Text Size
Thursday, January 17, 2019

On-site Training

These feature articles are published monthly by Quality Digest.  They are collected under the nom de plume of The Six Sigma Heretic, which tells you something about how we approach Six Sigma.  They are written by ROI President Steven Ouellette, and have a unique blend of humor and statistical depth that makes him one of Quality Digest's most popular authors.  Subscribe to our RSS Feed to be alerted about each month's article!

Performing a Long-Term MSA

Testing through time stability

hh, measurement system analysis—the basis for all our jobs because, as Lord Kelvin said, “… When you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind.” How interesting it is then, that we who thrive on data so frequently don't have any proof that the numbers we're using relate to the event we are measuring—hence my past few articles about the basics of measurement system analysis in “Letting You In on a Little Secret,” on how to do a potential study in “The Mystery Measurement Theatre, and on how to do a short-term study in “Performing a Short-Term MSA Study.” The only (and most important) topic remaining is how to perform a long-term study, which is the problem I left with you last month.

So read on to see how.

Performing a Short-Term Study

n the past couple of articles, we have been having fun together testing whether a measurement device is usable for the crazy purpose of determining if we are actually making product in or out of specification. Last month, we performed a measurement systems analysis (MSA) “potential study” using a snazzy MSA spreadsheet (if I do say so myself)*. We found that the Hard-A-Tron was not only pretty highly variable (compared to our spec), but that the material we were measuring actually might have been changing over time. But a potential study was not enough for you, was it? You asked, nay demanded, that we perform a short-term MSA, and I, your humble servant, gave you the data to do so. After the jump, we will perform the analysis, so unless you are the type of person that flips to the back of the book to see if you want to read it, finish up your analysis, and then click to read more.

The Mystery Measurement Theater

Determining sources of variations

if you can’t trust your measurement system, you can’t do anything with the data it generates. Last month, in “ Letting You In On a Little Secret,” we talked about the purpose of measurement system analysis (MSA) and I gave you a neat spreadsheet that will do MSA for you, as well as some data (repeated after the jump) from the gauge you want to buy, the Hard-A-Tron. I also left you with a mysterious statement that this study was trickier than it appeared. This month I’ll start off answering a question I received, and then we will see how well the Hard-A-Tron did—and what mysterious thing was going on in the data. After that, if you are good, I’ll give you another set of data to further test a measurement device.

Letting You In On a Little Secret

'Cause I’m a nice guy, I’m going to give you articles that explain the basics of MSA.

You know how sometimes you think everyone knows a secret that they haven’t let you in on? Well, I had the opposite happen to me the other day. I assumed everyone knew the purpose for measurement system analysis (MSA), a.k.a. gauge repeatability and reproducibility; but I found out that a number of people have a completely mistaken impression of what they are for, much less how to do them correctly. So I thought I would give away, (free of charge) articles that explain the basics of MSA, as well as a cool MSA spreadsheet to help you learn how to do them, just because that’s the kind of guy I am. Selfless. And humble. Yep.

You Might Be a Black Belt If...

Oh, the perils of mastering Six Sigma

I'm not saying that the following apply to you... really. But, you might be a Black Belt if...

Page 3 of 11

3

Six Sigma Heretic Article

These articles were originally published in Quality Digest, an online magazine. Subscribe to Quality Digest if you would like to receive these articles when they are published, or subscribe to our RSS feed.