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Teaching Systems Thinking in Spreadsheets

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Teaching Systems Thinking in Spreadsheets Powered By Docstoc
					Teaching Systems Thinking in Spreadsheets
Mohammad Mojtahedzadeh Attune Group, Inc

Deborah Upton Stonehill College

Thursday, April 29, 2004

1

Modeling Spectrum:

Exposé Spreadsheet

System Dynamics

Simple Manipulation
Build on Simple manipulation to arrive at Complex formulation
Thursday, April 29, 2004

Complex Formulation

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Modeling Spectrum:
Exposé
Spreadsheet

System Dynamics

Simple Manipulation
►Hidden ►Local ►One

Complex Formulation
►Visualization ►Global

relationships

of structure

in time and space

in time and space

way linkages Nonlinearity

►Circular

Causality ►Stock-and-Flow
►Data-Point

►Mathematical
Thursday, April 29, 2004

Nonlinearity
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The Spreadsheet Approach:
Hidden relationships:

Thursday, April 29, 2004

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The Spreadsheet Approach:
Hidden relationships

Makes it difficult to understand, analyze and, communicate…

Thursday, April 29, 2004

5

Exposé in MS Excel:
Tree Diagrams of Precedence
make the connections among the CELLS visible

Thursday, April 29, 2004

6

The Spreadsheet Approach:
Local in Time and Space Working with numbers (not equations)  One relationship, one time period  No clear model boundaries

…. makes it easy to master! …. but inadequate for modeling complexity!

Thursday, April 29, 2004

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The Spreadsheet Approach:
Local in Time and Space 1000 – 95.26 = ?
Savings (Jan)
Purchases (Jan)

Thursday, April 29, 2004

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From cell reference formulas to equations
►Translate

cell reference formulas to equations:

Savings (t) = Savings (t - 1) - Purchases
February

$1,000

January

$95.26

►Reconstruct

the structure

Thursday, April 29, 2004

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Exposé in MS Excel:
Tree Diagrams of Causal Drivers
make the connections among the VARIABLES visible

Thursday, April 29, 2004

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Exposé in MS Excel
Two distinguished tree diagrams
Tree Diagrams of Precedence Tree Diagrams of Causal Drivers

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The Value Proposition:
Can we build on what people know?
Global (interconnected)
System Dynamics
Complex Issues

Local (isolated)
Thursday, April 29, 2004

Spreadsheet
Simple Issues

Short term

Long term
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The Value Proposition:
From Numbers to Equations and back again
Exposé allows the user to interact with Numbers and Equations any time in the process of modeling
Sometimes it might be easier to start with Numbers and then move to Equations

Thursday, April 29, 2004

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Example:

From Numbers to Equations and back again

Sometimes, wouldn’t be easier to start with…
1000 – 95.26 = ?
Savings (Jan)
Purchases (Jan)

Thursday, April 29, 2004

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Example:

From Numbers to Equations and back again

….. in order to arrive at…..?

Savings = Integ( purchases, 1000)

Thursday, April 29, 2004

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The Spreadsheet Approach:
One way linkages:

Lack of focus on integration point and feedback processes makes spreadsheets inadequate to model dynamic systems

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Exposé in MS Excel
Make integration points visible

Launch Exposé with Examples from the book

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Exposé in MS Excel
Circular Causality
Identify and work with feedback processes

Launch Exposé with Examples from the book
Thursday, April 29, 2004 18

Exposé in MS Excel
Allows data-point non-linearity

Launch Exposé with the MARKET GROWTH MODEL

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Exposé in MS Excel
Do “what if” analysis more often

Launch Exposé perhaps with Market growth model

Thursday, April 29, 2004

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Not The End…. Just The Beginning…

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