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Statistical process control after W. Edwards Deming (2020)

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Re: Statistical process control after W. Edwards Deming (2020)

#21

Post by hencq »

mch82 wrote: post #14
larrydag wrote: post #5

Earlier quoted context omitted.

GE and other companies tried to implement Demings approach. They called it Six Sigma. Those that used Deming's concepts were successful. Yet too many misunderstood the idea of SPC and used in areas that was not meant for quality control. For instance trying to use SPC in the managerial process itself.

Six Sigma is to the field of Statistical Process Control what PowerPoint templates are to the field of graphic design. The biggest problem with Six Sigma is many of the people who roll it out understand how to follow the instructions in a Six Sigma book, but don’t understand the underlying statistics well enough to recognize when the templates will fail or need to be changed.

Amen. The principles behind Six Sigma are solid. They're just a repackaging of Deming's SPC principles after all. However, too often it devolves into a box ticking exercise. That being said, in my experience just educating everyone in your organization on the basic principles (e.g. what Six Sigma would call yellow belt) tends to be quite valuable. Even without a lot of statistics, teaching people to first properly define a problem statement and emphasizing finding root causes before taking action tends to lead to better decision making.

Re: Statistical process control after W. Edwards Deming (2020)

#23

Post by Zigurd »

s-luv-j wrote: post #16

>"You can not inspect quality into a product." ~Deming Yep. This applies double to software. Putting software under load and trending health measures to look for two standard deviations variance is very similar to how Deming instrumented production lines. The neat thing that software enables for both automobile manufacturing and software products themselves is that those exact same health measures can be trended and…

Deming is talking about repeatable manufacturing processes. The point of Statistical Process Control is that you sample metrics that tell you if the process will produce products reliably within tolerances.

Software is completely different, it is hardly ever a repeatable process to create software. Making the same software over and over is nonsensical, but making a billion identical contact lenses is exactly what you want.

There are forms of software "inspection," like pair programming, that amount to what Deming says you should not do in manufacturing: Inspect everything. But pair programming is pretty rare. Other practices like code review have been called into question. So it may still be true that you can't inspect your way to quality in software, but not for the same reasons that it is a bad idea in many cases in manufacturing.

Re: Statistical process control after W. Edwards Deming (2020)

#24

Post by devonkim »

eplanit wrote: post #11
larrydag wrote: post #5

Earlier quoted context omitted.

GE and other companies tried to implement Demings approach. They called it Six Sigma. Those that used Deming's concepts were successful. Yet too many misunderstood the idea of SPC and used in areas that was not meant for quality control. For instance trying to use SPC in the managerial process itself.

Gawd, Six Sigma was an ever-present factor in all our work when I was at IBM in the late 80's to early 90's. I have complete respect for Deming, but when anything becomes "religion" it gets damaged or mis-used a lot, as you say. In our software group, we were constantly battling with management that wanted to start to look at software development as a factory-like process, and to apply factory QA processes.

Cargo culting one’s way to attempt obtaining results seems like the default approach of leadership unable to really adapt the proper lessons from other organizations and apply them to their own. If I as a person look up to a world class bodybuilder as a scrawny weakling, the solution to achieve that goal isn’t to just eat like a bodybuilder but to train like one and that usually means dropping other activities like playing a bunch of video games (not that it’s mutually exclusive - see Henry Cavill). But we as humans do the same thing all the time (how many people think of rich people in terms of consumption or some sets of personalities from popular media rather than to look at the data fully). However, there is a lot to learn and enjoy in the process, and companies that do well learn to have clear goals and processes that seem genuine and that employees can connect with. When people stop feeling this connection, they simply stop doing the habits at the individual (not working out, relapsing, etc) or disengage in organizations (burn out, disillusionment, etc)

Re: Statistical process control after W. Edwards Deming (2020)

#25

Post by Zigurd »

WWWWH wrote: post #15

This is a great article, but is there a good modern source (say an introductory text book) on these ideas? I've a vague memory of doing this as a first year undergraduate, but that was a long time ago. And stupidly, I didn't think I'd ever need them...

Deming wrote very accessible books. Out of the Crisis is a general audience book but it covers statistical quality analysis in enough depth to understand how it works.

Re: Statistical process control after W. Edwards Deming (2020)

#26

Post by s-luv-j »

Zigurd wrote: post #23
s-luv-j wrote: post #16

>"You can not inspect quality into a product." ~Deming Yep. This applies double to software. Putting software under load and trending health measures to look for two standard deviations variance is very similar to how Deming instrumented production lines. The neat thing that software enables for both automobile manufacturing and software products themselves is that those exact same health measures can be trended and…

Deming is talking about repeatable manufacturing processes. The point of Statistical Process Control is that you sample metrics that tell you if the process will produce products reliably within tolerances. Software is completely different, it is hardly ever a repeatable process to create software. Making the same software over and over is nonsensical, but making a billion identical contact lenses is exactly what you…

You are 100% right that measuring the process of creating software is a terrible application of statistical process control. See Jira.

One way to look at how Deming/Shewart's work applies to software is to consider what happens when you apply their statistical analysis techniques to running software.

Re: Statistical process control after W. Edwards Deming (2020)

#27

Post by Zigurd »

larrydag wrote: post #5
neverartful wrote: post #2

My first job out of college (undergraduate) was working for a small consulting firm that did a lot of work in this area for the petrochemical industry and their suppliers. The owner had a PhD in decision sciences (statistics) and he did consulting work on statistical process control (SPC). This was my first exposure to this field and was so fascinated by it that after working there for a year, I quit my job so that I…

GE and other companies tried to implement Demings approach. They called it Six Sigma. Those that used Deming's concepts were successful. Yet too many misunderstood the idea of SPC and used in areas that was not meant for quality control. For instance trying to use SPC in the managerial process itself.

Six Sigma is a travesty of statistical process control. For one thing, only rarely does a process attain six sigma reliability. Six Sigma is about cult-like in-group/out-group dynamics for the Six Sigma Black Belts.

Re: Statistical process control after W. Edwards Deming (2020)

#28

Post by User23 »

Deming gets the credit, but in Japan it was Homer Sarasohn[1][2] who did the foundational work[3]. In fact, he handed the reins off to Deming.

One particularly interesting thing is that, at least once upon a time, Canon didn't even bother inspecting their copiers and printers, because the variance was so low it was a waste of time[4].

[1] https://en.wikipedia.org/wiki/Homer_Sarasohn

[2] https://honoringhomer.net/

[3] https://apnews.com/article/e2908339e16a48dc8efe37d77a905daa

[4] http://qualiticien.over-blog.com/article-679016.html

Re: Statistical process control after W. Edwards Deming (2020)

#29

Post by heymijo »

jihadjihad wrote: post #7

W. Edwards Deming is the source of one of my favorite quotes: "In God we trust; all others must bring data." One of the fascinating things about Deming's work is that Japan's automobiles went from being referred to pejoratively as "Jap Crap" to symbols of quality (Toyota, Honda, Subaru, Nissan, Mazda, etc.) within a short few decades--quite a feat for a nation struggling to regain its industrial footing after WWII.

I'm curious what makes that your favorite quote.

It gives me pause, mainly because I've seen it abused, ironically, often in contrast to some of Deming's core ideas.

YMMV

Re: Statistical process control after W. Edwards Deming (2020)

#30

Post by winslett »

I stumbled upon Deming's "Out of the Crisis" when wandering through the library in school. It has changed how I thought about system improvement ever since.

I use the things I learned for marketing, product, and engineering systems.

Want to improve a system? Before doing anything, collect data and measure. A system must be stable, else you cannot improve it. Marketing campaigns. Funnel optimizations. Performance improvement.

Most "stability" is achieved by simple things like squashing bugs (campaign bugs, performance bugs, or UX bugs).

Once you achieve stability of output (i.e. low standard deviation), then improve the system.

Simple, uh?

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