top of page

System Dynamics Glossary

This is the System Dynamics Glossary compiled by David N. Ford and Accepted by Yaman Barlas. It was published on November 7th 2019 here: https://doi.org/10.1002/sdr.1641.

​

Introduction

As a narrowly focused dictionary, this glossary defines commonly used terms that are central to traditional system dynamics and some more general terms that have special meanings or particular importance within system dynamics. General terms that have no special meanings in system dynamics, application‐specific terms, and software‐specific terms are not included. The reader is referred to the relevant literature for those definitions, as well as detailed descriptions, explanations, and examples of the terms included here.

​

Click on the Concept to View the complete Description.

Concept
Description
Controlling feedback loop
See balancing feedback loop.
Conveyor
A type of stock that represents a space into which material flows and stays for a fixed period of time, then exits. Its parameter determines transit time—how long material stays in the conveyor. Material that flows in at a given time is not mixed with material that flowed in earlier—a quantity that enters at t will flow out exactly at t + transit time. Also called a pipeline delay.
Counterintuitive behavior
When policies assuming a particular solution yield unexpected, surprising or paradoxical results that are very different from those intended or expected. Often, as troubles increase, well‐intentioned but flawed efforts are intensified, which reduce improvement or worsen the problem instead of improving the situation. See also policy resistance.
Co‐flow
A parallel stock‐and‐flow structure that mimics a primary stock‐and‐flow structure in which the co‐flow structure models an attribute or characteristic of the contents of the primary structure.
Cyclical behavior
See oscillation.
Dampening
A decrease in the magnitude of movements from an average value, typically in oscillations. Also a system response that is less than is seemingly implied by input variables.
Decision function
A policy statement that determines how information is used to generate actions for managing the system. Also the algorithm used to transform incoming information into a stream of decisions over time.
Delay
A phenomenon in which the effect of one variable on another does not occur immediately. A process by which the output lags behind its input in time.
Delta time
See solution interval.
Diffusion structure/behavior
A structure/behavior that describes the spread of products, ideas or beliefs, typically based on a model of new product adoption developed by Frank Bass.
Dimensional analysis
A procedure that checks for unit consistency in equations.
Disaggregation
The opposite of aggregation. Disaggregation is done to separate variables into components that do not have close enough effects on system behavior to be modeled with a single variable.

References

bottom of page