Archive for category science

Models responsible for whacky weather

Watching Brazilian supermodel Gisele Bundchen sashay across the Olympic stadium in Rio reminded me that, while these fashion plates are really dishy to view, they can be very dippy when it comes to forecasting.  Every time one of our local weather gurus says that their models are disagreeing, I wonder why they would ask someone like Gisele.  What does she and her like know about meteorology?

There really is a connection of fashion and statistical models—the random walk.  However, this movement would be more like that of a drunken man than a fashionably-calculated stroll down the catwalk.  For example, see this video by an MIT professor showing 7 willy-nilly paths from a single point.

Anyways, I am wandering all over the place with this blog.  Mainly I wanted to draw your attention to the Monte Carlo method for forecasting.  I used this for my MBA thesis in 1980, burning up many minutes of very expensive main-frame computer time in the late ‘70s.  What got me going on this whole Monte Carlo meander is this article from yesterday’s Wall Street Journal.  Check out how the European models did better than the Americans on predicting the path of Hurricane Sandy.  Evidently the Euros are on to something as detailed in this Scientific American report at the end of last year’s hurricane season.

I have a random thought for improving the American models—ask Cindy Crawford.  She graduated as valedictorian of her high school in Illinois and earned a scholarship for chemical engineering at Northwestern University.  Cindy has all the talents to create a convergence of fashion and statistical models.  That would be really sweet.

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Hold on a second—the lords of time elect to extend the year of 2016

The controllers of clocks at the International Earth Rotation and Reference Systems Service (IERS) decided recently that 2016 ought to leap an extra second to stay in synch with Earth’s rotation.  This will create a great deal of consternation for computers, thus IERS is giving six months’ notice for IT people to prepare themselves.  Despite that lead time, about 10 percent of networks around the world are expected to fail, e.g.; a worldwide airline booking system that went down in 2012 for several hours when its computers’ internal clocks could not reconcile the discrepancy with outside systems. (I suggest you stock up on water, food stuffs and toilet paper.)

Here are some stats I gleaned from reports on this astronomical happening by New Scientist and National Geographic:

  • Clocks will read 23:59:60 on the 31st of December (I am doubtful this will work on my timepieces)
  • 86,400 seconds tick off every day on the master atomic clock for Coordinated Universal Time (UTC), however; the push and pull of the Moon causes the Earths massively heavy oceans to slosh around, which decelerates the spin between 1.5 and two milliseconds every 24 hours, on average.
  • Gauging by sightlines from far off galaxies, IERS monitors changes to Earth’s spin. When it goes off by more than 0.9 seconds plus or minus, they mandate a 1 second adjustment.
  • In 1972, when the adjustments began, the world got 10 extra seconds to make up for lost time. Since then 16 more seconds have been added—the last one on June 30, 2015. IERS have never removed a second. (If you are a rocket scientist, please compute how long it will it be until the Earth stops and let me know so I have plenty of time to begin packing up my things.)

Since antiquity the Earth’s rotation has provided us with our timescale – it is the Earth’s rotation that gives us our most basic unit of time, the solar day.

— Rory McEvoy, Curator of Horology, Royal Observatory Greenwich

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American Statistical Association (ASA) defends itself against P-shooters

With the fundamental statistic of P value coming under severe attack, e.g., it being banned in early 2015 by the Basic and Applied Social Psychology (BASP) journal, the ASA has been compelled to issue an unprecedented press release with guidelines for avoiding misuse of hypothesis testing by scientists claiming significant experimental results.*  “The ASA statement is intended to steer research into a ‘post p<0.05 era,’” said Ron Wasserstein, the ASA’s executive director.

“To pounce on tiny P values and ignore the larger question is to fall prey to the ‘seductive certainty of significance.’”

– Geoff Cumming, emeritus psychologist, La Trobe University, Melbourne, Australia

The ASA statement on “Statistical Significance and P-Values” can be seen here.  It includes 6 guidelines on proper use of this essential tool for assessing research data, beginning with the assertion that “P-values can indicate how incompatible the data are with a specified statistical model.”

*See, for example, this Nature article that claims P values, the ‘gold standard’ of statistical validity, are not as reliable as many scientists assume.

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Technology advanced beyond any hope for healthy curiosity

I am watching the Syfy’s series “Childhood’s End” this week.  It is based on a science fiction novel by British author Arthur C. Clarke, one of my favorites growing up.  One of the main characters is a very bright boy who at the end of the premier episode last night becomes an astrophysicist, despite this scientific profession being made entirely superfluous by the advanced technology of the alien Overlords.

This morning Robert Scherrer, the chairman of the department of physics and astronomy at Vanderbilt University, lamented in an editorial* for Wall Street Journal that children no longer have any reason to be interested in science, mainly because most of our household gadgets fall into the category of magic—alluding to Clarke’s observation that “any sufficiently advanced technology is indistinguishable from magic.”

“The world’s now placid, featureless, and culturally dead: nothing really new has been created since the Overlords came. The reason’s obvious. There’s nothing left to struggle for, and there are too many distractions and entertainments.”

― Arthur C. Clarke, Childhood’s End

*How to Raise a Scientist in the Xbox Age

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Crater Experiment Makes a Big Impact

Craters are crazy and cool.  One that is quite amazing was created by the Barringer Meteorite that crashed into Arizona about 50,000 years ago with an explosion equal to 2.5 megatons of TNT.  Based on this detailing of what a 2 MT bomb would do I figure that Barringer would have completely wiped out my home town of Stillwater, Minnesota and its 20,000 or so residents, plus far more beyond us.  The picture my son Hank took of the 1 mile wide 570 foot deep crater does not do justice to its scale.  You really need to go see it for yourselfMeteor Crater as the two of us did.

Because of my enthusiasm for craters, making these rates number on my list of fun science projects in DOE It Yourself.  As noted there, members the Salt Lake Astronomical Society wanted to drop bowling balls from very high altitudes onto the salt flats of Utah, but workers in the target area from the U.S. Bureau of Land Management objected to the experiment.

Kudos to science educator Andrew Temme for leading students through a far more manageable experiment shown in this video.  In reply to me asking for permission for providing a link to his fantastic impact movies Andrew gave me this heads-up.  “I attended a NASA workshop to get certified to handle real moon rocks and meteorites at the NJ State Museum in Trenton.  This lab in the educator guide suggested mixing up your own lunar powder and throwing objects to simulate impact craters.  When I got home I ran the lab with a few of my classes and then made the video.  I used a Sony handheld camera that had a slow motion setting (300 fps).”  Awesome!

The other day I went up to the 9th floor of my condo building in Florida and tossed a football down on to the parking lot.  I am warming up to heaving a 15 pound mushroom anchor over on the beach side from atop one of the far pricier high rises along the Gulf.  However, I have to wait until the turtle nesting season is over.

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Believe it or not–sweet statistics prove that you can lose weight by eating chocolate

Keep calm and carry on eating chocolateA very happy lady munching on a huge candy bar caught my eye in The Times of India on Friday, May 25.  Not the lady—the chocolate.

After tasting a variety of delectable darks from a chocolatier in Belgium many years ago, I became hooked.  However, I never imagined this addiction would provide a side benefit of weight loss.  It turns out that a clinical trial set up by journalist John Bohannon and two colleagues came up with this finding and showed it to be statistically significant.  This made headlines worldwide.

Unfortunately, at least so far as I’m concerned, the whole study was a hoax based on deliberate application of junk science done to expose phony claims made by the diet industry.

It turns out to be very easy to generate false positive results that favor a dietary supplement.  Simply measure a large number of things on a small group of people.  Something surely will emerge that out of this context tests significantly significant.  What this will be, whether a reduction in blood pressure, or loss in weight, etc., is completely random.

Read the whole amazing story here.

My thinking is while Bohannan’s study did not prove that eating chocolate leads to weight loss, the subjects did in fact shed pounds faster than the controls.  That is good enough for me.  Any other studies showing just the opposite results have become irrelevant now—I will pay no attention to them.

Now, having returned from my travel to India, I am going back to dip into my horde of dark chocolate.

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Null hypothesis significance testing procedure (NHTSP) psyched out

My colleague Brooks Henderson alerted me to this new policy by the editors of the Basic and Applied Psychology (BASP) journal to ban the NHSTP. According to the editorial in their Feb 2015 issue, authors must remove all p-values and the like and not refer to “significant” differences. They also banned confidence intervals, which really makes this new policy onerous, in my opinion.

I do see the sense of focusing on effect sizes and allowing the readers, presumably subject matter experts, to judge their importance. However, although they do “encourage the the use of larger sample sizes”, it makes no sense, I feel, to disregard the impact of small studies on the uncertainty of the results.

Blaming the misuse of NHTSP and p-values in particular for bad science is like letting a bad guy go by saying the gun is at fault.

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Picking on P in these times of measles

Randall Munroe takes a poke at over-valuers of p in this XKCD cartoon

Getting science right by proper application of statistics should be at the forefront for all of us now who are in harm’s way of the current outbreak of measles.  This preventable disease is spreading because of parents who choose not to vaccinate their children for fear of autism—a long discredited side-effect reported erroneously based on a fraudulent 1999 study.  If this had never seen the light of day due to better vetting, it would have prevented a great deal of misery.  Sadly even the most well-meaning researchers tend to put too much faith in probability (P) values that seemingly provide significance to data they have collected as a test of their hypothesis.

Nature weighed in with their shots against scientists who misuse P values in this February 2014 article by statistics professor Regina Nuzzo.  She bemoans the data dredgers who come up with attention-getting counterintuitive results using the widely-accepted 0.05 P filter on long-shot hypotheses.  A prime example is the finding by three University of Virginia finding that moderates literally perceived the shades of gray more accurately than extremists on the left and right (P=0.01).  As they admirably admitted in this follow up report on Restructuring Incentives and Practices to Promote Truth Over Publishability, this controversial effect evaporated upon replication.  This chart on probable cause reveals that these significance chasers produce results with a false-positive rate of near 90%!

Nuzzo lays out a number of proposals to put a damper on overly-confident reports on purported scientific studies.  I like the preregistered replication standard developed by Andrew Gelman of Columbia University, which he noted in this article on The Statistical Crisis in Science in the November-December issue of American Scientist.  This leaves scientists free to pursue potential breakthroughs at early stages when data remain sketchy, while subjecting them to rigorous standards further on—prior to publication.

“The irony is that when UK statistician Ronald Fisher introduced the P value in the 1920s, he did not mean it to be a definitive test. He intended it simply as an informal way to judge whether evidence was significant in the old-fashioned sense: worthy of a second look.”

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The best accidental inventions of all time

I learned from my latest issue of Chemical and Engineering News that Stanley Stookey of Corning Glass Works died last month at age 99.  In 1952 he mistakenly heated an alumino-silicate glass to 900 degrees C meaning only to top out at 600.  After much cursing, according to the CEN story, Stookey found that instead of the molten mess expected, the material crystallized into a new type of material called a glass ceramic that proved to be “harder than carbon steel yet lighter than aluminum—shatterproof.”

Being in the business of planned experimentation it always amazes me to come across stories like this of serendipitous science.  Obviously chance favors the prepared mind because most of the momentous discoveries are made by world-class chemists such as Stookey and others of his kind in the fields of physics and so forth. 

I am a huge fan of 3M Post-It® Notes, not only due to their incredible usefulness, but also because it delights me to think of my fellow Minnesotan Art Fry coming up these by accident. For a list including him and a dozen other experts in their field who made the most of mishaps into inventions see 13 Accidental Inventions That Changed The World by Drake Baer of Business Insider.  The one I like best is George Crum (great surname for a chef!) who reacted to customer complaining about his French fries by slicing them into ridiculously thin and hard-backed pieces.  Never mind that it probably was his sister Katie who made the accidental discovery according to this Snopes investigation.  Either way this works out to be a delicious story.

My advice to our clients is to keep a close watch for any strange results that crop up as statistically deviant in the course of a designed experiment.  They may turn out to be really Crummy!

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The rarest of birds—a reproducible result from a scientific study

In The New York Times new column Raw Data, science writer George Johnson laments experimenters

“ways of unknowingly smuggling one’s expectations into the results, like a message coaxed from a Ouija board.”

– Science Times, 1/21/14

This, of course, leads to irreproducible findings.

As a case in point, only 6 of 53 landmark papers about cancer found support in follow up studies, even with the help of the original scientists working in their own labs, according to an article in the Challenges in Irreproducible Research archive of Nature cited by Johnson.

That is discouraging but I am not surprised.  I feel fairly sure that the any assertions of import get filtered very rigorously until only ones that reproduce reliably make it through.

The trick is to remain extremely skeptical of initial reports, especially those that get trumpeted and reverberate around the popular press and the internet.  Evidently it is human nature to then presume that when an assertion is repeated often enough then it must be true, even though it has not yet been reproduced.  Saying it’s so does not make it so.

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