Our Green Belt course includes an exercise where students create a histogram from a file of 100 data values. Here is the histogram of the data, with a normal probability distribution curve superimposed: Students are not asked to comment on the result, but most are unable to resist doing so. The majority who do comment […]

# Tag Archives: Six Sigma

The choice of which statistical test to use is often determined in part by whether the data is continuous or discrete. Our Green Belt course includes an exercise where students are asked to convert continuous data into discrete categories. For example, time to complete a transaction is continuous data. Discrete categories for delivering a package […]

Our Yellow Belt course includes an assignment that challenges students to think about improving the processes that serve their customers. One of my Yellow Belt students works for a non-profit foundation that raises funds that are used for providing scholarships to students and grants to educators. She recently submitted the following statement: “My organization’s customers […]

Process capability studies calculate the process capability indices Cp and Cpk. These statistics tell us how well the process is meeting specifications or requirements. Capability studies are designed for two-sided specifications that have an upper and a lower limit. Adjustments must be made when we have a one-sided specification and/or a boundary limit in place […]

In article 73 in this series, I discussed the issue of whether to transform data. Students of Six Sigma often think (incorrectly) that there is something inherently wrong with their data if it is not normally distributed. We should always strive to understand why the data is distributed the way it is and recognize that […]

The PDCA cycle (Plan-Do-Check-Act) is an iterative four-step approach for managing and improving products and business processes. Today we will discuss how the PDCA approach is used by sports teams, with an eye toward how this same thinking can be applied to improving the performance of business processes and products. The Plan Phase begins with […]

In our Black Belt program, we make extensive use of Minitab statistical software. The software performs the actual mathematical calculations, relieving the student of the burden of knowing how to do them using paper and pencil. To use Minitab effectively, students must be able to choose the appropriate test or analysis to perform for a […]

One of my Black Belt students recently submitted an interim project report. The goal of her project is to reduce the time it takes to complete a certain transaction. The project Y metric is success rate, where a success is defined as completing the transaction in 24 hours or less. The goal after improvement is […]

In the Improve phase of a Six Sigma project, we typically need to choose between two or more potential solutions to a problem. There are several tools to help in making this decision, one of which is pairwise ranking. Pairwise ranking is used by individuals or teams to qualitatively prioritize a list of alternatives. There […]

Our online Green Belt program includes an assignment where students are introduced to Six Sigma by reading a lecture, reading Chapter One in the text, and viewing several videos. They are then challenged to explain how the readings and videos either reinforced or changed their preconceived notion of what Six Sigma is, based on what […]