Chance News 63

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A survey released by researchers at George Mason University found that more than a quarter of television weathercasters agree with the statement “Global warming is a scam,” and nearly two-thirds believe that, if warming is occurring, it is caused “mostly by natural changes.” (The survey also found that more than eighty per cent of weathercasters don’t trust “mainstream news media sources,” though they are presumably included in this category.)

Elizabeth Kolbert, "Up In the Air", The New Yorker, April 12, 2010

Submitted by Margaret Cibes

Tiger’s effect on opponents

“Superstar Effect”
by Jonah Lehrer, The Wall Street Journal, April 3, 2010

Lehrer, author of How We Decide[1], states:

While challenging competitions are supposed to bring out our best, … studies demonstrate that when people are forced to compete against a peer who seems far superior, they often don't rise to the challenge. Instead, they give up.

The article is based, for the most part, on the paper “Quitters Never Win: The (Adverse) Incentive Effects of Competing with Superstars”, by Jennifer Brown, Northwestern University, September 2008. The paper includes detailed descriptive and inferential statistics.

Brown chose to study golf mainly because of the presence of Tiger Woods, whose playing dominates the game. She looked at data from professional golfers and found that the presence of Tiger Woods in a tournament resulted in the other golfers, taking, on average, 0.2 more strokes in the initial 18 holes and 0.8 more strokes in the whole tournament. (Note that Lehrer cites the figure 0.3 instead of Brown’s figure, 0.2.)[2]

Brown’s results apply to a field called economic tournament theory that investigates competitions in which relative, instead of absolute, performance is rewarded. She feels that the superstar effect is strongest when “there is a nonlinear incentive structure,” that is, when there is an extra incentive to finish first.

Lehrer also refers to a 2009 study[3] by University of Chicago psychologist Sian Beilock, who examined “choking” during golf competitions, possibly due to golfers over-thinking their actions.

We bring expert golfers into our lab, we tell them to pay attention to a particular part of their swing, and they just screw up. …When you are at a high level, your skills become somewhat automated. You don't need to pay attention to every step in what you're doing. ….

Lehrer concludes:

Regardless of the precise explanation for the superstar effect—are golfers quitting on themselves or thinking too much?

A blogger commented[4]:

But even the best do not intimidate every opponent. Ali did not intimidate Frazier, Federer did not intimidate Nadal (in fact it was the other way around until Nadal was weakened by injuries). Even Michael Jordan wasn't intimidating when he played without Scottie Pippen.

Submitted by Margaret Cibes

Dribbling data

"At the Free-Throw Line, 1...2...3...4 Whoosh"
by David Biderman, The Wall Street Journal, April 3, 2010

The author reports that, of the 425 free-throw attempts in the past 10 NCAA title games, players who dribbled 1, 2, 3, or 5 or more times before shooting were successful 60%, 66%, 68%, and 68% of the time, respectively, while those who dribbled 4 times were successful 77% of the time. Also, there were more NBA all-stars in the 4-dribble group than in any other group.

Submitted by Margaret Cibes


1. Buried in the article: The total sample size of free throws attempted was 425, with 60, 121, 191, 22 and 9 representing 1, 2, 3, 4 and 7 dribbles for a total of 403. No information is given for 5 and 6 dribbles but from the data, the inference is that the represent 22 (425-403) attempts. Given this data, how impressive does the 77% success rate for four dribbles appear?

2. Why didn’t the author choose to present a simple table of number of dribbles, free-throw attempts, free-throws made instead of dribbling the information all over the article? Is any insight provided by the following graphic from the article?

3. The headline in the print edition, but not in the online edition is, "At the Foul Line, Four is the Magic Number." Comment on the "magicness" of four given the actual data.

Submitted by Paul Alper

Bird brains vs. birdbrains

“Mathematicians vs. Birds vs. Monty Hall”
by Tom Bartlett, The Chronicle of Higher Education, March 17, 2010

“Pigeons Beat Humans at Solving ‘Monty Hall’ Problem”
by Charles Q. Choi, Live Science, March 3, 2010

In the February 2010 issue of the Journal of Comparative Psychology, two Whitman College researchers reported about their work comparing the success rates of 6 pigeons and 12 undergraduate student volunteers in solving the Monty Hall problem[5] by trial and error:

By day 30 of the experiment, the pigeons had “learned” to adopt the best, “switch,” strategy “96 percent of the time.” However, the students had not found the best strategy “even after 200 trials of practice each.”

See an abstract[6] of the paper “Are birds smarter than mathematicians?”

Submitted by Margaret Cibes

Odds are, it's wrong

Odds are, it's wrong
by Tom Siegfried, Science News, 27 March 2010

An essay on the limitations of significance testing. To be continued...

Submitted by Bill Peterson, based on a suggestion from Scott Pardee