What is the best way to count suicide attacks?

To be included in the database, an attack must meet two criteria: 1) at least one attacker must kill him or herself to kill others; and 2) suicide must be verified by at least two independent sources.  Failed suicide attacks – attacks in which the attack does not kill him or herself – and suicide missions – attacks where the attacker dies, but not by his or her own hand -- are not collected.  Possible suicide attacks -- attacks with only a single source indicating suicide, or attacks where sources give conflicting accounts -- are also not included.  Double verification of suicide is crucial: it greatly reduces bias from any single source to ensure the most accurate record of suicide attacks.  Accordingly, users of CPOST data can have high confidence that the attacks in the Suicide Attack Database have actually occurred.

What are the sources of potential bias?

Data on suicide attacks comes from a variety of possible sources, including governments, the media, and the groups that perpetrate suicide attacks themselves.  Each has its own potential for bias.  For example, governments may have an incentive to over-report attacks as suicide to mobilize support for costly counterinsurgency measures, or to under-report such attacks to make the group appear weak or less determined.  Groups routinely over-report suicide attacks and the casualties they inflict to mobilize support.  Media reports, especially those proximate to an event, might be based on preliminary evidence.  Requiring a minimum of two sources increases our confidence that the suicide attacks in the Suicide Attack Database is accurate in addition to comprehensive.

What about possible attacks?

While they are not included in the database, CPOST does keep track of possible suicide attacks it identifies.  CPOST collects possible suicide attacks because information may become available in the future to confirm the attack.  CPOST periodically reviews possible attacks. If, upon review, new information confirms a possible attack as suicide, the attack is added to the database.  The opposite is also true: if new evidence reveals that an attack no longer meets CPOST’s criteria for inclusion, it is removed.

Possible suicide attacks make up approximately 11% of all suicide attacks identified by CPOST for the period 1982-2013.  Possible attacks are not, however, evenly distributed across campaigns. Iraq, Afghanistan, and Sri Lanka account for the most possible attacks.  Iraq alone accounts for 50% of the total possible attacks, likely because Iraq also accounts for the largest share of confirmed suicide attacks (40%).  The figure below shows the breakdown of confirmed to possible attacks for all campaigns from 1982 to 2013.

Confirmed and Possible Suicide Attacks, 1982-2013

The 2014 Iraq data

Starting in 2013, the Islamic State, successor group to Al Qaida in Iraq and the Islamic State of Iraq and Syria (IS), dramatically escalated its insurgency in Iraq. In 2014, the group rapidly expanded and consolidated its control over the western portion of the country and is now threatening the capital Baghdad.  As in the past, suicide attacks play a major role in the group’s strategy.  To facilitate timely analysis, CPOST is making preliminary data on suicide attacks in Iraq for 2014, current through June 2014, available, a total of 108 confirmed suicide attacks.  Perhaps because these events are so recent, there are also a significant number of possible suicide attacks for Iraq in the first six months of 2014, comprising 27% of the total.  In keeping with CPOST inclusion policy, these attacks are currently excluded from the database pending the availability of additional information.

Iraq 2014 Confirmed and Possible Suicide Attacks