Archive for June, 2011

Fun summer-time experiment: Super-cool beer so it instantly freezes solid

It turns out that if a bottle of beer is put in the freezer for long enough, and then removed while it is still liquid and, lastly, given a sudden shock, the beer will instantly freeze solid.  I saw this confirmed by the pop-science TV show Mythbusters in their episode 153, originally aired on 11/10/10.  Based on trial-and-error experimentation their Build Team found that 3 hours of cooling time sufficed to create the delightful phenomenon.  See the instant beer-freeze demonstrated by EasyBarTricks.com here.  For detailed instructions on how to try this at home or in a classroom, plus a nerdy explanation (think PVNERT) by physics and math teacher Daryl Taylor, check out this website.

Of course I had to try this for myself.  However, not being one who ever leaves well-enough alone, I tried light beer (Miller, bottled in clear glass) side by side with the recommended Corona – two of each.  Could this be a factor (light versus regular brew)?  After being careful to wait at least 3 hours for the quartet of brews to super-cool, I brought them out for a family party.  Two of the beers crystallized when smacked on our kitchen cutting board, but the other two did not.  Here’s a twist, though: None of the bottles were uncapped first, so how does that gibe with the PV-nerd’s explanation?

Alas, one of the light beers crystallized and the other did not – ditto for the Corona, so my results, albeit semi-successful, were indeterminate on the issue of light vs regular brews.   The good news is that we salvaged two bottles of beer (the frozen ones become undrinkable).

Feel free to weigh in with your theories and experimental results from this beer trick.  One thing I learned from my first try – a lot more beer would be good, along with a walk-in freezer (or the backyard in mid-winter).

 

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Strategy of experimentation: Break it into a series of smaller stages

Tia Ghose of The Scientist provides a thought-provoking “Q&A” with biostatistician Peter Bacchetti on “Why small is beautiful” in her June 15th column seen here.  Peter’s message is that you can learn from a small study even though it may not provide the holy grail of at least 80 percent power.*  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).  Furthermore, a good strategy of experimentation is to proceed in three stages:

  • Screening the vital few factors (typically 20%) from the trivial many (80%)
  • Characterizing main effects and interactions
  • Optimizing (typically via response surface methods).

For a great overview of this “SCO” path for successful design of experiments (DOE) see this detailing on “Implementing Quality by Design” by Ronald D. Snee in Pharm Pro Magazine, March 23, 2010.

Of course, at the very end, one must not overlook one last step: confirmation and/or verification.

* I am loathe to abandon the 80% power “rule”** but, rather, increase the size of effect that you screen for in the first stage, that is, do not use too fine a mesh.

** For a primer on power in the context of industrial experimentation via two-level factorial design, see these webinar slides posted by Stat-Ease.

 

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Why coaches regress to be mean

In a column for Newsweek magazine, science writer Sharon Begley* discusses how ignorance about the statistical principle of regression to the mean** causes all sorts of crazy behavior.  For example, sufferers of colds try a new remedy that seems to make them better, but in reality, they were already recovering.  This behavior leads to over-use of antibiotics, which breeds drug-resistant bacteria.  Ultimately, according to this quote passed along by Begley:

“People die at a biblical scale because of such stupidity.”

– Ben Goldacre, author of Bad, Science: Quacks, Hacks and Big Pharma Flacks.

On a lighter (?) note, this tendency by people to attribute cause-and-effect relationships to random ups-and-downs explains why some teachers, coaches and instructors hold back praise and only berate their pupils.  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.  So now you know why coaches yell so much: It’s their regression to the mean.

* “Wanted: BS Detectors” – 11/8/10.

**First brought forward by France Galton in 1886 via this essay on “Regression towards Mediocrity in Hereditary Stature”

 

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How hot? 103 under our shade tree!

According to my morning newspaper (St. Paul Pioneer Press), yesterday’s record temperature made it hotter hereabouts than a billy goat in a pepper patch, or the devil’s underwear (I hope he is not a tweeter like that New York Congressman), or two bears fighting in a forest fire (down in Arizona, I suppose).  Even so, a vestige of the once 60-foot high pile of snow dump in downtown St. Paul remained intact.  Perhaps it will disappear today.  I hope so, because it will be back in the 60’s by Friday – colder than a basement toilet seat as Minnesotans like to say.

 

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