Sampling Jihadists' IPs

Great idea as a matter of fact :

"The following is based on an analysis of 4,593 IP addresses (1,452 unique IP addresses). The IPs were acquired from 19 of the more prominent of the Salafist/Jihadist forums, including both Arabic and non-Arabic forums, from 01 January through 30 April of this year."

Taking into consideration the per-country stats, do not exclude the logical possibility of IP cloaking while browsing these and also, the tiny number of intelligence and lone gunman info warriors gathering OSINT data. In another much more in-depth analysis on mapping the online jihad, the authors point out the emerging internationalization of jihad as well :

"The near exclusive use of the Arabic language in these significant jihadi websites likely accounts for the concentration of activity in the Middle East and North Africa. But with a reach to more than 40 countries, the virtual community within these ten influential sites assumes a global significance. The international jihadi movement's use of the internet to fuel the exchange of ideological expansion and its corresponding influx of support will increase the vulnerability of many countries to the appeal of extremism."

At least these organizations don't rely on setting up fake jihadist communities to come up with the sample data, but know exactly where to look for.