Dr. Wheeler
Donald J. Wheeler

Author

SPC Press

Dr. Wheeler is a fellow of both the American Statistical Association and the American Society for Quality who has taught more than 1,000 seminars in 17 countries on six continents. He welcomes your questions; you can contact him at djwheeler@spcpress.com.

Thu, 01/29/2009 - 14:03
More Capability ConfusionA little algebra, done correctly, can take you to places that don’t exist
Mon, 05/01/2017 - 12:03
Here we take a serious look at some nonsensical ideas about capability ratios. Following a quick review of predictability and capability and a brief discussion of the traditional ways of characterizing capability and performance, we will consider…
An F-Test for the 21st CenturyNo one wants to use 100-year-old techniques!
Mon, 04/03/2017 - 12:03
A recent question from a statistician in Germany led me to the realization that the F-test of analysis of variance (ANOVA) fame is in serious need of an update. What the F-ratio does The F-ratio, created by Sir Ronald Fisher around 1925, is a…
The Three-Way ChartSome data structures need more than an average and range chart
Mon, 03/06/2017 - 12:03
The average and range chart handles most situations where the data can be logically organized into homogeneous subgroups. However, this chart breaks down when faced with a hierarchical data structure containing two or more levels of routine…
Don’t We Need Good Measurements? Process behavior charts work with imperfect data
Mon, 02/06/2017 - 11:03
Good measurements are like apple pie and motherhood. Who could ever be against having good measurements? Since we all want good measurements, it sounds reasonable when people are told to check out the quality of their measurement system before…
Evaluating Destructive MeasurementsYou can still put an upper bound on measurement error
Mon, 01/09/2017 - 12:01
What can be done when a test is destructive? How do we characterize measurement error? How can we determine if a test method is adequate for a given product or application? How can we check for bias? All of the techniques for assessing the quality…
The Calibration of Measurement SystemsThe art of using a consistency chart
Mon, 12/05/2016 - 10:43
Who can be against apple pie, motherhood, or good measurements? This is why everyone stands up and salutes when we are told to maintain our measurement systems in good calibration. But what is good calibration? By what method will we achieve it?…
Election FraudIt’s not paranoia when they are stealing your votes
Wed, 11/23/2016 - 09:25
Opinion There was an election in Xanadu recently. One of the issues that was repeatedly brought up was the possibility of election fraud. So out west in the town of Hawtch-Hawtch, the people got some “Hawtch-Hawtch bee watchers” to go out and watch…
How Do You Get the Most Out of Any Process?With a process behavior chart: the locomotive of continual improvement
Mon, 11/07/2016 - 11:41
Now we come to the sixth way to use a process behavior chart. Here we are going to look at how one group of workers used their average and range chart to improve their process. Their part had only one critical dimension, and this dimension had a…
Input and Outcome Charts and EFAST StudiesThe fifth of six uses for process behavior charts
Mon, 10/03/2016 - 14:38
While we may tweak things in production, we rarely get permission to conduct formal experiments with an operating production line. Production’s job is to make product, whereas experiments are what they do in R&D. So how can we learn about an…
Homogeneity ChartsThe fourth of six uses
Tue, 09/06/2016 - 10:28
The question “Is this batch like the others?” is asked all over the world on a daily basis. It turns out that the process behavior chart provides a very effective answer for questions about the homogeneity of the product stream. In World War II,…