FACTOID # 15: A mere 0.8% of West Virginians were born in a foreign country.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > System dynamics

System dynamics is an approach to understanding the behaviour of complex systems over time. It deals with internal feedback loops and time delays that affect the behaviour of the entire system.[1] What makes using system dynamics different from other approaches to studying complex systems is the use of feedback loops and stocks and flows. These elements help describe how even seemingly simple systems display baffling nonlinearity. There are many definitions of complexity, therefore many natural, artificial and abstract objects or networks can be considered to be complex systems, and their study (complexity science) is highly interdisciplinary. ... It has been suggested that this article or section be merged with Feedback loop. ... A stock in business and social accounting refers to the value of an asset at a balance date (or point in time), while a flow refers to the total value of transactions (sales or purchases) during an accounting period. ... In mathematics, a nonlinear system is one whose behavior cant be expressed as a sum of the behaviors of its parts (or of their multiples. ...

Contents

Overview

Systems dynamics is an aspect of systems theory as a method for understanding the dynamic behavior of complex systems. The basis of the method is the recognition that the structure of any system — the many circular, interlocking, sometimes time-delayed relationships among its components — is often just as important in determining its behavior as the individual components themselves. Examples are chaos theory and social dynamics. It is also claimed that, because there are often properties-of-the-whole which cannot be found among the properties-of-the-elements, in some cases the behavior of the whole cannot be explained in terms of the behavior of the parts. An example is the properties of these letters which when considered together can give rise to meaning which does not exist in the letters by themselves. This further explains the integration of tools, like language, as a more parsimonious process in the human application of easiest path adaptability through interconnected systems. Systems theory is an interdisciplinary field of science. ... For other uses, see Chaos Theory (disambiguation). ... Social dynamics means the ability of a society to react to inner and outer changes and deals with its regulation mechanisms. ... Look up integration in Wiktionary, the free dictionary. ... Parsimonious adj. ... Illustration of a physical process: a geyser in action. Process (lat. ... For other uses, see Adaptation (disambiguation). ...


History

System Dynamics was founded in the late 1950s by Jay W. Forrester of the MIT Sloan School of Management with the establishment of the MIT System Dynamics Group. At that time, he began applying what he had learned about systems during his work in electrical engineering to everyday kinds of systems. The 1950s decade refers to the years 1950 to 1959 inclusive. ... Jay Wright Forrester (born 14 July 1918 Climax, Nebraska) is an American pioneer of computer engineering. ... The MIT Sloan School of Management is one of the five schools of the Massachusetts Institute of Technology, located in Cambridge, Massachusetts, USA. It is one of the worlds leading business schools, conducting research and teaching in finance, entrepreneurship, marketing, strategic management, economics, organizational behavior, operations management, supply chain... Electrical Engineers design power systems… … and complex electronic circuits. ...


Determining the exact date of the founding of the field of system dynamics is difficult and involves a certain degree of arbitrariness. Jay W. Forrester joined the faculty of the Sloan School at MIT in 1956, where he then developed what is now System Dynamics. The first published article by Jay W. Forrester in the Harvard Business Review on "Industrial Dynamics", was published in 1958. Year 1956 (MCMLVI) was a leap year starting on Sunday (link will display full calendar) of the Gregorian calendar. ...


The members of System Dynamics Society have chosen 1957 to mark the occasion as it is the year in which the work leading to that article, which described the dynamics of a manufacturing supply chain, was done. Year 1957 (MCMLVII) was a common year starting on Tuesday (link displays the 1957 Gregorian calendar). ...


Topics in systems dynamics

The elements of system dynamics diagrams are feedback, accumulation of flows into stocks and time delays.


To illustrate the use of system dynamics, imagine an organisation that plans to introduce an innovative new durable consumer product. The organisation needs to understand the possible market dynamics, in order to design marketing plans and production plans.


Causal loop diagrams

Main article: Causal loop diagram

A causal loop diagram is a visual representation of the feedback loops in a system. The causal loop diagram of the new product introduction may look as follows: A causal loop diagram(CLD) is a diagram that aids in visualizing how interrelated variables affect one another. ...

Causal loop diagram of new product adoption

There are two feedback loops in this diagram. The positive reinforcement (labeled R) loop on the right indicates that the more people have already adopted the new product, the stronger the word-of-mouth impact. There will be more references to the product, more demonstrations, and more reviews. This positive feedback should generate sales that continue to grow. Image File history File links Adoption_CLD.gif‎ Causal loop diagram of adoption, used to demontrate systems dynamics. ...


The second feedback loop on the left is negative reinforcement (or "balancing" and hence labeled B). Clearly growth can not continue forever, because as more and more people adopt, there remain fewer and fewer potential adopters.


Both feedback loops act simultaneously, but at different times they may have different strengths. Thus one would expect growing sales in the initial years, and then declining sales in the later years.


Stock and flow diagrams

Main article: Stock and flow

The next step is to create what is termed a stock and flow diagram. A stock is the term for any entity that accumulates or depletes over time. A flow is the rate of change in a stock. A stock in business and social accounting refers to the value of an asset at a balance date (or point in time), while a flow refers to the total value of transactions (sales or purchases) during an accounting period. ... A stock in business and social accounting refers to the value of an asset at a balance date (or point in time), while a flow refers to the total value of transactions (sales or purchases) during an accounting period. ...

A flow changes the rate of accumulation of the stock

In our example, there are two stocks: Potential adopters and Adopters. There is one flow: New adopters. For every new adopter, the stock of potential adopters declines by one, and the stock of adopters increases by one. Image File history File links Simple_stock_and_flow_diagram. ...

Stock and flow diagram of new product adoption

Image File history File links Adoption_SFD.gif‎ Stock and flow diagram of adoption Diagram created by contributor, from article by John Sterman (2001) Systems dynamics modeling: tools for learning in a complex world, California management review, Vol 43 no 1, Summer 2001 Permission is granted to copy, distribute and/or...

Equations

The real power of system dynamics is utilised through simulation. Although it is possible to perform the modeling in a spreadsheet, there is a variety of software packages that have been optimised for this. A spreadsheet is a rectangular table (or grid) of information, often financial information. ...


The steps involved in a simulation are:

  • Define the problem boundary
  • Identify the most important stocks and flows that change these stock levels
  • Identify sources of information that impact the flows
  • Identify the main feedback loops
  • Draw a causal loop diagram that links the stocks, flows and sources of information
  • Write the equations that determine the flows
  • Estimate the parameters and initial conditions. These can be estimated using statistical methods, expert opinion, market research data or other relevant sources of information.[2]
  • Simulate the model and analyse results

The equations for the causal loop example are:

  Adopters = int_{0} ^{t} mbox{New adopters },dt   mbox{Potential adopters} = int_{0} ^{t} mbox{-New adopters },dt   mbox{New adopters}=mbox{Innovators}+mbox{Imitators}   mbox{Innovators}=p cdot mbox{Potential adopters}   mbox{Imitators}=q cdot mbox{Adopters} cdot mbox{Probability that contact has not yet adopted}   mbox{Probability that contact has not yet adopted}=frac{mbox{Potential adopters}}{mbox{Potential adopters } + mbox{ Adopters}}   p=0.03   q=0.4  

Simulation results

The simulation results show that the behaviour of the system would be to have growth in adopters that follows a classical s-curve shape. The increase in adopters is very slow initially, then exponential growth for a period, followed ultimately by saturation.

Simulation results of new product adoption

Image File history File links Adoption_simulation_results. ...

Application

System dynamics has found application in a wide range of areas, for example population, ecological and economic systems, which usually interact strongly with each other. For the journal, see Ecology (journal). ... ‹ The template below is being considered for deletion. ...


System dynamics have various "back of the envelope" management applications. They are a potent tool to:

  • Teach system thinking reflexes to persons being coached
  • Analyze and compare assumptions and mental models about the way things work
  • Gain qualitative insight into the workings of a system or the consequences of a decision
  • Recognize archetypes of dysfunctional systems in everyday practice

Computer software is used to simulate a system dynamics model of the situation being studied. Running "what if" simulations to test certain policies on such a model can greatly aid in understanding how the system changes over time. System dynamics is very similar to systems thinking and constructs the same causal loop diagrams of systems with feedback. However, system dynamics typically goes further and utilises simulation to study the behaviour of systems and the impact of alternative policies.[3] Systems thinking is an approach to integration that is based on the belief that the component parts of a system will act differently when isolated from the systems environment or other parts of the system. ... A kind of internal symbol or representation of external reality, hypothesised to play a major part in cognition. ... It has been suggested that simulation software be merged into this article or section. ... An abstract model (or conceptual model) is a theoretical construct that represents something, with a set of variables and a set of logical and quantitative relationships between them. ... Systems thinking is an approach to integration that is based on the belief that the component parts of a system will act differently when isolated from the systems environment or other parts of the system. ... A causal loop diagram(CLD) is a diagram that aids in visualizing how interrelated variables affect one another. ...


See also

Systems theory is an interdisciplinary field of science. ... Systems thinking is an approach to integration that is based on the belief that the component parts of a system will act differently when isolated from the systems environment or other parts of the system. ... A causal loop diagram(CLD) is a diagram that aids in visualizing how interrelated variables affect one another. ... The current version of the article or section reads like an advertisement. ... Leverage Point Modeling (LPM) is a demonstrated approach for improved planning and spending for Operations and Support (O&S) activities. ... The concept of wicked problems was originally proposed by H. J. Rittel (a pioneering theorist of design and planning, and late professor at the University of California, Berkeley) and M. Webber (1) in a seminal treatise for social planning. ... The World3 model was a computer simulation of interactions between population, industrial growth, food production and limits in the ecosystems of the Earth. ...

References

  1. ^ http://sysdyn.clexchange.org
  2. ^ Sterman, John D. (2001). "System dynamics modeling: Tools for learning in a complex world". California management review 43 (1): 8-25. 
  3. ^ http://www.albany.edu/cpr/sds/

John Sterman is the Jay W. Forrester Professor of Management, and the current director of the MIT System Dynamics Group. ...

Literature

John Sterman is the Jay W. Forrester Professor of Management, and the current director of the MIT System Dynamics Group. ... Business dynamics is system dynamics as applied to business. ... Donella Dana Meadows (March 13, 1941 Elgin, Illinois, USA - February 20, 2001, New Hampshire) was a pioneering environmental scientist, a teacher and writer. ... Limits to Growth was a 1972 book modeling the consequences of a rapidly growing world population and finite resource supplies, commissioned by the Club of Rome. ... Peter Michael Senge was the Director of the Center for Organizational Learning at the MIT Sloan School of Management, and is presently (2005) on the faculty at MIT. He is the founding chair of the Society for Organizational Learning (SoL). ... The Fifth Discipline: The Art and Practice of the Learning Organization is a book by Peter Senge (a senior lecturer at MIT) focusing on group problem solving using the systems thinking method in order to convert companies into learning organizations. ... Jay Wright Forrester (born 14 July 1918 Climax, Nebraska) is an American pioneer of computer engineering. ...

External links

Organisations

Articles

Software

  • AnyLogic
  • Powersim Studio
  • CONSIDEO
  • Vensim
  • Stella and iThink
  • MapSys
  • Simile
  • GoldSim

  Results from FactBites:
 
Dynamical system - Wikipedia, the free encyclopedia (3731 words)
Linear dynamical systems and systems that have two numbers describing a state are examples of dynamical systems where the possible classes of orbits are understood.
The Poincaré recurrence theorem was used by Zermelo to object to Boltzmann's derivation of the increase in entropy in a dynamical system of colliding atoms.
Hyperbolic systems are precisely defined dynamical systems that exhibit the properties ascribed to chaotic systems.
Measure-preserving dynamical system - Wikipedia, the free encyclopedia (540 words)
In mathematics, a measure-preserving dynamical system is an object of study in the abstract formulation of ergodic theory.
A measure-preserving dynamical system is defined as a probability space and a measure-preserving transformation on it.
The set of symbolic names with respect to a partition is called the symbolic dynamics of the dynamical system.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m