Group 7 : OrientExpress Blog

Basic Theory Background
Dunbar’s number is an approximate number of social relationships that humans can maintain with stably over time. This theory is proposed by Robin Dunbar [1], who is an anthropologist in Oxford University of UK. It is derived according to ape’s intelligence and social networks. Dunbar’s number ranges from 100 to 150, defining the size of the group in which every member knows each other. It is determined by human’s mind capability. As the available capital of human’s mind is a constant [2], the number of close relationships is limited. In fact, people will let weaker relationships dissipate and spend efforts to maintain a core group of fewer than 150 or so. [3] In order to maintain a close relationship, considerable investments are required in both emotion and psychology.

Statistics from Facebook
Facebook’s own statistics suggests that the average number of user’s friends is about 130 [4], which is a fact that proves the theory of Dunbar’s number. Although the number of friends of different Facebook’s users is quite different (for example, some Facebook’s users have more than 500 friends), actually, in personal lists of friends, the number of friends that users contact with frequently is quite small and relatively stable. The more actively and closely friends contact with others, the less and more stable the number of such a group is.

Relevance to Our Project
Our social networking application based on mobile contacts aims to strength the interactions and relationships with user’s closest friends by ranking user’s social networks’ information. How to define user’s closest friends? Dunbar’s number tells us that most friends on our social networks are not people that we know and actually interact with most in real life. The closest friends are whom we care about and interact with in our daily lives and they are just in our contacts. Our project’s main idea is to calculate the relationship degrees between user and user’s contacts to quantify the relationships between user and contacts.

References:
[1] R. Dunbar. How Many Friends Does One Person Need? Dunbar’s Number and Other Evo-lutionary Quirks. Faber and Faber, 2010.

[2] Huiji Gao, Xufei Wang, Jiliang Tang and Huan Liu. “Network Denoising in Social Media”, Technical Report, TR-11-002, School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, Tempe, AZ 85287, 2011.

[3] Shyong (Tony) K. Lam and John Riedl, University of Minnesota. Are Our Online “Friends” Really Friends.

[4] See https://www.facebook.com/press/info.php?statistics/