Statistics Features

John Flaig's picture
John Flaig
Story update 9/26/2017: The words "distribution of" were inadvertently left out of the last sentence of the second paragraph. Some practitioners think that if data from a process have a “bell-shaped...
Davis Balestracci's picture
Davis Balestracci
I have reached one of those life landmarks (receiving my Medicare card) and have been reflecting back... a lot. I will remain every bit as passionate about improvement and don’t think I will ever...
Eston Martz's picture
Eston Martz
The Six Sigma quality improvement methodology has lasted for decades because it gets results. Companies in every country around the world, and in every industry, have used this logical, step-by-...
Donald J. Wheeler's picture
Donald J. Wheeler
Sometimes we use a chart for individual values and a moving range (an XmR chart) to assess the homogeneity of a finite data set. Since this is an "off-label" use for the XmR chart, we first...
Eston Martz's picture
Eston Martz
Six Sigma is a quality improvement method that businesses have used for decades—because it gets results. A Six Sigma project follows a clearly defined series of steps, and companies in every...
Harish Jose's picture
Harish Jose
It’s been a while since I’ve written about statistics. So in this column, I will be looking at the rules of three and five. These are heuristics, or rules of thumb, that can help us out. They are...
Ville Satopaa's picture
Ville Satopaa
At a 1906 livestock show in Plymouth, England, nearly 800 people participated in a contest to guess the weight of a slaughtered ox. The average of these estimates was 1,197 pounds. This is...
Barbara A. Cleary's picture
Barbara A. Cleary
If you get off the highway and take an alternate route when traffic slows to one lane, you are making a prediction. Likewise, if you decide to invite someone to dinner, that too is a prediction....
Davis Balestracci's picture
Davis Balestracci
Many of you work in organizations that keep track of customer complaints. Have you ever thought of how they are recorded and tallied? What could possibly be wrong with this process: The customer...
Dirk Dusharme @ Quality Digest's picture
Dirk Dusharme @ Quality Digest
Our August 11, 2017, episode of QDL looked at the role of technology in after-market service, stairs that help you up, Fidget Cubes, and more. “Climbing Stairs Just Got Easier With Energy-Recycling...
Phil Klotzbach's picture
Phil Klotzbach
June 1 marked the official start of the Atlantic hurricane season, which runs through the end of November. It’s a busy time for us at the Tropical Meteorology Project in Colorado State University’s...
Patrick Runkel's picture
Patrick Runkel
It’s usually not a good idea to rely solely on a single statistic to draw conclusions about your process. Do that, and you could fall into the clutches of the “duck-rabbit” illusion shown below...
John Niggl's picture
John Niggl
Ever wondered why quality control (QC) professionals check a sample instead of 100 percent of a shipment during inspection? Or maybe you’ve wondered why they use acceptance sampling, rather than...
Donald J. Wheeler's picture
Donald J. Wheeler
Last month I mentioned that we can put autocorrelated data on a process behavior chart. But what is autocorrelated data and what does it tell us about our processes? This article will use examples...
Davis Balestracci's picture
Davis Balestracci
Recently I demonstrated a common incorrect technique for comparing percentage rate performances—based of course in the usual normal distribution nonsense. Let’s revisit those data with a superior...
Donald J. Wheeler's picture
Donald J. Wheeler
The simplest type of process behavior chart is the chart for individual values and a moving range. It allows us to plot a point every time we get a value, making it perfect for data that occur one...
Steve Daum's picture
Steve Daum
I have daily conversations with manufacturer plant managers, quality managers, engineers, supervisors, and plant production workers about challenges when using statistical process control (SPC). Of...
Davis Balestracci's picture
Davis Balestracci
My last column mentioned how doctors and hospitals are currently being victimized with draconian reactions to rankings, either interpreted literally or filtered through the results of some type of...
Derek Benson's picture
Derek Benson
How early is too early to introduce quality into your everyday life? Have we missed out on improvement opportunities in our personal lives along our paths to achieving our career goals as quality...
Donald J. Wheeler's picture
Donald J. Wheeler
In their recent article, “We Do Need Good Measurements,” Professors Stefan H. Steiner and R. Jock MacKay take exception to two of my Quality Digest articles, “Don’t We Need Good Measurements?” and...