The concepts evaluation model (CEM) is a computer simulation model of ground and air warfare operations that is used by the U.S. Army Concepts Analysis Agency (CAA) to conduct analysis of the capabilities and requirements of forces engaged in warfare at theater level. The CEM has been applied to campaign analyses for numerous scenarios since the early 1970s. including Central Europe, Korea, Iran, and Iraq theaters of operation. The standard CEM is fully automated and deterministic, yielding a single outcome for any situation simulated, providing no confidence intervals, range, nor distribution of possible outcomes. Modern, faster computers have now reduced CEM execution time to a level that makes multiple replications of the CEM feasible. In this project a stochastic version of the CEM has been developed that makes use of individual replications of stochastic attrition input data, rather than averaged sample data. and that simulates commanders' decisions. the disposition of casualties and of combat-damaged vehicles, and certain other functions based on statistical distributions rather than on expected values. This article reports the methodology and results of an analysis of this stochastic version of CEM. indicating which stochastic features most influenced the variability among replications of one simulated campaign and outlining costs and benefits of using a stochastic version of the CEM 0 1995 John Wiley & Sons, Inc.*
1. BACKGROUND
A principal mission of the U.S. Army Concepts Analysis Agency (CAA) is to conduct analysis of the capabilities and requirements of forces engaged in warfare at theater level. The concepts evaluation model (CEM), described in Reference [l], is a computer simulation model of ground and air warfare at theater level that is frequently used at C A A to address this mission. CEM has been applied to campaign analyses of numerous scenarios since the early 1970s, including Central Europe, Korea, Iran, and Iraq theaters of operation. CEM aggregates conventional warfare results as a series of 4-day theater cycles. Decision processes are simulated at theater, army/front, corps, and division command levels. Four types of terrain, 51 types of weapons per side, arrivals of maneuver and artillery and maneuver units, weapon and personnel replacements, ammunition resupply, repair of damaged vehicles, and medical support are represented. CEM accepts unit composition data in terms of brigades on the Blue side and divisions on the Red side, requires a continuous forward edge of the battle area (FEBA), and assesses attrition and movement in combat engagements between Blue brigades and Red divisions over 12-hour time increments. CEM extrapolates from the combat engagement data produced by the combat sample generator (COSAGE) to determine attrition and ammunition expenditures. Outcome measures reported by CEM include location and posture of maneuver forces. losses of weapons and personnel, and resource expenditures. CEM is