D-4505-6 1 Road Maps 5 A Guide to Learning System Dynamics System Dynamics in Education Project2 A Guide To Learning System Dynamics D-4505-6 Road Maps 5 System Dynamics in Education Project System Dynamics Group Sloan School of Management Massachusetts Institute of Technology August 21, 1992 Latest Revision March 18, 2001 Copyright © 2001 by MIT Permission granted to copy for non-commercial educational purposes STELLA, STELLA II and ithink are trademarks of High Performance Systems Macintosh is a trademark of Apple Computers, Inc. Compiled under the direction of Professor Jay W. Forrester3 D-4505-6 Road Maps 5 Welcome to Road Maps Five! Road Maps is a self-study guide to learning the principles and practice of system dynamics. Road Maps Five is the fifth in the series of chapters in Road Maps. Road Maps One through Three gave you a broad introduction to system dynamics and focused on the building blocks of models: positive and negative feedback loops. Road Maps Four continued to broaden your understanding by introducing generic structures, policy analysis, computer simulation games, and tragedy of the commons. In Road Maps Five you will explore and challenge the understanding of system dynamics that you have built in Road Maps One through Four. Specifically, Road Maps Five introduces the modeling of delays, mental simulation of S-shaped growth, generic structures producing S-shaped growth, the dynamics of the spread of an epidemic, and the concept of model validity. You will also practice and improve your graphical integration skills. At the end of Road Maps Five, we recommend that you read Beyond the Limits, an insightful book about the need for a transition to a sustainable world. Topics Covered in Road Maps Five An Introduction to Delays in Computer Modeling - Answers to Exercises for Chapter 17: Introduction To Delays from Introduction to Computer Simulation: A System Dynamics Modeling Approach (D-4415) by Kamil Msefer and Mark Choudhari Beginner Modeling Exercises - Beginner Modeling Exercises Section 5: Mental Simulation of Combining Feedbacks in First Order Systems (D-4593-1) by Laughton Stanley and Helen Zhu Transferability of Structures - Generic Structures: S-Shaped Growth I (D-4432) by Terri Duhon and Mark Glick4 A Guide To Learning System Dynamics D-4505-6 Model Validity - Dynamic Simulation Models: How Valid Are They? (D-4463) by Ray C. Shreckengost The Spread of an Epidemic: S-Shaped Growth - Teaching System Dynamics: Looking at Epidemics (D-4243) by Will Glass Graphical Integration Exercises - Graphical Integration Exercises Part 3: Combining Flows (D-4596) by Kevin Agatstein and Lucia Breierova Limits to Growth - Beyond the Limits by Donella Meadows, Dennis Meadows, Jorgen Randers Things You’ll Need for Road Maps Five Modeling Software In order to complete Road Maps Five and subsequent Road Maps, you will need to have access to modeling software. The Road Maps guides and most papers included in Road Maps were written with the use of STELLA II for the Macintosh. STELLA II is currently available for both the Macintosh and the Windows platforms. If you have any questions about STELLA, contact High Performance Systems (see Appendix). Ask about prices for educational use. Vensim, Powersim, and DYNAMO are other software programs designed for building system dynamics models. Vensim is produced by Ventana Systems, which offers a free introductory version of its software, Vensim PLE, that can be downloaded off the World Wide Web. See the Appendix for more information about obtaining Vensim and Powersim. Notice written June, 2000: We have written a guide on how to use Vensim modeling software for each section of the Road Maps series that involves computer modeling. Each guide is5 D-4505-6 Road Maps 5 located in the back of the exercise document. When Chapters 1-9 of the Road Maps series were written, STELLA software was the most common beginner modeling program available. Now you may choose from a number of system dynamics modeling software packages. If you would like more information on Vensim, please go to http://www.vensim.com. A free version called Vensim PLE is located there. For more detailed information on using Vensim software in the Road Maps series, please refer to the paper titled: “Vensim Guide (D-4856)” in the Appendix section at the end of Road Maps. From now on as additional papers for the Road Maps series are written, the Vensim software will be used exclusively for modeling exercises. A Computer To run the latest version of STELLA, STELLA 5.0, on a Macintosh, you will need an Apple Macintosh computer (68020 processor or higher) with at least 8 MB of RAM, a 12 MB hard disk and System 7.1 or higher. To run STELLA 5.0 for Windows you will need an IBM PC-compatible computer with a 486-class processor running Windows 3.1 or greater. You will need at least 8 MB RAM, a hard disk with a least 16 MB of free space. Previous versions of STELLA have similar requirements. In either case, if you plan on continuing to model, it may be a good idea to have access to a computer with more memory, hard disk space and a faster processor. Books You will need the following books for Road Maps Five. Introduction to Computer Simulation, by Nancy Roberts et al, was previously required. Please note that selected chapters from this book are available for download on the SDEP server in electronic format. Roberts, Nancy, 1983. Introduction to Computer Simulation. Portland, Oregon: Productivity Press, 562 pp. Meadows, Donella H., Dennis Meadows, J? rgen Randers, 1992. Beyond the Limits: Confronting Global Collapse, Envisioning a Sustainable Future. Post Mills, VT: Chelsea Green Publishing Co., 300 pp.6 A Guide To Learning System Dynamics D-4505-6 To order a copy of this book, contact Chelsea Green Publishing Co. (see Appendix). How to Use Road Maps Five Road Maps Five explores several topics in system dynamics through selected readings and exercises. Before each reading or exercise is a short description of the reading and its most important ideas. After each reading or exercise, we highlight the main ideas before moving on. Each chapter in Road Maps contains readings that introduce and strengthen some of the basic concepts of system dynamics. Other readings focus on practicing the acquired skills through various exercises or simulation games. Most of the chapters conclude with a prominent paper from the literature in the