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.

Mon, 12/08/2025 - 12:03
Statistics 101 and Data Analysis: an Example There may be a pop quiz on the secret foundation of statistical inference
Mon, 03/07/2016 - 15:49
Here we look at a simple example to discover the commonalties of various data analysis techniques widely used in industry today. Careful consideration of the following may result in insights that were not part of your introductory class in…
The Levey-Jennings Chart How to get the most out of your measurement system
Mon, 02/01/2016 - 10:43
The Levey-Jennings chart was created in the 1950s to answer questions about the quality and consistency of measurement systems in the chemical and process industries. This column will illustrate the fatal flaw in this technique and show a better…
Statistical Tolerance Intervals How to make exact predictions
Mon, 01/04/2016 - 15:35
One computation that modern software offers to unsuspecting users is the statistical tolerance interval. Since this sounds very much like limits for individual values, some have been tempted to use them on process behavior charts in place of the…
The Secret Foundation of Statistical Inference What you don’t know can hurt you
Tue, 12/01/2015 - 15:14
When industrial classes in statistical techniques began to be taught by those without degrees in statistics it was inevitable that misunderstandings would abound and mythologies would proliferate. One of the things lost along the way was the secret…
Shewhart and the Probability Approach The difference is much greater than how we compute the limits
Mon, 11/02/2015 - 14:39
In theory, there is no difference between theory and practice. In practice, there is. During the past three months we have looked at three families of probability models and found that they share some remarkable properties. These properties provide…
Properties of Probability Models, Part 3 What they forgot to tell you about the lognormals
Mon, 10/05/2015 - 16:43
The best analysis is the simplest analysis that provides the needed insight. Of course this requires enough knowledge to strike a balance between the needed simplicity and unnecessary complexity. In parts one and two of this series we looked at the…
Properties of Probability Models, Part 2 What they forgot to tell you about the Gammas
Tue, 09/01/2015 - 15:53
Story update 9/8/2015: There was an error in the data set for columns "Skew" and "Kurt" in figure 7. The error has been corrected. Clear thinking and simplicity of analysis require concise, clear, and correct notions about probability models and…
Properties of Probability Models, Part 1 What they forgot to tell you about Weibull distributions
Mon, 08/03/2015 - 17:04
Some commonly held ideas about skewed probability models are incorrect. These incorrect ideas are one source of complexity and confusion regarding the analysis of data. By examining the basic properties of skewed distributions this article can help…
Rational Sampling More about the conceptual foundation of process behavior charts
Wed, 07/01/2015 - 17:03
While the computations for a process behavior chart are completely general and very robust, the secret to using a process behavior chart effectively lies in the art of rational sampling and rational subgrouping. Rational subgrouping was the topic…
Rational Subgrouping The conceptual foundation of process behavior charts
Mon, 06/01/2015 - 01:00
While the computations for a process behavior chart are completely general and very robust, the secret to using a process behavior chart effectively lies in the art of rational sampling and rational subgrouping. Rational subgrouping has to do with…