Why coaches regress to be mean
Posted by mark in Consumer behavior on June 13, 2011
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”
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.
Video of paper-helicopter fly-offs at South Dakota School of Mines & Technology
Posted by mark in design of experiments on May 10, 2011
Stat-Ease Consultant Brooks Henderson produced this video — it’s quite impressive!
For background on the paper helicopter experiment, see this previous StatsMadeEasy post.
Simple and cheap safety precautions against the small risk of drowning in an automobile
I always thought that if I was in a car that went into water, I’d be cool enough to roll down the windows, or wait until it submerges before opening the door (otherwise the pressure differential makes it impossible). Based on actual experimentation, the hosts of the television show Mythbusters felt the same way, that is, until viewers pointed out that many cars turn turtle as they sink. So in a show I watched last month they [Jamie Hyneman and Adam Savage] tried this. It was a disaster! The Mythbuster driver [Adam] survived only by breathing from an emergency air source, and the safety diver had to cut his way out of a seat belt that wouldn’t release! See this recap to learn what went wrong. What they don’t show is how at first the car just floated, so it seemed like no big deal; but then when it sank, the automobile went down incredibly fast. En route to the bottom of the lake the car spun around so much that the occupants would’ve drowned for sure. Scary!
After this epiphany, I ordered several of these inexpensive (<$5) safety hammers (see one pictured) for cars owned by me and my offspring.
Check out this post by First Aid Monster for another video showing how fast you can go underwater when a car runs into a canal, river, pond, lake or ocean. They suggest buying a safety hammer and provide a link to one similar to what I bought.
When I advised family and co-workers to be prepared for being trapped in a car that goes underwater, it was met by a few with great skepticism.
One individual wondered how many people die this way, figuring it being so unlikely as to not be worth any worries. From internet research, the best I can figure is that about 10% of all drowning occur in submerged cars. Then using statistics from this graphic by the National Safety Council putting the odds of death by drowning at 1 in 1000, I figure that dying this way in a car occurs at about a 1 in 10,000 rate – somewhat less likely than dying in a plane crash. I’ve flown hundreds of times and never yet come across anyone refusing to buckle up as required when taking off and landing. Why not?
Another person expressed strong doubts as to whether the hammers could break an automobile window. I cannot yet say from first-hand experimentation, but this video provides convincing evidence, I feel.
Anyways, I’m putting the little <$5 safety hammers in all my cars. Why not? It could come in handy some day, if not for me to escape a submerged car, then maybe for some other event that requires breaking glass – someone trapped in a car crash on land, for example.
Bear in mind that I am a Minnesotan — a state that boasts of having 10,000 lakes and where a bridge fell down into the Mississippi not that long ago. Furthermore, I live in a town (Stillwater) with a rotten old lift bridge that may be the next to fail according to this recent report by The History Channel.
Eggs-plosion in the aftermath of Easter
Posted by mark in science, Uncategorized on April 30, 2011
I’ve become accustomed to hard-boiling an egg for my breakfast so I was pleased to see a surplus of Easter eggs after celebrating this holiday last Sunday. My dexterity for shelling eggs is not a-pealing (ha ha) so I decided to try an eggs-periment: Microwave an Easter egg just long enough to heat it up and loosen it up for eggs-traction. If I’d have quit after my first try of 15 seconds, I may’ve succeeded. But the egg just didn’t feel hot enough so I added more time. Kapow! The eggs-plosion left nothing more than a millimeter of shell intact. The uniformity of organic matter throughout the inner surface of the microwave oven was very interesting, I think – quite impressive.
Although I consider this to be a very successful experiment, it’s one that I don’t feel needs to be replicated. My colleagues at Stat-Ease have provided a number of suggestions for another eggs-periment such as boiling the Easter eggs in vinegar or baking them. This creates a looser shell, they say.
Feel free to provide other ideas, but keep in mind that disaster seems to lurk behind me whenever I try an experiment. My failures tend to be quite spectacular. But, on the other hand, that’s what makes experimentation so eggs-citing!
An Easter experiment for those who still believe a bunny bears eggs* *(Beware of the green ones!)
Today’s Saint Paul Pioneer Press “Bulletin Board” provides an idea on how to provide some added delight for any children who still believe in the Easter Bunny: Have them plant one of their jelly beans, then watch for it to grow into a lollipop. Doesn’t that sound like a fun experiment!
By the way, be careful with the green jelly beans – they cause acne (p<0.05) according to this exhaustive statistical-study of every available color.
Winter not loosening its icy grip on Spring
I woke up to snow yesterday morning. It couldn’t quite cover the greening grass underneath, nor did it seem to discourage the budding bushes. Today the snow has disappeared and the near 40 degree F temperature seems mild with the power of April’s sun and the abatement of fierce northern winds. However, our Canadian neighbors are not faring quite as well, as evidenced by this very cool (literally and figuratively) photo from my sister – a resident of Calgary. Notice how the snow fingers feature icy nails — chilling!
When will Winter finally loosen up and let Spring spring free, eh? Maybe May…
Armed and dangerous – switchblades and statistics
Posted by mark in Basic stats & math on April 11, 2011
(Warning: Quirky material ahead =>)
Seeing this CBS News about Maine legalizing switchblades for one-armed people reminded me of a riddle about limbs that’s posed by some statisticians for educational purposes. Here it is: “The great majority of people in [fill in your country here] have more than the average number of [choose either arms or legs here].”
For an answer {UK, legs}, see this posting on averages by Kevin McConway, Professor of Applied Statistics in the Department of Mathematics and Statistics at The Open University. I heard this riddle also from Hans Rosling in his BBC TV program on “The Joy of Statistics.”* He spoke of his home country of Sweden, whose inhabitants on average have 1.999 legs.
I’m quitting while I’m ahead. Oops, this makes me wonder if I have an average number of heads – a scary thought, my hunch being that I’m below average for this. I never imagined that averages could be so creepy!
*See this StatsMadeEasy blog on Rosling
Supreme Court overturns tyranny of statistical significance
In today’s Wall Street Journal, The Numbers Guy (Carl Bialik) reports on a unanimous ruling by the Supreme Court that companies cannot hide behind statistical significance (lack thereof in this case) as an excuse for nondisclosure of adverse research. He passes along this practical advice:
“A bigger effect produced in a study with a big margin of error is more impressive than a smaller effect that was measured more precisely.”
— Stephen Ziliak, economics professor
However, this legal analysis of the ruling cautions that statistical significance remains relevant for assessing materiality of an adverse event.
Given all this, we can be certain of only one thing – more lawsuits.
First signs of Spring – premature return home by robins
As you can see from this photo taken Friday while cross-country skiing, Spring has not sprung in my neck of the woods. However, just overhead as I took this shot were several dozen robins perched in the birch. They were chattering a great deal – I imagine in complaint about which bird brain thought it was time to migrate back north.
A couple of years ago at this seasonal juncture I wrote about phenology – the study of timing for nature’s ways. For us in Minnesota the robins’ arrival is a sure sign of warmer weather around the corner.
Having just returned from a Spring break in Florida, I wondered how these southerners can detect seasonal changes. My searching on internet reveals little, other than this announcement of the first phenology workshop in Florida in 2009. The one sure sign of Spring for Floridians is the hordes of Minnesotans coming down for a break. They probably trump anything more subtle from Mother Nature.