Dynamics of ties in massive communication networks

 

ESTEBAN MORO EGIDO

UNIVERSIDAD CARLOS III DE MADRID

 

For decades, social science has measured relationships between individuals in the currency of tie strength, introduced by Granovetter [1]. Weak ties (loose acquaintances) can help to disseminate ideas and/or innovations between different groups, help to find a job or new information; while strong ties (family, trusted friends) hold together organizations and social groups and can affect emotional health. In the last years, this hypothesis has been tested in large social networks constructed from activity of human relationships like e-mail or mobile data, and by using intensity of relationships as a proxy for tie strength [2]. However, intensity is known to be a poor indicator and predictor of tie strength [3], something that has been confirmed recently in online social networks [4]. To understand social ties better, we study the dynamics of phone calls of more than 20 million users (2.5 billion ties). We find that intensity does not uniquely classify the dynamics of ties: in particular we find a large fraction of short-term ties with very different intensities. On the contrary we also find a great number of stable although infrequent communications. These findings suggest that stability of the tie could be a relevant variable to describe social relationships and indeed as in [3,4] we found that stability is a better predictor for social relationship. Finally we discuss the importance of stability of links in the structure of the social network and in the diffusion of information, where we find that short-term ties play a major role both in the local structure of the network and on the enhancement of information diffusion. References: 1. M. S. Granovetter, The Strength of Weak Ties, The American Journal of Sociology 78(6), 1360 (1973) 2. J.-P. Onnela, et al., Structure and tie strengths in mobile communications networks, PNAS 104, 7732 (2007). 3. P. V. Marsden, and K. E. Campbell Measuring Tie Strength Social Forces 63(2), 482 (1990). 4. E. Gilbert and K. Karahalios, Predicting Tie Strength with Social Media, presented in CHI 2009.