Category: Six Sigma

I’m an advocate of using the I-chart as the default control chart. If I am teaching statistical process control (SPC) and can only teach one chart, the I-chart is always the one that I teach. It’s the only control chart I cover in my Lean Six Sigma Green Belt training. It’s the only chart that…

One of the exercises I assign to students in my training involves creating two histograms from normally distributed random numbers. The results often look similar to those shown in figure 1. When I ask students to comment on their histograms I usually get comments about the averages, spread, and other statistical properties. However, that misses…

The web site indeed.com reports that the average Lean Six Sigma Black Belt salary as of March 14, 2011 is $101,000. This value is 38% higher than average salaries for all job postings in the US. Master Black Belt salaries average $115,000.

One of the early lessons in all of our courses asks students to enter a number for the “subjective probability of success” for the project. Several students enter a 1 in this worksheet cell. This indicates that they believe that the project is certain to succeed. In the real world, this is extremely unlikely. Considering…

If it were up to me, statistical hypothesis inference testing would be entirely replaced by confidence intervals. Both methods provide exactly the same information, however: If you do some research you’ll find quite a body of literature complaining about the hypothesis testing approach. This is my small contribution to that cause.

Here’s an exercise from Pyzdek Institute Green Belt training. At a pharmaceutical company they have developed an IV drip device that has an advertised drip rate of 5 drops per minute. A sample of 10 “drippers” is taken from the process and tested by counting the number of drips that occur during a 10 minute…

While I agree that the martial arts terminology is unfortunate and even a bit silly, I also believe that professional recognition serves an important purpose. If the certification is rigorous (a big if, I admit,) then it signals mastery of a well-defined body of knowledge to prospective employers. The employers can then validate the certification…

The following question came to me from a student in my online Six Sigma Black Belt course: QUESTION: I am calculating Ppk‘s for various processes and some values are, for example -1.2 and 1.2. Is it acceptable to take the absolute value for -1.2 and say that both process performances are equal even though the…

I’ve reviewed thousands of improvement projects. I’ve lost count of how many project presentations I’ve attended, either for certification purposes or for presentations to leaders. I’ve come to the conclusion that most Green Belts and Black Belts simultaneously present too much information, and not enough information. If I may speak to Green Belts and Black…