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SYSTEM DYNAMICS and Systems Thinking

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Title: SYSTEM DYNAMICS and Systems Thinking

1
SYSTEM DYNAMICS and Systems Thinking
• developed by James R. Burns

2
Why????
• Because of the frenetic increases in
complexitysociety is becoming increasing complex
and we need tools to cope with it
• This is certainly true in the IS/IT arena as well

3
Coping tools
• Causal modeling
• Simulation
• Discrete stochastic (Promodel)
• Continuous deterministic (Vensim)

4
System Dynamics and Vensim
• A tutorial on Vensim is provided at the end of
Chapter 6 in your copy packet, beginning on page
35 of that chapter

5
Dynamic problems appropriate for Vensim (rather
than promodel)
• There is change over time
• The changing character of the situation IS THE
PROBLEM
• The problem should be studied in aggregates
• The problem does not have a significant
stochastic component or complexion to it

6
• PURPOSE
• PERSPECTIVE
• PROBLEM
• MODE

7
What are we doing here????
• Attempting to characterize, cope with and
understand complexity
• Especially DYNAMIC complexity
• Inventing a physics for a systems or processes
for which there exists no physics
• You get to become a Newton, a Liebnitz, a
Galileo, an Einstein, a .

8
Steps
• Be problem-driven
• Interview people familiar with the problem
• Gather verbal descriptions of the problem
• Formulate a list of variables
• Develop a causal loop diagram
• Develop a stock-and-flow diagram
• Create a working simulation in VENSIM

9
How many of you have used a model to solve a
problem or make a decision?
• Youve been through this drill before!
• All of you have.all of the time!

10
Problem
Problem
SD Model
Mental Model
Mental Model
Decision
Decision
Action
Action
11
Uses to which these models can be put
• What IF experimentshands on experimentation
• Decision making
• Planning
• Problem solving
• Creativity
• Out of the box thinking
• Hypothesis testing
• Finding leverage points, points of intervention
• LEARNING

12
Some notation--
• CLD Causal Loop Diagram
• SFD Stock-and-Flow Diagram
• BOT Behavior Over Time Chart

13
A CLD of the US energy system
14
A roadmap for the U.S. energy system
15
BOTBehavior Over Time chart
• For US energy market

16
US energy consumption, by source, 1850-2000.
(Source Energy use in the United States.
Available from http//en.wikipedia.org/wiki/Energy
_use_in_the_United_States)
17
From CLD to SFD
• System dynamics model
• Causal loop diagram
• Stock-and-flow diagram

vs.
Mathematical representation for stock
18
Extraordinary Organizations
• Are those that engage peoples commitment and
capacity to learn at all levels in the
organization
• Will recognize that the only truly sustainable
competitive advantage is the rate at which
organizations learn
• Nothing compares to the exhilaration that comes
from working within learning orgs.

19
Ordinary Organizations.
• Learn slowly if at all
• Characterize an organization that you are aware
of..

20
Disciplines of the Learning Organization
• Personal Mastery
• Mental Models
• Shared Vision
• Team (Organizational) Learning
• Systems Thinking

21
Personal Mastery
• Continually clarifying and deepening our personal
vision
• Getting better at what we do best

22
Mental Models
• Deeply engrained assumptions, generalizations

23
Shared Vision
• Where there is genuine vision, people excel
• Where there is no vision the people perish

24
Team Learning
• The synergy of teams is the ultimate exhilaration
• Some people, having experienced it once, spend
the rest of their lives looking for it

25
Systems Thinking
• All human endeavors are systems

26
The Fifth Discipline
• IS, OF COURSE, SYSTEMS THINKING
• Subsumes and permeates all of the other
disciplines
• By enhancing the other disciplines, it
continually reminds us that the whole can exceed
the sum of its parts
• But ST also needs the other four disciplines to
realize its full potential

27
Metanoia--A shift of Mind
• The recreation of ourselves through learning
• Becoming able to do something we never were able
to do
• Re-perceiving the world and our relation to it
• Extending our capacity to create
• There is within each one of us a deep hunger for
this type of learning

28
Putting the Ideas into Practice
• SENGE The greatest societal problem facing us
today is the increased complexity of our systems
• FORRESTER Systems are counterintuitive.
Consequently, naïve policy makers implement
policies that have just the opposite of their
intended effect

29
Senges Metanoia
• Originally, he was interested only in public
sector problems
• But then corporate leaders came to him for help
• These were thoughtful people, deeply aware of the
• All shared a commitment and capacity to innovate
that was lacking in the public sector

30
Who were these people???
• William OBrien of Hanover Insurance
• Edward Simon from Herman Miller
• Ray Stata, CEO of Analog Devices
• Trammel Crow
• Arie De Geus of Shell Oil Co
• Leaders from Apple, Ford, Polaroid,
• 4000 Managers who attended the Innovations
Associates workshops over eleven years

31
I am my Position
• We are trained to be loyal to our jobsso much so
that we confuse our job with our personal
identity.
• Most people see themselves within a system over
which they can exercise little control
• There is a kind of myopia in American
organizations that causes individual workers to
focus only on their small part rather than on the
larger system as a whole
• APICS is trying to address this problem
• We need to see ourselves in the context of the
larger system

32
The Enemy is out There
• Generally, we tend to see the problem as outside
us
• no one can catch a ball in that darn field
• Thou shalt always find an external agent to
blame
• Marketing blames manufacturingquality is poor,
due dates are missed, etc.
• Manufacturing blames Engineering
• Engineering blames Marketing

33
The Enemy is out there is actually
• A byproduct of I am my position
• Because of the non-systemic ways of looking at
the world that it fosters
• When we focus only on our position, we do not see
how our actions extend beyond the boundary of
that position
• When those actions have consequences that go
beyond our position, they come back to hurt us

34
The Enemy is out there manifests itself with
statements like..
• the Japanese are killing us
• The labor unions are killing us
• The government regulators are killing us
• But this is always an incomplete story that fails
to recognize that out there and in here are
parts of the SAME SYSTEM

35
The Illusion of Taking Charge
• Being proactive is in vogue
• This means face up to difficult problems, stop
waiting for someone else to do something, solve
problems before they grow into crises, etc.
• We have a hooked on heroics cultureone that
always looks for leadership from the top

36
The Illusion of Taking Charge
• All too often pro-activeness is re-activeness in
disguise
• True pro-activeness comes from seeing how we
contribute to our own problems

37
The Fixation of Events
• We are conditioned to see life as a sequence of
events
• The situation unfolding in Kashmir is viewed as a
sequence of escalating events
• The situation in Israel/Palestine again is seen
as a situation involving events which can be used
to justify the position of either side

38
The Fixation of Events
• The media reinforces the fixation on events
• That is what they report
• It is part of our programming
• Distracts us from seeing the longer term patterns
of change that underlie events and from
understanding the causes that underlie the
patterns

39
Today, the primary threats to our survival\
• Stem not from events but from slow gradual
processes
• The environment
• The erosion of public education
• Generative thinking cannot be sustained if people
are focused on events

40
The Parable of the Boiled Frog
• What is it???

41
The Delusion of Learning from Experience
• We learn from taking an action and observing the
consequences of that actions
• What happens when we cannot observe the
consequences of our action?
• We all have a learning horizona span in time and
space within which we assess our effectiveness
• We learn best from experience but we never
directly experience the consequences of many of
our most important decisions

42
The Delusion of Learning from Experience
• Most people have short memories
• If cycles last longer than a year or two, they
are particularly hard to see and thus learn from
• To reduce the breadth of impact organizations are
decomposed into components
• But the departments create stovepipes that reduce
the observability of complex issues that cross
functional boundaries.

43
Reinforcing loops vs. Balancing loops
44
Stock involving both reinforcing and balancing
loops
45
Stock-and-Flow Diagram
Mathematical representation for Population
INTEGRAL ( ) function in the VENSIM
model Population INTEGRAL (Births Deaths,
Population(t0))
46
The Methodology once problem is identified
• Find substance
• Delineate CLDs, BOT charts
• Submit these for outside scrutiny
• Delineate SFD
• Implement simulation in VENSIM
• Submit for outside scrutiny
• Utilize model for policy experimentation

47
Find substance
• Written material
• Books
• Articles
• Policy and procedure manuals
• Order of magnitude more here
• Must conduct interviews, build CLDs, show them
to the interviewee to capture this

48
Delineate CLDs, BOTs
• CLD Causal Loop Diagram
• BOT Behavior-over-Time chart
• Collect info on the problem
• List variables on post-it notes
• Describe causality using a CLD
• Describe behavior using a BOT diagram

49
Submit these for outside scrutiny
• We simply must get someone qualified to assess
the substance of the model

50
Delineate SFD
• SFD Stock and Flow Diagram
• Translate CLD into SFD

51
What are stocks and flows??
• A way to characterize systems as stocks and flows
between stocks
• Stocks are variables that accumulate the affects
of other variables
• Rates are variables that control the flows of
material into and out of stocks
• Auxiliaries are variables that modify information
as it is passed from stocks to rates

52
Stock and Flow Notation--Quantities
• STOCK
• RATE
• Auxiliary

53
Stock and Flow Notation--Quantities
• Input/Parameter/Lookup
• Have no edges directed toward them
• Output
• Have no edges directed away from them

54
Inputs and Outputs
• Inputs
• Parameters
• Lookups
• Inputs are controllable quantities
• Parameters are environmentally defined quantities
over which the identified manager cannot exercise
any control
• Lookups are TABLES used to modify information as
it is passed along
• Outputs
• Have no edges directed away from them

55
Stock and Flow Notation--edges
• Information
• Flow

56
Some rules
• There are two types of causal links in causal
models
• Information
• Flow
• Information proceeds from stocks and
parameters/inputs toward rates where it is used
to control flows
• Flow edges proceed from rates to states (stocks)
in the causal diagram always

57
Robust Loops
• In any loop involving a pair of quantities/edges,
• one quantity must be a rate
• the other a state or stock,
• one edge must be a flow edge
• the other an information edge

58
CONSISTENCY
• All of the edges directed toward a quantity are
of the same type
• All of the edges directed away from a quantity
are of the same type

59
Population problem
• Population has grown in the last 102 years from
1.65 billion persons to 6.2 billion persons on
planet earth today
• WHAT IS THE CARRYING CAPACITY OF THE PLANET??
• Depends on what material standard living you
assume
• Birth rates, due to improved health, and death
rates are lower due again to improved health
• Corresponding to each, there is a normal
condition

60
List VARIABLES
• Population
• Birth rate
• Death rate
• Death rate normal
• Birth rate normal

61
Draw Causal Loop Diagram
62
Converting to a STOCK AND FLOW Diagram
• What is a STOCK?
• What is a FLOW?
• What is a RATE?
• What is a parameter?

63
Convert CLD to SFD
64
Determine equations
• BRN .04
• DRN .028
• BR BRNP
• DR DRNP
• P(t dt) p(t) dt(BR DR)

65
The Sector Approach to SD model formulation--
• Begin by identifying the sectors
• A sector is all the structure associated with a
single flow
• There could be several states in a single sector

66
The sector Approach, Continued
• Determine the within-sector structure
• Reuse existing molecules where possible
• Determine the between-sector information
infrastructure
• There are no flows and therefore no stocks or
rates here

67
A Single-sector Exponential goal-seeking Model
• Sonya Magnova is a television retailer who wishes
to maintain a desired inventory of DI television
sets so that she doesnt have to sell her
demonstrator and show models. Sonyas ordering
policy is quite simple--adjust actual inventory I
toward desired inventory DI so as to force these
to conform as closely as possible. The initial
inventory is Io. The time required for ordered
inventory to be received is AT.

68
A Two-sector Housing/population Model
• A resort community in Colorado has determined
that population growth in the area depends on the
availability of hoousing as well as the
persistent natural attractiveness of the area.
Abundant housing attracts people at a greater
rate than under normal conditions. The opposite
is true when housing is tight. Area Residents
also leave the community at a certain rate due
primarily to the availability of housing.

69
Two-sector Population/housing Model, Continued
• The housing construction iindustry, on the other
hand, fluctuates depending on the land
availability and housing desires. Abundant
housing cuts back the construction of houses
while the opposite is true when the housing
situation is tight. Also, as land for
residential development fills up (in this
mountain valley), the construction rate decreases
to the level of the demolition rate of houses.

70
What are the main sectors and how do these
interact?
• Population
• Housing

71
What is the structure within each sector?
• Determine state/rate interactions first
• Determine necessary supportng infrastructure
• PARAMETERS
• AUXILIARIES

72
What does the structure within the population
sector look like?
• RATES in-migration, out-migration, net death
rate
• STATES population
• PARAMETERS in-migration normal, out-migration
normal, net death-rate normal

73
What does the structure within the housing sector
look like?
• RATES construction rate, demolition rate
• STATES housing
• AUXILIARIES Land availability multiplier, land
fraction occupied
• PARAMETERS normal housing construction, average
• PARAMETERS land occupied by each unit, total
residential land

74
What is the structure between sectors?
• There are only AUXILIARIES, PARAMETERS, INPUTS
and OUTPUTS

75
What are the between-sector auxiliaries?
• Housing desired
• Housing ratio
• Housing construction multiplier
• Attractiveness for in-migration multiplier
• PARAMETER Housing units required per person

76
Can you construct the schematic model for this
Causal model?
77
We know what that is
78
79
We know what it is
80
Some rules
• There are two types of causal links in causal
models
• Information
• Flow
• Information proceeds from stocks and parameters
toward rates where it is used to control flows
• Flow edges proceed from rates to states (stocks)
in the causal diagram always

81
Loops
• In any loop involving a pair of quantities/edges,
• one quantity must be a rate
• the other a state or stock,
• one edge must be a flow edge
• the other an information edge

82
CONSISTENCY
• All of the edges directed toward a quantity are
of the same type
• All of the edges directed away from a quantity
are of the same type

83
Rates and their edges
84
Parameters and their edges
85
Stocks and their edges
86
Auxiliaries and their edges
87
Outputs and their edges
88
STEP 1 Identify parameters/inputs
• Parameters have no edges directed toward them

89
STEP 2 Identify the edges directed from
parameters
• These are information edges always

90
STEP 3 By consistency identify as many other
edge types as you can
91
STEP 4 Look for loops involving a pair of
quantities only
• Use the rules identified above

92
System Dynamics Software
• STELLA and I think
• High Performance Systems, Inc.
• best fit for K-12 education
• Vensim
• Ventana systems, Inc.
www.vensim.com
• Robust--including parametric data fitting and
optimization
• best fit for higher education
• Powersim
• What Arthur Andersen is using

93
What is system dynamics
• A way to characterize systems as stocks and flows
between stocks
• Stocks are variables that accumulate the affects
of other variables
• Rates are variables the control the flows of
material into andout of stocks
• Auxiliaries are variables the modify information
as it is passed from stocks to rates

94
A DEMO
95
Natures Templates the Archetypes
• Structures of which we are unaware hold us
prisoner
• The swimmer scenario
• Certain patterns of structure occur again and
again called ARCHETYPES

96
We are creating a language
• reinforcing feedback and balancing feedback are
like the nouns and verbs
• systems archetypes are the basic sentences
• Behavior patterns appear again in all
disciplines--biology, psychology, family therapy,
economics, political science, ecology and
management
• Can result in the unification of knowledge across
all fields

97
Recurring behavior patterns
• Do we know how to recognize them?
• Do we know how to describe them?
• Do we know how to prescribe cures for them?
• The ARCHETYPES describe these recurring behavior
patterns

98
The ARCHETYPES
• provide leverage points, intervention junctures
at which substantial change can be brought about
• put the systems perspective into practice
• About a dozen systems ARCHETYPES have been
identified
• All ARCHETYPES are made up of the systems
building blocks reinforcing processes,
balancing processes, delays

99
Before attacking the ARCHETYPES we need to
understand simple structures
• the reinforcing feedback loop
• the balancing feedback loop
• THE DEMO
• Pages 520-525 in Austin/Burns--your handout

100
ARCHETYPE 1 LIMITS TO GROWTH
• A reinforcing process is set in motion to produce
a desired result. It creates a spiral of success
but also creates inadvertent secondary effects
(manifested in a alancing process) that
eventually slow down the success.

101
Management Principle relative to ARCHETYPE 1
• Dont push growth or success remove the factors
limiting growth

102
ARCHETYPE 1 LIMITS TO GROWTH
• Useful in all situations where growth bumps up
against limits
• Firms grow for a while, then plateau
• Individuals get better for a while, then their
personal growth slows.
• Falling in love is kind of like this
• The love begins to plateau as the couple get to
know each other better

103
Structure
104
Understanding the Structure
• High-tech orgs grow rapidly because of ability to
introduce new products
• This growth plateaus as lead times become too long

105
How to achieve Leverage
• Most managers react to the slowing growth by
puching harder on the reinforcing loop
• Unfortunately, the more vigorously you push the
familiar levels, the more strongly the balancing
proces resists, and the more futile your efforts
become.
• Instead, concentrate on the balancing
loop--changing the limiting factor
• This is akin to Goldratts Theory of
Constraints--remove the bottleneck, the impediment

106
Applications to Quality Circles and JIT
• Quality circles work best when there is
even-handed emphasis on both balancing and
reinforcing loops
• JIT has had to focus on recalcitrant suppliers
• THERE WILL ALWAYS BE MORE LIMITING PROCESSES
• When once source of limitatiin is removed,
another will surface
• Growth eventually WILL STOP

107
Create your own LIMITS TO GROWTH story
• Identify a limits to growth pattern in your own
experience
• Diagram it
• What is growing
• What might be limitations
• Example--the COBA and University capital
campaigns
• NOW, LOOK FOR LEVERAGE

108
Test your LIMITS TO GROWTH model
experiments
• Run and re-run the simulation model
• Approach possible resistance and seek WIN-WIN
strategies with them

109
ARCHETYPE 2 shifting the burden
• An underlying problem generates symptoms that
demand attention. But the underlying problem is
difficult for people to address, either because
it is obscure or costly to confront. So people
shift the burden of their problem to other
solutions--well-intentioned, easy fixes that seem
extremely efficient. Unfortunately the easier
solutions only ameliorate the symptoms they
leave the underlying problem unaltered. The
underlying problem grows worse and the system
loses whatever abilities it had to solve the
underlying problem.

110
The Stereotype Structure
Symptiom-Correcting Process
Problem-Correcting Process
111
Special Case Eroding Goals
• Full employment meant 4 unemployment in the 60,
but 6 to 7 unemployment in the early 1980s
• Gramm-Rudman bill called for reaching a balanced
budget by 1991, but this was shifted to 1993 and
from 1993 to 1996 and from 1996 to 1998
• If all else fails, lower your goals..

112
EXAMPLE
113
Another Example
Raise tuition, add course fees, etc.
Costs of Higher Ed not funded by State
Perceived cost to the student
Lower enrollments
114
Still Another Example
Symptom-correcting process
Problem-correcting Process
115
Shifting the Burden is an insidious problem
• Is has a subtle reinforcing cycle
• This increases dependence on the symptomatic
solution
• But eventually, the system loses the ability to
apply the fundamental solution
• The system collapses

116
Senge Says
• Todays problems are yesterdays solutions
• We tend to look for solutions where they are
easiest to find

117
HOW TO ACHIEVE LEVERAGE
• Must strengthen the fundamental response
• Requires a long-term orientation and a shared
vision
• Must weaken the symptomatic response
• Requires a willingness to tell the truth about
these solutions

118
Create your own Shifting the Burden Story
• Is there a problem that is getting gradually
worse over the long term?
• Is the overall health of the system gradually
worsening?
• Is there a growing feeling of helplessness?
• Have short-term fixes been applied?
• The Casa Olay problem of using cupouns to
generate business and then cant get away from
using the coupons because their customer base is
hucked on coupons

119
• Identify the problem
• Next, identify a fundamental solution
• Then, identify one or several symptomatic
solutions
• Finally, identify the possible negative side
effects of the symptomatic solution

120
Review
• We have now seen two of the basic systems
archetypes.
• The Limits to Growth Archetype
• The Shifting the Burden Archetype
• As the archetypes are mastered, they become
combined into more elaborate systemic
descriptions.
• The basic sentences become parts of paragraphs
• The simple stories become integrated into more
involved stories

121
Seeing Structures, not just Trees
• Helps us focus on what is important and what is
not
• Helps us determine what variables to focus on and
which to play less attention to

122
WonderTech The Chapter 7 Scenario
• A lesson in Growth and Underinvestment
• What Senge gets out of this is the Growth and
Underinvestment Archetype
• A combination of variants of the Limits to Growth
Archetype and the Shifting the Burden Archetype

123
The WonderTech Scenario
• WonderTech continues to invest in the growth side
of the process. Sales grow but then plateau.
Management puts more sales people into the field.
Offers more incentives to sales force. But
because of long lead times, customers wane. Yes
you have a great product, but you cant deliver
know weve heard from your other customers.
In fact, the company relaxed its lead-time
standard out to twelve to sixteen weeks because
of insufficient capacity.

124
The Reinforcing Loop
125
The Balancing Loop Following the LTG Archetype
126
The Growth Curve Page 117
127
Whats happened?
• WTs management did not pay much attention to
their delivery service. They mainly tracked
sales, profits, market share and return on
investment. WTs managers waited until demand
fell off before getting concerned about delivery
times. But this is too late. The slow delivery
time has already begun to correct itself. The
management was not very concerned about the
relaxed delivery time standard of eight weeks.

128
The WonderTech Scenario
• The firm decides to build a new manufacturing
facility. But the facility comes on line at a
time when sales are declining and lead times are
coming back to the eight-week standard.
• Of every 10 startup companies, 5 will disappear
with five years, only 4 survive into their tenth
year and only 3 into their fifteenth year.

129
The Shifting the Burden Component
130
Put the whole thing together
131
• Sees problems as conforming to a finite number of
archetypes
• Formulates models based on combinations of the
archetypes
• What about situations and systems that are
technology-driven, dynamics-driven,
exogenously-driven, anything but problem-driven

132
More Comments on the Senge Methodology
• But does this become sufficiently general to
accommodate all dynamical scenarios and
situations?
• It is difficult to translate his archetypes and
causal models into running system dynamics
simulations
• A lot of variables (RATE VARIABLES, specifically)
get left out in terms of connections

133
More Comments on the Senge Methodology
• The focus is on characterizing the dynamics, not
on how to capture that in terms of stocks, flows
and information paths
• He doesnt label his edges with or - signs

134
Another methodology The Sector Approach to SD
model formulation
• Begin by identifying the sectors
• A sector is all the structure associated with a
single flow
• There could be several states in a single sector
• Determine the within-sector structure
• Reuse existing molecules where possible
• Determine the between-sector information
infrastructure
• There are no flows and therefore no stocks or
rates here

135
A Single-sector Exponential goal-seeking Model
• Sonya Magnova is a television retailer who wishes
to maintain a desired inventory of DI television
sets so that she doesnt have to sell her
demonstrator and show models. Sonyas ordering
policy is quite simple--adjust actual inventory I
toward desired inventory DI so as to force these
to conform as closely as possible. The initial
inventory is Io. The time required for ordered
inventory to be received is AT.

136
A Two-sector Housing/population Model
• A resort community in Colorado has determined
that population growth in the area depends on the
availability of hoousing as well as the
persistent natural attractiveness of the area.
Abundant housing attracts people at a greater
rate than under normal conditions. The opposite
is true when housing is tight. Area Residents
also leave the community at a certain rate due
primarily to the availability of housing.

137
Two-sector Population/housing Model, Continued
• The housing construction iindustry, on the other
hand, fluctuates depending on the land
availability and housing desires. Abundant
housing cuts back the construction of houses
while the opposite is true when the housing
situation is tight. Also, as land for
residential development fills up (in this
mountain valley), the construction rate decreases
to the level of the demolition rate of houses.

138
What are the main sectors and how do these
interact?
• Population
• Housing

139
What is the structure within each sector?
• Determine state/rate interactions first
• Determine necessary supportng infrastructure
• PARAMETERS
• AUXILIARIES

140
What does the structure within the population
sector look like?
• RATES in-migration, out-migration, net death
rate
• STATES population
• PARAMETERS in-migration normal, out-migration
normal, net death-rate normal

141
What does the structure within the housing sector
look like?
• RATES construction rate, demolition rate
• STATES housing
• AUXILIARIES Land availability multiplier, land
fraction occupied
• PARAMETERS normal housing construction, average
• PARAMETERS land occupied by each unit, total
residential land

142
What is the structure between sectors?
• There are only AUXILIARIES, PARAMETERS, INPUTS
and OUTPUTS

143
What are the between-sector auxiliaries?
• Housing desired
• Housing ratio
• Housing construction multiplier
• Attractiveness for in-migration multiplier
• PARAMETER Housing units required per person

144
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145
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146
Experiments with growth models
• Models with only one rate and one state