Mathematical Digest

Short Summaries of Articles about Mathematics
in the Popular Press

"TheNot So Random Coin Toss," by David Kestenbaum. All ThingsConsidered, National Public Radio, 24February 2004.

Flipping a coin is one of the most often cited examples of a random experiment.Yet Persi Diaconis, Susan Holmes, and Richard Montgomery have found that a cointoss may not yield the assumed 50-50 split. Kestenbaum interviews Diaconis,who says that he and his colleagues have discovered that "coins, when they'retossed by real people, are biased." They found that the probability that a coinwill wind up facing the same way as it was when it was tossed is more than .51.Diaconis talks about the particulars of his coin-tossing research and hislarger goal of cautioning people when they assume that things are random. Thesegment concludes with an excerpt from Bill Cosby's classic routine on thefootball coin toss. (Note: when listening to the interview online, you willfirst hear a ten-second ad for a tape from NPR.)

See also:
"Toss Out the Toss-Up: Bias in heads-or-tails," by Erica Klarreich, Science News, 28 February 2004;
"Heads or Tails?," by Ivars Peterson, Science News, 28 February 2004.

--- Mike Breen

American Mathematical Society