Five Decades of Terrorism in Europe: The TWEED Dataset

In: Journal of peace research, Volume 44, Issue 1, p. 109-121

Abstract

The article presents a regional dataset on internal terrorism, Terrorism in Western Europe: Event Data (TWEED), covering the period 1950 through 2004 for 18 West European countries. As the dataset covers internal terrorism, the distinction between this form of terrorism and international terrorism is discussed. In demarcating international from internal terrorism, the former is usually taken to mean terrorism involving nationals or territory of more than one state. In TWEED, however, terrorism is regarded as internal when terrorists act within their own political systems. Terrorists originating from outside Western Europe, but committing acts of terrorism inside the region, are excluded from TWEED. Next, the article discusses the selection of sources from which the coding is done. With its combination of continuous coverage and good reporting of Western Europe, Keesing's was chosen as the source for TWEED. The article discusses problems of source coverage related to relying on a single source. Finally, the article presents the structure of the dataset. The coding unit is the event related to terrorism, whether acts of terrorism or government acts directed against terrorists. A total of 11,245 events are recorded in TWEED, of which 86.5% are actions initiated by terrorist groups or non-state agents. TWEED records activities by 214 named terrorist groups. Events are coded for a range of 52 variables falling into two groups: attributes of the action, including basic information such as date and country of the terrorist attack, the agent (group) responsible and the number of deaths and injuries inflicted; and attributes of the agent, which records their ideological profile, regional context and attitude towards the state.