Statistics Features

Donald J. Wheeler's picture
Donald J. Wheeler
Capability ratios are widely used and sometimes misunderstood. The computer will gladly offer up values of each of the commonly used capability and performance indexes. Yet there is little...
Mike Richman's picture
Mike Richman
Sustainable performance improvement is simply impossible without a firm handle on the precepts and tools of statistical process control (SPC). It is for this reason that we cover industrial...
Bonnie Stone's picture
Bonnie Stone
Lean, also known as “lean manufacturing” or “lean production,” focuses on maximizing customer value by removing waste and eliminating defects. Lean tools are about understanding the process,...
Eston Martz's picture
Eston Martz
Control charts take data about your process and plot it so you can distinguish between common-cause and special-cause variation. Knowing the difference is important because it permits you to...
Scott A. Hindle's picture
Scott A. Hindle
In theory, a production process is always predictable. In practice, however, predictable operation is an achievement that has to be sustained, which is easier said than done. Predictable operation...
Barbara A. Cleary's picture
Barbara A. Cleary
Taking time off for vacation seems to be a diminishing phenomenon among U.S. workers. Each year, Americans fail to use 662 million vacation days, and with those days $236 billion in economic...
Davis Balestracci's picture
Davis Balestracci
In my last column, I reflected back on my career to date and issued a challenge. Based on the relatively lukewarm response, let’s see whether I can engage a few more of you to join me on my...
Donald J. Wheeler's picture
Donald J. Wheeler
How do extra detection rules work to increase the sensitivity of a process behavior chart? What types of signals do they detect? Which detection rules should be used, and when should they be used...
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...