Statistics Features

Anthony D. Burns's picture
Anthony D. Burns
Quality is related to processes. A process is “a series of actions or steps taken in order to achieve a particular end.” It doesn’t matter whether the process is the handling of invoices, customers...
Cheryl Pammer's picture
Cheryl Pammer
Confidence intervals show the range of values we can be fairly, well, confident, that our true value lies in, and they are very important to any quality practitioner. I could be 95-percent confident...
Rip Stauffer's picture
Rip Stauffer
A lot of people in my classes struggle with conditional probability. Don’t feel alone, though. A lot of people get this (and simple probability, for that matter) wrong. If you read Innumeracy by John...
Donald J. Wheeler's picture
Donald J. Wheeler
Some properties of a probability model are hard to describe in practical terms. The explanation for this rests upon the fact that most probability models will have both visible and invisible portions...
Mike Richman's picture
Mike Richman
There are many subjects that we cover regularly here at Quality Digest. Chief among these are standards (ISO 9001 or IATF 16949, for example) methodologies (such as lean, Baldrige, or Six Sigma), and...
Donald J. Wheeler's picture
Donald J. Wheeler
In The Music Man, the con man Prof. Harold Hill sells band instruments and uniforms and then tells the kids that they can play music if they will “just think about the notes and then play them.” In...
Evan McLaughlin's picture
Evan McLaughlin
As the vice president of quality for a $1.5 billion-dollar industrial corporation, Hermann Miskelly is responsible for leading its continuous improvement effort. Now in his 10th year of a lean Six...
Davis Balestracci's picture
Davis Balestracci
Customer satisfaction surveys are all the rage these days. Healthcare has a couple of “800 pound gorilla” surveyors whose services (and nontrivial expense) have been pretty much forced upon it. In...
Douglas C. Fair's picture
Douglas C. Fair
Here’s a quick rundown of what we covered in part one of our list of top 10 mistakes to avoid when using statistical process control (SPC): training everyone, charting everything, segregating control...
Douglas C. Fair's picture
Douglas C. Fair
As you think about your organization’s manufacturing quality efforts—what you’ve overcome and what you hope to accomplish in the future—there is something you need to know. You: What? Who? Me? Me...
Minitab Inc.'s picture
Minitab Inc.
Anticipating challenges is always a daunting task for continuous improvement professionals. Unforeseen inefficiencies in process or defects in product development can throw timelines and associated...
Donald J. Wheeler's picture
Donald J. Wheeler
Last month we looked at what the empirical rule tells us about the data in a histogram. This month we will consider if there are any commonalities between different probability models that will...
Davis Balestracci's picture
Davis Balestracci
Because of a growing movement in the health insurance industry toward not reimbursing hospitals for any expenses caused by a system-acquired infection, one health system made efforts to improve its...
Larry Silverberg's picture
Larry Silverberg
Some 20 years ago, my colleague Chau Tran and I developed a way to simulate the trajectories of millions of basketballs on the computer. We went to the coaches and assistant coaches at North...
Donald J. Wheeler's picture
Donald J. Wheeler
How can we use descriptive statistics to characterize our data? When I was teaching at the University of Tennessee I found a curious statement in a textbook that offered a practical answer to this...
Davis Balestracci's picture
Davis Balestracci
The Individuals chart is the “Swiss Army knife” of control charts. It usually approximates the supposedly “correct” chart under most conditions, and its use is much easier to understand and explain...
NIST's picture
NIST
On February 14, 1929, gunmen working for Al Capone disguised themselves as police officers, entered the warehouse of a competing gang, and shot seven of their rivals dead. The St. Valentine’s Day...
Donald J. Wheeler's picture
Donald J. Wheeler
Whenever we make a measurement, we have to decide how many digits to record. Traditional answers for this question are often little more than guesswork glorified by time. And with digital readouts...
Andrew Hwang's picture
Andrew Hwang
National discussions of crucial importance to ordinary citizens—such as funding for scientific and medical research, bailouts of financial institutions, and revised tax laws—inevitably involve...
Donald J. Wheeler's picture
Donald J. Wheeler
The precision to tolerance ratio is commonly used to characterize the usefulness of a measurement system. While this ratio is appealingly simple, it overstates the damage due to measurement error....