Turkey's state security force members are composed of soldiers, police officers and village guards. Crisis Group uses press reports of funerals and official announcements by the Turkish Armed Forces to verify fatalities in this category. In addition to individuals killed in direct clashes with PKK militants, security force deaths include security officials targeted as such, but slain while off duty. Crisis Group does not count traffic accidents, suicides or other non-conflict fatalities unless they are explicitly linked to security operations.

Civilian deaths are checked by Crisis Group via reports in Turkish-language press, as well as by reports from local human rights groups, including the Turkish Human Rights Foundation (TIHV) which has a strong track record as dependable sources of named fatalities.

Those fatality claims are subsequently confirmed by Crisis Group, which considers an individual a civilian if they can be affirmed as non-combatants by press reports or other sources, if their age or other factors made their participation in armed hostilities unlikely, or/and if they died outside an active conflict zone.

The line between civilian and combatant has been blurred by the emergence of plainclothes PKK youth militias in urban areas throughout the south east, in particular between December 2015-June 2016. As a result, some individuals could not be positively identified as civilians, though they also remain unclaimed by the PKK or its affiliates. Crisis Group classifies  individuals between the ages of 16 and 35 killed in areas of armed clashes and not identifiable as either civilians or combatants as “individuals of unknown affiliation”.

Militants are identified through reports from the Turkish language press or from media outlets directly affiliated with the People's Defense Force (HPG) -- the most active military wing of the PKK in Turkey; the Civil Protection Units (YPS); and the Kurdistan Freedom Falcons (TAK) -- the PKK affiliate (considered an “offshoot with no operational ties to the PKK” by some researchers), all of which release names and biographies of killed militants.

Confirmation of militant deaths is limited by the PKK's practice, the reasons for which are unknown, to sometimes announce the names of dead militants weeks, months, or even years after they are killed, adding a delay to the PKK militant fatality count.

Turkish officials claim that over 10,000 PKK militants were “neutralised” since July 2015. Crisis Group only counts fatalities which can be confirmed through its open-source methodology, and its numbers should not be seen as a refutation of fatality claims made by the Turkish government.

The exact day of death cannot be established for over 100 confirmed fatalities, including civilians, “individuals of unknown affiliation” and PKK militants. These individuals overwhelmingly died in urban areas under prolonged curfews or in remote mountainous regions, and only the week or month of their deaths can be identified by Crisis Group. In the Crisis Group database, their names are added to the last day of each identified week or month.

Crisis Group classified as seasoned those PKK militants the HPG announced as “commanders” or attributed substantial battlefield roles to (ie, leading a group of militants in the battlefield, being responsible for operations in a certain location). Where available, data for seasoned militants was cross-checked with militants’ date of joining, age and whether they were classified as “senior” in Turkish-language news. Militant fatalities announced as senior by the Turkish military, but not classified as such by the HPG were not included.