Rethinking the Hierarchy of Analytic Models and Simulations for Conflicts

F or decades, analysts within the defense community have categorized their analytic models and simulations for decision support through a hierarchy expressed in terms of resolution. The hierarchy is usually depicted as a pyramid that has levels of ‘‘engineering and physics,’’ ‘‘engagement,’’ and ‘‘mission,’’ to the most aggregate level of ‘‘campaign’’ models. In this article, we accomplish three enhancements. First, we document the importance of applying a hierarchy of models and simulations, which some have questioned because of increased computer speed. Second, we list factors to consider in describing a model or simulation’s resolution, which we hope aids interfacing model results and calibrating across levels. Third, we propose expanding the hierarchy to include two more levels beyond campaign to include levels of ‘‘defense enterprise’’ and ‘‘government, nongovernment, and coalition instruments of power.’’ We use these levels to categorize models constructed to aid decisions requiring evaluations beyond a single campaign’s results. The growing emphasis on disparate coalition operations along with the increasing interplay of broader government and nongovernmental capabilities points to a need to extend this traditional hierarchy. We propose refining the hierarchy to depict both model and simulation breadth (scope) and depth (resolution) along with our recommended two additional levels of abstraction.