Stats Made Easy

A fellow graduate from University of Minnesota’s chemical engineering school told me this week that “I am afraid the average person’s level scientific understanding in this country is in the dark ages.” His skeptical comment, with which I am sorry to say I agree, stemmed from an inflammatory email passed along to both of us by a mutual friend, an attorney who has been deemed a “super-lawyer” by his peers. No offense, but I do not think his expertise extends to the scientific arena. (Similarly, I make no claim to knowledge of law.) The email he circulated from internet comes with this cover comment “An engineer friend of mine sent this and added that it ‘Seems to be legitimate!’ Wow!” Attached are photographs from a simple comparative experiment that apparently supports the commentator’s contention that “microwaved anything…corrupts the DNA in the food so the body can not recognize it.” It concludes by saying: “Proof is in the pictures of living plants dying. Remember You are also Living. Take Care.” See the photos and commentary for yourself at Snopes.com — a site maintained by Barbara and David Mikkelson that follow up on “urban legend.” Their articles seem to be well-researched, intelligent, and full of common sense. Why do average people, or in this case — clearly someone far above the mean for general intelligence, seem to be so gullible about legends like this one about the dangers of microwaves? David Mikkelson provides this explanation: “The power of illustrative anecdotes often lies not in how well they present reality, but in how well they reflect the core beliefs of their audience.”

Our periodic search of internet netted a Google group exchange on “…the biggest Frisbee made”* in which someone named “Burp” (whose email starts with “Beerme”!) provides the link to this incredible photo. It was sent to me in 2002 by Darrell W. Pepper, Ph.D., Dean, College of Engineering, University of Nevada Las Vegas, who said “I enjoyed your article in the September issue of the Stat-Teaser regarding the flying rings/disks with your daughter (Sixth-Graders Experiment with Flying Disks). I just thought you might like to know that we built the world’s largest flying disk (10 ft in diameter) some years ago – as well as a 10 ft ring (using mylar and PVC pipe). I also had a grad student do his MS thesis on frisbee/disk aerodynamics a few years back. See the attached picture of one of our former engineering students (who also played center for the UNLV football team) actually throwing the disk (Adler design – like Aerobie but solid). The disk was made from composite material and foam – total weight was about 20 lbs. The student tossed the disk about 75 feet. By the way, when we transported it to Reno for the annual AIAA meeting (about 400 mi), a wind came up and blew it off the trailer – the student walked over 1000 feet in the desert to pick it up (an unofficial distance record?) The following year I had some students work on a giant machine to toss the disk. It never materialized, but the idea seemed good. We then went on to build solar airplanes, etc. One more thing – there was a report of a UFO disk-shaped object flying over the highway.”

PS. Other readers of my original article on the experiment by my daughter weighed in on the effect of color on the plastic disks’ physical properties, the impact of a learning curve for throwing them, and the throwers’ level of expertise — see item #2 at my October 2002 DOE FAQ Alert. (Feel free to subscribe at DOE FAQ Alert signup.)

*If you are a fan of flying disks and do not mind some playground language, take a look at the topic in rec.sport.disc.

“Welcome to the nebulous world of aromatherapy, where, for a small price, you can, say its proponents, sniff yourself to a sharper mental state, which could lead to more productive workouts. But be wary, for this can be a realm populated by hobbits, trolls and fairy godmothers–more fiction than fact.” — Frank Claps, Training Scents, Men’s Fitness, May, 2002.

Recent research by Alan Hirsch of The Smell & Taste Treatment and Research Foundation in Chicago found that bowlers who wore surgical masks impregnated with the aroma of jasmine knocked down 27 percent more pins than those who went scent free*! In a special to the Stamford Advocate picked up by my local newspaper, humorist Jerry Zezima, interviewed Hirsch, who speculated that jasmine counteracts the negative smells in bowling alleys — smoke, sweaty socks, stale beer, spicy pizza and the like. Zezima’s attempts to try reproducing this dubious aromatherapeutic effect provide a great lesson in how not to do an experiment. Here are the results:

— Game #1, a “few pins” more with jasmine mask (alternated frame-by-frame with scentless) — final score: 124.

— Game #2, “much better” with beer sprinkled on scentless mask (vs jasmine) — final score: 93.

I suppose one could say that Zezima’s results go back to frame number 1, that is, they provide no confirmation of Hirsch’s findings favoring jasmine. The reason all this caught my eye is that I am the author of tutorial on setting up a simple comparative bowling experiment: Design-Expert 7 Software General One-Factor Tutorial. However, I have no interest in applying better design of experiments (DOE) to this questionable effect of scents. The mask would get in the way of drinking my beers and talking with my bowling buddies. That’s what’s really important! Who cares about the score?

PS. Obviously I am not a very ‘scents’itive fellow, so jasmine would be wasted on me. The sweaty socks are tolerable, but I do believe that eliminating smoking would definitely enhance the athletics and general healthiness of outings to the neighborhood alley.

*EFFECTS OF AROMA ON AMATEUR TEN-PIN BOWLING PERFORMANCE presented to Association for Chemoreception Sciences on April 30, 2006

“I feel like the researchers were trying to manipulate their data to match their conclusion.” Linda Bacon of the University of California at Davis said this about a 10-year study of more than half a million slightly overweight U.S. adults. The researchers, led by the National Cancer Institute,* concluded that, once these somewhat “gravity-challenged” Americans reached age 50, they were 20 to 40 percent more likely to die in their next decade than those in their cohort who maintained a healthy weight. A body mass index (BMI) between 25 to 29 is considered overweight — above a BMI of 30 you fall into the obese category, for which there’s seemingly no question about associated health problems. However, Glenn Gaesser of the University of Virginia at Charlottesville joins critic of this recent study by saying “They are presenting the data in a way that paints overweight and obesity in the worst possible light.” Paul Ernsberger, associate professor of nutrition at Case Western University, piled on with this comment: “They’re standing on their heads squinting at it backwards trying to make it fit.” The criticisms stem from the reliance by researchers on participant’s recollections, which can be very unreliable. Critics also note the high number of people excluded from the final analysis, thus introducing possible bias. Furthermore, previous studies, especially one by the Centers for Disease Control and Prevention, indicated a beneficial effect of being slightly overweight. In any case, this study provides some food for thought by the large numbers of us baby-boomers that fall into this category of being a bit bloated after all these years of good living in the USA.

*New Study Shows That Being Overweight at Middle Age Can Be Harmful

In 1987 a survey of educational departments resulted in all 50 states claiming their children to be above average in test scores for the USA. This is a common fallacy that is defined in Wikipedia as the Lake Wobegon Effect after the mythical town in Minnesota, where according to author Garrison Keillor, all women are strong, the men good looking, and their children above average. I see the Lake Wobegon Effect manifested in reports on this year’s ACT college-assessment scores. My daily newspaper, the Saint Paul Pioneer Press, reported on August 16 that “Minnesota…[is] best at college test.” They based this ranking on the percent passing all four benchmark scores.* Counteracting this, State Superintendent Elizabeth Burmaster reports “Overall, Wisconsin beat the nation on the ACT.” Then again the Deseret Morning News reports “Utah tops U.S. on ACT.” I cannot see how any of these self-congratulatory reports can be inferred from the actual 2006 Average ACT Scores by State. However, I suppose someone might explain the necessary contortions for patting themselves on the back. The ACT statistics actually back up the Boston Globe pronouncement that “Massachusetts’ class of 2006 scored the highest of any state on the ACT math exam and scored behind only Connecticut on the overall exam.” However, it turns out only 13 percent of high school graduates took this test versus well over 50 percent in Minnesota, Wisconsin and other midwestern USA states that rely on the ACT for screening college applicants. (I believe that the eastern states use the SAT exam.) Sorting the ACT scores on the average composite score (a handy feature offered at their web site), I see that all seven states ahead of Minnesota had fewer that 20% of their graduates taking the test, so I have no qualms saying that my home state is the smartest of all!

*PS. I am very alarmed at the poor results for science (37%) and math (52%) relative to english (76%) and reading (62%). 🙁

The most recent issue of National Geographic magazine features a unique graphic that visualizes your odds of dying by various causes. You can see the chart and underlying statistics at a website maintained by the National Safety Council (NSC). The total odds of dying by any cause in the USA (and possibly in other countries too!) are 1 in 1 or 100 percent. I suggest you get over this without too much thought (maybe later!), and check out the less likely things that could kill you. For example, I see that the odds of dying by earthquake or flood are roughly the same — less than 1 in 100,000. I’d be more worried living along a coastline in an area riddled with fault lines (take heed you Californians!) than here in Minnesota, although we’ve got more than our share of lakes and rivers. At about 50,000 to 1 odds, lightning and bee stings create more concern for survival — ouch! The NSC reports a 1 in 5000 chance that an American will die in an air accident versus only about 1 in 2 million odds that a venomous reptile will put an end to things. However, they do not calculate the deadly combination of Snakes on a Plane. That would be very scary!

“More people die on the last day of their life than on any other day.”
–– Statistic purportedly published by the Houston Post on 20 July 1989

As a practitioner of statistically designed experiments I am a big believer in randomizing the order of runs specified by standard templates. This counteracts time-related lurking variables such as material degradation, machine warm-up and increasing ambient temperature. Thus it was a shock to read this passage in a book I’m reading that’s titled The Traveler: “…anyone who used random numbers to guide his life should be hunted down and exterminated.” It turns out that the good guys in this novel carry RNG’s — random number generators — to confound the forces of evil. If you harbor paranoia about the ever-increasing intrusions on privacy by government and big business, you will like this book. Otherwise it comes across as “New Age Nonsense,” as noted by the Washington Post. Oh, and by the way, is there any significance to the fact that the publisher is Random House?

In last week’s Parade magazine column, Marilyn vos Savant fields a question from a fellow whose friend invests effort into anything at all that provides the tiniest advantage.* Marilyn sums things up nicely with her observation that “Too many people spend time and money pursuing lots of goals just a little.” I see this happening from time to time to clients of Stat-Ease who pore over the statistical analyses of their experiments and get hung up on tiny, but potentially signicant effects. The advent of robotic chemistry with systems such as Sagian AAO make it ever more likely that significant effects of no practical importance will be uncovered via well-designed experiments. The problem is that by focusing attention on these trivial things one loses sight of the really important opportunities that merit a full investment of their time and money. The question then is one of statistical significance versus practical importance.

*Ask Marilyn

My wife Karen mentioned yesterday that she might cook an egg bake for an upcoming family get-together. I asked her what this was and she said “it is a food made out of eggs that is baked and eaten.” That leaves me still in the dark. I do know how to make a toad in the hole: Butter a piece of bread, tear out the a circle in the middle and fry an egg in it. Coincidentally, Karen alerted me to a strange-looking bird peering out of the little house we have mounted on a tree off our back porch. Can you identify it?