Introduction

Teachers often encourage students to know their audience when writing. The same holds true in modeling. Before you even open Vensim PLE, you should be able to answer these questions:

• What am I trying to model, and why?
• Who will be using the model?

For the first question, you must know your content. Is this a model of disease spread, of finance, of a falling object? What will be included in the model? What will be left out? How much accuracy is necessary? How long can it take to simulate my model?

All of these questions point towards the next issue: knowing the model's audience. A model designed for a sixth grade science class is likely to differ considerably from a model used by an industrial researcher. A model introducing software to a novice will probably be less complex than weeklong student project. Knowing the audience gives a model direction. Considering the purpose of a model will generally reveal how much accuracy is necessary. It can also help determine what kind of interface, explanations, and documentation to include in a model.

Once you know what you plan to model and how you plan to model it, you can begin working with the software.