Archive for category science
Misuse of statistics calls into question the credibility of science
Posted by mark in science, Uncategorized on March 28, 2010
The current issue of Science News features an indictment of statistics by writer Tom Siegfried. He pulls no punches with statements like this:
“…a mutant form of math has deflected science’s heart..”
“Science was seduced by statistics…”
“…widespread misuse of statistical methods makes science more like a crapshoot.”
“It’s science’s dirtiest secret: …testing hypotheses by statistical analysis stands on a flimsy foundation.”
“Even when performed correctly, statistical tests are widely misunderstood and frequently misinterpreted. As a result, countless conclusions in the scientific literature are erroneous…”
Draw your own conclusions on whether science fails to face the shortcomings of statistics by reading Siegried’s article Odds Are, It’s Wrong.
My take on all this is that the misleading results boil down to several primary mistakes:
- Confusing correlation with causation
- Extrapolating from the region of experimentation to unstudied areas
- Touting statistically significant results that have no practical importance
- Reporting insignificant results from studies that lack power to see differences that could be very important as a practical matter.
I do not think statistics itself should be blamed. A poor workman blames his tools.
Test and evaluation of the Great Panjandrum – a spectacular failure for weaponry
Posted by mark in history, science, Uncategorized on March 23, 2010
When time becomes available – mainly while I do cardio-exercise on my home elliptical, I’ve been watching a classic 26-episode BBC series on The World at War that my oldest son gave me. It’s extremely compelling – rated 9.7 out of 10 by over two thousand voters at the Internet Movie Database (IMDb).
This morning I watched the chronicle of D-Day. Being that I just returned from the Annual National Test & Evaluation Conference by the National Defense Industry Association (NDIA), it was interesting to see what the boffins of Britain invented to defeat the defenses put up along the Normandy beaches. Perhaps the most amazing device was the Great Panjandrum, a rocket-propelled cart, which according to this write-up for Wikipedia was developed by the Admiralty’s Directorate of Miscellaneous Weapons Development. (One wonders about the “miscellaneous” bit.) The clip I viewed on the spectacular failure of the Great Panjandrum can be seen (along with other incredibly-inept military devices for D-Day) in a video on British Secret Wartime Follies posted in this article by UK’s Daily Mail. Check it out!
PS. The Brits continue to come up with the most audacious inventions, such as this flame-throwing moped developed as a deterrent against derelict drivers competing for motorway lanes.
Beware of bugs bearing backpacks
Posted by mark in science, Uncategorized on March 3, 2010
I am attending a conference sponsored by the National Defense Industry Association (NDIA). They provided all of us participants a copy of the latest issue (March) of their publication National Defense. While wiling away the time listening to some long-winded higher-ups I paged through the magazine and admired the weaponry developed to keep our war-fighters supported to the max. However, on page 17 a very odd picture caught my eye – a cockroach carrying a radiation sensor on its back! A researcher at Texas A&M reports that these bugs are ideal for sweeping potentially contaminated areas, ideally in teams of twenty. They can be operated remotely via devices that stimulate their leg muscles.
There is one problem though: Cockroaches cannot crawl backward. One had better hope that none of the bad guys wear pointy-toed cowboy boots, because they will be ideal for killing the sensor-bearing bugs that become stuck in the corners.
Skepticism versus cynicism about science experiments
Eric Felten’s latest “De Gustibus” column in Wall Street Journal reports New Episodes of Scientists Behaving Badly. It details various scandals, for example the retraction of a landmark publication linking autism to childhood vaccines. This creates a great deal of cynicism such as that expressed by this parent of a kid she helped on a science project:
“The experiments never turned out the way they were supposed to, and so we were always having to fudge the results so that the projects wouldn’t be screwy. I always felt guilty about that dishonesty, but now I feel like we were doing real science.”
Ouch!
Coincidentally, Stat-Ease received an email from someone who goes by the pen-name “The Pyrrhonist.” (I see a trend here: I need to work on a scholarly-sounding moniker.) While researching pyrrhonism, I came across this skeptical quote by a Greek named Carneades who set the stage for his countryman Pyrrho:
“Nothing can be known, not even this.”
That’s tough to get around!
I truly believe that some degree of skepticism is healthy, such as judicious use of the null hypothesis for assessing the outcome of experiments. However, it’s not good for experimenters to abandon all standards by succumbing to an attitude of scornful or jaded negativity, especially a general distrust of the integrity or professed motives of others – the definition of cynicism (according to the Free Dictionary).
So, be skeptical, but not cynical.
Tiny rotifers defeat the Red Queen
This week’s NPR Science Friday presented a fascinating report on rotifers, also known as “wheel animalcules”* due to the way they rotor food into their cylindrical bodies.** Besides being so funny-looking, these critters are unique in being only female — no guys to bother with (a bit of a bummer coming up as we are to Valentine’s Day). According to the Red Queen hypothesis this single gender situation should have put rotifers at an evolutionary disadvantage. However, these animalcules manage to thrive, albeit plagued by parasites. They survive by tolerating dehydration for amazing-long periods while riding the wind to their next home – typically a single drop of water.
Check out this entertaining Science Friday video on rotifers, which features new research by Paul Sherman and Chris Wilson of Cornell University. Warning: Although this production would be rated “G” for gender, it may not be suitable for children due to some horrifying imagery of lethal fungal parasites.
*Detailed in Welcome to the Wonderfully Weird World of Rotifers
**Seen in the brief video Life in a Drop of Water: Rotifer
Apples and oranges comparison of diets?
Posted by mark in science, Uncategorized, Wellness on January 21, 2010
While exercising on my elliptical machine this morning watching ABC’s Good Morning America the show captured my attention with a report that Weight Watchers (“WW”) this week filed a lawsuit against one of its top competitors, Jenny Craig (“JC”). The dispute stems from a claim by JC that their clients lost, on average, over twice as much weight as those on the largest weight loss program. WW alleges that this claim is deceptive due it comparing a study by JC done this year versus one done by WW 10 years ago. According to this news release by Weight Watchers the complaint states that generally accepted standards of biomedical research require Jenny Craig to compare the two current offerings of both companies through a head-to-head randomized clinical trial.
“You can’t compare studies that were done in different locations at different times using different groups of people.”
– Louis Aronne, M.D, New York Presbyterian Hospital weight loss expert and author of Eat This, Not That
Although the judge has put a temporary restraining order against their offending ad, I wouldn’t rule out the JC claim prima facie. After all, as Smartmoney Magazine writer Angie Marek stated in her column on The Skinny on Big, Fat Diet Programs “the science on most of these plans is hardly conclusive, since most of the research has been paid for by the diet companies themselves.” In fact, I predict that this case will keep at least two statisticians fat and sassy as expert witnesses (one on each side of this tug-of-war).
Atlantic claws coming to town this Christmas
I came across this unusually bold crab a few weeks ago while beach-walking in Florida.
Perhaps the size of this creature is explained by findings of marine geologist Justin Ries of the University of North Carolina, who reports that rising levels of atmospheric carbon dioxide may lead to larger crabs, shrimp and lobsters.
See a summary of Ries’s research and a picture of a monster lobster in this post by NPR. Wow, these exoskeletoned creatures really like carbon!
PS. All this talk of large lobsters reminds me of an illustration of evolutionary operation (EVOP) by Box and Draper.* Their process improvement method calls an ongoing series of two-level factorial designs that illuminate a path to more desirable manufacturing conditions. I will talk more about this in a future blog.
*Box, G. E. P. and N. R. Draper, Evolutionary Operation, Wiley New York, 1969. (Wiley Classics Library, paperback edition, 1998.)
Running hot and cold in Apalachicola – steaming to cook clams and steaming to make ice
My wife and I are celebrating our 35th anniversary with a Thanksgiving week getaway on the panhandle of Florida. Later today we will enjoy a southern version of the traditional banquet, this one will featuring all sorts of grits – the chef’s specialty. I expect some oysters too – mainly harvested just down-beach at Apalachicola. Also, at the local Piggly-Wiggly I noticed lots of sweet potato pies laid out, along with pecan pies, of course. If I lay off the grits, maybe I will keep some room for a piece of the pecan pie, preferably with some whipped cream on top.
Earlier this week we stopped by an interesting museum in Apalach’ (as the locals refer to it). It celebrates the achievements of a local physician, John C. Gorrie, who invented the ice-making machine. He is also considered to be the father of refrigeration and air conditioning. Obviously the folks here in Florida hold Dr. Gorrie in high esteem for his dedication to cooling things off. What interests me, being that I am a chemical engineer, is how steam powered Gorrie’s ice machine. That seems very counter-intuitive, but the thermodynamics are explained nicely here by the inventor:
“If the air were highly compressed, it would heat up by the energy of compression. If this compressed air were run through metal pipes cooled with water, and if this air cooled to the water temperature was expanded down to atmospheric pressure again, very low temperatures could be obtained, even low enough to freeze water in pans in a refrigerator box.”
For a picture of what he patented in 1851 and historical background, see this Wired magazine article by Randy Alfred.
Getting back to the Thanksgiving feast this afternoon and thinking about the oysters, I suppose we will be given a choice of raw ones laid out on ice (thanks to the local inventor) or one cooked with steam. Coming from the middle of our continent, it may be too much of a stretch to eat uncooked shellfish. In fact, it makes me a bit queasy just thinking of it. Although I fancy myself an experimentalist, sometimes I must draw a line in the sand.
PS. One thing I find curious is that the oystermen (sorry ladies) still do their harvesting the old-fashioned way with tongs – see this video, for example .
Statisticians do not see global cooling trend
This story by Seth Borenstein, AP Science Writer, is sure to create a lot of heat from those who dispute global warming. Without revealing what the numbers represented, his news organization gave temperature data to four independent statisticians and asked them to look for trends. They found no evidence of any decline – only a long-term increase over the last 130 years, thus taking away fuel for the fire that the world is now cooling.
I like the idea of this being a blind analysis, although I wonder if these four statisticians might’ve seen through this. Also, what is a good sample size for statisticians? Four seems meager. Do you pick statisticians at random, or what?
Anyways, I am more concerned about my Minnesota Gophers going to a new outdoor stadium in what will turn out to be one of the coldest Octobers ever in this region. They play Saturday night, which is Halloween – scary enough on a college campus –but it might be wickedly cold as well. Fortunately I have a good collection of Gopher shirts, sweats and jackets to put on layer-by-layer. I noticed something funny about being outdoors after so many years of under the Metrodome: People clapping with mittens on just doesn’t work as well for cheering purposes.
NASA shoots the Moon
I got up a bit earlier than usual to set up my 8-inch reflector telescope for a view of the 6:31 AM CDT collision of NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS). The weather was ideal – clear skies with no wind. Never mind that we had our first frost – Minnesotans like me don’t mind temperatures at the freezing point (knowing full well that soon this will be considered balmy!). However, despite a spectacular view of the Moon’s South Pole, I saw no evidence of the “man in the moon” getting ‘goosed.’ To placate the alarmists who thought the Moon might be destroyed, NASA likened their crash to an eyelash hitting a jetliner. From what I could see myself and the video by NASA, that is an apt analogy, assuming the eyelash came off a gnat.
So LCROSS proved to be a lot less dramatic than us skywatchers hoped for. However, if the follow-up satellite sensed water blown up by its self-destructive predecessor, the mission will be a big success. This will take a while to decipher as noted by Wired magazine’s GeekDad blogger Brian McLaughlin. If you are geeky like me, you will keep an eye out for the final outcome of this shoot-for-the-moon experiment.
PS. All this is mindful of the book by Jules Verne From the Earth to Moon posted with illustrations from an 1886 edition by NASA in their Space Educators Handbook
(“One small click for all mankind.”). It’s fantastic!