Tag Archives: Six sigma

Understanding Design of Experiments (DoE) in Protein Purification

This webcast, from GE Life Sciences, seeks to provide an understanding Design of Experiments (DoE) using an example of protein purification. It begins with a good overview of the reason why multi-factorial experiments must be used while changing multiple factors at the same time in order to see interactions between factors. These interactions are completely missed by one-factor-at-a-time experiments.

While it is a good introduction it might be a bit confusing if you are not familiar with multi-factorial designed experiments. You may want to read some of the links below or take advantage of the ability to pause the video to think about what he says or to replay portions you don’t pick up immediately.

I have discussed the value of design of experiments in multiple posts on this blog in the past, including: Introductory Videos on Using Design of Experiments to Improve Results by Stu Hunter, Design of Experiments: The Process of Discovery is Iterative and Factorial Designed Experiment Aim.

He also provides a good overview of 3 basic aims of multivariate experiment (DoE):

  • screening (to determine which factors have the largest impact on the results that are most important)
  • optimization (optimize the results)
  • robustness testing (determine if there are risks in variations to factors)

Normally an experiment will focus on one of these aims. So you don’t know the most important factors you may choose to do a screening experiment to figure out which factors you want to study in detail in an optimization experiment.

It could be an optimized set of values for factors provides very good results but is not robust. If you don’t have easy way to make sure the factors do not vary it may be worthwhile to choose another option that provides nearly as good results but is much more robust (good results even with more variation within the values of the factors).

Related: YouTube Uses Multivariate Experiment To Improve Sign-ups 15% (2009)Combinatorial Testing for Software (2009)Marketers Are Embracing Statistical Design of Experiments (2005)

Stu Hunter Discussing Bill Hunter, Statistics for Experimenters and EVOP

In this clip, Stu Hunter talks about Bill Hunter (my father, and no relation to Stu Hunter), Statistics for Experimenters and EVolutionary OPerations (EVOP).

Stu mentions Bill Hunter’s work with the City of Madison, which started with the First Street Garage (Out of the Crisis included a short write up on this effort by Dad, which, I believe, was the first application of Deming’s ideas in the public sector).

There was also a great deal of work done with the Police department, as the police chief, David Couper, saw great value in Deming’s ideas. The Police department did some great work and David’s blog shares wonderful ideas on improving policing. I don’t think Dad was that directly involved in what happened there, but it is one of the nice benefits of seeding new ideas: as they take root and grow wonderful things happen without any effort on your part.

As to why Dad got involved with the city, he returned from a summer teaching design of experiments and quality improvement methods in China (this is just before China was really open, a few outsiders were let in to teach). We had also lived overseas several other times, always returning to Madison. He decided he wanted to contribute to the city he loved, Madison, and so he talked to the Mayor about helping improve performance of the city.

The mayor listened and they started with a pilot project which Dad work on with Peter Scholtes. Dad talked to Peter, who he had know for years, and who worked for the city, before talking to the mayor. Read more about the efforts in Madison via the links at the end of this post.

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Getting Known Good Ideas Adopted

This month Paul Borawski asked ASQ’s Influential Voices to explore two questions; first, what is the most important challenge the quality community faces in ensuring that the value of quality is fully realized for the benefit of society?

I really think it is just getting the good ideas to improve management, that have been around for decades, adopted. This might not seem that important. But I hear almost no talk about this and tons of talk about all sorts of “new ideas” for management.

The “new ideas” that I look into don’t seem like very new ideas to me. The best of these ideas are usually well thought out tweaks and enhancements (along with a potentially better presentation of the core ideas) that are useful. But they are really just about getting old ideas adopted, it seems to me. Still this is good and useful work.

Unfortunately the vast majority seems to me to be overly simplistic ideas that involved more thought in creating something to market than in creating something to improve the practice of management.

We seem to spend all sorts of time and energy focused on new branding for management ideas when we would be better off focusing on how to get organizations to adopt good practices. I think the distraction with finding new ways of clothing the same old ideas is a distraction that prevents focus where it would be more worthwhile. This is especially true because those rebranding old ideas often don’t understand the old idea. They seem to see it would easier to sell if it were simplified so they do that and rebrand it but they don’t understand that they left of critical components and it won’t work – even if it is easier to sell.

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George Box

I would most likely not exist if it were not for George Box. My father took a course from George while my father was a student at Princeton. George agreed to start the Statistics Department at the University of Wisconsin – Madison, and my father followed him to Madison, to be the first PhD student. Dad graduated, and the next year was a professor there, where he and George remained for the rest of their careers.

George died today, he was born in 1919. He recently completed An Accidental Statistician: The Life and Memories of George E. P. Box which is an excellent book that captures his great ability to tell stories. It is a wonderful read for anyone interested in statistics and management improvement or just great stories of an interesting life.

photo of George EP Box

George Box by Brent Nicastro.

George Box was a fantastic statistician. I am not the person to judge, but from what I have read one of the handful of most important applied statisticians of the last 100 years. His contributions are enormous. Several well know statistical methods are known by his name, including:

George was elected a member of the American Academy of Arts and Sciences in 1974 and a Fellow of the Royal Society in 1979. He also served as president of the American Statistics Association in 1978. George is also an honorary member of ASQ.

George was a very kind, caring and fun person. He was a gifted storyteller and writer. He had the ability to present ideas so they were easy to comprehend and appreciate. While his writing was great, seeing him in person added so much more. Growing up I was able to enjoy his stories often, at our house or his. The last time I was in Madison, my brother and I visited with him and again listened to his marvelous stories about Carl Pearson, Ronald Fisher and so much more. He was one those special people that made you very happy whenever you were near him.

George Box, Stuart Hunter and Bill Hunter (my father) wrote what has become a classic text for experimenters in scientific and business circles, Statistics for Experimenters. I am biased but I think this is acknowledged as one of (if not the) most important books on design of experiments.

George also wrote other classic books: Time series analysis: Forecasting and control (1979, with Gwilym Jenkins) and Bayesian inference in statistical analysis. (1973, with George C. Tiao).

George Box and Bill Hunter co-founded the Center for Quality and Productivity Improvement at the University of Wisconsin-Madison in 1984. The Center develops, advances and communicates quality improvement methods and ideas.

The Box Medal for Outstanding Contributions to Industrial Statistics recognizes development and the application of statistical methods in European business and industry in his honor.

All models are wrong but some are useful” is likely his most famous quote. More quotes By George Box

A few selected articles and reports by George Box

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Podcast Discussion on Management Matters

I continue to record podcasts as I promote my new book – Management Matters: Building Enterprise Capability. This the second part, of 2, of my podcast with Joe Dager, Business 901: Management Matters to a Curious Cat. The first part featured a discussion of 2 new deadly diseases facing companies.

image of the cover of Managmenet Matters by John Hunter

Management Matters by John Hunter

Listen to this podcast.

Links to more information on some of the topics I mention in the podcast:

More podcasts: Process Excellence Network Podcast with John HunterBusiness 901 Podcast with John Hunter: Deming’s Management Ideas Today (2012)Leanpub Podcast on Management Matters: Building Enterprise Capability

Special Cause Signal Isn’t Proof A Special Cause Exists

One of my pet peeves is when people say that a point outside the control limits is a special cause. It is not. It is an indication that it likely a special cause exists, and that special cause thinking is the correct strategy to use to seek improvement. But that doesn’t mean there definitely was a special cause – it could be a false signal.

This post relies on an understand of control charts and common and special causes (review these links if you need some additional context).

Similarly, a result that doesn’t signal a special cause (inside the control limits without raising some other flag, say a run of continually increasing points) does not mean a special cause is not present.

The reason control charts are useful is to help us maximize our effectiveness. We are biased toward using special cause thinking when it is not the most effective approach. So the control chart is a good way to keep us focused on common cause thinking for improvement. It is also very useful in flagging when it is time to immediately start using special cause thinking (since timing is key to effective special cause thinking).

However, if there is result that is close to the control limit (but inside – so no special cause is indicated) and the person that works on the process everyday thinks, I noticed x (some special cause) earlier, they should not just ignore that. It very well could be a special cause that, because of other common cause variation, resulted in a data point that didn’t quite reach the special cause signal. Where the dot happened to land (just above or just below the control limit – does not determine if a special cause existed).

The signal is just to help us systemically make the best choice of common cause or special cause thinking. The signal does not define whether a special cause (an assignable cause) exists of not. The control chart tool helps guide us to use the correct type of improvement strategy (common cause or special cause). But it is just a signaling device, it isn’t some arbiter of whether a special cause actually exists.

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Management Improvement Blog Carnival #179

The Curious Cat Management Blog Carnival has been published since 2006. The carnival links to great management blog posts; it is published twice a month. I hope you find these post interesting and find some new blogs to start reading. Follow me online: Google+, Twitter and elsewhere.

  • Lean Versus Historical TPS by Art Smalley – “identify what are your impediments to improvement and work on those. In particular as what are barriers to higher equipment uptime, higher process capability, safer equipment, higher capital and labor productivity without adding cost, more highly trained personnel, and you will be on the right track. I call this building better process stability and it is an essential yet often ignored element of the historical Toyota Production System.”
  • 5 Critical Control Chart Characteristics You May Not Be Aware Of by Ron Pereira – “No matter if you call yourself a ‘lean practitioner’ or ‘six sigma practitioner’ or some combination of the two… one ‘tool’ you should have a deep understanding of is the control chart.”
  • photo of Mount Merapi in Indonesia

    Mount Merapi, Yogyakarta, Java, Indonesia by John Hunter.

  • Adaptability vs Evolutionary Change by David J. Anderson – “Organizations with evolutionary capability have resilience – they remain relevant despite changing circumstances and maintain high levels of effectiveness as the environment around them changes. Kanban is a means to install evolutionary capability and deliver on higher level agility. Evolutionary capability defines second generation Agile methods.”
  • Completion: Limiting WIP Post II by Jim Benson – “When we limit work-in-progress, we not only limit the number of projects we are working on, but also the number of tasks. This helps us complete tasks efficiently and effectively. When we are done, we understand what we did. While we are doing the tasks we are fully aware of how long they are taking.”
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My New Book: Management Matters

Image of the book cover of Management Matters by John Hunter

Management Matters by John Hunter is now available.

I have a new book in progress: Management Matters. It is now available in “pre-release format” via leanpub. The idea I am experimenting with (supported by leanpub) is pre-publishing the book online. The ebook is available for purchase now, and comes with free access to the updates.

My plan is to continue working on the book for the next few months and have it “release ready” by October, 2012. One of the advantages of this method is that I can incorporate ideas based on feedback from the early readers of the book.

There are several other interesting aspects to publishing in this way. Leanpub allows a suggested retail price, and a minimum price. So I can set a suggested price and a minimum price and the purchaser gets to decide what price to pay (they can even pay over suggested retail price – which does happen). The leanpub model provides nearly all the revenue to the author (unlike traditional models) – the author gets 90% of the price paid, less 50 cents per book (so $8.50 of a $10 purchase).

They provide the book in pdf, mobi (Kindle) and epub (iPad, Nook, etc.) formats. And the books do not have any Digital Rights Management (DRM) entanglements.

Management Matters covers topics familiar to those who have been reading this blog for years. It is an attempt to put in one place the overall management system that is most valuable (which as you know, based on the blog, is largely based upon Dr. Deming’s ideas – which means lean manufacturing are widely covered too).

I hope the book is now in a state where those who are interested would find it useful, but it is in what I consider draft format. I still have much editing to do and content to add.

Leanpub also provides a sample book (where a portion of the content can be downloaded to decide if you want to buy). If you are interested please give it a try and let me know your thoughts.

Management Improvement Blog Carnival #170

The Curious Cat management blog carnival is published 3 times a month with hand picked recent management blog posts. I also collect management improvement articles for the Curious Cat Management Articles site; an RSS feed of new article additions is available.

  • Standardized Confusion by Art Smalley – “Changing of a work standard was done very infrequently and normally an engineering activity for the types of items I just described. Maybe we wanted to improve the life of a tool, or alter how the part was clamped in response to a problem on the shop floor, etc. Problems or kaizen sometimes drove us to reconsider work standards but by and large these did not and should not change very often if we planned and launched the process correctly.”
  • Deming’s Speech at Mount Hakone, Japan (1950) – “The first step, therefore, belongs with management. First, your company technicians and your factories must know that you have a fervor for advancing product quality and uniformity and a sense of responsibility for product quality.
    Nothing will come of this if you only speak about it. Action is important…
    At first do it on a small scale, and once you think that has value, then expand.”
  • photo of an iridescent green beetle

    Green Beetle at the Clifton Gorge State Nature Preserve in Ohio, by John Hunter.

  • How we reduced our cancellation rate by 87.5% by Kareem Mayan – “Since implementing changes 1-3 two months ago, we’ve seen our cancellation rate drop from 40% to 5% – an 87.5% decrease. We’re going to run another cohort analysis in a couple months to isolate the impact of each change as it’s still too early to know the long-term impact of these changes”
  • Design of Experiments: “Fractionating” and “Folding” a DOE by Bruno Scibilia – “In science and in business, we need to perform experiments to identify the factors that have a significant effect. The objective of DOE is to reduce experimental costs—the number of tests—as much as possible while studying as many factors as possible to identify the important ones.”
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Introductory Videos on Using Design of Experiments to Improve Results

The video shows Stu Hunter discussing design of experiments in 1966. It might be a bit slow going at first but the full set of videos really does give you a quick overview of the many important aspects of design of experiments including factorial designed experiments, fractional factorial design, blocking and response surface design. It really is quite good, if you find the start too slow for you skip down to the second video and watch it.

My guess is, for those unfamiliar with even the most cursory understanding of design of experiments, the discussion may start moving faster than you can absorb the information. One of the great things about video is you can just pause and give yourself a chance to catch up or repeat a part that you didn’t quite understand. You can also take a look at articles on design of experiments.

I believe design of experiments is an extremely powerful methodology of improvement that is greatly underutilized. Six sigma is the only management improvement program that emphasizes factorial designed experiments.

Related: One factor at a time (OFAT) Versus Factorial DesignsThe purpose of Factorial Designed Experiments

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