach to brokerage that casts light on the integrated online and offline foundations of social capital. Drawing on a data set of 37,722 Foursquare users in London, we extend the notion of brokerage by examining users’ positions in an online social network and their offline mobility patterns through check-ins. We find that social and geographic brokerage positions are distinct and asymmetric across the social and co-location networks. On the one hand, users may appear to be brokers online when in fact their ability to intermediate would be mitigated if their offline positions were also taken into account. On the other, users who appear to have little brokerage power offline may be active brokers within networks that combine both online and offline interactions.