The Brookings Project on U.S. Relations with the Islamic World – An Analysis Paper | No. 20, March 2015. The ISIS Twitter Census – Defining and describing the population of ISIS supporters on Twitter. J.M. Berger and Jonathon Morgan.

“The Islamic State, known as ISIS or ISIL, has exploited social media, most notoriously Twitter, to send its propaganda and messaging out to the world and to draw in people vulnerable to radicalization. By virtue of its large number of supporters and highly organized tactics, ISIS has been able to exert an outsized impact on how the world perceives it, by disseminating images of graphic violence (including the beheading of Western journalists and aid workers and more recently, the immolation of a Jordanian air force pilot), while using social media to attract new recruits and inspire lone actor attacks. Although much ink has been spilled on the topic of ISIS activity on Twitter, very basic questions remain unanswered, including such fundamental issues as how many Twitter users support ISIS, who they are, and how many of those supporters take part in its highly organized online activities…We set out to answer some of these important questions using innovative techniques to create a large, representative sample of accounts that can be clearly defined as ISIS supporters, and to attempt to define the boundaries of ISIS’s online social network…”