Circular Error ProbableADDPMP693
In the military science of ballistics, circular error probable (CEP) is a measure of a weapon system’s precision. It is defined as the radius of a circle, centred on the mean, whose perimeter is expected to include the landing points of 50% of the rounds. That is, if a given munitions design has a CEP of 100m when 100 munitions are targeted at the same point, 50 will fall within a circle with a radius of 100m (328ft) around their average impact point, the distance between the target point and the average impact point being referred to as bias. The concept of CEP also plays a role when measuring the accuracy of a position obtained by a navigation system, such as GPS.