It’s
Models
All
the
Way
Down
Jim
Hines
Ventana
Systems
Popula<on
=
INTEG(
net
birth
rate
,
10)
Units:
people
net
birth
rate
=
Popula<on
*
fer<lity
Units:
people
/
year
fer<lity
=
0.03
Units:
frac<on
/
year
a. Causal Loop Diagram
b. Stock and flow diagram
b. List of Equations
Population
44.80
people
36.10
27.40
18.70
10
0
5
10
15
20
25
30
Time (year)
35
40
45
d. Graph of behavior over time
50
Bounce
Pass
hRp://viscog.beckman.illinois.edu/flashmovie/15.php
Light
Bulbs
in
the
AYc
What
is
a
model?
hRp://www.rsc.org/educa<on/teachers/learnnet/pdf/learnnet/miscon3/
evidence.pdf
What’s
the
best
model?
What
Is
the
Goal
of
Teaching?
•  Prac<cal
–  Get
into
college
–  RI
wants
to
be
compe<<ve
•  Truth
–  We
want
our
students
to
get
the
things
that
they
(as
enlightened
people)
want.
–  We
want
to
make
our
students
smarter.
Let’s
Make
People
Smarter
•  “Na<ve
intelligence”
–  Size
of
working
memory
–  Speed
of
mental
manipula<on
•  BeRer
models
•  BeRer
modelers
Ozymandias
By
Percy
Bysshe
Shelley
(1792‐1822)
I
met
a
traveller
from
an
an<que
land,
Who
said
‐‐
"two
vast
and
trunkless
legs
of
stone
Stand
in
the
desert
...
near
them,
on
the
sand,
Half
sunk
a
shaRered
visage
lies,
whose
frown,
And
wrinkled
lips,
and
sneer
of
cold
command,
Tell
that
its
sculptor
well
those
passions
read
Which
yet
survive,
stamped
on
these
lifeless
things,
The
hand
that
mocked
them,
and
the
heart
that
fed;
And
on
the
pedestal
these
words
appear:
My
name
is
Ozymandias,
King
of
Kings,
Look
on
my
Works
ye
Mighty,
and
despair!
Nothing
beside
remains.
Round
the
decay
Of
that
colossal
Wreck,
boundless
and
bare
The
lone
and
level
sands
stretch
far
away."
‐‐
Models
and
Modeling
Languages
in
Business
Models
of
the
Company
Modeling
Languages
•  Management
hierarchy
•  Accoun<ng
•  Available
but
liRle
known
•  Natural
language
(English)
•  Lists
–  CAPM
–  Black
and
Scholes
–  Corporate
data
bases
–  Importance
–  Sequencing
•  2
x
2
Matrices
•  Arithme<c
•  Available
but
liRle
used
– 
– 
– 
– 
Probability/sta<s<cs
SD
Agent
based
Algebra
2X2
Matrix
.
Lowy,
Alex
and
Phil
Hood.
2004.
The
Power
of
2
X
2
Ma.rx.
Jossey‐Bass
a
Wiley
Impriny.
www.Josseybass.com
,
fig.
7.15
What’s
the
best
model?
Quick
and
Healthy
(Useful):
How
to
Compensate
Sales
Force
•  $
sales
(commission)
•  Unit
sales
•  New
customers
Healthy
(useful)
and
Delicious
If
someone
pulled
the
trigger,
then
the
gun
fired.
Someone
pulled
the
trigger.
But
the
gun
did
not
fire.
Ask
why
5
<mes
(Sakichi
Toyoda)
Richardson,
George.
1981.
Introduc.on
to
System
Dynamics
Modeling
with
DYNAMO.
Cambridge,
Ma:
MIT
Press.
Senge,
Peter.
1990.
The
FiOh
Discipline.
New
York:
Currency
Doubleday.
From
Morecros,
John.2007.
Strategic
Modelling
and
Business
Dynamics.
John
Wiley
&
Sons.
Sterman,
John.
2000.
Business
Dynamics.
Boston:
McGraw‐Hill.
Kinds
of
Things
in
the
World
(Abstract
Analogies)
English
SD
•  Nouns
(subjects
and
objects)
•  Verbs
•  Adjec<ves
•  Adverbs
•  Stocks
&
Flows
•  Feedback
loops
•  PaRerns
of
behavior
Probability
•  Events
•  Outcomes
•  Distribu<ons
How
to
handle
more
things
•  SD
– 
– 
– 
– 
– 
Aggrega<on
A
number
of
Stocks
and
flows
become
causal
loop
Causal
loop
(very
compact)
Several
causal
loops
becomes
a
dynamic
system
Con<nuity
(paRern)
•  Hierarchical
modeling
–  Aggrega<on
–  Hierarchy
Abduc<on
(sa<sfying)
Effect
Vehemence
Cause
Time
I
met
a
traveller
from
an
an<que
land,
Who
said
‐‐
"two
vast
and
trunkless
legs
of
stone
Stand
in
the
desert
...
near
them,
on
the
sand,
Half
sunk
a
shaRered
visage
lies
…
?
Feeling
of
loss
Feeling
of
humility
Abduc<on
(sa<sfying)
Effect
Vehemence
Cause
Time
Binomial Distribution
P(heads) = 0.5
?
Julia
is
in
Atlanta
or
Raphael
is
in
Tacoma,
or
both
Julia
is
in
SeaRle
or
Paul
is
in
Philadelphia,
or
both
What,
if
anything
follows?
Raphael
is
in
Tacoma
or
Paul
is
in
Philadelphia,
or
both.
From
Johnson‐Laird,
Philip.
2008.
How
We
Reason.
New
York:
Oxford
University
Press,
p.
286.
From
Johnson‐Laird,
Philip.
2008.
How
We
Reason.
New
York:
Oxford
University
Press,
p.
287.
Smarter
People
•  Natural
Intelligence
–  Working
memory
–  Speed
of
thought
•  BeRer
modeler
users
and
model
creators
–  Provide
useful
models
–  Provide
languages
for
modeling
–  Make
people
aware
that
they
are
modeling
System
Dynamics
as
A
Modeling
Language
System
Dynamics
•  Causality
(loops
super
causality)
•  Few
things
in
the
world
Example
/
analogy
•  Ways
of
thinking
of
more
things
–  Aggrega<on
–  Loops
–  Con<nuity
•  Abduc<on
•  Mathema<cs
•  “Manipulable”
Pictures
Modeling
as
thinking
Mathema<cal
modeling
Poetry
Hierarchies
Science
and
par<cular
models