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
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
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
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
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
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...
Stefan H. Steiner
In his February 2017 Quality Digest column, “Don’t We Need Good Measurements?” Donald J. Wheeler recommends that a measurement system contributing up to 80 percent of the overall variation (on the...
Joel Smith
In parts one and two of “Gauging Gage,” we looked at the numbers of parts, operators, and replicates used in a gage repeatability and reproducibility (GR&R) study and how accurately we could...
Joel Smith
In part one of “Gauging Gage,” I looked at how adequate a sampling of 10 parts is for a gage repeatability and reproducibility (GR&R) study and provided some advice based on the results.
Now...
Davis Balestracci
Don’t tell me you’re not tempted to look when you spot a magazine cover saying, “How does your state rank in [trendy topic du jour]?” Many of these alleged analyses rank groups on several factors,...
Joel Smith
‘You take 10 parts and have three operators measure each two times.”
This standard approach to a gage repeatability and reproducibility (GR&R) experiment is so common, so accepted, so...
Fred Faltin
All of us draw conclusions based on what we see happening around us. Often what we’re observing is a sample from some larger population of events, and we draw inferences based on the sample without...
Donald J. Wheeler
Here we take a serious look at some nonsensical ideas about capability ratios. Following a quick review of predictability and capability and a brief discussion of the traditional ways of...
Steve Moore
When I entered college in the fall of 1970, I had a nice slide rule (or “slipstick” as some of us called it) that I proudly carried in a leather case to my engineering and chemistry classes....
Davis Balestracci
Many talk about reducing variation to improve quality. Does that include human variation, where everyone takes a different approach to improving overall improvement processes? What would...
Quality Transformation With David Schwinn
This month’s column comes from a convergence of finishing my article, “Statistical Thinking for OD Professionals,” for the OD Practitioner, and reading “How Statistics Lost their Power—and Why We...
Donald J. Wheeler
A recent question from a statistician in Germany led me to the realization that the F-test of analysis of variance (ANOVA) fame is in serious need of an update.
What the F-ratio does
The F-...
Patrick Runkel
Did you ever wonder why statistical analyses and concepts often have such weird, cryptic names?
One conspiracy theory points to the workings of a secret committee called the ICSSNN. The...
Davis Balestracci
According to Mark Graham Brown, from his book Keeping Score (Productivity Press, 2006), 50 percent of the time leaders spend in meetings involving data is waste, 80 percent of the pounds of...
Donald J. Wheeler
The average and range chart handles most situations where the data can be logically organized into homogeneous subgroups. However, this chart breaks down when faced with a hierarchical data...
