A New Approach for Finding Dominant Feedback Loops: Loop By Loop Simulation for Tracking Feedback Loop Gains

Abstract

Traditionally, feedback loops have been analyzed in two ways. First, as in causal loop analysis, the positive or negative relationships between variables are summed up to judge the polarity of feedback loops. This approach can be said as a qualitative method. Second approach for analyzing feedback loops are analytic methods mainly developed for dealing with linear models. For the problems of understanding the behavior of feedback loops, the qualitative methods and analytic approaches give little help to modellers. In this paper, third approach for understanding the behavior of feedback loops are suggested. That is a loop by loop simulation method for tracing the feedback loop gains. First parts of this paper explain the concept of feedback loop gain and the loop simulation method. Second parts of this paper experiment the loop simulation method with two S.D. models; the commodity cycle model which shows equilibrium forces and the two shower model which shows fluctuating system behaviors without external shocks. Last parts of this paper discuss about the dangers of understanding S.D. model with qualitative analysis of causal loops and raise a question on the way of interpreting cyclic or chaotic behavior as shifts in dominant feedback loops.