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Introduction to Systems Thinking: System Structures and
Behaviour
Sydney Limited WIP SocietyJason Yip
[email protected]://jchyip.blogspot.com
@jchyip
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Select a problem as a working example. It should be somewhat
complicated, and not too simple.
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What is a system?
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A system is a set of things interconnected in such a way that
they produce their own pattern of behaviour over time
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A system is more than the sum of its parts
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http://mennodiscuss.com/viewtopic.php?f=6&t=16392#p456262
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Systems consists of three things
1. Elements2. Interconnections3. Function (non-human system) or
Purpose
(human system)
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Examples of systems
Digestive system Sports team School City Factory Corporation
National Economy
Animal Tree Forest Earth Solar system Galaxy IT system
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https://flic.kr/p/97JeYs
Bicycle system
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Frog system
https://flic.kr/p/mKKug
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Systems mostly cause their own behaviour; outside events unleash
that behaviour
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Do politicians cause recessions and booms? Or is it inherent to
market economies?
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Do competitors cause companies to lose market share? Or do their
own policies create losses that competitors exploit?
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Every system is perfectly designed to achieve the results it
gets.
Dr. Don Berwick
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Describe your situation as a system
What are the elements? What are the interconnections between
the
elements? What is the purpose of the system?
Intended vs actual based on behaviour?
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Stocks and Flows
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Stocks are the elements you can see, feel, count, or measure at
any given time
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Examples of Stocks
Water in a bathtub A population Books in a book store Wood in a
tree Money in a bank
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Stocks change over time via Flows
Work flow Information flow Both inflow and outflow
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http://lssacademy.com/2008/02/24/lets-create-a-current-state-value-stream-map/
Information Flow
Work Flow
Stocks
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https://flic.kr/p/9az8q1
Inflow
Outflow
Information flow
Stock
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Stocks provide a memory of flows
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Stocks act as shock absorbers
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Stocks introduce delay.
It takes time for flows to affect stocks.
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Delays decouple inflow and outflow
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Examples of stocks decoupling flows
Gasoline storage tanks Wood in a forest Water reservoir
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Stocks are pretty much queues
Me
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Lets try describing a typical Agile team using stocks and
flows
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How might stocks and flows change how you describe your
situation?
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Feedback loops
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Systems run themselves via feedback loops
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Balancing feedback loops
Thermostat Guided missile Iterative, incremental software
development
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A stock with two competing balancing loops
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How feedback fails
Late, lost, unclear, incomplete, hard to interpret
information
Weak, delayed, resource-constrained, ineffective response
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Two competing balancing loops with delays
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The problem with forecast-driven supply chains
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A delay in a balancing feedback loop makes a system likely to
oscillate
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Aside: This is generally solved by using kanban
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Reinforcing feedback loops
Market collapse: uncertainty -> remove money -> more
uncertainty
Compound interest Death march: Too much to do -> work
harder -> more bugs -> work even harder
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A stock with one reinforcing loop and one balancing loop
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If A causes B, is it possible that B also causes A?
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How might feedback loops change how you describe your
situation?
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Dealing with systems
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Systems consists of three things
1. Elements2. Interconnections3. Function (non-human system) or
Purpose
(human system)
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Changing elements usually has the least effect; changing
interconnections or purpose is usually more dramatic
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Examples
Change all members of a sports team vs change rules of the game
or the definition of winning
Change people in the organisation vs change the way of working
or the definition of organisational success
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Focus more on interconnections and interactions than elements
Interaction flow / sequence over class
structure Work flow / value stream over org structure
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System interactions operate through information flow
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Address incongruent purposes
System purposes do not necessarily match the intention of the
designers or actors within it
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How might you intervene in your situation to improve the
system?
