Wednesday, June 10, 2015

Embracing Simulation

Over the last 10 years, more than a thousand students have attended one or more of my simulation classes. I have seen successful and not so successful students. There are ways to help ensure success and here I provide some guidance on avoiding the most common mistakes.

Simulation modeling can be challenging for a beginner.  There is a sharp learning curve not only on the mechanics and nuances of the software, but also with managing a simulation project.  However, there is a magic formula and here it is in a nutshell. Make sure you have…

  • Training on the software
  • Support from a mentor
  • An appropriate first project
  • Support from the rest of the company
    • Access to data
    • Subject matter experts to educate yourself on the process
  • Time to work on the project
  • Time to verify and validate the project
  • Time to measure its success

Training & Mentoring
Get training on the tool as well as a mentor - both are crucial.  The cost of a one-week training class will save two to three months of learning and struggling on your own.  I also would recommend spending some time with a modeling mentor.  If your company has other modelers, buddy up with one of the experts for a couple of models.  If no one else uses simulation at your company, you might want to consider hiring someone to help build the first model.  After the first project, consider hiring that consultant again as a mentor through the next project.  It is difficult for a new modeler to build a good model without knowing what a good model looks like.  I have seen modelers using simulation for years but using the same bad habits they originally started out with because they have never seen it done differently.  So get started out on the right track.

Successful Initial Projects
The first project should be selected with care.  It should be used to help you get comfortable with simulation.  The purpose of your FIRST simulation project should NOT be to create a model that automagically generates the optimal schedule for the factory!  Although that is a lofty goal, first pick a simple project, possibly a subset of what will eventually become part of a larger model.  Start out small.  Pick something that will be successful.  Learn how to manage a simulation project.  Don’t be afraid to make mistakes.  Yes, make mistakes!  We actually learn the most when we make mistakes and correct ourselves. 

Get support from the rest of the company.  A simulation model needs data, often lots of it.  A simulation model needs process knowledge.  As a new modeler, you often do not have either of those within your immediate grasp.  You must go find the information from others within the company.  This information will take resources that you often can’t commandeer yourself.  It takes a certain level of management support to commandeer those resources.  Without this support, you can’t get data plus you can’t get the information you need regarding the process.  So without the right level of management support, the project can’t succeed.

Give yourself time to work on the project.  If you have other responsibilities, quite often your simulation responsibility will fall to the bottom of the task list.  I have seen this way too often.  When a new modeler has other responsibilities and is always starting and stopping frequently; it can be detrimental!  Each time a modeler revisits the model they tend to have forgotten the last few things they had done and waste a lot of time getting back into the groove.  This has a similar effect with experienced modelers, but not to the same extent as a new modeler.

Verification & Validation
Budget plenty of time to verify and validate the model.  A computer will do what you tell it to do, which is not necessarily what you want it to do. While you are building the model, constantly take time to verify that the model is doing what you intended. As you complete stages of the model, validate that it is a reasonable representation of the real system. For validation, you will need the same subject matter experts that helped you understand the process. This step will not only help to ensure that the model is accurate, it will make others more confident in the model.

Measuring Success
This is not easy, but if you can, compare a decision made without the model to one made with the model. Compare the performance of the implemented system with the model. If there are any significant differences, make note of them so that they can be accounted for in the future. If the model proved to be accurate, use this as political capital for future projects.

Here is a link to a paper I co-authored with Dave Krahl (now at Kromite LLC) a few years ago on getting started with simulation.   It is a great read and contains more details. Dave also helped write this post as well, thanks Dave.


  1. Very good and usefull blog.

  2. This is a very useful article. Having taught simulation and published books on the subject, I completely agree with this advice.


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