Statistics Article Features

Paul Laughlin's picture
Paul Laughlin
As I started reading The Book of Why: The New Science of Cause and Effect, by Judea Pearl and Dana Mackenzie (Basic Books, 2018), I was reminded how often analysts trot out the bromide “correlation...
Donald J. Wheeler's picture
Donald J. Wheeler
Students are told that they need to check their data for normality before doing virtually any data analysis. And today’s software encourages this by automatically providing normal probability plots...
Donald J. Wheeler's picture
Donald J. Wheeler
Acceptance sampling uses the observed properties of a sample drawn from a lot or batch to make a decision about whether to accept or reject that lot or batch. Although the textbooks are full of...
Danielle Underferth's picture
Danielle Underferth
As municipalities clamor for a slice of President Biden’s $1.2 trillion infrastructure spending bill, one Johns Hopkins scientist is re-examining one of the basic elements of road-building:...
Scott A. Hindle's picture
Scott A. Hindle
In 2010, new to the world of statistical process control (SPC), I was intrigued by Don Wheeler’s statement that “No data have meaning apart from their context” (from his book, Understanding...
Tristan Mobbs's picture
Tristan Mobbs
All too often the topic of fixing dirty data is neglected in the plethora of online media covering artificial intelligence (AI), data science, and analytics. This is wrong for many reasons. To...
Donald J. Wheeler's picture
Donald J. Wheeler
Last month we looked at analyzing observational data. Here we will consider experimental data and discover a weakness in the way they are obtained that can contribute to the problem of...
Atul Minocha's picture
Atul Minocha
Do you ever feel like you’re spending money like crazy on marketing and getting little or nothing in return? If so, you might be tempted to pull the plug on marketing altogether. That would be a big...
Donald J. Wheeler's picture
Donald J. Wheeler
Most of the world’s data are obtained as byproducts of operations. These observational data track what happens over time and have a structure that requires a different approach to analysis than that...
Anthony D. Burns's picture
Anthony D. Burns
I’m a chemical engineer. The fundamentals of the chemical engineering profession were laid down 150 years ago by Osborne Reynolds. Although chemical engineering has seen many advances, such as...
Donald J. Wheeler's picture
Donald J. Wheeler
On the face of it, it seems to be impossible for skewed variables to add up to a normally distributed result. Yet both common experience and mathematical theory combine to show us that this does...
Donald J. Wheeler's picture
Donald J. Wheeler
Management requires prediction. However, when making predictions it is easy to torture the data until they surrender and tell you what you expect to hear. Even though this torture may be...
W. Edwards Deming's picture
W. Edwards Deming
Editor’s note: The following is from a transcript of a forgotten speech given in Tokyo in 1978 by W. Edwards Deming for the Union of Japanese Scientists and Engineers (JUSE). Because the original was...
Donald J. Wheeler's picture
Donald J. Wheeler
One of the most common questions about any production process is, “What is the fraction nonconforming?” Many different approaches have been used to answer this question. This article will compare the...
Steve Moore's picture
Steve Moore
In this year’s April issue of the Bridge Bulletin, the ACBL (American Contract Bridge League) unveiled a new logo as part of a rebranding campaign to promote the beloved game of bridge to a wider...
Donald J. Wheeler's picture
Donald J. Wheeler
First, let it be known that all charts for count-based data are charts for individual values. Regardless of whether we are working with a count or a rate, we obtain one value per time period and want...
Jay Arthur—The KnowWare Man's picture
Jay Arthur—The KnowWare Man
There are many control chart rules to detect special causes (i.e., out-of-control conditions). Although most of these rules are clear, the one that seems to befuddle most people is the rule about...
Donald J. Wheeler's picture
Donald J. Wheeler
What do the shape statistics known as skewness and kurtosis tell us about our data? Last month we saw how the average and standard deviation define the balance point and radius of gyration for our...
William A. Levinson's picture
William A. Levinson
Part one of this article showed that it is possible, by means of a Visual Basic for Applications program in Microsoft Excel, to calculate the fraction of in-specification product that is rejected by...
William A. Levinson's picture
William A. Levinson
IATF 16949:2016 clause 7.1.5.1.1 requires measurement systems analysis (MSA) to quantify gage and instrument variation. The deliverables of the generally accepted procedure are the repeatability or...