Thinking_in_Systems Flashcards
3 Parts of a System
- Elements
- Interconnections
- Function / Purpose
System
Interconnected set of elements that is coherently organized in a way that achieves something
Interconnections
Relationships that hold the elements together.
Can be physical flows or flows of information
If the interconnections change, the system may be greatly altered
“A system is more than the sum of its parts. It may exhibit adaptive, dynamic, goal-seeking, self-preserving, and something evolutionary behavior”
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Purpose
TODO
Best way to deduce the system’s purpose is to watch for a while to see how the systems behave
Deduced from behavior not from rhetoric or stated goals
An important function of almost every system is to ensure its own perpetuation
“Many of the interconnections in system operate through the flow of information. Information holds systems together and plays systems together and plays a great role in determining how they operate.”
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“The least obvious part of the system, its function or purpose, is often the most crucial determinant of the system’s behavior”
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Stock
The foundation of any system. Elements of the system that you can see, feel, count, or measure at any given time.
Change over time through the actions of a flow
The present memory of the history of changing flows within the system
Allows inflows and outflows to be independent of each other and temporarily out of balance with each other
Flows
The increase or decrease of the stock of a system
The filling and draining, births and deaths, purchases and sales, growth and decay, deposits and withdrawals, successes and failures.
“A stock is the memory of the history of changing flows within the system”
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Dynamics
The behavior over time of the stocks and flow of a system
Dynamic Equilibrium
When the flow of stock is such that the stock does not change. Inputs and outputs change at a constant rate with each other
“A stock can be increased by decreasing its outflow rate as well as by increasing its inflow rate. There’s more than one way to fill a bathtub!”
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“All models, whether mental models or mathematical models, are simplifications of the real world”
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“Stocks generally change slowly, even when the flows into or out of them change suddenly. Therefore, stocks act as delays or buffers or shock absorbers in systems”
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