All Features
Bruno Scibilia
The Cp and Cpk are well-known capability indices commonly used to ensure that a process spread is as small as possible compared to the tolerance interval (Cp), or that it stays well within specifications (Cpk). Yet another type of capability index exists: the Cpm, which is much less known and used…
Michelle Shemo
As a member of Minitab’s technical support team, I get the opportunity to work with many people using design of experiments (DOE).
People often will call after they’ve already chosen their design, run the experiment, and identified the important factors in their process. But now what? They have…
Patrick Runkel
Right now I’m enjoying my daily dose of morning joe. As the steam rises off the cup, the dark, rich liquid triggers a powerful enzyme cascade that jump-starts my brain and central nervous system, delivering potent glints of perspicacity into the dark crevices of my still-dormant consciousness.…
Davis Balestracci
I have evolved to using fewer, simpler tools in my consulting and have never been more effective, as I commented upon in my last column. It made me ponder the relevance of much of what I learned in my master’s statistics program. Thinking of the most basic concepts, I decided to look up what the…
The purpose of this article is to point out a problem when using percentages for subgroups over time, or for members in a larger group, where the size of the denominator varies and probabilities are being estimated. Also to introduce a solution: adjusted p-chart scores (APC), a new way to score or…
Thomas R. Cutler
This is the last in a series about how lean manufacturing has affected the people and the companywide culture at Hytrol Conveyors, a designer and manufacturer of advanced conveyor systems. As described in part 1 and part 2, dozens of interviews were conducted with a wide range of employees at the…
Dawn Keller
I really can’t make this stuff up.
I wrote a post a couple of years ago titled: “How to Talk to Your Kids About... Quality Improvement,” in which I lamented about Community Hero Day in my daughter’s first-grade class and the need to explain to her why I wasn’t at the “community-hero level” of…
Mark Rosenthal
The title of this article is a search term that recently hit The Lean Thinker site. It’s an interesting question—and interesting that it gets asked.
“Kaizen” is now an English word—it’s in the OED—and defined as such: “Noun. A Japanese business philosophy of continuous improvement of working…
Matthew Barsalou
There are many tools available for investigating quality problems. One useful and easy-to-use set of statistical tools is John W. Tukey’s exploratory data analysis (EDA), which quality engineers can use for generating hypotheses. Tukey’s EDA provides many different methods for looking at data, and…
Thomas R. Cutler
In November 2014, Quality Digest Daily published the first in a series about companywide lean cultures and how a lean journey affects people and companies. Jonesboro, Arkansas-based Hytrol Conveyors, a designer and manufacturer of advanced conveyor systems, allowed an in-depth examination of why…
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…
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…
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 “…
Gary Phillips
For decades now, the measurement systems analysis (MSA) approach has been the predominant method for evaluating measurement systems capability. Although this method is widely considered to be an acceptable and comprehensive approach throughout most of the world, a growing number of specialized…
Abdallah Samaha
Lin Engineering is a California-based manufacturer of hybrid step motors that was founded in 1987 as a consulting company specializing in step-motor applications. Today, Lin Engineering is the largest manufacturer of 0.9-degree step motors in the motion control industry. As the quality and custom-…
Jay Arthur—The KnowWare Man
When looking at any existing process, people often have a hard time visualizing the enormous amount of delay, waste, and nonvalue-added work involved. That’s where a time value map comes in; it makes the invisible waste visible. A time value map shows value-added and nonvalue-added activities and…
Lean Math With Mark Hamel
Available time for changeovers per period (Ta∆), also called available time for (internal) setups, represents the time per a given period (e.g., day, shift, week) during which a machine, equipment, or resource can be changed over (i.e., from one product to another, prepared for a different medical…
David Muil
Management systems are sometimes misunderstood as nothing more than a heavy administrative burden providing limited business benefit. In fact, many organizations with management systems in place haven’t effectively defined the processes they actually employ at all. Perhaps it’s because they think…
Donald J. Wheeler
Why bother to plot your data? A simple shortcut is available that will allow you to do your analysis without the data getting in the way. How do you accomplish this breakthrough? Read on.
This marvelous advance in analysis is known as the “data-free graph.” As usual we begin with a collection of…
Matthew J. Savage
Lori, a software customer, phoned to ask if Cpk is the best statistic to use in a process that slits metal to exacting widths. As a PQ Systems technical support analyst, I too wondered what index would be best suited for her application, a highly specialized one. Perhaps Cpk, Ppk, Cpm, or some…
Bruno Scibilia
My main objective is to encourage greater use of statistical techniques in the service sector and present new ways to implement them.
In a previous blog, I presented an approach you can use to identify process steps that may be improved in the service sector (quartile analysis). here I’ll show…
Bob Emiliani
Let’s get rid of value stream maps. I can hear it now: “Why would you say such a thing? Value stream maps are great. We can’t see waste without them.”
Precisely.
Value stream maps have developed an outsized importance in relation to other types of basic information that one gathers when trying to…
John Flaig
Engineers have used safety margins for centuries to protect their companies and customers from the consequences of product degradation and failure. Sometimes the safety margins are fairly obvious (e.g., maximum-load limits posted in elevators), and other times they’re not.
Design margins are…