Tumblr: a directed social network
http://technolog.msnbc.msn.com/_news/2011/09/09/7690677-tumblr-marks-its-10-billionth-post
Tumblr, a blogging platform founded in 2007 by David Karp, recently marked its 10 billionth post. The platform allows users to post pictures, text, videos, links, quotes, and audio to their blog, which they can choose to keep open to the public or private. The rise in popularity of this blog could be accounted for due to its easy use and way of connection to friends and those with similar common interests.
Analyzing Tumblr’s social network yields interesting results. The network of all Tumblr users is a directed network in a sense, similar to the network on Twitter. Assuming that a user’s blog isn’t set on private, any other Tumblr user can follow it, even without the other user’s permission. Many times users’ connections may be one sided (directed) because one user may follow another one but the connection isn’t returned. Because of this directed network, the ties between users on Tumblr may be a weak indication of how their connection is in reality. Close friends may access each other’s Tumblr’s very often, and monitoring their Tumblr actions could suggest that they have a strong ties. But two people who don’t actually know each other could also have strong ties on Tumblr just by viewing each other’s posts. A user’s close friend may also view their blog numerous times, but since that person doesn’t have an account, there is so node in the network for him/her and the connection is undocumented. Rather than using the strength of Tumblr connections as a measurement of strength of friendships, the ties could be used to isolate various groups of users who have common interests with each other.
Tumblr blogs often have a theme to them, for example food, travels, movies, etc, or are filled with pictures, videos, and blogs of interest to the user itself. Another user who has interest in the same type of things may come across this blog and choose to follow it. These two nodes of users are then connected due to a similar interest, rather than actually knowing each other. Because people are more inclined to follow blogs that are more similar to what they are interested in, it would imply that in the network there would be clustering of nodes. It would be very likely for two users who follow each other to follow other same blogs because of this idea of common interest. In this sense, triadic closure is displayed in the Tumblr network. However it’s hard to say how clustered nodes will be based on common interests because some friends may not be interested in the same types of things but they will still follow each other’s blogs because of the connection they already have with each other.