Author Archives: developers

You can’t judge a book by its cover

In our Green Belt program we have an exercise where students create a histogram from a set of data.  Most students use Excel to create their histogram, and here is the resulting graph: When submitting their work, students quite often include a statement to the effect that the data is “normally distributed” because it appears […]

Six Sigma training – online or classroom?

One of the dilemmas that students face when choosing Six Sigma certification training is whether to attend a live, instructor led course in a traditional classroom setting or an online course.  Both types of delivery have pluses and minuses. In the classroom, you will have the benefit of interaction with your instructor and the other […]

Multiple Intelligences and Six Sigma Training

I am often asked to provide recommendations on how to develop and/or select Six Sigma training programs.  An interesting and very useful theory of how people develop and learn is the theory of Multiple Intelligences, developed by Howard Gardner, PhD, Professor of Education at Harvard University. This theory explains that each of us has a […]

Lies and Statistics……

One of my Black Belt students recently submitted his final project report.  He used the two proportions test in Minitab to compare the proportion of on time performance for completion of employee appraisals, before and after improvement.  I sent him the following feedback regarding this test. “Hi.  Your null and alternate hypotheses are correctly stated.  […]

The Central Limit Theorem

Although the central limit theorem can seem abstract and devoid of any practical application, this theorem is actually quite important to the practice of statistics.  As we will see, this theorem allows us to make some assumptions about a population. In order to understand the basis for the Central Limit Theorem, consider a population of […]

Waste and Contributors to Waste

We should constantly strive to provide exactly what the customer wants when working on process improvement.  One way to do so is to identify activities that are wasteful and then work to reduce or eliminate those activities.  Waste is defined as an activity that consumes resources but does not add any value for the customer.   […]

Evaluating Gage Bias and Linearity

In an earlier article in this series, I introduced some basic issues in measurement systems analysis such as granularity, accuracy, reproducibility, repeatability, stability and linearity.  In this article we will explore in more detail how to evaluate the performance of a measurement system with respect to bias and linearity. Gage bias examines the difference between […]