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Modelling with Vensim 101: Basics
The document introduces the basics of system dynamics modeling using VenSim, explaining that models represent real-world systems through stocks, flows, and feedback loops. Stocks represent accumulations like people or goods that change over time due to inflows and outflows. The document walks through building a simple model of a rabbit population as an example, adding stocks, flows, equations, and simulation to represent the dynamics of births and deaths over time.
Modelling with Vensim 101: Basics
- 1. MODELING WITH VENSIM101: BASICS
- 2. First: System dynamics… How is my inventory policy affecting my cash flow? Is an ERP the ‘answer’ to our problems? How can people respond to a tax increment? It’s all about understanding the structural causes that affects the system
- 3. Stocks People Goods Rabbits Meters Gallons Pollution RABBITS Whatever you see when picturing it… those are stocks! Let’s take a mental photo of… let’s say a bunny colony
- 4. Stocks are likea glass… they fill up… or drain out…
- 5. FLOWS People/year Goods/Shift Rabbits/Month Meters/Second Pollution/year Unit/Time How do you fill up/drain out that glass?
- 6. Fills it Rabbits Births Deaths Drains it Warning! Rabbits in the area
- 7. If it’s nota stock… if it’s not a flow It‘s either an auxiliary variable or a constant.
- 8. Population Dynamics Conceptual Model Or… Stock and flows model
- 9. Our first model Can you picture it? What’s the main stock here?? What’s feeding that stock? What are the flows? Let’s go to a warehouse… a quite simple one
- 10. Our first model:The bones It should look something like this:
- 11. Let’s build thatup!!! Flow
- 12. Let’s build thatup!!!
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- 19. Mario Andrés López mlopez0301@gmail.com