What does Circular Error Probable (CEP) measure?

Circular Error Probable (CEP) is a statistical measure that quantifies the accuracy of a weapon system, specifically how close a projectile impacts to a desired target point. It represents the radius of a circle, centered on the mean point of impact, in which a certain percentage (commonly 50%) of the impacts are expected to fall. In other words, it indicates the mean distance from the desired point of impact, reflecting the precision of the aiming and firing process.

While grouping of shots on a target can provide insight into the performance of a firearm, it does not directly define the CEP, which focuses on the probability distribution of impact points. The total rounds fired pertains to how many shots were taken but does not contribute to calculating the accuracy in terms of distance from the target. Similarly, evaluating the accuracy of a firearm under varying conditions involves broader factors that extend beyond just the circular error probable, encompassing environmental influences and weapon handling variables. Thus, the correct answer captures the essence of CEP as a measurement of precision relative to a target.