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© 2017 Elsevier B.V. Ego networks models describe the social relationships of an individual (ego) with its social peers (alters). The structural properties of ego networks are known to determine many aspects of the human social behavior, such as willingness to cooperate and share resources. Due to their importance, we have investigated if Online Social Networks fundamentally change the structures of human ego networks or not. In this paper we provide a comprehensive and concise compilation of the main results we have obtained through this analysis. Specifically, by analysing several datasets in Facebook and Twitter, we have found that OSN ego networks show the same qualitative and quantitative properties of human ego networks in general, and therefore that, somewhat counter-intuitively, OSNs are just “yet another” social communication means which does not change the fundamental properties of personal social networks. Moreover, in this paper we also survey the main results we have obtained studying the impact of ego network structures on information diffusion in OSNs. We show that, by considering the structural properties of ego networks, it is possible to accurately model information diffusion both over individual social links, as well at the entire network level, i.e., it is possible to accurately model information “cascades”. Moreover, we have analyzed how trusted information diffuses in OSNs, assuming that the tie strength between nodes (which, in turn, determines the structure of ego networks) is a good proxy to measure the reciprocal trust. Interestingly, we have shown that not using social links over a certain level of trust drastically limits information spread, up to only 3% of the nodes when only very strong ties are used. However, inserting even a single social relationship per ego, at a level of trust below the threshold, can drastically increase information diffusion. Finally, when information diffusion is driven by trust, the average length of shortest paths is more than twice the one obtained when all social links can be used for dissemination. Other analyses in the latter case have highlighted that also in OSNs users are separated by about 6 (or less) degrees of separation. Our results show that when we need trustworthy “paths” to communicate in OSNs, we are more than twice as far away from each other.

Original publication




Journal article


Online Social Networks and Media

Publication Date





44 - 55