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


Events and DecisionsEvents and Decisions

Patterns of BehaviorPatterns of Behavior

System StructureSystem Structure

ReactiveReactive

AdaptiveAdaptive

GenerativeGenerative

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A Systems Perspective

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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...”





ReactiveReactive

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The Systems Perspective

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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


Unemployment (%)

11

10

9

8

7

6

5

4

3

21948 1958 1968 1978 1988 1998

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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


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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Here’s where we went wrong...Here’s where we went wrong...

Strive for Insights





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The Systems Perspective

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•• 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


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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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


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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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.


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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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


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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Examples of Feedback Loops

Quality ofcommunication

Quality ofcommunicationbetween teams

Quality ofcommunicationwithin teams

TeamworkRisk taking

Trust

Solvency ofa Bank

Perceived solvencyof the Bank

Deposits Withdrawals


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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Examples of Reinforcing Loops

Number of privatebusinesses

Tax base

Tax rate

Expected profitabilityof business

Attractivenessfor business

PopulationBirths peryear

Performance

Motivation

+

+

+ +

+

+

+

––


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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World Population (billions)

8

6

4

2

01500 1600 1700 1800 1900 2000


Self-reinforcing processes in worldpopulation growth

PopulationBirthsper year

Deathsper year

AveragelifespanCapital

accumulation

Knowledgeaccumulation

R

R

R

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Gypsie mothsGypsie mothnet growth

Wasps Wasp netgrowth

Examples of Counteracting Loops

Desired amount ofwater in glass

Waterin glass

Pouring rate

Fractionfilled

+

–

+

+–

-

+

Population Outmigration

+

–

+


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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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.


Presentation Dynamics

ClarifyingquestionsAudience

understanding

Clarity ofpresentation

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Presentation Dynamics- Which loop dominates?

Willingness toask questionsSelf–confidence

ClarifyingquestionsAudience

understanding

Clarity ofpresentation


An “Open Loop” Policy View for Mt. Monadnock

Services

Damage to theenvironment

Value of theexperience

Crowding

ContactareaVisitors

per year

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A Compensating Feedback Loop forMonadnock

-

Services

Damage to theenvironment

Value of theexperience

Crowding

ContactareaVisitors

per year


A Feedback View ofMt. Monadnock

Disappearanceof damage

Regenerationtime

Damagedensity

Environmentaldamage

Incidenceof

damage

Damageper visitor

Contact area

NaturalareaCrowding

Visitors per year

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Feedback Loop Examples:Reinforcing or Counteracting?

Price

Profits Number ofcompetitors

Attractivenessof market

Interestpayments

Governmentdebt

Governmentspending

Pressure tocut spending

Budgetdeficit


Deficit and Debt

Budgetdeficit

GovernmentdebtPressure to

cut spending

Governmentspending

Interestpayments

(B) (B)

(R)

–

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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 -+


Stock and Flow DiagrammingConventions

outflow valveinflow value

sinksource

ShipmentsProductionInventory

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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:


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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Stocks and Flows inSelf-Reported Drug Use

Haveeverused

Past users

Frequentusers

Occasionalusers

Potentialusers


Stocks and Flows in Loops

Deficit

Totalrevenue

Totalspending

Interestpayments

on debt

Programspending

Debtreplayment

Treasuryborrowing

Federaldebt

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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


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.

Tools for Systems Thinking and Modeling - albany.edu · Tools for Systems Thinking and Modeling...

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