User Groups in Social Networks: An Experimental Study on YouTube

While some social networking sites such as Orkut or Friendster are purely social, others such as YouTube, Flickr, and LiveJournal are highly content-oriented yet maintaining a social component. The nature of the interaction between content and connections is fundamentally important not just from a social science perspective but also to answer how the relevant content and connections can be found more easily. YouTube recently added the ability for users to form groups, in which explicit category affiliation is noted too. YouTube is ripe for consideration of how content and contacts are related. This is amongst the seminal works dealing with YouTube groups in general, not only in the context of categories, and we are amongst the first to study what motivates group membership in YouTube in the context of other observable group activities. We also investigate the role of users in groups, how groups evolve and the structure of these groups organized under a category change over time. Finally we find what form of linkage motivates new members to join these groups.