World’s longest pedestrian suspension bridge
Posted by mark in pop, Uncategorized on May 27, 2016
While taking the scenic route back to Munich from Mad King Ludwig’s fairy-tale Neuschwanstein Castle Neuschwanstein Castle, I looked up and saw this flimsy strand several hundred feet overhead just over the Austrian border. My daughter and her husband insisted on hiking up to walk across it. Being a sucker for a dare, I could not resist joining them. (My wife wisely stayed behind.) It was awesome being up so high and swaying in the wind on the 1,322 foot journey each way above the chasm.
The Tibetan-style footbridge is called the Highline179 after the tourist route that winds through this part of the Tyrol. It supposedly can hold up to 500 people. However, I would not like to do a confirmatory test of this specification. By the way, the ruins in the background are Fort Claudia–an outpost of Ehrenberg Castle.
If you are not afraid of heights, check out this video made during construction of Highline179.
Lottomania revving up with Powerball pot approaching a half billion dollars
Despite odds of only 1 in nearly 300 million for a win, Americans are lining up to buy tickets for a chance at the ninth largest jackpot in U.S. history. Why bother? Evidently most of us, e.g., my wife,* suffer from “availability bias”. This occurs due to the diabolical way that lottery officials publicize winners, which when magnified by the media, makes is seem that these windfalls are commonplace.
Another fallacy, which tricks analytical types like me, is assuming that expected value becomes positive when the jackpot builds. That is, for every $1 invested, more than that is likely to be returned, at least on average. The flaw in this calculation is that lottomaniacs swarm on the big pots, thus making it very likely that the payoff must then be shared among multiple winners. For details, follow this thread on XKCD’s forum.
*I asked her “If you won the lottery, would you still love me?’” and she said: “Of course I would. I’d miss you, but I’d still love you.” (Credit goes Irish comedian Frank Carson for this witty comeback.)
Men who have children make more money and live longer–correlation or causation?
Posted by mark in pop, Uncategorized on April 29, 2016
Hey guys, if you want to make more money and live longer, have kids. Anyways that seems to be the gist of two studies reported this month, at least from my perspective as a father of five. Here is the scoop:
- “Men in the top 1 percent distribution level live about 15 years longer than men in the bottom 1 percent on the income distribution in the United States.” – Raj Chetty, professor of economics at Stanford University, quoted in this report by NPR on an article in The Journal of American Medical Association on “The Association Between Income and Life Expectancy in the United States, 2001-2014” he lead-authored.
- Working fathers enjoy 21% ‘wage bonus’ over childless colleagues according to a study by United Kingdom’s Trades Union Congress reported here
Before you run off madly making babies, that correlation may not be causation. For example, as reported in this expose by Slate, statistics indicate that eating ice cream turns people into killers. Could that really be the scoop?
American Statistical Association (ASA) defends itself against P-shooters
With the fundamental statistic of P value coming under severe attack, e.g., it being banned in early 2015 by the Basic and Applied Social Psychology (BASP) journal, the ASA has been compelled to issue an unprecedented press release with guidelines for avoiding misuse of hypothesis testing by scientists claiming significant experimental results.* “The ASA statement is intended to steer research into a ‘post p<0.05 era,’” said Ron Wasserstein, the ASA’s executive director.
“To pounce on tiny P values and ignore the larger question is to fall prey to the ‘seductive certainty of significance.’”
– Geoff Cumming, emeritus psychologist, La Trobe University, Melbourne, Australia
The ASA statement on “Statistical Significance and P-Values” can be seen here. It includes 6 guidelines on proper use of this essential tool for assessing research data, beginning with the assertion that “P-values can indicate how incompatible the data are with a specified statistical model.”
*See, for example, this Nature article that claims P values, the ‘gold standard’ of statistical validity, are not as reliable as many scientists assume.
Big data puts an end to the reign of statistics
Posted by mark in Basic stats & math on March 3, 2016
Michael S. Malone of the Wall Street Journal proclaimed last month* that
One of the most extraordinary features of big data is that it signals the end of the reign of statistics. For 400 years, we’ve been forced to sample complex systems and extrapolate. Now, with big data, it is possible to measure everything…
Based on what I’ve gathered (admittedly only a small and probably unrepresentative sample), I think this is very unlikely. Nonetheless, if I were a statistician, I would reposition myself as a “Big Data Scientist”.
*”The Big-Data Future Has Arrived”, 2/22/16.
Colder States report sleeping more—65 degrees F evidently the ideal
Check out the Center for Disease Control (CDC) figures on sleep in the USA map in this Stat report. Note how dark it gets up in our neck of the woods of Minnesota, i.e., us being able to sleep better.
Dark is good but even better is the cold according to this new YouTube video posted by the Wall Street Journal.
There being a sweet spot on temperature makes perfect sense to me, this being based on many sleepless nights camping in the cold or hot. However the worst night I can remember was an overnight ice-fishing outing with a bunch of boy scouts. They could not stop fiddling with the space heater, which cycled us from freezing to boiling for some hours before finally stabilizing at a reasonable temperature. That is when the farting began and the giggling commenced. The whole troop deserved a merit badge for flatulence. But I digress…
A Data Sherlock’s best friend: IBM’s Watson
According to this report last week by eWeek, more than 1 million users have registered for IBM’s Watson Analytics service since it launched a little over 1 year ago. Evidently this artificially intelligent (AI) statistician-in-a-box will enable “citizen data scientists” to decipher patterns in the massive pile of information that now flow in from all quarters. Current clients featuring by eWeek range from multinational law firm using it to identify new areas of practice to a UK a care provider looking for factors that improve worker safety. IBM itself now operates an enterprise called Watson Health that deciphers medical imagery, and they bought the digital assets of the Weather Company to help businesses defend themselves against Mother Nature.*
Unfortunately for one of the early adopters of Watson—the MD Anderson Cancer Center at University of Texas (UT)—AI’s current IQ still falls far short of initial hopes.
“On Jeopardy! [Where Watson made its name 5 years ago by defeating the human champions] there’s a right answer to the question [actually the right question for the answer], but, in the medical world, there are often just informed decisions.”
— Lynda Chin, chief innovation officer for health affairs, UT
So it seems that, for the moment, at least, human statistical Sherlocks will not be replaced by AI’s overseen by amateurs at sleuthing out the culprits for cancer or other highly prized information. However, Watson might be as capable an assistant as ‘his’ literary namesake.
*1/6/16 Financial Times “Big Read” on “Artificial Intelligence”, p 5 sidebar.
Too many dogs at farmers markets?
Today’s “Gray Matter” column in the New York Times provides an exceptionally well-balanced report that casts doubt on the healthiness of food from farmers markets—read it here. What caught my eye is how the author, a professor at University of Minnesota (my alma mater), lays out a number of positive correlations (being careful not to conclude causation) between farmers markets and various food-borne illnesses, including one attributed to the ‘droppings’ from dogs and the like. But the thing I most admire is him admitting to “a number of dogs that did not bark”, i.e., a number of outbreaks that did not show a statistically significant connection to farmers markets.
This suggestion of possible health issues with farmers markets is heavily hedged—very possibly it will not be borne out by subsequent research. Nevertheless it would only be prudent to thoroughly wash locally grown and sold produce.
Sine illusion makes peaks and valleys on graphs look overly variable
An article in the latest Journal of Computational and Graphical Statistics (JCGS, Vol 24, Num 4, Dec 2015, p1170)) alerted me to a fascinating misperception called the “sine illusion” that causes misinterpretation of trends in variability. See it nicely illustrated here by vision researcher Micheal Bach. The JGCS, Susan VanderPlas and Heike Hofmann, detail “Signs of Sine Illusion—Why We Need to Care” and provide methods to counteract its misleading effects.
If you see a scatter plot that goes up and down with seemingly large scatter at the bends, get out a ruler to get the true perspective. That is my take home message for those like me who like to be accurate in their assessments of data.
“The illusion is explained in terms of a perceptual compromise between the vertical extent and the greater overall dimensions of the section at the turn of the sine-wave figure.”
– RH Day and EJ Stecher, “Sine of an illusion,” Perception, 20; 1991, 49–55.
A knotty problem—how to keep track of stuff without computers or even pen and paper
Posted by mark in history, Uncategorized on January 3, 2016
The New York Times reports today on the recent discovery of several knotted string records, called khipus, that ancient Incas used to record things such as the colorful potatoes I photographed at a Peruvian market. From what I saw on my travels there—see this blog on Incan agriculture experiments, a great deal of food must have been produced and stored.
Based on this Times picture I suspect these “mops that have seen better days”, as George Gheverghese Joseph, a mathematics historian at the University of Manchester, U.K., put it, must be a bit easier to untangle than Christmas lights. But then there remains the problem of deciphering them.
Thus far researchers have picked up on mathematical aspects of the khipus. However, the latest trove of colored strings provides a chance at figuring out the Incan scheme for identifying what was being counted. Here is where database capability and statistical methodology comes in handy.
I amazes me how all of the technology we now have at our disposable is challenged by methods developed 600 or so years ago. Hats off to Incan ‘thinken!
“Many now think that although khipu probably began as accounting tools, they had evolved into a writing system—a kind of three-dimensional binary code, unlike any other on Earth—by the time the Spanish arrived.”
— Cracking the Khipu Code Science magazine.