An Empirical Examination on the Severity of Lone-Actor Terrorist Attacks

Lone-actor terrorists have increasingly attracted the attention of researchers, policymakers, and practitioners alike. Despite this enhanced interest, few studies have compared the outcomes of lone-actor terrorist attacks with other terrorists, and those that have do not consider the terrorists' intention to kill in an attack. This study utilizes a sample of 230 terrorist homicide incidents from the Extremist Crime Database to examine the extent to which lone-actors perpetrate more severe attacks than other terrorists. We find that lone-actors are significantly associated with more severe attack outcomes when controlling for the intention to kill. We conclude by commenting on the utility of these findings in U.S. counterterrorism policy and the importance for future research to account for actors' intentions when assessing terrorist attack severity