Global Terrorism Database (GTD)

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ABOUT GTD

OVERVIEW OF THE GTD   |   HISTORY OF THE GTD   |   GTD TEAM ALUMNI

Overview of the GTD

The Global Terrorism Database™ (GTD) is an open-source database including information on terrorist events around the world from 1970 through 2020. Unlike many other event databases, the GTD includes systematic data on domestic as well as transnational and international terrorist incidents that have occurred during this time period and now includes more than 200,000 cases. For each GTD incident, information is available on the date and location of the incident, the weapons used and nature of the target, the number of casualties, and--when identifiable--the group or individual responsible.

Statistical information contained in the Global Terrorism Database is based on reports from a variety of open media sources. Information is not added to the GTD unless and until we have determined the sources are credible. Users should not infer any additional actions or results beyond what is presented in a GTD entry and specifically, users should not infer an individual associated with a particular incident was tried and convicted of terrorism or any other criminal offense. If new documentation about an event becomes available, an entry may be modified, as necessary and appropriate.

The National Consortium for the Study of Terrorism and Responses to Terrorism (START) makes the GTD available via this online interface in an effort to increase understanding of terrorist violence so that it can be more readily studied and defeated.

Characteristics of the GTD

• Contains information on over 200,000 terrorist attacks

• Currently the most comprehensive unclassified database on terrorist attacks in the world

• Includes information on more than 88,000 bombings, 19,000 assassinations, and 11,000 kidnappings since 1970

• Includes information on at least 45 variables for each case, with more recent incidents including information on more than 120 variables

• More than 4,000,000 news articles and 25,000 news sources were reviewed to collect incident data from 1998 to 2017 alone

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History of the GTD

The Global Terrorism Database--or GTD--began in 2001 when researchers at the University of Maryland obtained a large database originally collected by the Pinkerton Global Intelligence Services (PGIS).

From 1970 to 1997, PGIS trained researchers--mostly retired Air Force personnel--to identify and record terrorism incidents from wire services, government reports, and major international newspapers to assess the risk of terrorism for their clients. With funding from the National Institute of Justice, the Maryland team finished digitizing the original Pinkerton data in December 2005, making corrections and adding additional information wherever possible. PGIS lost data for 1993 in an office move, and these data have never been fully recovered.

In April 2006, the National Consortium for the Study of Terrorism and Responses to Terrorism (START), working with the Center for Terrorism and Intelligence Studies (CETIS), received additional funding from the Human Factors Division of the Department of Homeland Security (DHS) to extend the GTD beyond 1997. This effort is distinct from the original collection because CETIS analysts had to search archival sources for documented attacks, rather than recording events as they occurred. Some earlier media sources are simply unavailable, undoubtedly reducing the total number of attacks that were identified since 1997. In addition, efforts begun for post-1997 cases used a slightly modified definition of terrorism (with information on specific criteria for identification as a terrorist incident included for each case) and expanded the number of variables collected for each attack.

By August 2008 data collection was completed for incidents that occurred through 2007. In Fall 2008, the GTD team applied the newly-developed inclusion criteria to the earlier GTD data in order to form a single source of information on terrorist attacks, covering the entire period 1970 to 2007 (see the "Synthesis" section of Data Collection and Methodology).

In Spring 2008, analysts from the Institute for the Study of Violent Groups (ISVG) at the University of New Haven began collecting data for inclusion in the GTD. ISVG's collection effort, which ended in the Spring of 2012, included data on terrorist attacks that occurred between April 2008 and October 2011. Research assistants at START at the University of Maryland integrated these data into the database, while continuing to make improvements to the earlier data. GTD staff members at START routinely review a wide array of sources to identify additional cases and additional information about previously identified cases, to help ensure that GTD is as comprehensive and accurate as possible for its entire time span. Data from these collection efforts are also integrated into the current version of GTD. Additional information on these collection efforts can be found in the codebook (see dbsource field). Beginning with attacks that occurred in November 2011, all ongoing GTD data collection efforts are conducted by START staff at the University of Maryland.

Since moving the ongoing collection of the GTD to the University of Maryland in the spring of 2012, START staff have made significant improvements to the methodology that is used to compile the database. These improvements include using a vastly expanded and more diverse set of news media sources for identifying and coding the incidents that are included in the GTD; using machine learning and data mining techniques to identify news articles that include information about terrorist attacks; and developing and utilizing a proprietary Data Management System (DMS) to compile the database. More information about these improvements can be found both in the GTD codebook and in this START Discussion Point on The Benefits and Drawbacks of Methodological Advancements in Data Collection and Coding: Insights from the Global Terrorism Database (GTD). As a result of these improvements, a direct comparison between 2011 and 2012 data likely overstates the increase in total attacks and fatalities worldwide during this time.

In sum, the Global Terrorism Database is a compilation of distinct data collection efforts from 1970 to the present. From 1970 to 1997 the data were constructed primarily from incidents recorded in real-time by PGIS using a broad-based definition of terrorism. Data from this period are updated and corrected on an ongoing basis. The data from 1998 through 2007 were primarily collected retrospectively, while data on more recent events are being collected in real-time and with the benefit of more robust media archives and improved collection methodology. Users should note that differences in levels of attacks and casualties before and after 1997, 2008, and 2012 may be at least partially explained by differences in data collection; researchers should adjust for these differences when modeling the data. Nonetheless, criteria for collecting data were established and applied to the full set of cases to assure the adherence to a broad definition of terrorism and also to allow users to filter out cases that may be inappropriate for their specific analytical interests. The data now form a complete series from 1970 through 2020--except for 1993.

GTD Team Alumni

Principal Investigators

Gary LaFree, Professor, University of Maryland
Laura Dugan, Professor, Ohio State University
Erin Miller

Research Staff

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