Terrorist Group Brutality and the Emergence of the Islamic State

We assess the certainty with which terrorist groups can repeatedly inflict fatalities in terrorist attacks. A terrorist group is particularly dangerous that can inflict higher levels of fatalities with more certainty than other groups. We develop a fatalities-to-variability (F-V) measurement statistic to shed some light on the risk-adjusted brutality of terrorist groups. A relatively high F-V ratio indicates that a terrorist group demonstrates a capability to inflict fatalities with less variable outcomes across attacks than other groups. An increasing F-V ratio indicates an enhancement of this capability. Terrorist groups observed to be increasing the F-V ratio of their actions may be special cause for concern, especially when F increases concomitant with decreases in V. We compute the F-V statistic for every terrorist group that was active during the period 2000 to 2008. We assess the results and compare the relative brutality of terrorist groups. We examine several prominent cases including Algerian terrorism, Al-Qa`ida, the Taliban, the Lord’s Resistance Army (LRA) and the Islamic State (ISIS). ISIS has been accorded considerable attention recently. However, its emergence as a terrorist group with a relatively high F-V ratio can be traced to as early as 2007.