Poll says no MOE to the current Congress—83 percent disapprove
I just saw this NBC/WSJ poll graphically displayed on the nightly news. In the small print I saw “MOE +/- 3%” which threw me for a moment wondering if this data was being disrupted by the leader of the Three Stooges. But then I realized this was the margin of error. For a helpful detailing of MOE that breaks things down to simpler terms—a giant jar of a 200 million jelly beans—check out this white paper by Roper Center. Despite the inherent uncertainty of polls (estimated by MOE), the politicians in Washington cannot discount this clarion call (a record percent!) for change.
“naked statistics” not very revealing
Posted by mark in Basic stats & math, pop on July 18, 2013
One of my daughters gave me a very readable book by economist Charles Wheelan titled “naked statistics, Stripping the Dread from the Data”. She knew this would be too simple for me, but figured I might pick up some ways to explain statistics better, which I really appreciate. However, although I very much liked the way Wheelan keeps things simple and makes it fun, his book never did deliver any nuggets that could be mined for my teachings. Nevertheless, I do recommend “naked statistics” for anyone who is challenged by this subject. It helps that author is not a statistician. ; )
By the way, there is very little said in this book about experiment design. Wheelan mentions in his chapter on “Program Evaluation” the idea of a ‘natural experiment’, that is, a situation where “random circumstances somehow create something approximating a randomized, controlled experiment.” So far as I am concerned “natural” data (happenstance) and results from an experiment cannot be mixed, thus natural experiment is an oxymoron, but I get the point of exploiting an unusually clean contrast ripe for the picking. I only advise continued skepticism on any results that come from uncontrolled variables.*
*Wheelan cites this study in which the author, economist Adriana Lleras-Muney, made use of a ‘quasi-natural experiment’ (her term) to conclude that “life expectancy of those adults who reached age thirty-five was extended by an extra one and a half years just by their attending one additional year of school” (quote from Whelan). Really!?
Kids & Science
Posted by mark in pop, science, Uncategorized on June 23, 2013
I am heartened to hear of great work being done by current and former colleagues to get K-12 kids involved in Science, Technology, Engineering, and Mathematics (STEM). For example, Columbia Academy, a middle school (grades 6-8) in Columbia Heights (just north of Minneapolis), held an Engineering and Science Fair last month where two of our consultants, Pat Whitcomb and Brooks Henderson, joined a score of other professional engineers who reviewed student projects. Winners will present their projects this summer at the University of Minnesota’s STEM Colloquium.
Also, I ran across a fellow I worked with at General Mills years ago who volunteers his time to teach middle-schoolers around the Twin Cities an appreciation for chemistry. He makes use of the American Chemical Society (ACS) “Kids & Chemistry” program, which offers complete instructions and worksheets for many great experiments at middle-school level. Follow this link to discover:
– Chemistry’s Rainbow: “Interpret color changes like a scientist as you create acid and base solutions, neutralize them, and observe a colorful chemical reaction.”
– Jiggle Gels: “Measure with purpose and cause exciting physical changes as you investigate the baby diaper polymer,* place a super-absorbing dinosaur toy in water, and make slime.”
– What’s New, CO2? “Combine chemicals and explore the invisible gas produced to discover how self-inflating balloons work.”
– Several other intriguing activities contributed by ACS members.
Kudos to all scientists, engineers, mathematician/statisticians who are engaging kids in STEM!
*(The super-slurpers invented by the diaper chemists really are quite amazing as I’ve learned from semi-quantitative measurements of weight before and after soakings by my grandson. Thank goodness! Check out this video by “Professor Bunsen”, which includes a trick to recover the liquids that I am not going to try.)
My man Mauer breaks a very curious baseball record
Listening to the Twins tonight and hearing my fellow high-school alumnus Joe Mauer strike out it occurred to me that he’s been doing this a lot lately. It turns out that Joe is whiffing at double his normal rate. However, this has had no effect on his performance other that saving him the trouble of legging out ground-ball outs. (I think that is Joe’s plan all along, that is, preserving energy.) Anyways, by racking up so many “K”s Mauer accomplished a 15-game hitting streak during which he struck out at least once in each game. According to Elias Sports Bureau, that breaks the previous record of 11 games for this oddly hot/cold hitting–at least since 1910, when the major leagues began keeping track of strikeouts.
That reminds me of a fellow I golfed with on Monday at a charity outing where we played best ball. He led off our four-some on the first tee with a mighty swing that raised a lot of dust but not the ball. Re-gathering his wits he swung even harder, but to no avail–the golf ball remained teed up. But the third time proved the charm–an awesome drive straight and far down the fairway that ended up being our best ball–none of the others of us could top it. So that works…albeit it is very nerve wracking for spectators, I must say.
Issues on inflation, such as 79.6 billion percent in one month
May’s National Geographic pictured a very impressive One Hundred Trillion Dollar bill from the Reserve Bank of Zimbabwe, which in November of 2008 hit the 79.6 billion percent level for inflation before stabilizing their currency. Check out the 100T note here. You can buy one of your own for less than ten bucks USD!
Meanwhile back home in here in the USA everyone is up in arms over a measly 0.1 percent difference in inflation caused by “chaining” our CPI. The gist of this is explained in this recent Time-magazine personal-finance column. It seems like much ado about very little. However, those who get cost-of-living adjustments (COLA) fight like crazy over anything that reduces their income. Here’s a spin on statistics: A 0.1 percent reduction from 1.5 percent is actually a 7 percent loss in COLA. No wonder seniors want to throw off those chains!
The fiddling with money supply and shenanigans on inflation computations reached a new low not long ago in Argentina when the government forced out statistician Graciela Bevacqua for rounding rather than dropping decimal points, which made the government look better with their official rate. It’s all reported here by The Economist. Now working in private industry Bevacqua continued to present a truer calculation on inflation and got fined $100,000 for her honesty. After an uproar from far and wide, including the American Statistical Association (ASA), the courts in Argentina overruled the government and spared this outspoken statistician, according to this news from Buenos Aires Herald. Someone ought to give her a medal for speaking the truth. But as the great statistician George E. P. Box said:
“Whenever we see virtue rewarded, we are completely surprised.”
Who foresees the future better—the Hedgehog or the Fox?
Posted by mark in pop, Uncategorized on June 5, 2013
“The fox knows many things, but the hedgehog knows one big thing.”
– Archilochus
In the June 3rd issue of Chemical & Engineering News Frederick M. Peterson, a chemical engineer who went on to achieve a doctorate in economics, dissects what happens when “Scientists Tackle Finance.” He warns against the tendency of experts in one field being overly bullish about their ability to manage things outside of their specialty. These are the hedgehogs—people who make bold predictions and happen to be right long enough that they attract a strong following.
On the other hand, the foxes, who observe many things and adapt readily to differing situations, lack confidence about the chances of any particular path leading to success. They are seen as being weak and wish-washy, which is not very popular. Nevertheless, it may not be surprising that foxes do better than hedgehogs at forecasting, according to Peterson, who cites a seminal study by the School of Business at University of California, Berkeley.
The moral of this story is to be wary of anyone who expresses too much certainty about the shape of things to come. It does not pay to follow hedgehogs—they will ultimately go beyond their narrow limits of competence and roll into something very prickly.
Educational fun with Galton’s Bean Machine
Posted by mark in Basic stats & math on June 3, 2013
This blog on Central limit theorem animation by Nathan Yau brought back fond memories of a quincunx (better known as a bean machine) that I built to show operators how results can vary simply by chance. It was comprised of push-pins laid out in the form of Pascal’s triangle on to a board overlaid with clear acrylic. I’d pour in several hundred copper-coated BB’s through a funnel and they would fall into the bins at the bottom in the form of a nearly normal curve.
Follow the link above to a virtual quincunx that you can experiment on by changing the number of bins. To see how varying ball diameters affect the results, check out this surprising video posted by David Bulger, Senior Lecturer, Department of Statistics, Macquarie University, Sydney, Australia.
Mind over matter—scale malfunction leads to temporary euphoria
Posted by mark in Consumer behavior on May 26, 2013
I’ve diligently recorded my weight every several days for some years now. The short-term variation always astounds me—going up and down by a number of pounds from one week to the next. However, on average month-by-month my weight remains surprisingly stable. Unfortunately the trend over years is very slightly, but significantly, upwards. Thus my battle against the bulge continues.
A few weeks ago I stepped up for a weighing and received a pleasant surprise: It seemed that I’d dropped 10 pounds during a five-day business trip. Although deep down I knew this could not be, I indulged myself for the day with the thought that something magical had whisked away this weight. Then after getting home from work I got back down to earth by discovering that the base of the scale had got off kilter. I mentioned this to my wife and daughter. It was funny seeing them being so crestfallen—they also were hanging on to the belief in a mysterious, but real reduction.
I suppose all this supports the use of control charting* for filtering out common-cause variability (not worth reacting to) from statistically-significant process upsets (special causes that merit attention). At least that’s what my logical side says. On the other hand, it was fun to believe for some hours in supernatural forces. Ignorance can be bliss!
*(See this detailing posted by the George Mason University College of Health and Human Services.)
Brain disturbers make folks smarter or dumber (believe it or not)
Based on the underpowered experimental designs by neuroscientists reported in my previous blog, I am skeptical of these new findings, but they are very intriguing, nonetheless:
- Shocks to the Brain Improve Mathematical Abilities. (You ‘mathaletes’ should do some calculating before wiring up because the sample size for these findings is miniscule!)
- Brain, Interrupted-How distractions make us dumber. (The news here is mixed:Multitasking may be a myth but perhaps some people, with practice, can handle it.)
I hope this blog did not derail your train of thought. If so, go lick a battery to reverse the brain drain.
Brain scientists flunk statistical standards for power
Last week The Scientist reported that “Bad Stats Plague Neuroscience”. According to researchers who dissected 730 studies published in 2011, neuroscientists pressed ahead with findings on the basis of only 8 percent median statistical power. This falls woefully short of the 80 percent power that statistician advise for experimental work. It seems that the pressure to publish overwhelms the need to run enough tests for detecting important effects.
“In many cases, we’re more incentivized to be productive than to be right.”
– Marcus Munafo, University of Bristol, UK