Category Archives: Statistics

2011 Management Blog Roundup: Stats Made Easy

The 4th Annual Management blog roundup is coming to a close soon. This is my 3rd and final review post looking back at 2001, the previous two posts looked at: Gemba Panta Rei and the Lean Six Sigma Blog.

I have special affinity for the use of statistics to understand and improve. I imaging it is both genetic and psychological. My father was a statistician and I have found memories of applying statistical thinking to understand a result or system. I also am comfortable with numbers, and like most people enjoy working with things I have an affinity for.

photo of Mark Anderson

Mark Anderson

Mark Anderson’s Stats Made Easy blog brings statistical thinking to managers. And this is not an easy thing to do, as one of his posts shows, we have an ability to ignore data we don’t want to know. Wrong more often than right but never in doubt: “Kahneman examined the illusion of skill in a group of investment advisors who competed for annual performance bonuses. He found zero correlation on year-to-year rankings, thus the firm was simply rewarding luck. What I find most interesting is his observation that even when confronted with irrefutable evidence of misplaced confidence in one’s own ability to prognosticate, most people just carry on with the same level of self-assurance.”

That actually practice of experimentation (PDSA…) needs improvement. Too often the iteration component is entirely missing (only one experiment is done). That is likely partially a result another big problem: the experiments are not nearly short enough. Mark offered very wise advice on the Strategy of experimentation: Break it into a series of smaller stages. “The rule-of-thumb I worked from as a process development engineer is not to put more than 25% of your budget into the first experiment, thus allowing the chance to adapt as you work through the project (or abandon it altogether).” And note that, abandon it altogether option. Don’t just proceed with a plan if what you learn makes that option unwise: too often we act based on expectations rather than evidence.

In Why coaches regress to be mean, Mark explained the problem with reacting to common cause variation and “learning” that it helped to do so. “A case in point is the flight instructor who lavishes praise on a training-pilot who makes a lucky landing. Naturally the next result is not so good. Later the pilot bounces in very badly — again purely by chance (a gust of wind). The instructor roars disapproval. That seems to do the trick — the next landing is much smoother.” When you ascribe special causation to common cause variation you often confirm your own biases.

Mark’s blog doesn’t mention six sigma by name in his 2011 posts but the statistical thinking expressed throughout the year make this a must for those working in six sigma programs.

Related: 2009 Curious Cat Management Blog Carnival2010 Management Blog Review: Software, Manufacturing and Leadership

Eliminate the Waste of Waiting in Line with Queuing Theory

One thing that frustrates me is how managers fail to adopt proven strategies for decades. One very obvious example is using queuing theory to setup lines.

Yes it may be even better to adopt strategies to eliminate as much waiting in line as possible, but if there is still waiting in line occurring and you are not having one queue served by multiple representatives shame on you and your company.

Related: Customer Focus and Internet Travel SearchYouTube Uses Multivariate Experiment To Improve Sign-ups 15%Making Life Difficult for Customers

Dr. Deming in 1980 on Product Quality in Japan and the USA

I posted an interesting document to the Curious Cat Management Library: it includes Dr. Deming’s comments as part of a discussion organized by the Government Accounting Office in 1980 on Quality in Japan and the United States.

The document provides some interesting thoughts from Dr. Deming and others; Dr. Deming’s statements start on page 52 of the document. For those really interested in management improvement ideas it is a great read. I imagine most managers wouldn’t enjoy it though (it isn’t giving direct advice for today, but I found it very interesting).

Some selected quotes from the document follow. On his work with Japan in 1950:

This movement, I told them, will fail and nothing will happen unless management does their part. Management must know something about statistical techniques and know that if they are good one place, they will work in another. Management must see that they are used throughout the company.
Quality control must take root with simple statistical techniques that management and everyone in the company must learn. By these techniques, people begin to understand the different kinds of variation. Then quality control just grow with statistical theory and further experience. All this learning must be guided by a master. Remarkable results may come quick, but one has no right to expect results in a hurry. The learning period never ends.

The statistical control of quality is not for the timid and the halfhearted. There is no way to learn except to learn it and do it. You can read about swimming, but you might drown if you had to learn it that way!

One of the common themes at that time was Deming’s methods worked because Japanese people and culture were different. That wasn’t why the ideas worked, but it was an idea many people that wanted to keep doing things the old way liked to believe.

There may be a lot of difference, I made the statement on my first visit there that a Japanese man was never too old nor too successful to learn, and to wish to learn; to study and to learn. I know that people here also study and learn. I’ll be eighty next month in October. I study every day and learn every day. So you find studious people everywhere, but I think that you find in Japan the desire to learn, the willingness to learn.

You didn’t come to hear me on this; there are other people here much better qualified than I am to talk. But in Japan, a man works for the company; he doesn’t work to please somebody. He works for the company, he can argue for the company and stick with it when he has an idea because his position is secure. He doesn’t have to please somebody. It is so here in some companies, but only in a few. I think this is an important difference.

At the time the way QC circles worked in Japan was basically employee led kaizen. So companies that tried to copy Japan told workers: now go make things better like the workers we saw in Japan were doing. Well with management not changing (and understanding Deming’s ideas, lean thinking, variation, systems thinking…) and staff not given training to understand how to improve processes it didn’t work very well. We (those reading this blog) may all now understand the advantages one piece flow. I can’t imagine too many people would jump to that idea sitting in their QC circle without having been told about one piece flow (I know I wouldn’t have), and all the supporting knowledge needed to make that concept work.

QC circles can make tremendous contributions. But let me tell you this, Elmer. If it isn’t obvious to the workers that the managers are doing their part, which only they can do, I think that the workers just get fed up with trying in vain to improve their part of the work. Management must do their part: they must learn something about management.

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One factor at a time (OFAT) Versus Factorial Designs

Guest post by Bradley Jones

Almost a hundred years ago R. A. Fisher‘s boss published an article espousing OFAT (one factor at a time). Fisher responded with an article of his own laying out his justification for factorial design. I admire the courage it took to contradict his boss in print!

Fisher’s argument was mainly about efficiency – that you could learn as much about many factors as you learned about one in the same number of trials. Saving money and effort is a powerful and positive motivator.

The most common argument I read against OFAT these days has to do with inability to detect interactions and the possibility of finding suboptimal factor settings at the end of the investigation. I admit to using these arguments myself in print.

I don’t think these arguments are as effective as Fisher’s original argument.

To play the devil’s advocate for a moment consider this thought experiment. You have to climb a hill that runs on a line going from southwest to northeast but you are only allowed to make steps that are due north or south or due east or west. Though you will have to make many zig zags you will eventually make it to the top. If you noted your altitude at each step, you would have enough data to fit a response surface.

Obviously this approach is very inefficient but it is not impossible. Don’t mistake my intent here. I am definitely not an advocate of OFAT. Rather I would like to find more convincing arguments to persuade experimenters to move to multi-factor design.

Related: The Purpose of Factorial Designed ExperimentsUsing Design of Experimentsarticles by R.A. Fisherarticles on using factorial design of experimentsDoes good experimental design require changing only one factor at a time (OFAT)?Statistics for Experimenters

Factorial Designed Experiment Aim

Multivariate experiments are a very powerful management tool to learn and improve performance. Experiments in general, and designed factorial experiments in particular, are dramatically underused by managers. A question on LinkedIn asks?

When doing a DOE we select factors with levels to induce purposely changes in the response variable. Do we want the response variable to move within the specs of the customers? Or it doesn’t matter since we are learning about the process?

The aim needs to consider what you are trying to learn, costs and potential rewards. Weighing the various factors will determine if you want to aim to keep results within specification or can try options that are likely to return results that are outside of specs.

If the effort was looking for breakthrough improvement and costs of running experiments that might produce results outside of spec were low then specs wouldn’t matter much. If the costs of running experiments are very high (compared with expectations of results) then you may well want to try designed experiment values that you anticipate will still produce results within specs.

There are various ways costs come into play. Here I am mainly looking at the costs as (costs – revenue). For example the case where if the results are withing spec and can be used the costs (net costs, including revenue) of the experiment run are substantially lower.
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Managing Our Way to Economic Success

From Managing Our Way to Economic Success, Two Untapped Resources by William G. Hunter, my father. Written in 1986, but still plenty relevant. We have made some good progress, but there is much more to do: we have barely started adopting these ideas systemically.

there are two enormously valuable untapped resources in many companies: potential information and employee creativity. The two are connected. One of the best ways to generate potential information to turn it into kinetic information that can produce tangible results is to train all employees in some of the simple, effective ways to do this. Rely on their desire to do a good job, to contribute, to be recognized, to be a real part of the organization. They want to be treated like responsible human beings, not like unthinking automatons.

W. Edwards Deming has illustrated one of the troubles with U.S. industry in terms of making toast. He says, “Let’s play American industry. I’ll burn. You scrape.” Use of statistical tools, however, allows you to reduce waste, scrap, rework, and machine downtime. It costs just as much to make defective products as it does to make good products. Eliminate defects and other things that cause inefficiencies, and you reduce costs, increase quality, and raise productivity. Note that quality and productivity are not trade-offs. They increase together.

Potential information surrounds all industrial processes. Statistical techniques, many of which are simple yet powerful, are tools that employees can use to tap and exploit this potential information so that increasingly higher levels of productivity, quality, and innovation can be attained. Engaging the brains as well as the brawn of employees in this way improves morale and participation…and profits.

What is called for is constant, never-ending improvement of all processes in the organization. What management needs, too, is constant, never-ending improvement of ideas.

Related: William Hunter, articles and booksInvest in New Management Methods Not a Failing CompanyThe Importance of Management ImprovementStatistics for Experimenters

Actionable Metrics

Metrics are valuable when they are actionable. Think about what will be done if certain results are shown by the data. If you can’t think of actions you would take, it may be that metric is not worth tracking.

Metrics should be operationally defined so that the data is collected properly. Without operationally definitions data collected by more than one person will often include measurement error (in this case, the resulting data showing the results of different people measuring different things but calling the result the same thing).

And without operational definitions those using the resulting data may well mis-interpret what it is saying. Often data is presented without an operational definition and people think the data is saying something that it is not. I find most often when people say statistics lie it is really that they made an incorrect assumption about what the data said – which most often was because they didn’t understand the operational definition of the data. Data can’t lie. People can. And people can intentionally mislead with data. But far more often people unintentionally mislead with data that is misunderstood (often this is due to failure to operationally define the data).

In response to: Metrics Manifesto: Raising the Standard for Metrics

Related: Outcome MeasuresEvidence-based ManagementMetrics and Software DevelopmentDistorting the System (due to misunderstanding metrics)Manage what you can’t measure

Statistical Engineering Links Statistical Thinking, Methods and Tools

In Closing the Gap Roger W. Hoerl and Ronald D. Snee lay out a sensible case for focusing on statistical engineering.

We’re not suggesting that society no longer needs research in new statistical techniques for improvement; it does. The balance needed at this time, however, is perhaps 80% for statistics as an engineering discipline and 20% for statistics as a pure science.

True, though I would put the balance more like 95% engineering, 5% science.

There is a good discussion on LinkedIn:

Davis Balestracci: Unfortunately, we snubbed our noses at the Six Sigma movement…and got our lunch eaten. Ron Snee has been developing this message for the last 20 years (I developed it in four years’ worth of monthly columns for Quality Digest from 2005-2008). BUT…as long as people have a computer, color printer, and a package that does trend lines, academic arguments won’t “convert” anybody.

Recently, we’ve lost our way and evolved into developing “better jackhammers to drive tacks”…and pining for the “good ol’ days” when people listened to us (which they were forced to do because they didn’t have computers, and statistical packages were clunky). Folks, we’d better watch it…or we’re moribund

Was there really a good old days when business listened to statisticians? Of course occasionally they did, but “good old days”? Here is a report from 1986 the theme of which seems to me to be basically how to get statisticians listened to by the people that make the important decisions: The Next 25 Years in Statistics, by Bill Hunter and William Hill. Maybe I do the report a disservice with my understanding of the basic message, but it seems to me to be how to make sure the important contributions of applied statisticians actually get applied in organizations. And it discusses how statisticians need to take action to drive adoption of the ideas because currently (1986) they are too marginalized (not listened to when they should be contributing) in most organizations.
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Soren Bisgaard

photo of Soren Bisgaard

Soren Bisgaard died earlier this month of cancer. Soren was a student of my father’s who shared the commitment to making a difference in people’s lives by using applied statistics properly. I know this seem odd to many (I tried to describe this idea previously, also read his acceptance of the 2002 William G. Hunter award). Soren served as the director of the director of the Center for Quality and Productivity Improvement at the University of Wisconsin-Madison (founded by William Hunter and George Box) for several years.

Most recently Soren Bisgaard, Ph.D. was Professor of technology management at Eugene M. Isenberg School of Management at the University of Massachusetts – Amherst. He was an ASQ Fellow; recipient of Shewart Medal, Hunter Award, George Box Medal, among many others awards.

I will remember the passion he brought to his work. He reminded me of my father in his desire to improve how things are done and allow people to have better lives. Those that bring passion to their work in management improvement are unsung heroes. It seems odd, to many, to see that you can bring improvement to people’s lives through work. But we spend huge amounts of our time at work. And by improving the systems we work in we can improve people’s lives. Soren will be missed, by those who knew him and those who didn’t (even if they never realize it).

Contributions in honor of Søren may be made to The International Mesothelioma Program or to the European Network for Business and Industrial Statistics. Read more articles by Søren Bisgaard.

The Future of Quality Technology: From a Manufacturing to a Knowledge Economy and From Defects to Innovations (pdf) by Soren Bisgaard

Related: The Work of Peter ScholtesManagement Improvement LeadersThe Scientific Context of Quality Improvement by George Box and Soren Bisgaard, 1987 – Obituary Søren Bisgaard at ENBISObituary: Soren Bisgaard, Isenberg Professor in Integrative Studies

Highlights from Recent George Box Speech

The JMP blog has posted some highlights from George Box’s presentation at Discovery 2009

Infusing his entire presentation with humor and fascinating tales of his memories, Box focused on sequential design of experiments. He attributed much of what he knows about DOE [design of experiments] to Ronald A. Fisher. Box explained that Fisher couldn’t find the things he was looking for in his data, “and he was right. Even if he had had the fastest available computer, he’d still be right,” said Box. Therefore, Fisher figured out how to study a number of factors at one time. And so, the beginnings of DOE.

Having worked and studied with many other famous statisticians and analytic thinkers, Box did not hesitate to share his characterizations of them. He told a story about Dr. Bill Hunter and how he required his students to run an experiment. Apparently a variety of subjects was studied [see 101 Ways to Design an Experiment, or Some Ideas About Teaching Design of Experiments]

According to Box, the difficulty of getting DOE to take root lies in the fact that these mathematicians “can’t really get the fact that it’s not about proving a theorem, it’s about being curious about things. There aren’t enough people who will apply [DOE] as a way of finding things out. But maybe with JMP, things will change that way.”

George Box is a great mind and great person who I have had the privilege of knowing my whole life. My father took his class at Princeton, then followed George to the University of Wisconsin-Madison (where Dr. Box founded the statistics department and Dad received the first PhD). They worked together building the UW statistics department, writing Statistics for Experimenters and founding the Center for Quality and Productivity Improvement among many other things.

Statistics for Experimenters: Design, Innovation, and Discovery shows that the goal of design of experiments is to learn and refine your experiment based on the knowledge you gain and experiment again. It is a process of discovery. If done properly it is very similar to the PDSA cycle with the application of statistical tools to aid in determining the impact of various factors under study.

Related: Box on QualityGeorge Box Quotationsposts on design of experimentsUsing Design of Experiments