Onset Data

Release Database, Access file (zipped) (zip)
Annual Onset, Stata file (dta)
Calendar-time Onset, Stata file (dta)
README, Text file (txt)

The causes of armed conflict is most common focus among conflict researchers, and the Armed Conflict Dataset has repeatedly been used to analyze this problem. Previous versions have not contained an authoritative definition of what an onset is, and this has caused unnecessary confusion. With this release, we also provide users with a clear and user-friendly operational definition of conflict onset.

When using the data, please cite Gleditsch et al. (2002) and Strand (2006)

The data are available in two versions, country-year and calendar-time The country-year file is based on the Gleditsch/Ward definition of the international system, and will inform the user whether the year observed an onset or not. All users of the Uppsala/PRIO data will know that a key question in this respect is how many years on inactivity we must observe within one dyad before we code a new onset between previously active parties. The country-year file comes with three pre-defined cutoff points of two, five and eight years, which allows for limited robustness checks.

The calendar-time data structure, in comparison, allows for much more thorough robustness checks. This structure, originally presented by Raknerud & Hegre (1997), is based on observations of all independent countries on the day where one of them experienced an onset. Since the relevant control group is closely linked to the observation on an onset, several types of filters can be applied within the same dataset, in order to check for robustness along various dimensions.


Gleditsch, Nils Petter; Peter Wallensteen, Mikael Eriksson, Margareta Sollenberg & Håvard Strand, 2002. ‘Armed Conflict 1946–2001: A New Dataset’, Journal of Peace Research 39(5): 615–637.

Strand, Håvard, 2006. 'Onset of Armed Conflict: A New List for the period 1946–2004, with Applications', Under review at Conflict Managment and Peace Science.

Onset and Duration of Intrastate Conflict