Archive for category science
Caffeine helpful for brain health…or not—a mindbender
The other day I watched CBS News medical contributor Dr. Celine Gounder report new findings that drinking caffeinated coffee reduces the likelihood of dementia. She warned that this may be due to correlation, not causation—creating puzzled looks from the hosts. Then Dr. Gounder explained that individuals in poor physical and mental health will often be put on a diet that restricts caffeine. Aha!
It never ceases to amaze me how often people fall for correlation being causation. Here are some of my favorite examples:
- As I reported in a blog a few days before Christmas of 2012,* partygoers took advantage of a buy-one-get-one-free (BOGO) sale on a fine wine—paying $17 for one bottle and a nickel ($0.05) for the other. They drank the first bottle and thus worried greatly if it would be OK to bring the cheap wine to the party.
- Per Google’s AI, the most popular example of correlation versus causation is that ice cream sales and shark attacks both increase during the summer months. While they correlate, eating ice cream does not cause shark attacks; rather, a third variable—hotter weather—causes both, leading people to eat more ice cream and swim. Banning ice cream (addressing the correlation) would not reduce shark attacks (the causation), highlighting the mistake of assuming one directly causes the other.
- Most popular with statistics teachers—Umbrellas and wet streets both increase on rainy days, but umbrellas do not cause the streets to get wet.
- Being called in to troubleshoot processes at our manufacturing sites the operators explained to me that performance varied due to the phase of the moon.
“Cars with flames painted on the hood might get more speeding tickets. Are the flames making the car go fast? No. Certain things just go together. And when they do, they are correlated. It is the darling of all human errors to assume, without proper testing, that one is the cause of the other.”
― Barbara Kingsolver, Flight Behavior
But don’t become too skeptical about seemingly spurious connections between cause and effect, such as me questioning my daughter’s assertion that the color of otherwise identical flying disks affect their performance.
*Correlation of price of wine with the fineness of its taste–an absurd example
Stats add teeth to gripping news about Tyrannosaurus rex
In a page ripped out of Michael Crichton’s book Jurassic Park, featuring brilliant mathematician and “chaotician” (chaos theory specialist) Ian Malcom, three scientists applied a new statistical approach to combine analyses from 17 different T. rex specimens, thus revealing that these tyrant lizard kings did not reach maturity until age 40.* Enjoy some fearsome pictures of T. rex’s big and small in this press release from Oklahoma State University citing lead author Dr. Holly Woodward, professor of anatomy and paleontology.
Dr. Woodward says that previous studies estimated that T. rex growth stopped around age 25. The longer development time expands the role of knife-teethed, fleet-footed juvenile T. rex’s to dominate the mid-carnivore niche.
A four-decade growth phase may have allowed younger tyrannosaurs to fill a variety of ecological roles within their environments. That could be one factor that allowed them to dominate the end of the Cretaceous Period as apex carnivores.
– Coauthor Jack Horner, technical advisor for the Jurassic Park films (inspiring the Alan Grant character)
Sensational!
Shocking outcome from purple potato
Along the lines of the video below, my oldest grandson Archer came up with some very interesting results from his 8th grade science project: Magic Molly purple potatoes produce more electricity gram-for-gram than Yukon Gold or Red Norland; 10.6 vs 7.9 vs 7.6 millivolts; respectively. All the potatoes came fresh from his family’s garden. He chained 3 potatoes together for each voltage measurement, thus dampening out potato-to-potato variation.
Archer also tested a sweet ‘potato’, which did very poorly on his voltage measurement (5.9 mV)—perhaps not surprisingly, it not actually being a potato.*
Archer had hypothesized that “all of the potatoes will create the same amount of volts because the phosphoric acid in the potatoes that gives them power has no color, and color is the difference between most potatoes; therefore, there shouldn’t be a difference in voltage output.” However, given his sample size being only one per variety of potato, further testing would be needed to disprove his hypothesis with adequate statistical power (e.g., p<0.05).
I advise starting with at least 4 of each potato variety and doing the testing via a randomized plan, that is a proper design of experiment. It would also be interesting to do add other factors, such as boiled versus raw and extend the test out for some days to see if the voltage drops.**
Who knew such an unglamorous vegetable (“starchy tubers”, ha ha) could be so much fun?
* See Carnegie Museum of Natural History’s explanation: Potatoes, Sweet Potatoes, and Yams: What’s the Difference?
** For clues on this, see The Not So Humble Boiled Potato! by Samantha Parker, Museum Educator, National Electronics Museum, 2020.
Design of experiments (DOE): Secret weapon for model rocketry
Posted by mark in science, Uncategorized on June 27, 2024
Attracted by its focus on model rockets, I took a summer class on physics at Macalester College in my early teens. What a blast—literally! I really enjoyed learning about force, mass, acceleration and all the other aspects underlying aerospace. (Keep in mind this being the height of the 1960s race to the Moon.) But the best part was building a scale model of the Saturn V featuring multiple solid propellant motors and a parachute recovery system. For the grand finale of our class, we successfully launched our rocket. The parachute did deploy. However, our ship drifted over Saint Paul’s magnificent urban forest (soon to be decimated by Dutch elm disease) and got hopelessly hung up 100 feet overhead.
These great memories from my youth came back to me earlier this year when asked for advice on validating the OpenRocket simulator. The question came in from a mentor using Stat-Ease® 360 software on a low-cost educator license to support a high-school rocket club achieve the American Rocketry Challenge goals for altitude and flight duration. I happily deferred this request for stat help to my colleague Joe—a physics PhD who plays a dual role providing statistical advice and programming. Without getting into the details (after all, this is rocket science!), suffice it to say that, yes, our DOE software does provide “the right stuff.”
By the way, just last week a NASA sounding rocket carrying student experiments reached an altitude of 70 miles. See the video for the launch. (I advanced it to the countdown. After the blast off, move on. That is the only exciting bit.)
What I find most amazing is that the nose cone on this rocket can carry up to 80 plastic cubes as payload. These accommodate experiments by 11-18 year old students. Check out this Cubes in Space STEM program. Page down to the BREAKING NEWS about an important discovery made by a group of elementary students from Ottawa. I recommend you watch the CTV video—very impressive to hear from such science-savvy grade-schoolers. They will go far!
A solution for saving migrating birds from disorienting light pollution
Posted by mark in Education, Nature, science, Uncategorized on May 3, 2024
My grandson Archer and his class of sixth graders at Stillwater Middle School advanced to last week’s national Solve for Tomorrow competition in Washington, DC–an amazing accomplishment at their age. The event, sponsored by Samsung, empowers students in grades 6–12 to leverage the power of STEM (science, technology, engineering and math) to create innovative solutions addressing critical issues in their local communities.
Archer and his classmates focused their attention on reducing the impact of light on bird migration patterns in the St. Croix Valley. They developed a very inventive plan that featured bioluminescence; sensors to reduce unnecessary light and a flower-petaled, controllable cover for directing streetlights downward.
Being one of just 10 schools across the country to be named national finalists, they earn $50,000 in Samsung technology and supplies for their classroom. To top it off, Archer and his classmates won an additional $10,000 by winning the Community Choice award based on a popular vote.
I expect Archer and all will go far by their STEM power. Hopefully, the birds will also continue to go far by being better protected from light pollution along their way.
Chance discovery on random walk in Utrecht
Posted by mark in science, Uncategorized on December 11, 2023
Last week I taught a class on design of experiments to a biotech company in Leiden, Netherlands. Afterwards I spent a few days in Utrecht with some friends from Germany. Imagine my excitement (nerd alert!) when on my first walk from our hotel to the city center just a few hundred feet down the sidewalk I encountered this mural featuring a differential equation.
Not being a physicist, I did not immediately grasp the formula’s importance, nor the clue provided by the fellow high-stepping down a street. It turns out this fellow is a drunk whose walk has become random. The mural, as explained by Utrecht University, pays homage to their famous professor Leonard Ornstein who, in the early 1900s along with another physicist—George Uhlenbeck—developed an important variant of the “random walk”—a term introduced by pioneering statistician Karl Pearson. The Ornstein-Uhlenbeck process is used to derive models from “big” financial data, including inflation rates, commodity prices and stock values.
I did not expect to gain an education on a vacation expedition.
Very cool!
PS: I thought about asking my colleague Martin Bezener, a PhD statistician, for his opinion on the chances of coming across something so relevant to our mission at Stat-Ease while on a random walk. But I will not bother, because I already know what he would say: “One-hundred percent: It already happened”.
British system of messed up measures hilariously skewered
Upon graduation as a chemical engineer in 1975 I took a job as a process developer at a California oil company. There I learned that a barrel amounted to 42 gallons—not the 55 in the drums at my previous employer—a specialty chemical company. In the wacky British system of volumes, the number of gallons in a barrel depends on the material—31 for beer, 53 for rum (yo ho ho!), 60 for wine, etc. Their weights and distances are just as unfathomable (pun intended).
That same year of 1975 that I first became employed as a degreed engineer, President Gerald Ford signed the Metric Conversion Act, which went nowhere before being abolished in 1982 by President Reagan. Having endured all this measurement mess throughout my career, I thoroughly enjoyed this October 28 Saturday Night Live skit:
I raise my US pint (16 fluid ounces) of beer to SNL’s clever comedy writers, though a British pint (20 fluid ounces) would be more filling and a liter even sweeter. Let’s not get into US versus Imperial ounces (or gallons)—that would get us over our head by at least a fathom (equivalent to 4 cubits, by the way).
PS. This rant about measures brings me full circle to an outburst at the outset of this year involving a whimsical unit of distance called the ‘smoot’.
Data detectives keep science honest
Posted by mark in science, Uncategorized on October 6, 2023
An article in Wall Street Journal last week* drew my attention to a growing number of scientists who moonlight as data detectives sleuthing out fraudulent studies. Thanks to their work the number of faulty papers retracted increased from 119 in 2002 to 5,500 last year. These statistics come from Retraction Watch who provide a better, graphical, perspective on the increase based on percent retractions per annual science and engineering (SE) publication–not nearly as dramatic given the explosion in publications over the last 20 years, but still very alarming.
“If you take the sleuths out of the equation it’s very difficult to see how most of these retractions would have happened.”
Ivan Oransky, co-founder of Data Colada –a blog dedicated to investigative analysis and replication of academic research.
Coincidentally, I just received this new cartoon from Professor Nadeem Irfan Bukhari. (See my all-time favorite from him in the April 27, 2007 StatsMadeEasy blog Cartoon quantifies commitment issue.)
It depicts statistics as the proverbial camel allowed to put its nose in the tent occupied by science disciplines until it become completely entrenched.
Thank goodness for scientists like Nadeem who embrace statistical tools for design and analysis of experiments. And kudos to those who guard against faulty or outright fraudulent scientific publications.
*The Band of Debunkers Busting Bad Scientists, Nidhi Subbaraman, 9/24/23
Smoot points about measurements
Posted by mark in science, Uncategorized on January 4, 2023
Does it really matter that the calendar turned over from December 2022 to January 2023? From where I sit nothing much changed from one day—12/31/22—to the next—1/1/23. It’s just as cold here in Minnesota—below freezing (32 F or 0 C: Take your pick). Must we pay any attention to an irrelevant measure of time passing by? Of course, the answer is “yes” for everyone to party on a timely basis for the New Year, birthdays, and anniversaries. However, I feel badly for my niece’s daughter born on Leap Day 2020—no 1st birthday until 2024. That’s a measurement failure. Anyways, Happy New Year!
Also, why do we continue to favor English versus metric units here in the USA? That is a huge waste! Let’s begin the conversion by expanding the football fields to 100 meters. The players won’t even notice the 10 percent increase in required effort. My feeling is that this will be the breakthrough to the far more sensible and scientific metric system—a movement that seemed certain to succeed when Congress passed the Metric Conversion Act in 1975. Unfortunately, this became a political football when folks here in the Midwest resisted being told to post their distances in kilometers rather than miles.
The silliness of the archaic English anthropometric measures, such as height in feet and quantities of spices in pinches, came to a head in 1958 when frat brothers from MIT flipped a pledge named Oliver Smoot over-and-over the length of the Mass. Ave. bridge for a total of 364.4 Smoots (plus “one ear”*). In 2016, the MIT Alumni magazine published this April Fool’s joke that the Institute planned to recalibrate the Smoot to its namesakes current height (presumably a bit shrunken by the decades). What I find most interesting is that Smoot later served as chairman of the American National Standards Institute and president of the International Organization for Standardization. He went all out, literally, for the sake of measurements!
By way, it snowed 4 and 3/16ths of an inch yesterday according to my double Helix measuring ‘stick’. For my own purposes, I always use the metric side of this ruler—much preferring its decimal system (m/cm/mm, etc.) over the cumbersome fractions of inches. But to keep things simple, I pay the teenager next door by the inch.
PS It snowed another 6 inches overnight, bringing the total to 25 cm or so (deliberately mixing measurement scales to make my point). In any case, I need a taller ruler!
*Per Smoot in this 1995 interview. I first heard of him from the November 21st Wall Street Journal review of “Beyond Measure: The Hidden History of Measurement from Cubits to Quantum Constants.” For details and reader ratings (assuming you like accurate measurements!) of this new book, I recommend you go to this Goodreads site.
Spacecraft DART scores a direct hit on asteroid Dimorphos
Posted by mark in science, Uncategorized on September 27, 2022
It was amazing to see today the videos from NASA showing a direct hit by their spacecraft DART (an acronym for “Double Asteroid Redirection Test”) on the asteroid Dimorphos.
Here are some amazing statistics on this astounding feat of physics:
- DART traveled 56,000 miles to accomplish its $330 million suicidal mission against the 560-foot diameter Dimorphos.
- DART came in at 1,260 pounds to impact the 11-billion-pound Dimorphos, similar in scale to a house-fly smashing into an NFL running back. This seems harmless if not for the fact that the fly is going 15,000 miles per hour!
- NASA’s boffins predict that the impact will shift the orbit of Dimorphos around its bigger sibling Didymos by 1%–reducing it by 7 minutes from the current rate of about 12 hours per revolution.
The big question is: Could we really deflect an asteroid heading for Earth? Given the success of DART, I am now a lot more optimistic that, by the time a planet-threatening object comes our way, a defense system will be in place.
“We do not currently know of any object of “moderate” size which has a chance of impact in the next 100 years. …Please keep in mind that anything smaller than about 30 meters in size will have an airburst and is unlikely to reach ground (excluding metallic NEAs). Our atmosphere is very efficient at protecting us from small impacts.”
– Asteroid scientist Marina Brozovic