The index provides a comprehensive summary of the key global trends and patterns in terrorism since 2000. It produces a composite score in order to provide an ordinal ranking of countries on the impact of terrorism.
The GTI is based on data from the Global Terrorism Database (GTD) which is collected and collated by the National Consortium for the Study of Terrorism and Responses to Terrorism (START) at the University of Maryland. The GTD has codified over 150,000 cases of terrorism.
There is no single internationally accepted definition of what constitutes terrorism The GTI therefore defines terrorism as “the threatened or actual use of illegal force and violence by a non-state actor to attain a political, economic, religious, or social goal through fear, coercion, or intimidation”. This definition recognizes that terrorism is not only the physical act of an attack, but also the psychological impact it has on a society for many years after.
In order to be included as an incident in the GTD the act has to be: “an intentional act of violence or threat of violence by a non-state actor". This means an incident has to meet three criteria in order for it to be counted as a terrorist act:
The incident must be intentional – the result of a conscious calculation on the part of a perpetrator.
The incident must entail some level of violence or threat of violence — including property damage, as well as violence against people.
The perpetrators of the incidents must be sub-national actors. This database does not include acts of state terrorism.