A Portfolio-Analysis Tool for Missile Defense (PAT-MD)

This report documents the underlying methodology of RAND’s Portfolio-Analysis Tool for Missile Defense (PAT-MD), an analytic tool developed to facilitate high-level discussion of program tradeoffs and adjustments in the Missile Defense Agency (MDA). PAT-MD provides summary portfolio-style characterizations of alternative investment options, including projected capabilities in different missions, the balance of emphasis across missions, the managing of risks, and economic considerations such as relative cost-effectiveness. PAT-MD and a companion tool, RAND’s Capabilities Analysis Model for Missile Defense (CAMMD), make it possible to “zoom” to higher levels of detail in order to understand the basis of high-level characterizations and how they would change if assumptions or priorities were changed. PAT-MD provides five scoring and aggregation methods that correspond mathematically to alternative aggregation functions. The appropriate method — e.g., simple linear weighted sums or nonlinear methods that enforce the concept that a system with several critical components will fail if any of its critical components fail — depends on the analysis and context. Significantly, PAT-MD also provides a straightforward way to test sensitivity to goals and thresholds in order to ensure that results are not unduly sensitive to arbitrary assumptions. The report also serves as a user’s guide to PAT-MD.