Inadequacy of Cost Per “Kill” as Measure of Effectiveness

Abstract

Cost per enemy “kill” is a commonly used measure for determining the relative worth of competitive components for a defense system. If the defense system components are employed in such a manner that they do not affect each other, this measure of effectiveness appears to be suitable for many situations. If there are interactions among the components of a defense system, however, a comparison based on cost per enemy “kill” which is not obtained from consideration of the over-all defense system can be misleading. This paper presents an analysis which indicates that such misleading situations often exist. To perform this analysis, a somewhat simplified mathematical model is developed to represent the actions and outcomes of an enemy attack against a defense system. The mathematical model permits partial analytical treatment of moderately complicated attack-defense situations and may be useful in many types of military operations-research work.