‘Roid rage
Posted by mark in Nature, Uncategorized on October 12, 2017
Let’s not get caught off guard by an Earth-killing asteroid. As Dylan Thomas said: “Do not go gentle into that good night, …rage against the dying of the light.”
That is the mission of NASA. If you are reading this, chances are that Asteroid 2012 TC4 whizzed by today at 30,000 miles per hour—closely monitored by a network of observatories. Check out the details at this NASA website. They take asteroid defense very seriously. Their defense plans for redirecting asteroids will be tested out in 2022 on a double asteroid Didymos B as explained here.
Keep in mind that asteroid 1950DA, about three-quarters a mile wide—big enough to destroy our planet, has a 0.1% chance of hitting the earth 2818. In case NASA does not succeed in their defense efforts, start digging now and you might get hunkered down enough to survive for a short while after that.
The hero of zero
Posted by mark in Basic stats & math, history on October 9, 2017
Breaking news about nothing: Dating done with the Oxford Radiocarbon Accelerator Unit now puts the invention of the number zero 500 years earlier than previously believed. As explained in this post by The Guardian, the hero of zero is Indian mathematician Brahmagupta who worked out this pivotal number in 628 AD. Isn’t that something?
The development of zero in mathematics underpins an incredible range of further work, including the notion of infinity, the modern notion of the vacuum in quantum physics, and some of the deepest questions in cosmology of how the Universe arose – and how it might disappear from existence in some unimaginable future scenario.
– Hannah Devlin,
What happens if you walk backward while carrying a cup of coffee?
Posted by mark in pop, Uncategorized on October 1, 2017
One would assume that walking backward with coffee, especially when it’s piping hot, would be nearly as dangerous as running with scissors. Not so, according to the 2017 Ig Nobel Prize winning study for Fluid Dynamics. According to Korean physicist Jiwon Han, you will likely spill less walking backward than forward. However, your chances of tripping, or crashing into a colleague (also walking backward with coffee, ha ha) “drastically increase”.*
“Rarely do we manage to carry coffee around without spilling it once. In fact, due to the very commonness of the phenomenon, we tend to dismiss questioning it beyond simply exclaiming: ‘Jenkins! You have too much coffee in your cup!’”
– Jiwon Han
As reported in this “SmartNews” post by Smithsonian Magazine, Han advises a claw-like grip on top of your cup, rather than using the handle. Other tips from University of California researchers, reported here by LiveScience, are to gradually accelerate to a very slow walk, thus avoiding disruptive oscillations, and keep your eyes on the cup, not the ground.
My secret to stop spillage is to use a very large cup and fill it only two-thirds of the way, e.g., 12 ounces of hot coffee in a 16-ounce Styrofoam cup. The ultimate solution is to use a spill-proof, lidded container. However, I prefer drinking from a cup, if possible.
*(Source: Chemical and Engineering News, 9/18/17, Newscripts—“Curating quirky science since 1943.”)
Eclipse chasing a total success
Posted by mark in Uncategorized on August 21, 2017
Some time ago I hatched a plan to take a Sunday drive down to mid-Iowa from where our party of Andersons could shoot off south or east and catch today’s eclipse. Little did I know how wily the weather gods can be for obscuring the heavens. For the last week, the forecasts ping-ponged me unmercifully between Nebraska and Missouri. I went to bed last night with Nebraska in my sights, but just before hitting the road the updated outlook pointed clearly to Missouri as our only chance, albeit very slim, to get a view of the sun at totality.
Heading south through very heavy rains we went off-interstate south of Iowa once we hit the path of the eclipse, and then zig-zagged tortuously through the back-country of Missouri until we finally reached the edge of the cloud deck near Columbia—just in time for the awesome sight of the sun being snuffed out by the moon.
From a statistical perspective, it is ironic how astronomers can be so precise in their predictions of the moon shadow, whereas the meteorologists cannot provide very accurate forecasts of cloud cover. This made this whole venture of eclipse chasing very challenging, but, given the thrilling conclusion, a great experience.
“Keep your face to the sun and you will never see the shadows.”
― Helen Keller
Buttered toast lands butter up for once
I cannot recall this happening before today, but when I dropped half a bagel, it landed on the dry side. This allowed me to apply the 5-second rule and swoop it up for breakfast. That led me to this research from Manchester MET University reported by London’s Daily Mail that this (a fortuitous landing) occurs less than 20 percent of the time. These boffins of butter found that the height from which the bread is dropped makes all the difference.
“If you want to ensure your toast lands butter side up then you should invest in a higher table approximately 8ft high that allows the toast to rotate a full 360 degrees. Failing that – try not to drop the toast.”
– Chris Smith, Professor of Food Science and Technology
More good news from the UK food-science front came in March of this year when germ expert Professor Anthony Hilton of Aston University approved the 5-second rule. However, I am not going along with the photo of toast being jelly-side down in this report by The Independent. Eating that would be really gross.
54 billion bacterial cells per cubic centimeter
That’s the density of microbial growth—laden with pathogens—in a typical kitchen sponge. For all the disgusting details, see this Nature report by German (emphasis on “germ”) researchers at the Institute of Applied Microbiology in Geissen.
I came across this while searching internet for advice on what to do about the off-putting sponges laying about the sink in our office, which no one will clean—the tragedy of the commons. The study says that sanitation by boiling or microwave kills most of the bacteria. However, because that bad actors are more hardy, the end result over time may be a more sickening microbiome. The only solution is to replace sponges regularly—at least every week according to this Today show guidance. They suggest that between times you wash your sponges in hot, soapy water, microwave them for one minute, or put them in the dishwasher. After reading the Nature report I am tempted to do all three sanitation procedures, or just quit using sponges.
Average American works 3.5 hours a day
Posted by mark in pop, Uncategorized on July 1, 2017
This headline statistic makes it seem that Americans are slackers. However all this work is being done by only 60% of our population and on weekends to boot. An alarming downward trend in sleep-time is being counteracted by increased proportion of work being done at home. Based on how I’ve been laboring later and later at my home office, I think these two statistics may be inversely correlated—more work means less sleep. For more details, see this Wall Street Journal briefing on the statistics released by the Labor Department last Tuesday. It includes data on how much cooking and housework the men do versus women. I’m taking a hands-off position on that. ; )
P.S. Bloomberg Business recently reported that Europeans work an hour less a day than Americans. See their statistics here. We really need to take cue from our colleagues across the Atlantic and take more vacation. Also, Europeans retire earlier than Americans. Here in the U.S. more people are working past 65 than at any point in the past 50 years. This strikes close to home with me turning 64 this month and still working full time. However, I like to keep busy and enjoy my work (and the pay), so I cannot complain. Also, I am thankful not to be forced into retirement. But one of these days…
Errors, blunders & lies
Posted by mark in Basic stats & math, pop on June 27, 2017
David S. Salsburg, author of “The Lady Tasting Tea”*, which I enjoyed greatly, hits the spot again with his new book on Errors, Blunders & Lies-How to Tell the Difference. It’s all about a fundamental statistical equation: Observation = model + error. The errors, of course, are normal and must be expected. But blunders and lies cannot be tolerated.
The section on errors concludes with my favorite chapter: “Regression and Big Data”. There Salsburg endorses my favorite way to avoid over-fitting of happenstance results—hold back at random 10 percent of the data and see how well these outcomes are predicted by the 90 percent you regress.** Whenever I tried this on manufacturing data it became very clear that our high-powered statistical models worked very well for predicting what happened last month. 😉 They were worthless for seeing into the future.
Another personal favorite is the bit on spurious correlations that Italian statistician Carlo Bonferroni*** guarded against, also known as the “will of the wisps” per the founder of Yale’s statistics school—Francis Anscombe.
If you are looking for statistical insights that come without all the dreary mathematical details, this book on “Errors, Blunders & Lies” will be just the ticket. Salsburg concludes with a timely heads-up on the statistical lies caused “curbstoning” (reported here by the New York Post), which may soon combine with gerrymandering (see my previous post) to create a perfect storm of data tampering in the upcoming census. We’d all do well to sharpen up our savvy on stats!
The old saying is that “figures will not lie,” but a new saying is “liars will figure.” It is our duty, as practical statisticians, to prevent the liar from figuring; in other words, to prevent him from perverting the truth, in the interest of some theory he wishes to establish.
– Carroll D. Wright, U.S. government statistician, speaking to 1889 Convention of Commissioners of Bureaus of Statistics of Labor.
*Based on the story told here.
**An idea attributed to the inventor of modern day statistics—R. A. Fisher, and endorsed by famed mathematician John Tukey, who suggested the hold-back be 10 percent.
***See my blog on Bonferroni of Bergamo.
Gerrymanderers may soon be sent packing for doing too much cracking
Wisconsin Governor Scott Walker and his cohort of Republicans might have gone too far in redrawing their State’s political boundaries to their advantage. Last November, a federal district court declared these maneuvers, called gerrymandering,* unconstitutional. However, as discussed in this Chicago Tribune article, the Supreme Court might consider overturning the ruling—these gerrymanders being partisan, not racially discriminatory.
One of the most infamous of all gerrymandered districts—1992’s 12th Congressional District in North Carolina-is pictured here. It became known as the “I-85 district” due to being no wider than the freeway for stretches that connected the desired populations of voters.
North Carolina’s 12th was a kind of in vitro offspring of an unromantic union: Father was the 1980s/1990s judicial and administrative decisions under the Voting Rights Act, and Mother was the partisan and personal politics that have traditionally been at redistricting’s core. The laboratory that made this birth possible was the computer technology that became available for the 1990s redistricting cycle. The progeny won no Beautiful Baby contests.
— North Carolina Redistricting Cases: the 1990s, posted at Minnesota Legislature Web Site
You may wonder, as I did, how gerrymandering works. The latest issue of Nature explains it with their graphic on “packing and cracking” here. Also, see the figures on measuring compactness. Mathematicians approach this in various ways, e.g., the area of the district compared to with that of the smallest polygon that surrounds it (called the convex hull). Quantifying the fairness of boundaries creates a great deal of contention–which measure to use being chosen for greatest advantage of whomever is wielding the figures.
Partisan gerrymandering, if not outlawed, will be catalyzed by the 2020 census. Keep an eye on this.
*A word coined in 1812 when Massachusetts’s Governor Gerry redrew a district north of Boston into the shape of a salamander.
One-factor-at-a-time (OFAT) food experiments not very nourishing
Knowing of my interest in experiment design,my son-in-law (a newly minted PhD chemist) showed me his book on Cooking for Geeks. It offers a lot of fun detail on chemistry for a fellow like him. As a chemical engineer by profession, I like that too. Furthermore, I am all for the author’s enthusiasm for experimentation. However, his methodology, quoted below, lacks any sophistication or statistical power.
Make a recipe twice, changing just one thing (cookies: melt the butter or not?), and see what changes (if anything). If you’re not sure which way to do something, try both and see what happens. You’re guaranteed to learn something—possibly something the recipe writer didn’t even understand.
– Jeff Potter, author of Cooking for Geeks
Potter is not alone in remaining mired in OFAT and sample sizes of one (n1). This is also the methodology of the prestigious Cooks Illustrated as seen by this experiment on roasting ribs. Chris Kimball who launched this magazine, and, until recently, hosted “Americas Test Kitchen” on PBS, contacted me soon after Forbes recommended Stat-Ease software for multivariable testing (MVT) in March of 1996 (“The New Mantra: MVT”. I gave him a briefing on multifactor (as I prefer to deem it) design of experiments. However, Chris told me that his cooks were artists, not scientists, and they would not take to anything other than n1 OFAT. That works only when you make gross changes, such as roasting at 250 versus 450 degrees F. Even then, I’d like to see at least 4 of each level done in a randomized plan, and, better yet, a multifactor experiment.
The one nice thing about these poorly executed food experiments is that you can re-do them yourself. I might take on the question of roasting ribs, for example. Yum!