Figuring out what tools to use during the course of a Six Sigma project is a challenge. Not all tools will be used on all projects. The analogy I use in the classroom is a mechanic with a toolbox. In the tool box are different types of tools – screwdrivers, wrenches, pliers, and so on. The tool that the mechanic will select depends on what needs to be done. If there is a Phillips head screw that needs to be turned, then a Phillips screwdriver is appropriate. If a bolt needs to be tightened, then a wrench should be used.
It is not possible for someone to teach you every possible situation when you might need one of these tools. Instead, we teach what a screwdriver does, and teach you how to recognize a screw. It is up to you to understand that whenever you need to insert or remove a screw, you need to use a screwdriver. In the same way, you need to learn each of the Six Sigma tools and what they do, and then recognize the circumstance when it is appropriate to use the tool.
For example, if you want to see what is happening over time, use a run chart. To see if the process is stable or not, use a control chart. If you want to see how the data is distributed by size, use a histogram. If you want to see if the data fits a particular distribution, use a probability plot. And so on.
The biggest issue for most Six Sigma students is that they have only been briefly exposed to each of the tools. It takes a great deal of time and experience to become proficient in the use of the many charts, graphs and statistical tests that are available. Here are some ways to deal with this problem.
We provide our Green Belt students with a book entitled The Lean Six Sigma Pocket Toolbook by Michael A. George, David Rowlands, Mark Price and John Maxey. It contains detailed explanations of how, when and why to use nearly 100 tools. The ISBN for this book is 0-07-144119-0 and it is available in Kindle format.
Our Black Belt course requires students to complete a real-world project. A template is provided that lists the requirements for completing the project. This template includes guidelines on which tools must be used at different points in the project as well as those that may be appropriate under a particular set of circumstances. For example, all projects are required to have a Charter. A designed experiment, on the other hand, is appropriate only under a specific set of circumstances.
Our Black Belt course also includes a series of decision flow charts to help students understand what statistical test or chart to use based on the type of data being analyzed and what we are trying to accomplish. Here is an example, a decision flow chart for comparing a single group of data to a target value.
Your comments or questions about this article are welcome, as are suggestions for future articles. Feel free to contact me by email at firstname.lastname@example.org.
About the author: Mr. Roger C. Ellis is an industrial engineer by training and profession. He is a Six Sigma Master Black Belt with over 48 years of business experience in a wide range of fields. Mr. Ellis develops and instructs Six Sigma professional certification courses for Key Performance LLC. For a more detailed biography, please refer to www.keyperformance.com.