tools for systems thinking and modeling - albany.edu · tools for systems thinking and modeling...
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1G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Tools for Systems Thinkingand Modeling
Dynamics: Graphs over timeDynamics: Graphs over time
Structure:Structure: Causal-loop Diagrams Causal-loop Diagrams
2G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Events and DecisionsEvents and Decisions
Patterns of BehaviorPatterns of Behavior
System StructureSystem Structure
ReactiveReactive
AdaptiveAdaptive
GenerativeGenerative
Incr
easi
ngle
vera
geIn
crea
sing
leve
rage
A Systems Perspective
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3G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
A systems view stands back just far enough to...A systems view stands back just far enough to...
•• Deliberately blur discrete events into patternsDeliberately blur discrete events into patternsof behaviorof behavior
•• Deliberately move from a focus on individualDeliberately move from a focus on individualdecisions to a focus on policy structuredecisions to a focus on policy structure
“Distancing...”
4G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Events and DecisionsEvents and Decisions
Patterns of BehaviorPatterns of Behavior
System StructureSystem Structure
ReactiveReactive
AdaptiveAdaptive
GenerativeGenerative
Incr
easi
ngle
vera
geIn
crea
sing
leve
rage
The Systems Perspective
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5G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Dynamics
•• Define problems in terms of graphs over time.Define problems in terms of graphs over time.–– Graph important variablesGraph important variables
–– Graph historical dataGraph historical data
–– Graph anticipated dynamicsGraph anticipated dynamics
–– Graph preferred dynamicsGraph preferred dynamics
•• Use these to focus systems thinking andUse these to focus systems thinking andmodelingmodeling
6G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Unemployment (%)
11
10
9
8
7
6
5
4
3
21948 1958 1968 1978 1988 1998
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7G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
New York City Populations
8000000
7000000
6000000
5000000
4000000
3000000
2000000
1000000
0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990
BronxBrooklynManhattanQueens
8000000
7000000
6000000
5000000
4000000
3000000
2000000
1000000
0 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990
BronxBrooklynManhattanQueens
8G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Unemployment & Welfare inDutchess County, NY
0%
2%
4%
6%
8%
10%
12%
02000400060008000100001200014000160001800020000
0%
2%
4%
6%
8%
10%
12%
02000400060008000100001200014000160001800020000
Unemployment
Welfare roll
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9G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Here’s where we went wrong...Here’s where we went wrong...
Strive for Insights
10G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Events and DecisionsEvents and Decisions
Patterns of BehaviorPatterns of Behavior
System StructureSystem Structure
ReactiveReactive
AdaptiveAdaptive
GenerativeGenerative
Incr
easi
ngle
vera
geIn
crea
sing
leve
rage
The Systems Perspective
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11G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
•• Accumulations (populations, resourcesAccumulations (populations, resources……))
•• Causal structure: Causal structure: ““feedbackfeedback”” loops loops
•• DelaysDelays
•• Perceptions (a kind of accumulation)Perceptions (a kind of accumulation)
•• PressuresPressures
•• Affects, emotions, (Affects, emotions, (irir)rationalities)rationalities
•• Policies governing decisionsPolicies governing decisions
Systems Structure
12G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Causal Loop Diagrams
•• Causal mapping is aCausal mapping is apowerful tool forpowerful tool forrepresenting structurerepresenting structurein complex systems.in complex systems.
Quality of city life
Crime rate Retail outlets
Neighborhoodhealth clinics
Absenteelandlords
PopulationInmigration Outmigration
•• Arrows indicateArrows indicatecausal causal influence.influence.
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13G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Polarities of Causal Links
•• Positive and negativePositive and negativesigns show thesigns show thedirection of causality:direction of causality:
Quality of city life
Crime rate Retail outlets
Neighborhoodhealth clinics
Absenteelandlords
PopulationInmigration Outmigration
– +
+ –
+ –
+ + ... ... ““directdirect”” relation relation
–– …“…“inverseinverse”” relation relation
14G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Definitions of Link Polarities
All words phrases are expressed as All words phrases are expressed as quantitiesquantities that have a that have aclear sense of increase or decrease.clear sense of increase or decrease.
No verbs No verbs —— the action is in the arrows. the action is in the arrows.
A A addsadds to B, or to B, or
∆∆A leads to A leads to ∆∆B in the B in the samesamedirectiondirection
C C subtractssubtracts from D, or from D, or∆∆C leads to C leads to ∆∆D in the D in the oppositeoppositedirectiondirection
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15G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Simple test for link polarity
An increase in AAn increase in Amakes B makes B higherhigher than it than itwould have beenwould have beenwithout the change.without the change.
An increase in CAn increase in Cmakes D makes D lowerlower than it than itwould have beenwould have beenwithout the change.without the change.
16G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Examples
“Ceteris paribus”...All other influences held constant as we assign polarities.
Emigration Emigration subtractssubtracts from frompopulation: An increase inpopulation: An increase inemigration means less (aemigration means less (adecrease means more) thandecrease means more) thanwewe’’d have without the changed have without the change
More lawyers mean More lawyers mean moremorelitigation; fewer lawyers,litigation; fewer lawyers,less litigationless litigation
Lawyers Court cases+
PopulationOutmigration–
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17G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Exercises
Concentration ofgreen house gases in
atmosphere
Ratiation of heat awayfrom the earth
Global averagetemperature
Anxiety Productivity
Reglatory delays inthe planning process
Citizen participation inthe planning process
Citizen ownership ofthe outcomes
18G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Feedback Loops
A feedback loop exists when decisions changeA feedback loop exists when decisions changethe state of the system, changing the conditionsthe state of the system, changing the conditionsand information that influence future decisions.and information that influence future decisions.
Decisions State ofthe system
Action
Perceptions
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22G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Examples of Feedback Loops
Quality ofcommunication
Quality ofcommunicationbetween teams
Quality ofcommunicationwithin teams
TeamworkRisk taking
Trust
Solvency ofa Bank
Perceived solvencyof the Bank
Deposits Withdrawals
23G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Two kinds of feedback loops
•• Positive loopsPositive loops–– self-reinforcingself-reinforcing
–– growth producinggrowth producing
–– destabilizingdestabilizing
–– acceleratingaccelerating
–– even number of even number of ––’’ss
•• Symbolized bySymbolized by
•• Negative loopsNegative loops–– counteractingcounteracting
–– goal seekinggoal seeking
–– stabilizingstabilizing
–– balancingbalancing
–– odd number of odd number of ––’’ss
•• Symbolized bySymbolized by
Self–confidence
R C B
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24G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Examples of Reinforcing Loops
Number of privatebusinesses
Tax base
Tax rate
Expected profitabilityof business
Attractivenessfor business
PopulationBirths peryear
Performance
Motivation
+
+
+ +
+
+
+
––
25G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Typical Reinforcing Loop Behaviors20,000
15,000
10,000
5,000
00 25 50 75 100
10,000
9,000
8,000
7,000
6,0000 25 50 75 100
Population and Births Loop
Businesses and Taxes Loop
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26G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
World Population (billions)
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6
4
2
01500 1600 1700 1800 1900 2000
27G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Self-reinforcing processes in worldpopulation growth
PopulationBirthsper year
Deathsper year
AveragelifespanCapital
accumulation
Knowledgeaccumulation
R
R
R
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31G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Gypsie mothsGypsie mothnet growth
Wasps Wasp netgrowth
Examples of Counteracting Loops
Desired amount ofwater in glass
Waterin glass
Pouring rate
Fractionfilled
+
–
+
+–
-
+
Population Outmigration
+
–
+
32G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Typical Counteracting LoopBehaviors
20
15
10
5
00 10 20 30 40
Filling a Glass
10,000
7,500
5,000
2,500
00 25 50 75 100
Population andemigration
•0 •7.5 •15 •22.5 •30
Predator-prey interactions
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33G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Tips for Determining Link and LoopPolarities
•• For each link, determine the effect of anFor each link, determine the effect of an increase increase in the in thevariable at the tail of the arrow:variable at the tail of the arrow:–– If the variable at the head If the variable at the head increasesincreases, assign a , assign a plusplus..
–– If the variable at the head If the variable at the head decreasesdecreases, assign a , assign a minusminus..
•• For each loop, count the number of negative signs:For each loop, count the number of negative signs:–– An An eveneven number of negative links is a number of negative links is a reinforcingreinforcing (R) loop. (R) loop.
–– An An oddodd number of negative links is a number of negative links is a balancingbalancing (B) loop. (B) loop.
•• Most important: For each loop, tell a self-reinforcingMost important: For each loop, tell a self-reinforcingor balancing/counteracting story, and check that theor balancing/counteracting story, and check that thestory matches the loop polarity.story matches the loop polarity.
34G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Presentation Dynamics
ClarifyingquestionsAudience
understanding
Clarity ofpresentation
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35G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Presentation Dynamics- Which loop dominates?
Willingness toask questionsSelf–confidence
ClarifyingquestionsAudience
understanding
Clarity ofpresentation
36G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
An “Open Loop” Policy View for Mt. Monadnock
Services
Damage to theenvironment
Value of theexperience
Crowding
ContactareaVisitors
per year
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37G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
A Compensating Feedback Loop forMonadnock
-
Services
Damage to theenvironment
Value of theexperience
Crowding
ContactareaVisitors
per year
38G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
A Feedback View ofMt. Monadnock
Disappearanceof damage
Regenerationtime
Damagedensity
Environmentaldamage
Incidenceof
damage
Damageper visitor
Contact area
NaturalareaCrowding
Visitors per year
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39G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Feedback Loop Examples:Reinforcing or Counteracting?
Price
Profits Number ofcompetitors
Attractivenessof market
Interestpayments
Governmentdebt
Governmentspending
Pressure tocut spending
Budgetdeficit
40G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Deficit and Debt
Budgetdeficit
GovernmentdebtPressure to
cut spending
Governmentspending
Interestpayments
(B) (B)
(R)
–
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41G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Stocks and Flows
Stocks are accumulations.Stocks are accumulations.–– Stocks are increased by Stocks are increased by inflowsinflows and decreased by and decreased by
outflowsoutflows..
–– When a link means When a link means ““addadd”” or or ““subtractsubtract”” we have a we have astock-and-flow structure.stock-and-flow structure.
–– Example: InventoryExample: Inventory
ShipmentsInventoryProduction -+
42G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Stock and Flow DiagrammingConventions
outflow valveinflow value
sinksource
ShipmentsProductionInventory
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43G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
A Stock and Flow Example
Experiencedquit rate
Gainingexperience
rateHiringrate
Experiencedworkers
Inexperiencedworkers
Hiring rate
Inexperiencedworkers
Gainingexperience
rateExperienced
quit rate
Experiencedworkers+ - + -
Explicit stocks and flows:
The corresponding causal-loop diagram:
44G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Stocks and Flows Solve a Puzzle inthe Dynamics of Poverty
People in and out of poverty
Peoplerecently in
poverty
Flow out oflong termpoverty
Flow out ofshort term
poverty
Flow ofpeople
intopoverty
People in longterm poverty
People in shortterm poverty
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45G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Stocks and Flows inSelf-Reported Drug Use
Haveeverused
Past users
Frequentusers
Occasionalusers
Potentialusers
46G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Stocks and Flows in Loops
Deficit
Totalrevenue
Totalspending
Interestpayments
on debt
Programspending
Debtreplayment
Treasuryborrowing
Federaldebt
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50G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Exercise: Sign & tell a story
Averagecommuting time
Averagecommutingdistance
Averagecommuting speed
Tolerablecommuting time
Pressure for more andwider high speed roads
Lane-miles of highspeed roads
Attractivenessof outlying areas
Population inoutlying areas
Number ofcommuters
Net migration tooutlying areas
Highwayconstruction
51G.P.Richardson, Rockefeller College of Public Affairs and Policy, University at Albany
Guidelines for Conceptualization
•• Focus on a problem.Focus on a problem.–– DonDon’’t try to build a model of a system.t try to build a model of a system.
•• Graph dynamics of key variables.Graph dynamics of key variables.–– Focus on patterns of behavior over time, not eventsFocus on patterns of behavior over time, not events–– Distinguish obvious stocks and flows from other quantities.Distinguish obvious stocks and flows from other quantities.
•• Set model boundaries.Set model boundaries.–– Temporal: the time horizonTemporal: the time horizon–– Conceptual: whatConceptual: what’’s included and excludeds included and excluded–– Causal: whatCausal: what’’s endogenous and exogenouss endogenous and exogenous
•• Develop loop diagrams.Develop loop diagrams.–– Explain the problem behavior in terms of feedback structure.Explain the problem behavior in terms of feedback structure.–– Start simply. Build to complexity and completeness.Start simply. Build to complexity and completeness.