The Global Terrorism Index (GTI) is a report published annually by the Institute for Economics and Peace (IEP), and was developed by IT entrepreneur and IEP's founder Steve Killelea. The index provides a comprehensive summary of the key global trends and patterns in terrorism since 2000. It is an attempt to systematically rank the nations of the world according to terrorist activity. The index combines a number of factors associated with terrorist attacks to build an explicit picture of the impact of terrorism, illustrating trends, and providing a data series for analysis by researchers and policymakers. 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 190,000 cases of terrorism, it covers 163 countries, consisting 99.7% of the world's population.
The GTI was developed in consultation with the Global Peace Index expert panel. The aim is to examine trends and to help inform a positive and practical debate about the future of terrorism and the required policy responses.
Methodology
There is no single internationally accepted definition of what constitutes terrorism. IEP accepts the terminology and definitions agreed to by the authors of the GTD, the National Consortium for the Study of Terrorism and Responses to Terrorism (START) researchers and its advisory panel. The GTI therefore defines terrorism as "the threatened or actual use of illegal force and violence by a state and non-state actor to attain a political, economic, religious, or social goal through fear, coercion, or intimidation". This definition recognises 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.
Indicators and weighting
The GTI score for a country in a given year is based on a unique scoring system to account for the relative impact of incidents in the year. There are four indicators counted in each country's yearly score:
Total number of terrorist incidents in a given year
Total number of fatalities caused by terrorism in a given year
Total number of injuries caused by terrorism in a given year
The approximate level of total property damage from terrorist incidents in a given year
Each of the indicators is weighted differently:
The greatest weighting is thus in general attributed to a fatality. The property damage measure is further disaggregated into four bands depending on the measured scope of the property damage inflicted by one incident. These bandings are shown in the table below, whereby incidents causing less than US$1 million are accorded a weight of 1, between $1 million and $1 billion, and more than $1 billion. A great majority of incidents are coded in the GTD as an 'unknown' level of property damage, thus scoring nil, with 'catastrophic' events being extremely rare.
Example of a country's indicator weighting
To assign a relative number to how a country has been directly impacted by terrorism in any given year, for every incident recorded, the GTI calculates a weighted sum of all indicators. To illustrate, the table below depicts a hypothetical country's score for a given year:
Final score
A five-year weighted average is applied to reflect the lingering psychological effect of terrorist acts over time.
The GTI reports are titled by their publication year. The index is calculated up to the preceding year, e.g. the reference year of the 2020 GTI is 2019.
The resulting raw scores are then quasi-logarithmically transformed onto a scale of 0–10 by way of 20 bands. A raw score of corresponds to a GTI of 0. The next 20 steps corresponding to on the GTI scale are defined by
,
where are the steps in the raw score, is the lowest recorded raw score, and the highest recorded raw score.