Road Maps

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Road Maps 6

Welcome to Road Maps Six!
Road Maps is a self-study guide to learning the
principies and practice of system dynamics. Road Maps Six
is the sixth in the series of chapters in Road Maps. Road
Maps One through T hree g ave you a broad introduction to
the field of systern dynarnics, focusing on understanding the
structure and behavior of systems through positive andnegative feedback loops. Road Maps Four introduced generic
( or t ransferable) structures, and gave you ataste of policy
analysis using the Fish Banks model. Road Maps Five introduced the use of
delays in cornputer rnodels, explained the transferable structures causing S-shaped
growth, looked at the spread of an epidernic, and s tarted exploring model
validity.
In Road Maps Six, you willbe able to apply your skills to rnodeling
economic supply and dernand. We introduce a transferable structure that
produces oscillation, with two real-life oscillating systerns presented as examples,
and we develop the study of generic structures producing S-shaped prowth. Road
Maps Six a lso p rovides e xercises that allow you to c reate y our own models f rom
given information. Finally,Systenis thinking: critical thinking s killsfor the
1990s und beyond f ocuses on addressing current global problems using critical
thinking skills acquired through systerns thinking.

Topics Covered i i Road Maps Six
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S ystem Dynamics in Economics
Economics Supply and Demand (D-4388)
by Kamil Msefer and Joseph Whelan
T ransferability of Structures
Generic Structures in Oscillating Systems /(D-4426- 1 )
by Celeste Chung

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A Cuide to Leaming System Dynamics

Rxploring S-Shaped Groivth (D-4476)
by Leslie Martin
b

M odeling Exercises
Modeling Exercises: Section 1 (D-4421)
by Joseph Whelan
Critica1 T hinking Skills
Systems thinking: critical thinking skills for the 1990s and beyond ( D4565)
by B arry R ichmond

Things You'll Need for Road Maps Six

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M odelingSoftware
In order to complete Road Maps Six and subsequent Road Maps, you will
need to h ave access to modeling software. The Road Maps guides and most
1
papers included in Road Maps were wntten with the use of STELLA 1 f or the
Macintosh. STELLA 11 i s c urrently available for both the Macintosh and the
Windows p latfonns. If you h ave a ny questions about STELLA, contact High
PerformanceSystems (see Appendix). Ask about p rices f or educational use.
Vensim, Powersim, and DYNAMO are other software progranis d esigned
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 m ore information
about obtaining Vensim andPowersim.

A C omputer
T o 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 M B hard disk and System 7.1 or higher. T o riin S TELLA
5.0 for Windows you will need an IBM PC-compatible computer with a 486-class
p rocessor running Windows 3 .1 o r 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.

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Road Maps 6

5

In either case, if you plan on coritinuing t o m odel, it may be a good idea to
h ave a ccess to a computer with more memory, h ard disk space and a faster
p rocesaor.

H ow to Use Road Maps Six
Road Maps Five explores several t opics in systemdynarnics 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 i deas before moving on.
Each chapter in Road Maps contains readings that introduce and strengthen
s ome of the basic concepts of system dynamics. Other readings f ocus o n
practicing the...