Modeling with Vensim
The following steps are typical for building and using Vensim models.
| • | Construct a model or open an existing model. |
| • | Examine the structure using the structural Analysis tools (Tree Diagrams.). |
| • | Simulate the model moving around model parameters to see how it responds. |
| • | Examine interesting behavior in more detail using the dataset Analysis tools (Graphs and Tables). |
| • | Perform controlled simulation experiments and refine the model. |
| • | Present the model and its behavior to your audience using SyntheSim results, Analysis tool output customer Graphs and Tables. |
Constructing, examining, and modifying models should follow an iterative approach. Starting from simple models with few feedback loops and little detail allows the quick construction of a working simulation model. The working model can then be modified and improved as necessary to show the desired level of detail and complexity.
Vensim has a unique approach to displaying simulation output, allowing you to instantly see simulation results for all variables on the screen. During simulation, dynamic behavior is stored for all variables in the model. You can select the any variable of interest and click on the appropriate Analysis tool to display more detailed results.
The Workforce Inventory Example
In this tutorial, you will work through the mechanics of using Vensim with a workforce inventory model. This is a simple, but quite valuable model to study. It demonstrates how the interaction of inventory management policies and hiring practices can lead to instabilities in production. It also demonstrates the somewhat counterintuitive result that being more aggressive about hiring and laying people off can actually lead to a more stable workforce. The Workforce Inventory Model is explored in detail in the Modeling Guide section of this documentation.
Starting Vensim on Windows
| Ø | Click on the Start button then Programs>Vensim>Vensim XXX (where XXX is one of PLE, PLE Plus, Professional or DSS). |
Starting Vensim on a Macintosh
| Ø | Double click on the Vensim icon. |
Vensim will open with a new (empty) model, or the last model you were working with. We could start developing our model here, but instead we will open and simulate an existing model.
