D-4500-3 1System Dynamics in Education ProjectRoad MapsA Guide to Learning System Dynamics2 A Guide to Learning System Dynamics D-4500-3Road MapsSystem Dynamics in Education ProjectSystem Dynamics GroupSloan School of ManagementMassachusetts Institute of TechnologyAugust 21, 1992Latest Revision October 5, 1996Copyright © 1994 by MITPermission granted to copy for non-commercial educational purposesMacintosh is a registered trademark of Apple Computer, Inc.Compiled under the direction of Professor Jay W. ForresterD-4500-3 Road Maps 3Welcome to Road Maps!Many books and thousands of papers cover the field ofsystem dynamics. With all of these resources available, it isdifficult to know where to begin learning about systemdynamics. The System Dynamics in Education Project at MITis putting together Road Maps to help sort through this vastlibrary of books and papers. Road Maps is a series of self-study guides that use modeling exercises and selected literatureto provide a resource for learning about the principles andpractices of system dynamics. In its present form, Road Mapsis not meant to be a teaching curriculum for classroom use.The Spiral Learning ApproachA new concept is usually not fully mastered after reading about it onlyonce. Also, learning usually involves building one’s understanding up from onelevel to a higher level. For this reason, Road Maps utilizes a spiral learningapproach, in which each new concept isrepeatedly reinforced in successivechapters. This repetition moves upwardalong a spiral as more advanced conceptsbuild upon basic ones.In constructing this spiral, RoadMaps has been divided into chapters.The end of each chapter marks thecompletion of a particular subset ofconcepts, with the next chapter buildingon the material just learned. Eachchapter comes as a separate document sothe reader can request them as needed.OrganizationThe Road Maps series begins with Road Maps One, which introduces theconcepts of causal loops and circular feedback in systems. In addition, some ofthe applications and history of system dynamics are presented.4 A Guide to Learning System Dynamics D-4500-3Road Maps Two takes you through your first system dynamics model,and introduces computer simulation and the concept and methods of graphicalintegration. Two basic elements of system dynamics models, the stock and flow,are presented. You will need a computer and STELLA software for this andsubsequent chapters of Road Maps.Road Maps Three presents two of the most common structures in systemdynamics: the first-order positive and negative feedback loops. Systemsexhibiting exponential growth and decay are examined, and the idea of loopdominance in systems is introducedRoad Maps Four introduces generic structures and discusses the use ofcomputer simulation games in teaching system dynamics. After playing the FishBanks game, you will construct a model of the scenario and learn about thetragedy of the commons. Using your computer model, you will simulate andanalyze several policies for this system.Road Maps Five probes the structure of system dynamics models,emphasizing some important features that you may not have noticed, and explainsthe spread of an epidemic. Road Maps Five also introduces testing for modelvalidity in the system dynamics context. How do you know that your model is agood representation of the real system?In Road Maps Six, the dynamics of economic supply and demand areexplored and more modeling exercises are provided. Also, oscillatory systemsare used to show the transferability of structures. More modeling exercisessharpen your modeling skills and develop intuition about systems.Road Maps discusses the principles and characteristics of systems, exploresthe interrelationship between structure and behavior of dynamic models, providesguidelines for good modeling practice, and discusses the applications of systemdynamics. From Road Maps One on, the spiral of learning returns to theseprimary areas several times by introducing more advanced material whilebuilding on fundamental concepts. After completing Road Maps, you should havea strong working knowledge of system dynamics, have developed intuition aboutthe fundamental principles of systems and be ready to explore the application ofsystem dynamics in any area of interest.D-4500-3 Road Maps 5How to Use Road MapsFirst, you need to determine where you should begin in Road Maps. Somereaders have had more background in system dynamics than others. Thisintroduction should help you find a good starting point in Road Maps.Road Maps explores several topics in system dynamics through selectedreadings and exercises. Before each reading or exercise is a short description ofthe reading and its most important ideas. After each reading or exercise, wehighlight the main ideas before moving on.Each chapter in Road Maps contains readings that introduce and strengthensome of the basic concepts of system dynamics. Other readings focus onpracticing the acquired skills through various exercises or simulation games.Most of the chapters conclude with a prominent paper from the literature in thesystem dynamics field.We present the fundamental concepts of system dynamics as SystemPrinciples in Road Maps. These principles are enclosed in boxes that highlightthem from the rest of the text to emphasize their importance. The progression ofsystem principles in Road Maps allows you to revisit each principle several times.Each time a principle is revised in Road Maps, you will build upon your previousunderstanding of the principle by learning something new about the principle.The system principles are the core of Road Maps around which the readings,exercises, and papers are built.As part of the spiral learning approach that we use in Road Maps, manyconcepts will be briefly introduced early on and then explained later in greaterdetail. Road Maps contains a number of series of papers that are spread out oversuccessive chapters. Each of these series focuses on a specific topic in systemdynamics or the developing of a particular skill. The series start out with asimple paper, and progress to further develop the idea in subsequent chapters.Things You’ll Need for Road MapsSTELLA II SoftwareIn order to complete Road Maps Two and subsequent Road Maps, you willneed to have access to STELLA II. STELLA II is currently available for bothMacintosh and Windows, but the Road Maps guides and most of the readings and6 A Guide to Learning System