All Features
Donald J. Wheeler
Whenever the original data pile up against a barrier or a boundary value, the histogram tends to be skewed and non-normal in shape. In 1967 Irving W. Burr computed the appropriate bias correction factors for non-normal probability models. These bias correction factors allow us to evaluate the…
Tripp Babbitt
In my last column I wrote about the seven perspectives that pollute customers and culture. These perspectives rule the design of our organizations. They are inherent to our work cultures and thinking. They put us on autopilot as we toil in our everyday work. The first step to change that is to…
David Schwinn
My wife, Carole, and I recently participated in the 16th Annual ILA (International Leadership Association) Global Conference. The theme was conscious leadership. At the conference, Meg Wheatley was given a Lifetime Achievement Award. That puts her in the company of Peter Drucker, Warren Bennis,…
Meredith Griffith
During the last year or so I've heard a lot of people asking, "How can I calculate B10 life in Minitab?" Despite my being a statistician and an industrial engineer (mind you, one who's never actually been in the field) and having taken a reliability engineering course, I'd never heard of B10 life…
Mike Micklewright
Editor’s note: This article discusses topics covered at greater length in episodes 19–23 of a new streaming video training series, Creating and Sustaining Lean Improvements—Integrating Principles, Culture, and Tools by the author and 360 Performance Circle, a sister company to Quality Digest.…
Bruce Hamilton
There was a time when it was unfashionable for managers to associate with front-line employees. Alluding to an old adage, I used to joke that you could not even lead the horse (i.e., the manager) to water, let alone make him drink. Division of labor at that time was a great divide. In my early…
Donald J. Wheeler
There is no virtue in obedience when we do not have a choice. But when we have a choice it helps to understand both the law and the reason behind the law. This column is about bad choices that are being made on a daily basis by the users of statistical software. These bad choices violate the laws…
Walter Garvin
The foundation of lean manufacturing is kaizen, or continuous improvement. Although this principle usually targets manufacturing processes, it can also extend to the people who plan and implement lean projects—individuals that grow professionally and personally as a result of new skills and…
Danei Edelen
With multiple projects vying for your budgetary dollars, every purchase is scrutinized. With regards to statistical process control (SPC) software, companies view it primarily as a production efficiency tool, but they should expect more from their SPC software solution.
When evaluating SPC…
Bob Emiliani
Have the leading figures in the lean community walked the “Respect for People” talk? Not in my view.
Most of these leaders have only recently begun to understand and embrace the “Respect for People” principle. Although there are many dimensions to the “Respect for People” principle within lean,…
Bruno Scibilia
Using statistical techniques to optimize manufacturing processes is quite common now, but using the same approach on social topics is still an innovative approach. For example, if our objective is to improve student academic performances, should we increase teachers’ wages, or would it be better…
Donald J. Wheeler
Much of modern statistics is concerned with creating models which contain parameters that need to be estimated. In many cases these estimates can be severely affected by unusual or extreme values in the data. For this reason students are often taught to polish up the data by removing the outliers…
Mike Micklewright
You and your spouse go out to dinner to your favorite restaurant, on a “date” no less, to celebrate a big anniversary. You have been looking forward to this evening all week, and after a long, hard day at work, you’re famished and excited to eat your favorite meal. As you order dinner, the waiter…
Davis Balestracci
My last article demonstrated a common incorrect technique—based in “traditional” statistics—for comparing performances based on percentage rates. This article will use the same data to show what should be done instead.
To quickly review the scenario: In an effort to reduce unnecessary expensive…
Steve Moore
Up until a few years ago, I wasn’t a big fan of run charts. Why not just go ahead and construct a process behavior chart and move on? Well, sometimes a run chart is more appropriate for certain data structures.
For example, some data are “chunky”—see Donald Wheeler’s treatment of chunky data in…
Patrick Runkel
The word “kurtosis” sounds like a painful, festering disease of the gums. But the term actually describes the shape of a data distribution.
Frequently, you’ll see kurtosis defined as how sharply “peaked” the data are. The three main types of kurtosis are shown below.
Lepto means “thin” or “…
David Schwinn
Shortly after the death of the brilliant comedian and actor Robin Williams, his daughter Zelda quit Twitter and Instagram following online harassment over his death. How sad. We seem to somehow like to see the dark side of the world.
Even my three tennis buddies seem unable to keep from trash…
Jim Frost
In a previous article, I showed why there is no R-squared for nonlinear regression. Anyone who uses nonlinear regression will also notice that there are no P values for the predictor variables. What’s going on?
Just like there are good reasons not to calculate R-squared for nonlinear regression,…
Davis Balestracci
My last column, “Dealing With Count Data and Variation,” showed how a matrix presentation of stratified count data could be quite effective as a common-cause strategy. I’ll use this column to review some key concepts of count data as well as to demonstrate the first of two common statistical…
Akhilesh Gulati
An important concept within TRIZ is that someone, somewhere, has already solved your current problem. In other words, they have “been there, done that.” Or course, the problem has to be clearly stated, in a generic sense, to enable the recognition of existing valid solutions.
TRIZ is not alone in…
Bob Emiliani
The lean community continues to face a problem that hurts efforts to advance progressive lean management: It is the great difficulty in clearly separating and effectively communicating the difference between real lean and fake lean, i.e., lean management done right vs. lean management done wrong…
Arun Hariharan
On a recent visit to Japan, I had an opportunity to visit Toyota’s headquarters. During a meeting with some of its top executives, I asked one of them what role the senior leadership played in Toyota’s much-admired quality philosophy. The reply I received was, like many things about Toyota and…
Joel Smith
Learning to ride a bike is a rite of passage for any kid, so much so that we even use the expression “taking the training wheels off” for all kinds of situations. We say it to mean that we are going to let someone perform an activity on his own after removing some safeguard, even though we know he…
David Schwinn
Last evening my wife, Carole, and I attended a celebratory dinner for the family of one of my former students. Luca, my student, originally from Italy, brought his wife, Olivia, and his young daughter, Kendra.
Olivia, originally from Uganda, is a family physician working primarily with…
Patrick Runkel
If you teach statistics or quality statistics, you’re probably already familiar with the cuckoo egg data set.
The common cuckoo has decided that raising baby chicks is a stressful, thankless job. It has better things to do than fill the screeching, gaping maws of cuckoo chicks, day in and day out…