Lesson 8: Model Building Techniques

There’s not a right way to build a model. Most problems can be approached from many different angles and use different solutions. One of the benefits of simulation is that you can try several approaches to see which gives the best results before actually implementing the changes in your actual process. However, you should take some basic steps to have the greatest success with the least amount of rework and troubleshooting.


Start small

Some people try to build their entire model with all the detail they can right from the start. Even if you understand your process well, this approach can cause lots of headaches and rework. Even if your real process uses multiple entities, build your initial model with just one entity. It’s much easier to “watch” your simulation run and see trouble spots when there is only one entity to track. Don’t add resources until you are confident that your flow is correct and entities are routed to the proper locations. Don’t worry about times, capacities, or quantities at first. Just get the flow working. Then start adding details.

Test as you go

You can save yourself a lot of grief by building a small section of your model and testing it to ensure you are getting the expected results. If you build large sections, add functionality like resources and action logic, and then test when you’re finished building, you may have a troubleshooting nightmare. You will always have a good idea of where to look for problems by testing small changes.


Start adding times, capacities, arrival information, etc. If you need multiple entities in your model, start adding them before adding resources and action logic. Then add resources and action logic, testing as you go.

Remember, ProcessModel is an estimating tool that allows you to see trends and the impact of changes to a process. It isn’t intended as scheduling, order management, or MRP system. It’s important to make your model reflect reality as much as possible. But if your costs don’t match the real process penny for penny, that doesn’t mean the model is broken or can’t significantly impact business decisions, which can save millions of dollars.

Quick Model Building

Let’s take a closer look at the shape palette. There are 3 basic types of graphical objects: entities, activities, and resources.