James Fearon, a scholar of civil wars at Stanford University, defines a civil war as "a violent conflict within a country fought by organized groups that aim to take power at the center or in a region, or to change government policies". Ann Hironaka further specifies that one side of a civil war is the state. The intensity at which a civil disturbance becomes a civil war is contested by academics. Some political scientists define a civil war as having more than 1,000 casualties, while others further specify that at least 100 must come from each side. The Correlates of War, a dataset widely used by scholars of conflict, classifies civil wars as having over 1000 war-related casualties per year of conflict. This rate is a small fraction of the millions killed in the Second Sudanese Civil War and Cambodian Civil War, for example, but excludes several highly publicized conflicts, such as The Troubles of Northern Ireland and the struggle of the African National Congress in Apartheid-era South Africa.