Abstract for:Understanding Model Behavior Using Loops That Matter

The link between structure and behavior is central to System Dynamics, but effective tools for understanding that relationship still elude us. The current state of the art in the field of loop dominance analysis relies on either practitioner intuition and experience or complex algorithmic analysis in the general forms of eigenvalue analysis or pathway participation metrics.  This paper presents a new and distinct method to find the 'loops that matter' in generating model behavior. This is a numeric method capable of determining the loop impact of each and every loop across the entire model.  The method is derived via logical demonstrations and empirical evaluation.  Forrester's 1968 market growth model is analyzed, shedding new light on the current understanding of this model and pointing to key insights that have not been adequately brought out in past analyses.  In addition to explaining behavior, the method show promise for improving model visualization and aggregation.