This is a short introduction to the fundamentals of system dynamics: stock and flow models with connectors and feedback loops; rules of "grammar" and a couple of example models.
2. World Economic Forum
in collaboration with :
Marsh & McLennan Companies
Swiss Reinsurance Company
Wharton Center for Risk Management,
University of Pennsylvania
Zurich Financial Services
GlobalRisks
2011
SixthEdition
An initiative of the Risk Response Network
World Economic Forum
January 2011
Climate change
most important risk
of next 10 years
(January 2011)
WORLD ECONOMIC FORUM
6. futureproofed.com
A range of systems thinking skillsA range of systems thinking skills
Apply
Systems Thinking
Skills
95-100%
Build
Simple Maps
40-50%
Build
Simple
Models
15-20%
Build Complex
Models
2%
Source: sustainability institute
7. futureproofed.com
Applying systems’ thinking
Source: sustainability institute
Applying systems thinking
The following curve is instructive regarding how to apply system dynamics
There’s value to be added at many points along the curve!
Value/
Utility
Effort/Time Expended;
Skill Required
“Conversational” use of thinking skills
Simple stock & flow map
Simple model/interface
Complex model/interface
“Mother of all Models”
10. futureproofed.com
“Laundry list” thinking mental model
Source: tracing connection (voices of systems thinkers)
Good teachers
Good parenting
High motivation
Positive classroom
environment
Academic success
11. futureproofed.com
Systems’ thinking mental model
Source: tracing connection (voices of systems thinkers)
Good teachers
Good parenting
High motivation
Positive classroom
environment
Academic success
12. futureproofed.com
Stock & flow models
Source: Tracing connections, sustainability institute
Flow Stock
Stocks represent accumulation of, for
example people, things, cars, stress...
Flows represent actions or activities that
fill or drain accumulations over time
13. futureproofed.com
Artic ice cover
Ocean freezing Artic ice thawing
Artic ice cover
Ocean freezing Artic ice thawing
One stock, two flows
Stress Stress
Building stress from
overworking
Decreasing stress
from relaxing
Artic ice cover
Ocean freezing Artic ice thawing
Public transport
Choosing the bus Giving up on the bus
Bus riders
(people)(people/month) (people/month)
Natural capital
Tree growth Deforestation
Healthy
rainforest
cover
(km2)(km2/year) (km2/year)
Artic ice cover
Ocean freezing Artic ice thawing
Bathtub water
in tub
inflow outflow
(liter)(liter/min) (liter/min)
18. Haïti Dominican Republic
The climate project
Ecosystem services:
“interest” on
natural capital
Living systems (capital)
Ecosystem services (interest)
Ecosystem services
futureproofed.com
19. Haïti Dominican Republic
The climate project
Ecosystem services:
“interest” on
natural capital
Living systems (capital)
Ecosystem services (interest)
Ecosystem services
• Water purification
• Flood management
• Pollination
• Buffering extreme weather
• Soil formation
• Photosynthesis:
CO2 to O2
Ecosystem services
futureproofed.com
24. futureproofed.com
Basic stock and flow models
Source: Thinking in systems; Futureproofed
Rain
Water in lake
River inflow River outflow
Evaporation
Mining
Fossil fuel reserves
26. futureproofed.com
Stocks & flows
Rules of grammar
Source: sustainability institute; Futureproofed
All flows into and out of a stock must
bear the same units-of-measure as the
stock itself, but on a per time basis.
All physical flows come from somewhere
(i.e., deplete some feedstock), and go to
somewhere (i.e., fill some repository).
Artic ice cover
Ocean freezing Artic ice thawing
(km2)(km2/year) (km2/year)
Being hired Losing jobs
Employed youth
(people)(people/year) (people/year)
Rule 1: Respect unit consistency Rule 2: Respect conservation laws
Employed youth
Being hired
Candidate pool
Losing jobs
Former employees
In building a model, you must draw the
boundary of the system you want to model.
Heat from furnace Heat to outside
Room temperature
Learning Forgetting
Knowledge
27. futureproofed.com
Flow
Converter
Stock
The basics
Examples of basic stock & flow models
Source: Tracing connections, sustainability institute
Connector
Stocks represent accumulation of, for
example people, things, cars, stress...
Flows represent actions or activities that
fill or drain accumulations over time
Connectors show causal relationships
that drive the generation of activity
Converters modify flows and other
converters. One of their most common
uses is to tell how quickly an action
happens
28. futureproofed.com
Flow Stock
Converter
The basics
Examples of basic stock & flow models
Source: Tracing connections, sustainability institute
Connector Feedback
Stocks represent accumulation of, for
example people, things, cars, stress...
Flows represent actions or activities that
fill or drain accumulations over time
Connectors show causal relationships
that drive the generation of activity
Converters modify flows and other
converters. One of their most common
uses is to tell how quickly an action
happens.
A feedback loop is formed when changes
in the stock affect the flow into or out of
that same stock.
29. futureproofed.com
Models with feedback loops
Source: Futureproofed, Barry Richmont
Flow Stock
Converter
Interest rate
Feedback
Earning interest
Cash on
bank
account
Flow Stock
Converter
Methane release
rate per °C warming
Feedback
Methane release
from permafrost
Global
warming
Converter
yx
Growing apart
Health of
relation
rate of decay
of relationship
Converter
yx
forgetting
Memoriz
ed facts
memory time
constant
39. example- Storytelling Nuage Vert Helsinki
Continuous process of visualising, inspiring with
gamification element. Allowing for broader media-support.
44. From the Drivepower Technology Atlas.
Tunneling through the cost barrier
FACTOR 10 improvement at lower initial cost
Pipes Larger diameter; straight layoutLarger diameter; straight layoutLarger diameter; straight layout
Pump specs. Smaller pumps and motorsSmaller pumps and motorsSmaller pumps and motors
Capital investment Lower than original designLower than original designLower than original design
Pumping power (hp) before: 95 after: 7 saving: 93%
-90 %
45. How to specify flows
Summary of Generic Flow Templates
Stock-Generated
Flow-Generated
Compounding
Infected
Population
becoming
infected
infection
rate
becoming = Infected * infection
infected Population rate
pumping = Oil Wells * well productivity
External Resource
Barrels of Oil
pumping
Oil
Wells
well
productivity
Co-flow
eroding = water running off * soilunit of water
Top
Soil
eroding
water running off
soilunit of water
Stock-adjustment
changing = gap * adjustment fraction
changing = gap / adjustment time
Perceived
Quality
adjusting
perception
gap
Current
Quality
adjustment fraction
or time constant
Draining
discharging = Patients * daily discharge fraction
or
discharging = Patients / average time in hospital
Patients
discharging
daily disharge
fraction
Generic flow templates
Source: sustainability institute
futureproofed.com
46. futureproofed.com
Software and web-resources
Leverage Points Blog
Sustainability Institute
Category:Stock & Flow - SystemsWiki
Vensim - systems thinking software
Consideo - Modeler & iModeler software
isee systems - SystemsThinking Software
47. futureproofed.com
Books
Thinking in Systems is a concise and crucial book offering insight
for problem-solving on scales ranging from the personal to the
global.
This essential primer brings systems thinking out of the realm of
computers and equations and into the tangible world, showing
readers how to develop the systems-thinking skills that thought
leaders across the globe consider critical for 21st-century life.
While readers will learn the conceptual tools and methods of
systems thinking, the heart of the book is grander than
methodology.
Donella Meadows was known as much for nurturing positive
outcomes as she was for delving into the science behind global
dilemmas. She reminds readers to pay attention to what is
important, not just what is quantifiable, to stay humble and to
continue to learn.
In a world growing ever more complicated, crowded, and
interdependent,Thinking in Systems helps readers avoid
confusion and helplessness, the first step toward finding
proactive and effective solutions.A vital read for students,
professionals and all those concerned with economics, business,
sustainability and the environment
48. Tracing
ConnectionsVoices of Systems Thinkers
Twelve of the world’s
foremost systems thinkers
share how they use this
powerful thinking tool
to change lives.
This book will leave you
with a better understanding
for what systems thinking
is, who is using it, and why
applying systems thinking is
critical in an interdependent
world.
In tribute to their colleague
and friend Barry Richmond,
this volume’s contributors
include pioneers who
studied under Jay Forrester
at MIT, teachers and
colleagues trained by Barry,
and a client from the World
Bank who came to embrace
systems thinking in his work.
The proceeds from this
book will support and
train educators in systems
thinking through the
Creative Learning Exchange,
helping further Barry’s
mission of getting systems
thinking into the hands of as
many people as possible.
Ali Mashayekhi
Professor of
Management,
Sharif University of
Technology, Tehran
Steve Peterson
Principal Consultant,
Lexidyne, LLC, West
Lebanon, New
Hampshire
Frank Draper
Physics and field
sciences teacher,
Catalina Foothills
School District,
Tucson, Arizona
Tracy Benson
Coordinator of the
Waters Foundation,
Systems Thinking
in Schools project,
Tucson, Arizona
Diana M. Fisher
Math teacher,
Wilson High School,
Portland, Oregon
John Morecroft
Professor of
Management Science
and Operations,
London Business
School, London
Corey Peck
Managing Director,
Lexidyne, LLC,
Colorado Springs,
Colorado
John L. Newman
Lead Economist,
Poverty and
Gender Group,
Latin America and
Caribbean Region,
The World Bank
James K. Doyle
Associate Professor
of Psychology,
Worcester Poly-
technic Institute,
Worcester,
Massachusetts
Khalid Saeed
Professor of Social
Science and Policy
Studies, Worcester
Polytechnic Insti-
tute, Worcester,
Massachusetts
Jeanine Skorinko
Assistant Professor
of Social Science and
Policy Studies,
Worcester Poly-
technic Institute,
Worcester,
Massachusetts
Peter M. Senge
Author of The
Fifth Discipline,
Founding Chair
of the Society for
Organizational
Learning, and
senior lecturer,
MIT, Cambridge,
Massachusetts
Systems thinking provides
the missing intellectual and
cognitive underpinning for
education for sustainability
and global citizenship.
This extraordinary book
could not come at a
better time as more and
more people realize that
patching up our industrial
age schools will achieve
neither the innovation
nor the inclusiveness so
desperately needed.
Building on Barry Richmond’s
seminal work on the critical
thinking skills embedded in
rigorous systems thinking,
the book gives a wide
sampling of the progress
that has been made by
innovative educators in the
past two decades in curricula
and pedagogy.
Long regarded as the stuff
of graduate education, these
skills are being embedded
in primary education and
developed to remarkably
advanced levels in
secondary education.
—Peter Senge
MIT and SoL
CONTRIBUTING AUTHORSTracing Connections is for anyone who’s
ever wondered how SystemsThinking can
be effectively used to significantly and
successfully transform education,
business, public policy, and research.
In ten chapters, teachers,World Bank
Executives, corporate consultants,
researchers and college professors lead
the reader through an amazing spectrum
of applied SystemThinking that leads to
unexpected realizations and critical
understanding.
Inspired by Barry Richmond, Systems
Thinking pioneer, isee systems founder,
and creator of STELLA and iThink,Tracing
Connections reveals how a new way of
thinking can radically improve your ability
to work through complex issues and
uncover elegant solutions. futureproofed.com