F.Toriumi, I.Okada, H.Yamamoto, H.Suwa, K.Izumi and Y.Hashimoto
We analyzed data for a large number of small social network services (SNSs) and classified them in terms of their structures and communication patterns. Using this classification, we analyzed their features and found that most of them have small world, scale free, and negative assortativity characteristics. We also classified them on the basis of calculated network indexes and compared the four types. Finally, we classified their communication patterns and identified four types of friend networks: partial, parity, inclusive, and independent.