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Why Doesn’t SPC Work, Part 4

If you have been following my articles over the last few months, you have seen that even though statistical process control (SPC) charts are very powerful tools for examining a process, it turns out that there are a lot of ways to mess up SPC. This month, I am going to finish up with a few more things to watch out for as you use them, so you never have to ask, “Why doesn’t SPC work here?”

Read more: Why Doesn’t SPC Work, Part 4

Project Selection for DMAIC

One of the most frequent questions I get from Black Belts and Green Belts I train is about the characteristics of a good Six Sigma project, particularly a first project. Define, measure, analyze, improve, control (DMAIC) is a procedure that is useful for certain types of projects and terrible for others.

Read more: Project Selection for DMAIC

Why Doesn't SPC Work? Part 2

Have you ever met people who “do” statistical process control (SPC) only to get some screwy-looking control chart, and then text: OMG I H8 SPC! (If you don’t understand that, ask your nine-year-old child or grandchild.)

Last month we saw how it is not a failure of SPC, but rather an EBKAC (error between keyboard and chair). As I wrote in my last article, “Why Doesn't SPC Work?” perhaps they are not doing the measurement system analysis first, or perhaps autocorrelation in a continuous process. But you batch process folks are not off the hook, which is what this month’s article is about.

Read more: Why Doesn't SPC Work? Part 2

Why Doesn't SPC Work? Part 3

Over the past couple of articles, we have explored how an incomplete understanding of how SPC limits are calculated can lead to constructing control charts that look strange. But using some of the things I mentioned, hopefully you can see that these “strange” control charts actually reveal quite interesting information about what is going on (and what to do about it). In the last article I left you with a weird looking control chart to see if you could figure out what was going on in the process. Instead of throwing out the chart and concluding that “SPC doesn’t work here,” let’s take a look at that and see what we could have learned about the process.

Read more: Why Doesn't SPC Work? Part 3

Why Doesn't SPC Work? Part 1

One of the most useful diagnostic tools for understanding what is going on in a process is the statistical process control chart (SPC). This is also a frequently misunderstood tool, and these misunderstandings lead to misdirected effort during a Six Sigma process, resulting in lost time and money. All the questions related to these foiled efforts boil down to this, “I used my software to make a control chart, but the chart looks all messed up. Why doesn’t SPC work?”

It does, if you avoid some common pitfalls. So today, I am kicking off a few articles about these pitfalls that I hope will make your projects less frustrating and more efficient.

Read more: Why Doesn't SPC Work? Part 1

Random Heresy

By the time you are reading this, you will have made your New Year’s resolutions, and I will have already broken mine. But I have an idea for a resolution that you might be interested in keeping, and one that could make your New Year happy and profitable. It is s...

News Flash

Six Sigma's lead instructor Steven Ouellette wrote an article with Dr. Jeffrey Luftig on "The Decline of Ethical Behavior in Business."



Six Sigma Online's lead instructor Steven Ouellette was profiled in the June 2008 issue of Quality Digest magazine. If you want to learn more about Steve's peculiar view of the world, as well as what he studied for a year in Europe, read the profile online.




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