Understanding the Modeling Process

At the Center for Agent-Based Modeling, we believe that it is important to spend constructive time thinking about the modeling process to prepare you to create your own models.

This study guide should provide you with a solid foundation for creating your own models.  It is designed to be done in conjunction with Learning Lab 6, which provides a detailed lab for starting with an idea and ending up with a completed original model, although if you are new to NetLogo, you are probably better offer completing the earlier Learning Labs first as Lab 6 is more advanced.   

Let’s begin by discussing the modeling process

When we create a model we do so to better understand some phenomena. Models are built as a better way to understand the world. As scientists, modeling is an essential way of testing our theories. And thus, it is essential that there be a tight connection between a theory or explanation of the phenomena being modeled and the hypotheses and rule-sets used within the model. Nobel Prize winner Linus Pauling once wrote that

“The construction of the model may represent the development of a theory and with a model it needs to be a precise theory. If you have fuzzy vague ideas, then you find that you can’t build a model, because a model must be precise.”

Models that lack theory or which have a lose connection to theory are more likely to encounter significant problems throughout the development process. Thus, we begin the process by tying the idea for a model with theory.

The Seven-Step Process

The Modeling process can be visually described as a seven-step process illustrated below: 

Click here to view a larger version of this graphic.

We’ll look at each step in this process in a bit of detail:

1. Brainstorming

We find that it is very valuable to begin the process of model-building through an open-ended brainstorming session.  Before you even think about writing a line of code, ask yourself:

• How will it help you gain an understanding of the topic you are exploring
• Will it be a “snapshot” of an idea you have?
• Will you use the model to gather data?
• What is the it that you want to model?
• What ideas do you want to explore?
• What parts of the system you are looking at provide the building-blocks for the system, and what parts are

If you are working as a team on a model, brainstorming might take place using a white-board and a outpouring of ideas among team-members.  But brainstorming can just as easily be accomplished by the solo-modeler; often times with a pad of paper, and a pile of books (or resources) you use to work through the idea for the model. Or maybe a pen and a napkin at a late-night session at a coffee shop.

Regardless of how you accomplish the task, the important part of brainstorming is to begin the creative process of thinking about how to capture the essential elements of the system you are planning to model.

Continue this study guide.