Generic Structures First-Order Negative Feedback

D-4475-2 195. Summary of important characteristicsStructure:The loop is a negative feedback loop if the flow is specified as an outflow in themodel and the draining fraction is positive (or if the draining fraction is negative and theflow is specified as an inflow in the model). 4Behavior:Figure 10 contains a summary of the behaviors that the negative feedback loop canexhibit. Although negative feedback loops are best known for their exponential decay,they do exhibit other behaviors.The generic structure of a first-order negative loop can exhibit three types ofbehaviors: asymptotic decay to equilibrium, constant at equilibrium, and asymptoticgrowth to equilibrium. All three types of behavior are goal-seeking.The behavior of the stock is in italicsfor each combination of parametervalues.Stock(assume goal = 0)Negative Zero PositiveZeroequilibrium atequilibrium atequilibrium atDrainingneg. valuezeropos. valueFractionasymptoticasymptoticPositivegrowth toequilibrium atdecay toequilibriumzeroequilibriumFigure 10. Summary of the behavior of a negative feedback loop