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Eston Martz

I’m not a “math” person, but I've overcome fear of statistics and acquired a real passion for it. And if I can learn to understand and apply statistics, so can you. Continue Reading »

In my last post, I showed how to use Minitab Statistical Software to create an acceptance sampling plan by variables, using the scenario of a an electronics company that receives monthly shipments of LEDs that must have soldering leads that are at least 2 cm long. This time, we'll compare that plan with some other possible options.  The variables sampling plan we came up with to verify the... Continue Reading
Earlier, I shared an overview of acceptance sampling. Now we'll look at how to do acceptance sampling by variables, facilitated by the tools in Minitab Statistical Software. If you're not already using it and you'd like to follow along, you can get the free 30-day trial version.  In contrast to acceptance sampling by attributes, where inspectors make judgment calls about defective items,... Continue Reading
If you're just getting started in the world of quality improvement, or if you find yourself in a position where you suddenly need to evaluate the quality of incoming or outgoing products from your company, you may have encountered the term "acceptance sampling." It's a statistical method for evaluating the quality of a large batch of materials from a small sample of items, which statistical softwar... Continue Reading
Many of us have data stored in a database or file that we need to analyze on a regular basis. If you're in that situation and you're using Minitab Statistical Software, here's how you can save some time and effort by automating the process. When you're finished, instead of using File > Query Database (ODBC) each time you want to perform analysis on the most up-to-date set of data, you can add a... Continue Reading
When you work in data analysis, you quickly discover an irrefutable fact: a lot of people just can't stand statistics. Some people fear the math, some fear what the data might reveal, some people find it deadly dull, and others think it's bunk. Many don't even really know why they hate statistics—they just do. Always have, probably always will.  Problem is, that means we who analyze data need to com... Continue Reading
Not long ago, I couldn’t abide statistics. I did respect it, but in much the same way a gazelle respects a lion. Most of my early experiences with statistics indicated that close encounters resulted in pain, so I avoided further contact whenever possible. So how is it that today I write about statistics? That’s simple: it merely required completely reinventing the way I thought about and approached... Continue Reading
P-values are frequently misinterpreted, which causes many problems. I won't rehash those problems here here since my colleague Jim Frost has detailed the issues involved at some length, but the fact remains that the p-value will continue to be one of the most frequently used tools for deciding if a result is statistically significant.  You know the old saw about "Lies, damned lies, and... Continue Reading
This week is the annual Thanksgiving holiday in the United States, a period where we are encouraged to eat turkey and cranberries, then consider the blessings in our lives before falling into a comfortable pre-football nap. That includes many of us here at Minitab.  Consequently, we won't have new posts for you over the next two days.  But one of the things I'm grateful for is having had the... Continue Reading
Since it's the Halloween season, I want to share how a classic horror film helped me get a handle on an extremely useful statistical distribution.  The film is based on John W. Campbell's classic novella "Who Goes There?", but I first became  familiar with it from John Carpenter's 1982 film The Thing.   In the film, researchers in the Antarctic encounter a predatory alien with a truly frightening... Continue Reading
People who are ill frequently need medication. But if they miss a dose, or receive the wrong medication—or even get the wrong dose of the right medication—the results can be disastrous.  So medical professionals have a lot at stake in making sure patients get the right medicine, in the right amount, at the right time. But hospitals and other medical facilities are complex systems, and mistakes do... Continue Reading
I read trade publications that cover everything from banking to biotech, looking for interesting perspectives on data analysis and statistics, especially where it pertains to quality improvement. Recently I read a great blog post from Tony Taylor, an analytical chemist with a background in pharmaceuticals. In it, he discusses the implications of the FDA's updated guidance for industry analytical... Continue Reading
Whatever industry you're in, you're going to need to buy supplies. If you're a printer, you'll need to purchase inks, various types of printing equipment, and paper. If you're in manufacturing, you'll need to obtain parts that you don't make yourself.  But how do you know you're making the right choice when you have multiple suppliers vying to fulfill your orders?  How can you be sure you're... Continue Reading
When we take pictures with a digital camera or smartphone, what the device really does is capture information in the form of binary code. At the most basic level, our precious photos are really just a bunch of 1s and 0s, but if we were to look at them that way, they'd be pretty unexciting. In its raw state, all that information the camera records is worthless. The 1s and 0s need to be converted... Continue Reading
Statisticians say the darndest things. At least, that's how it can seem if you're not well-versed in statistics.  When I began studying statistics, I approached it as a language. I quickly noticed that compared to other disciplines, statistics has some unique problems with terminology, problems that don't affect most scientific and academic specialties.  For example, dairy science has a highly... Continue Reading
If you've read the first two parts of this tale, you know it started when I published a post that involved transforming data for capability analysis. When an astute reader asked why Minitab didn't seem to transform the data outside of the capability analysis, it revealed an oversight that invalidated the original analysis.  I removed the errant post. But to my surprise, the reader who helped me... Continue Reading
Last time, I told you how I had double-checked the analysis in a post that involved running the Johnson transformation on a set of data before doing normal capability analysis on it. A reader asked why the transformation didn't work on the data when you applied it outside of the capability analysis.  I hadn't tried transforming the data that way, but if the transformation worked when performed as... Continue Reading
I don't like the taste of crow. That's a shame, because I'm about to eat a huge helping of it.  I'm going to tell you how I messed up an analysis. But in the process, I learned some new lessons and was reminded of some older ones I should remember to apply more carefully.  This Failure Starts in a Victory My mistake originated in the 2015 Triple Crown victory of American Pharoah. I'm no... Continue Reading
Before I joined Minitab, I worked for many years in Penn State's College of Agricultural Sciences as a writer and editor. I frequently wrote about food science and particularly food safety, as I regularly needed to report on the research being conducted by Penn State's food safety experts, and also edited course materials and bulletins for professionals and consumers about ensuring they had safe... Continue Reading
All processes have some variation. Some variation is natural and nothing to be concerned about. But in other cases, there is unusual variation that may need attention.  By graphing process data against an upper and a lower control limit, control charts help us distinguish natural variation from special cause variation that we need to be concerned about. If a data point falls outside the limits on... Continue Reading
This week I'm at the American Society for Quality's World Conference on Quality and Improvement in Nashville, TN. The ASQ conference is a great opportunity to see how quality professionals are tackling problems in every industry, from beverage distribution to banking services.  Given my statistical bent, I like to see how companies apply tools like ANOVA, regression, and especially... Continue Reading