Couchsurfing visualized

My collaborator Bogdan State of Stanford University created a video of the evolution of a local “Couchsurfing” network, as part of our research project on the evolution of trust within the Couchsurfing movement. Couchsurfing is an international community through which travelers can find a place to spend the night (aka a “couch”).Among other things, we are interested in how the obvious trust problems involved with having a stranger spend the night in your house are solved, and how Couchsurfing  creates local communities, both online and offline. The video below focuses on Couchsurfers within San Francisco, and shows how the social network among them evolves.

From the description of the video on YouTube:

Blue ties represent friendships from outside the organization. Red ties represent friendships formed within the CouchSurfing organization. We have no information about grey ties. The width of tie is proportional with the indicated strength of the friendship: i.e., from “acquaintance” to “best friend.”
The movie was done in SoNiA, a highly-recommended free dynamic network visualization tool.

One of the cool things to observe in this video is that the read ties, which were formed through Couchsurfing, appear to form the core of the network and to be crucial in keeping the large community together. Also, you can observe the rather sudden emergence of a giant component.