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Introduction to Fractional Factorial Designed Experiments

Posted on June 10, 2013  Comments (6)

Scientific inquiry is aided by sensible application of statistical tools. I grew up around the best minds in applied statistics. My father was an eminent applied statistican, and George Box (the person in the video) was often around our house (or we were at his). Together they wrote Statistics for Experimenters (along with Stu Hunter, not related to me) the bible for design of experiments (George holds up the 1st edition in the video).

The video may be a bit confusing without at least a basic idea of factorial designed experiments. These introductory videos, by Stu Hunter, on Using Design of Experiments to Improve Results may help get you up to speed.

[the video has been removed from the internet]

This video looks at using fractional factorials to reduce the number of experiments needed when doing a multifactor experiment. I grew up understanding that the best way to experiment is by varying multiple factors at the same time. You learn much quicker than One Factor At a Time (OFAT), and you learn about interactions (which are mainly lost in OFAT). I am amazed to still hear scientists and engineers talk about OFAT as a sensible method or even as the required method, but I know many do think that way.

To capture the interactions a full factorial requires an ever larger number of experimental runs to be complete. Assessing 4 factors requires 16 runs, 6 would require 64 and 8 would require 256. This can be expensive and time consuming. Obviously one method is to reduce the number of factors to experiment with. That is done (by having those knowledgable about the process include only those factors worth the effort), but if you still have, for example, 8 very important factors using a fractional factorial design can be very helpful.

And as George Box says “What you will often find is that there will be redundant factors… and don’t forget about those redundant factors. Knowing that something doesn’t matter is almost as important as knowing what does.” If you learn a factor isn’t having an affect you may be able to save money. And you can eliminate varying that factor in future experiments.

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George Box 1919 to 2013 – A Great Friend, Scientist and Statistician

Posted on March 30, 2013  Comments (2)

Reposted from my management blog.

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

Related: It is not about proving a theorem it is about being curious about things – Box on Quality – Soren Bisgaard – Learning Design of Experiments with Paper Helicopters – Peter Scholtes

Circumhorizontal Arcs – Fire Rainbows – Cloud Rainbows

Posted on December 20, 2012  Comments (4)

photo of rainbow in a cloud

Fire Rainbow, Johor Bahru by John Hunter

Yesterday afternoon I spotted this odd, colorful, spectrum seemingly in a cloud in Johor Bahru, Malaysia. The colors are similar to a rainbow but the prism effect takes on a bit different form than a rainbow as I learned with a bit of searching online. I added a short post to this blog, about the phenomenon a few years ago.

photo of a large cloud over Johor Bahru

Johor Bahru under a large cloud which is topped with a fire rainbow.

A circumhorizontal arc is an optical phenomenon – an ice-halo formed by plate-shaped ice crystals in high level cirrus clouds. They are also known as “fire rainbows,” if the cloud is at the right angle to the sun, the crystals will refract the sunlight just as when rainbow is created.

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Healthy Diet, Healthy Living, Healthy Weight

Posted on January 4, 2012  Comments (8)

Living and eating healthily is tricky but not entirely confusing. The whole area of eating healthy food and what is a healthy weight is one where the scientific inquiry process and the complexity of scientific research on what is healthy for us is clear. Scientists study various issues and learn things but creating simple rules has proven difficult. Different studies seem to show benefits of contradictory advice, advice once seen as wise is now seen as wrong…

This is an area I am far from knowledgable about. Still I try to pay some attention as I like being healthy. Being sick is the quickest way to appreciate how great it is to be healthy. From various things I have skimmed it seems there is more evidence from several studies about how difficult it is to lose weight. Our bodies seem to work against our efforts.

And this, it seems to me, makes the problem of increasing childhood and teen obesity even more important to deal with as soon as issues arise.

It seems to me the most important thing to take from this, is the importance of maintaining a healthy weight: since you can’t just easily make up for a bad year of weight gain. I am not sure why I haven’t seen this note in most of what I have read – I suspect it is our reluctance to make value judgements about what is healthy. The problem I see with that is, the best advice we have is confusing enough without people with more knowledge being reluctant to state their best advice given the current knowledge. That doesn’t mean the suggestions are right, but at least they are educated guesses.

I try to eat relatively healthily. Which for me means taking steps to increase the amount of vegetables I eat (especially greens and some fiber) and decrease the amount of sweets and heavily processed food I eat (I still eat way too much heavily processed food). And I try to exercise as it seems to have many benefits including helping make up for some weaknesses in your diet (like eating too many calories and too many “empty calories). In my opinion (which on this topic may well not be worth much) eating a bit more stuff that really isn’t so good for you and exercising more is an easier tradeoff than trying to eat perfectly and do the minimum amount of exercise needed to stay healthy.

I also eat yogurt – I like it and the beneficial benefits of some bacteria seems likely. I heard recently something that surprised me which is that the beneficial bacteria remain for close to 2 weeks. I figured they would be gone in a couple days. I only heard that from one source (I can’t remember now but some seemingly knowledgable source – scientist researching the area), so it might not be accurate but it was interesting.

Here is an example of one of these health studies. They find that a low protein diet resulted in a loss of “lean weight” (muscle…) and more fat than a comparable diet with more protein. The same weight with a higher percentage of fat is not a good thing for human health. Thus the message is that a lower protein diet has this risk that must be considered (and therefor higher protein diets may well be wise). Of course things get much more complicated than that when we actually try to live by a diet.

Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating

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Nice Interaction with a Group of Wild Mountain Gorillas Strolling Through Camp

Posted on December 22, 2011  Comments (0)

An amazing encounter with a troop of wild mountain gorillas near Bwindi Impenetrable National Park, Uganda. The reality is that these many natural environments will be maintained only with economic incentives. A certain amount of wilderness can be maintained with economic support from outside (government, charity…). But reasonable accommodations to find ways to make retaining natural wonders economically viable are likely a key to saving much of these environments for the future. Unfortunately there are big incentives to destroy nature from those rich tourists who don’t follow the rules and push their guides to break the rules (guides often do this as they have seen great monetary rewards [in tips] for breaking the rules (bothering animals, going too close, going to off limits areas…). It is sad how often tourists at national parks show utter disregard for nature and preserving things for later generations.

It seems like this video wasn’t about that type of behavior though. Instead it is just an example of how cool nature can be at times. Animals are not quite as predictable as some believe. Like this group that wandered into the camp (as they do a couple times a year) animals often stray from their normal behavior.

Providing good jobs and sharing revenue from tourists with local residents (paying for schools…) is a very good way to encourage residents to support natural heritage sites. This is true in Africa and also near park in the United States, or anywhere else. Here is an example of an organization doing that: Conservation Through Public Health.

I am a huge fan of tying in economic benefits to natural parks and resources. I think this is part of making them not environmentally sustainable but economically sustainable. If the areas do not make a contribution to the economic well being of those living there, there is a danger the land will be tapped for uses that will damage their natural heritage value. We do have to be careful as often these economic interests can turn into greedy people just wanting whatever they can get now (I am saddened by how often tourists behave in this way at natural wonders).

People are going to determine how land is used. We can hope that purely altruistic motives will result in long preserved natural habitats. But I don’t think that hope is as sustainable as creating a situation where it is also in people’s economic interests to maintain the environments. A combination of altruistic, long term thinking and economic interest is more likely to preserve natural environment (in my opinion).

Related: Massive Western Lowland Gorilla Population in Northern Republic of Congo – Grauer’s Gorilla (Eastern Lowlands Gorilla) – African Parks (a business approach to conservation) – Travel photos from National Parks

I was Interviewed About Encouraging Kids to Pursue Engineering

Posted on November 21, 2011  Comments (4)

Amanda Moreno interviewed me about Encouraging Kids to Pursue Engineering over on the Knovel Blog.

What can parents do to cultivate an interest in science in their kids early on?

John Hunter: Ask questions. Answer questions. Explain how things work. Explain why things are done the way they are. Kids want the attention of their parents, and when they are younger they are constantly trying to get it (dad look, mom look, watch me!). They have similar feelings when they are older, but are not as forthright about saying what they want. If you take a sincere interest in their questions, you’ll motivate them to continue pondering how the world works. Make it fun to learn. Kids have an intrinsic motivation to learn. Keeping their curiosity alive is the first step.
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So, on the university level, professors generally aren’t student-centric enough. What other factors are discouraging students in the classroom?

JH: I have one belief that is close to heresy. I don’t see why publication has to be so important for professors (if what we are after is good teachers, not authors). …

Read the rest of the interview.

Related: Backyard Wildlife: Sharpshinned Hawk – Qubits Construction Toy – What Kids can Learn By Playing – Encouraging Curiosity in Kids

Encouraging Curiosity in Kids

Posted on October 28, 2011  Comments (25)

How do you help make your children scientifically literate? I think the biggest thing you can do is encourage curiosity.

One way to encourage curiosity it is by answering their questions (and not saying: I am too busy, don’t bother me, don’t ask me?, stop asking why…). I know adults are busy and have all sorts of stuff we are trying to get done; and the question about why I need to wash my hands doesn’t seem worth answering. But I think anytime a kid is asking why is an opportunity to teach and encourage them to keep being curious.

It is very easy to shut off this curiosity, in our society anyway (we do it to the vast majority of people). The biggest difference I see between adults and kids is not maturity or responsibility but curiosity (or lack thereof in adults) and joy (versus adults who seem to be on valium all the time – maybe they are).

As they grow up kids will have lots of science and technology questions that you don’t know the answers to. If you want them to be curious and knowledgeable, put in the effort to find answers with them. You have to help them find the answers in a way that doesn’t turn them off. If you just say – go look it up yourself (which really they can do), maybe the 2% that are going to become scientists will. But most kids will just give up and turn off their curiosity a little bit more (until eventually it is almost gone and they are ready to fit into the adult world). Which is very sad.

Once you get them used to thinking and looking things up they will start to do this on their own. A lot of this just requires thinking (no need to look things up – once a certain base knowledge is achieved). But you need to set that pattern. And it would help if you were curious, thought and learned yourself.

Photo of kids intently studying on a Malaysian beach

My mom with a group of Malaysia kids apparently intent on learning something. I am there, but not visible in this photo. Photo by my father.

While walking in the park, see one of those things you are curious about and ask why does…? It is good to ask kids why and let them think about it and try and answer. Get them in the habit of asking why themselves. And in those cases when no-one knows, take some time and figure it out. Ask some questions (both for yourself – to guide your thinking – and to illustrate how to think about the question and figure things out). If you all can’t find an explanation yourselves, take some time to look it up. Then at dinner, tell everyone what you learned. This will be much more interesting to the kids than forcing them to elaborate on what they did today and help set the idea that curiosity is good and finding explanations is interesting.

It is fun as a kid if your parent is a scientist or engineer (my father was an engineering professor).

You often don’t notice traits about yourself. In the same what I know what red looks like to me, I figure we both see this red shirt you see the red that I do. But maybe you don’t. I tend to constantly be asking myself why. If I see something new (which is many, many times a day – unless I am trapped in some sad treadmill of sameness) I ask why is it that way and then try and answer. I think most of this goes on subconsciously or some barely conscious way. I actually had an example a few months ago when I was visiting home with my brother (who is pretty similar to me).

As we were driving, I had noticed some fairly tall poles that seemed to have really small solar panels on top. I then noticed they were space maybe 20 meters apart. Then saw that there seemed to be a asphalt path along the same line. I then decided, ok, they are probably solar panels to power a light for the path at night. Then my brother asked why are there those small solar panel on top of that pole?

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The Politics of Anti-Science

Posted on August 30, 2011  Comments (8)

In the 1960’s the USA had an unrealistic view of how much studying and learning about science and engineering could do. Investing is science and engineering is an extremely wise economic (and cultural) endeavor but it isn’t going to solve all the problems that exist. Somehow today we find ourselves with a large number of politically powerful people we take strong anti-science positions. These tactics reduce funding and support for beneficial research and are short sited approaches to public administration. This is an unfortunate turn of events that is damaging the American economy and will have huge damages going forward.

Thankfully other countries have seen how wise investing in science and engineering is and have more than taken up the slack created by the anti-science community. Two favorite tactics of the anti-science leaders is to try and create confusion where there is none and to turn the focus away from serious matters and instead playing silly political games. The silly games will draw donors and voters so if they care about those things more than the country and the future of the country it is a sound tactic. The damage it causes the country however I would hope would limit the use of such tactics however that has not been the case recently.

‘Shrimp On A Treadmill’: The Politics Of ‘Silly’ Studies

Take the case of the “shrimp on a treadmill.” Burnett says the senator’s report linked that work to a half-million-dollar research grant. But that money actually went to a lot of different research that he and his colleagues did on this economically important seafood species.

The treadmills were just a small part of it, a way to measure how shrimp respond to changes in water quality. Burnett says the first treadmill was built by a colleague from scraps and was basically free, and the second was fancier and cost about $1,000. The senator’s report was misleading, says Burnett, “and it suggests that much money was spent on seeing how long a shrimp can run on a treadmill, which was totally out of context.”

John Hart, a Coburn spokesperson, said in an email that “our report never claimed all the money was spent on shrimp on a treadmill. The scientists doth protest too much. Receiving federal funds is a privilege, not a right. If they don’t want their funding scrutinized, don’t ask.”

What the politicians are doing is exactly what this spokesperson suggests – they are withdrawing from the anti-science culture created by some in Washington: they are moving their research to countries that support rather than attack science. That is a very bad thing for the USA. There are a number of very bad economic policies a government can take. Driving scientists and engineers into the arms of other countries is one of the worst.
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What Happens If the Overuse of Antibiotics Leads to Them No Longer Working?

Posted on August 9, 2011  Comments (3)

Antibiotics have been a miraculous tool to keep up healthy. Like vaccines this full value of this tool is wasted if it is used improperly. Vaccines value is wasted when they are not used enough. Antibiotics lose potency when they are overused. The overuse of anti-biotics on humans is bad (especially the huge amount of just lazy, not scientific use). But the massive overuse in livestock is much worse, it seems to me.

The health system in the USA is broken in a huge way in which it is broken is the failure to address creating systemic behavior that promotes human health and instead just treating illness. It is much better to avoid a situation where we breed super bugs and then try to treat those super bugs that have evolved to be immune to the antibiotics we have to use.

When antibiotics no longer work

While the source of the current salmonella outbreak remains murky, we can reasonably speculate about the genesis of the bug’s drug-resistance: the reportedly endemic overuse of antibiotics by the agricultural industry.

Drugs are given to livestock for multiple reasons. An obvious one is for the treatment of diseases. When livestock are sick, veterinarians administer a significant dosage in hopes of eliminating the animal’s affliction. Another reason is preventative. Animals in close quarters are more susceptible to infection, so farmers will often administer medicine to healthy animals in order to nip anything nasty in the bud. Most controversially, though, members of the agricultural industry use antibiotics for the express purpose of promoting livestock growth.

It’s a well-known, if not entirely intuitive, fact that healthy animals who are fed small, or “sub-therapeutic,” doses of antibiotics will wind up larger than their unmedicated counterparts. In many such cases, these drugs are given to livestock through their feed or water, and without the prescription or oversight of a veterinarian, according to Dr. Gail Hansen, a senior officer at the Pew Campaign on Human Health and Industrial Farming.

An estimated 80 percent of all antibiotics in the U.S. are given to food-producing livestock, according to the FDA. And approximately 83 percent of that medicine is “administered flock- or herd-wide at low levels for non-therapeutic purposes, such as growth promotion and routine disease prevention,” according to a lawsuit filed against the FDA in May. These figures could have very real consequences for public health, because the Catch-22 of this antibiotic abandon is the widespread development of drug-resistant bacteria, colloquially referred to as “super-bugs.”
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In 2006, the European Union banned all use of antibiotics on livestock for growth promotion. And the U.S. Senate will consider similar legislation this year. Sen. Dianne Feinstein, D-Calif., reintroduced the “Preservation of Antibiotics for Medical Treatment Act” last month, which would significantly rein in agricultural drug use, and strictly prohibit the application of sub-therapeutic doses of drugs that have benefits for humans.

Still, the agricultural industry disputes data about its use of antibiotics and the rise of super-bugs, and it has aggressively fought efforts to legislate the matter. As a result, it’s hard to tell how far the legislation might proceed.

Related: Antibiotics Too Often Prescribed for Sinus Woes – Overuse of Antibiotics (2005) – FDA May Make Decision That Will Speed Antibiotic Drug Resistance (2007)

The end of the era of antibiotics

How did this happen? The driving forces are Darwin and human carelessness. Bacteria are constantly evolving, adapting to the changing conditions they face. Antibiotics usually kill bacteria. But sometimes a bacteria will develop a biological defense – particularly if too small a dose is used.
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Antibiotics require a prescription in America, but our nation is still very much a part of the problem. Patients routinely demand these drugs, and doctors acquiesce, for respiratory infections and other ailments that will not respond to antibiotics because they are caused by a virus. We use soap with antimicrobial agents when regular soap does equally well. And we allow farmers to feed antibiotics to livestock in horrifying amounts, not to treat illnesses but to make farming more efficient.

The Potential Role of Concentrated Animal Feeding Operations in Infectious Disease Epidemics and Antibiotic Resistance

This working group, which was part of the Conference on Environmental Health Impacts of Concentrated Animal Feeding Operations: Anticipating Hazards—Searching for Solutions, considered the state of the science around these issues and concurred with the World Health Organization call for a phasing-out of the use of antimicrobial growth promotants for livestock and fish production. We also agree that all therapeutic antimicrobial agents should be available only by prescription for human and veterinary use.

Antibiotic Resistance in Livestock: More at Risk Than Steak
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Letting Children Learn – Hole in the Wall Computers

Posted on July 19, 2010  Comments (7)

The hole in the wall experiments are exactly the kind of thing I love to lean about. I wrote about them in 2006, what kids can learn.

Research finding from the Hole in the Wall foundation:

Over the 4 year research phase (2000-2004), HiWEL has extensively studied the impact of Learning Stations on children. Hole-in-the-Wall Learning Stations were installed in diverse settings, the impact of interventions was monitored and data was continually gathered, analyzed and interpreted. Rigorous assessments were conducted to measure academic achievement, behaviour, personality profile, computer literacy and correlations with socio-economic indicators.
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The sociometric survey found:

  • Self-organizing groups of children who organize themselves into Leaders (experts), Connectors and Novice groups.
  • Leaders and Connectors identified seem to display an ability to connect with and teach other users.
  • Key leaders on receiving targeted intervention, play a key role in bringing about a “multiplier effect in learning” within the community.
  • Often girls are seen to take on the role of Connector, who initiates younger children and siblings (usually novices with little or no exposure to computers) and connects them to the leaders in the group

I believe traditional education is helpful. I believe people are “wired” to learn. They want to learn. We need to create environments that let them learn. We need to avoid crushing the desire to learn (stop de-motivating people).

If you want to get right to talking about the hole in the wall experiments, skip to the 8 minute mark.

Related: Providing Computer to Remote Students in Nepal – Teaching Through Tinkering – Kids Need Adventurous Play – Science Toys You Can Make With Your Kids

Backyard Wildlife: Hawk

Posted on June 30, 2010  Comments (8)

photo of a hawk on my deck

Nice view out my window from my desk today. This wonderful hawk landed on my deck and I was lucky enough to have my camera right next to me. It is so nice to be able to have this view instead of a view like the IT Crowd staff have in their basement IT office.

If you let me know what type of hawk you think this is that would be great – including links to an identification page would be appreciated too. Last time people helped identify a Sharp-shinned Hawk enjoying a meal. Enjoying nature in your back yard is a wonderful thing.

Related: Backyard Wildlife: Great Spreadwing Damselfly – Backyard Wildlife: Fox – Backyard Wildlife: Turtle – Backyard Wildlife: Birds