IE673Session 3 - System Thinking1 An Introduction to System Thinking

IE673Session 3 - System Thinking2 Contents What is a system? System Stability Things in Common Change and Growth Putting the Pieces Together Complex Systems

IE673Session 3 - System Thinking3 What is a System? Use “system” in everyday sense A collection of parts which interact with each other to function as a whole A “heap” is not a system “Heaps” are not essentially change by adding or subtracting from the “heap” A system can be part of larger systems –subsystems form a hierarchy

IE673Session 3 - System Thinking4 Hierarchical System Particle Atom Molecule Cell Nucleus Brain Cell Brain Nervous System Individual Local community State Nation World Civilization World Ecosystem Planet Earth Solar System Galaxy Universe

IE673Session 3 - System Thinking5 Systems and Stability If start at different point, still same results -- why? A system of smaller units is more stable –Protons & neutrons - smallest natural particles –Large atoms unstable - uranium

IE673Session 3 - System Thinking6 Systems and Stability (continued) Holds true for maximum size of animals –Whales and dinosaurs A group of 5 versus 5000 A large group is a mob unless higher levels of system organizations are created

IE673Session 3 - System Thinking7 Systems and Stability (continued) Even if gigantic low-level systems were possible, a series of higher level systems would be easier –Millions of possible molecules –92 atoms –3 particles - protons, neutrons, electrons

IE673Session 3 - System Thinking8 Systems and Stability (continued) System definition key word - interact One part has effect on system - system has effect on one part –Circular relationship or loop Example - bicycle and rider –A two part system –Combined, can do things individual can not –Constant small adjustment for “errors”

IE673Session 3 - System Thinking9 Systems and Stability “Input”BrainMusclesBicycle“Output” Information

IE673Session 3 - System Thinking10 Systems and Stability Feedback loop –Provides Stability –Cancels out slight changes –“Negative” feedback loop Negative feed back loops –Occur by the thousands –Are in our everyday life

IE673Session 3 - System Thinking11 Stability Negative feedback loops are everywhere –The thermostat –Body temperature –Float valves –Thirst –Inventories –Group membership –Predator and prey

IE673Session 3 - System Thinking12 Stability Systems can –“Aim” at a fixed “target” –“Track” a moving “target” Tracking systems –Get feedback on how far it is from where it should be –Uses the feedback to reduce the difference

IE673Session 3 - System Thinking13 Stability Tracking systems –Set-back thermostat –Radar-controlled anti-aircraft guns –Satellite docking systems –Sun tracking solar collectors –Driving a car –Riding a bicycle

IE673Session 3 - System Thinking14 Stability Tracking systems –Human/Mechanical Person starts system going Guides with series of corrections System works so fast and so smoothly in some cases - hard to believe there is time for negative feedback to work Common in natural and social systems –Sunflower –Politicians –Companies

IE673Session 3 - System Thinking15 Things in Common Self-stabilizing systems make an active response to change –Bicycle An active response to change requires the use of energy –Wind generator

IE673Session 3 - System Thinking16 Active Systems Almost all living systems are active in sense that they continue to function and use energy even when dormant –Must stay active when at rest or die

IE673Session 3 - System Thinking17 Active Systems General rule –The more complex a system - the more energy spent on maintenance –Holds for social systems Isolated peasant community vs a modern community

IE673Session 3 - System Thinking18 Things in Common System limitations –Amount and kind of change “Exposure” “Heat Stroke” –Many negative feedback systems stable over wide range, but fail abruptly when pushed beyond its limits

IE673Session 3 - System Thinking19 Things in Common Loose systems –Negative feedback does not prevent change –Negative feedback responds to change and keeps it under control –The result is a characteristic wobble - “sloppy”

IE673Session 3 - System Thinking20 Things in Common Reaction times –Every negative feedback system has time limits –Reaction time is most important –The minimum amount of time necessary for one complete circuit –If too slow, fast change can damage system

IE673Session 3 - System Thinking21 Anticipation –Sometimes can’t afford the delay –Systems cope - react to warnings –Need ability to interpret warnings –Inadequate reaction time due to responding to problems rather than warnings Things in Common

IE673Session 3 - System Thinking22 Counter-intuitive systems –Behavior contrary to common sense –Predator - prey –High blood pressure –Rent control The “obvious” solution doesn’t work –negative feedback loops fight direct intervention –Change the way pieces interact –Don’t try to “out-muscle” the system Things in Common

IE673Session 3 - System Thinking23 Hidden systems –Hard to predict how system will react –Feedback loops needed are not in sight African village 1929 tariff on imports Things in Common

IE673Session 3 - System Thinking24 Vulnerable systems –Even the most stubborn system is vulnerable to interference with information flow Slight breeze and bicycle –Can be used to advantage to change way system acts Things in Common

IE673Session 3 - System Thinking25 How? –Negative feedback loop breakdown –system becomes unstable and breaks down –A different kind of feedback - positive Change and Growth

IE673Session 3 - System Thinking26 Negative feedback works to cancel out change Positive feedback works to cause more change –Sound amplifier - “squawk” –Interest on money –Living things –Knowledge –Power Change and Growth

IE673Session 3 - System Thinking27 Plus and minus –The organization of every complex system is built out of the same two elements - positive and negative loops –Can apply knowledge about one system to another Putting Things Together

IE673Session 3 - System Thinking28 Simple system - one of each type of loop –Population growth Multiple loops –Add factors that could affect the loops Putting Things Together

IE673Session 3 - System Thinking29 Characteristics Self-stabilizing Goal-seeking Program-following Self re-programming Anticipatory Environment modifying Self-replication Self-maintaining and repairing Self-reorganizing Self-programming Complex Systems

IE673Session 3 - System Thinking30 Problems of complexity The tragedy of the Commons Cost of information –Rule of thumb Make each decision at the lowest possible level, but be ready to shift the control of the situation to a higher level if a serious problem occurs The distortion of feedback Loss of predictability (due to flexibility) Complex Systems