Tracking the declines in ISIS oil production
Oil has been a key revenue source for ISIS, yet new data shows that production has steadily declined in areas under the group's control.
Historically, it has been difficult to get an accurate measure of ISIS's oil production. Past estimates extrapolated from chance observations at a small number of production sites — typically wherever journalists have had a source or intelligence documents have been seized. But that is like counting employees at a few McDonalds locations to draw conclusions about the number of workers across the fast food industry.