dcsimg
 

Process Capability

Blog posts and articles about tools for assessing the capability of a process in manufacturing and service situations.

Suppose that you plan to source a substantial amount of parts or subcomponents from a new supplier. To ensure that their quality level is acceptable to you, you might want to assess the capability levels (Ppk and Cpk indices) of their manufacturing processes and check whether their critical process parameters are fully under control (using control charts). If you are not sure about the efficiency... Continue Reading
In quality initiatives such as Six Sigma, practitioners often need to assess the capability of a process to make sure it can meet specifications, or to verify that it produces good parts. While many Minitab users are familiar with the capability analysis tools in the Stat menu and in Minitab’s Assistant, the Assistant includes a less-frequently used feature—the Capability Snapshot. What Is the... Continue Reading
There is more than just the p value in a probability plot—the overall graphical pattern also provides a great deal of useful information. Probability plots are a powerful tool to better understand your data. In this post, I intend to present the main principles of probability plots and focus on their visual interpretation using some real data. In probability plots, the data density distribution... Continue Reading
In an earlier post, I shared some great hidden helpers in Minitab Statistical Software that even many veteran users don't know about. Here are a few more! Everything In Its Right Place Minitab’s Project Manager allows you to navigate, view, and manipulate various parts of your project. Right-clicking either the folders or their contents lets you access a variety of menus that allow you to manage... Continue Reading
Remember "The Little Engine That Could," the children's story about self-confidence in the face of huge challenges? In it, a train engine keeps telling itself "I think I can" while carrying a very heavy load up a big mountain. Next thing you know, the little engine has done it...but until that moment, the outcome was uncertain. It's a wonderful story for teaching kids about self-confidence. But... Continue Reading
It's all too easy to make mistakes involving statistics. Powerful statistical software can remove a lot of the difficulty surrounding statistical calculation, reducing the risk of mathematical errors—but  correctly interpreting the results of an analysis can be even more challenging.  No one knows that better than Minitab's technical trainers. All of our trainers are seasoned statisticians with... Continue Reading
Now that you’ve seen how to automatically import data and run analyses in my previous post, let’s create the Monthly Report! I will be using a Microsoft Word Document (Office 2010) and adding bookmarks to act as placeholders for the Graphs, statistics, and boilerplate conclusions. Let’s go through the steps to accomplish this: Open up an existing report that you have previously created in Microsoft... Continue Reading
As a member of Minitab’s Consulting and Custom Development Services team, I get to help companies across a variety of industries create many different types of reports for management. These reports often need to be generated weekly or monthly. I prefer to automate tasks like this whenever possible, so that new or updated reports can be created without much effort. A little investment up front can... Continue Reading
Ughhh... your process is producing some parts that don't meet your customer's specifications! Fortunately, after a little hard work, you find a way to improve the process. However, you want to perform the appropriate statistical analysis to back up your findings and make it easier to explain the process improvements to your boss. And it's important to remember that your boss is much like the boss... Continue Reading
Transformations and non-normal distributions are typically the first approaches considered when the when the Normality test fails in a capability analysis. These approaches do not work when there are extreme outliers because they both assume the data come from a single common-cause variation distribution. But because extreme outliers typically represent special-cause variation, transformations... Continue Reading
We're frequently asked whether Minitab has been validated by the U.S. Food and Drug Administration (FDA) for use in the pharmaceutical and medical device industries. Minitab does extensive testing to validate our software internally, but Minitab’s statistical software is not—and cannot be—FDA-validated out-of-the-box. Nobody's can. It is a common misconception that software vendors can go through a... Continue Reading
In my previous post, I shared a case study of how a small bicycle-chain manufacturing company in India used the DMAIC approach to Six Sigma to reverse declining productivity. After completing the Define, Measure, and Analysis phases, the team had identified the important factors in the bushing creation process. Armed with this knowledge, they were now ready to make some improvements. The Improve... Continue Reading
Using data analysis and statistics to improve business quality has a long history. But it often seems like most of that history involves huge operations. After all, Six Sigma originated with Motorola, and became adopted by thousands of other businesses after it was adopted by a little-known outfit called General Electric. There are many case studies and examples of how big companies used Six Sigma... Continue Reading
Capability statistics are wonderful things. These statistics tell you how well your process is meeting the specifications that you have. But there are so many capability statistics that it's worth taking some time to understand how they’re useful together. Two capability statistics that are hard to keep straight are Cp and Cpk. Their names are different by only a single letter. A single letter... Continue Reading
by Jeff Parks, guest blogger Being a Cincinnati Bengals fan is tough. It's true that Bengals fans don't have it as bad as, say, long-suffering Chicago Cubs fans...nevertheless, the Bengals haven’t won a playoff game since January 1991. That's currently the longest streak in the NFL. In the 1990s they were voted the worst sports franchise by ESPN. Not the worst football team, mind you, but the worst... Continue Reading
To promote ethical and moral responsibility in shaping its graduates, Rose-Hulman Institute of Technology created a sustainability initiative to reduce its own environmental footprint. As part of that team's efforts, Six Sigma students at Rose-Hulman conducted a project to reduce food waste at the campus dining center. We got the opportunity to learn more about the project by talking with Dr. Diane... Continue Reading
The DMAIC methodology for completing quality improvement projects divides project work into five phases: define, measure, analyze, improve, and control. It’s also probably the most well-known and most used project methodology for projects that focus on improving an existing process. (Many other methodologies exist, such as DMADV, which focuses on using quality improvement techniques to create a... Continue Reading
A while back my colleague Jim Frost wrote about applying statistics to decisions typically left to expert judgment; I was reminded of his post this week when I came across a new research study that takes a statistical technique commonly used in one discipline, and applies it in a new way.  The study, by paleontologist Zhijie Jack Tseng, looked at how the skulls of... Continue Reading
When you learned statistics, most of what you learned was centered around the Normal distribution.  Maybe you became close friends and you later found out his birth name was Gaussian, but either way you probably just call him Normal. You might know Normal’s a pretty popular guy with plenty of relationships with other distributions.  There are some obvious connections, like how eNormal is Lognormal,... Continue Reading
Unless you’re 3 years old, you probably can’t have things just the way you want them all the time.   You can’t always have peanut butter and ranch dressing on your toast. Or ketchup on your pineapple. Or sugar sprinkles on your peas. But there is one small arena in life over which you can still exert your control.  Tools > Options in Minitab's statistical softwareallows you to change selected default... Continue Reading