CPH Exam: Definitions - Systems Thinking and Informatics

Accumulation - correct answer The collection of some quantity over time. Examples of accumulation include water in a bathtub, savings in a bank account, inventory . In the STELLA modeling software, the accumulator is also referred to as a Stock or Level. Aggregation - correct answer The incorporation of numerous distinct system components into one variable . Aggregation is done for simplicity when combination generates the same behavior of interest as representing the components separately. Amplification - correct answer A system response that is greater than is seemingly implied by input causes. Amplification occurs in information-feedback systems when policies adjust levels to values that change with varying flow rates. It is associated with delays , order/inventory processes, forecasting, etc. Asymptotic growth/decay - correct answer Goal-seeking behavior produced by negative feedback . The stock of the system moves towards the goal, slowing down as it approaches the goal. Auxiliary equation/variable - correct answer An equation that takes the present value of variables (levels, constants, or other auxiliary variables) to compute the present value of an auxiliary variable. Auxiliary variables are part of a rate equation connecting a level to a rate. Auxiliary equations embody unit consistency and are symbolized by a circle in a flow equation. Balancing loop - correct answer A loop that seeks equilibrium — it tries to bring stocks to a desired state and keep them there. It limits and constrains, and is also called a negative loop . When a balancing process has a long delay, the response may overcorrect, often leading to instability, the opposite of what is intended.