Stats Made Easy

Practical Tools for Effective Experimentation

Friday, March 27, 2009

Phenology -- the study of the timing of natural events

Not to be confused with phrenology (measuring ones skull to assess character and intelligence -- both of which appear lacking in the subject pictured), the scientific discipline of phenology provides valuable barometers of climate change by its observation of seasonal natural events, for example --the dates that daffodils bloom near Cambridge, England. A chart on this is featured in the latest National Geographic alert on the environment. I wondered about the validity of the upward trend line superimposed on a broad scatter of data. However after seeing this presentation by Tim Sparks of the UK Phenology Network I am convinced: Flowers are definitely blooming earlier nowadays.

Here are upper Midwest USA phenological observations made for this month of March by the University of Wisconsin in Green Bay. It’s latest entry details the record flooding along the border of Minnesota and North Dakota – a disaster in the making. A bit cheerier is the news of someone sighting the first blooming of Symplocarpus foetidus (skunk cabbage). Whoopee!

Anyways, all this is an excuse for me to upload a photo I took last week along the Natchez Trace in Mississippi while on spring break last week. I do not know the identity of the plant in the foreground, but it caught my attention -- especially with the wonderful profusion of blooming azealas as a backdrop.
I did see the first robin in our front yard last week -- a sure sign that spring will come soon -- perhaps after the major snowstorm forecast for early next week.

Saturday, March 21, 2009

Nearly 90% of cardiologist-approved heart therapies are not supported by high-quality scientific testing

Recently the Wall Street Journal reported that a Study Questions Evidence Behind Heart Therapies -- specifically by this alarming statistic: “Just 11% of more than 2,700 recommendations approved by cardiologists for treating heart patients are supported by high-quality scientific testing.” It seems that the vast majority of prescribed treatments remain unratified by multiple randomized clinical trials – the highest level of evidence according to guidelines issued jointly by the American College of Cardiology and the American Heart Association.

I am caught up in this personally due to having had one heart attack some years ago. Ever since then I’ve been working hard to avoid a second one. My daily aspirin is strongly supported by scientific study, but it’s not very sure that I should be keeping on with the platelet inhibitor Clodiprogel (Plavix™, Bristol-Meyers Squibb/Sanofi Pharmaceuticals) prescribed after getting my clogged artery stented. I have to credit my cardiologist though – he is utterly impartial on the Clodiprogel – I cannot get any signal – pro or con. What can he say? As pointed out in this related article by US News & World Report no clinical trials exist beyond about one year (even that time is a bit vague!) of the heart surgery.

So as not to let all this cause me too much stress (possibly bad for the heart, but not strongly supported by solid scientific study) I picked up on this promising therapy – waltzing as a form of cardio-exercise. Evidently this works as well as trudging the treadmill and the dancing leads to a better quality of life as measured by the Minnesota Living With Heart Failure Questionnaire.* I note that the subjects were selected at random – that’s good, but “the study was not blinded, neither to the investigators nor to the patients.” Obviously it would not do to waltz blindly along, no matter how blissful that might be – until one hits the wall!

*I’d be skeptical if this weren’t based on Minnesota standards, that is, bitter cold, biting insects and so forth. ;)

Sunday, March 15, 2009

Basketball players fail to cash in on free throws

Tonight the NCAA filled out their 65-team* bracket for their annual Division I basketball championship. The quality of basketball will no doubt be better than ever, at least since 1995 when Kevin Garnett broke barriers by jumping directly from high school to the Minnesota Timberwolves. That really provides no excuse though for what Larry Wright, and adjunct professor of statistics at Columbia, says is a “mind boggling” lack of improvement in the rate at which college players make free throws. In this article by the New York Times, John Branch reports that in 1965 NCAA teams shot 69 percent. This year they cashed in from the 15 foot charity stripe at a rate of only 68.8 percent.

Some athletic endeavors leap ahead due to an innovation in technique, such as the Fosbury Flop in high jumping or skating on cross country skis. I wonder why more players don’t throw up free throws underhanded like Rick Barry did as depicted by this NBA website on The Art of the Free Throw. His 90 percent rate set the NBA bar when he retired.

I saw an interesting shooting variation at the halftime of a Timberwolves game a few weeks ago. They gave a fan one shot from half court to win a million dollars. The contestant was an older fellow who seemingly had no chance throw a basketball that far. However, he succeeded on distance by flinging it backward over his head, an approach used by this more accurate fan who won a car by sinking the 47-foot shot shown here.

It would be interesting to experiment with an accomplished basketball player to see how their shooting percentage would vary facing forward versus backward from the free-throw line. Surely the success rate would fall precipitously.** Actually, that might make things a lot more interesting – even the seemingly static 69 percent rate is too boringly accurate.

*One aspect of this “March Madness” is that it commences with a “play-in” game that makes one team the absolute loser!

**An exception might be 41 percent free thrower Ben Wallace seen missing the iron completely in this video . He should do the same as the fans watching him at the line -- don't look.

Friday, March 06, 2009

Detecting outliers graphically

My son Hank, 'blogmeister' of StatsMadeEasy, just forwarded me this cartoon from Randall Munroe's blog xkcd. It dovetails nicely with my presentation to the ASQ Lean Six Sigma Conference this week titled "Friend or Foe? How to Use Graphical Diagnostics for Scoping Out Discrepant Data."*

As I am wont to do, I started my talk with a humorous anecdote on the topic. This is a story on seeking something out using visual clues. It's a matter of being on guard for something unusual like Nassim Taleb's Black Swan but being a Minnesotan my thinking differs a bit on what's distinctive.

"A fellow borrowed a neighbor’s fishing car** to sneak in some last-minute anniversary gift shopping at Mall of America (MOA) without his wife knowing. After wandering the vast hallways of MOA for a long period of time, he found just the thing. However, by then he’d forgotten where the car was and even what it looked like. All he could think of to tell the security staff was that the front right tire did not have a hub cap. After a thorough search the car was located. However, it would have been easier for the MOA staff if the fellow had thought to mention that the car had a red canoe strapped to the roof! "

*For the basis of my talk, see this manuscript.
**Fyi Minnesotans generally keep two spare automobiles -- a 'winter beater' that stands up to all the snow and road slop, plus an old 'fishing car' that can be kept at the ready with rods and all (and allowed to get stinky with fish and bait).