Mathematics Weblog

Coin tossing is not fair

Saturday 20 March 2004 at 11:02 pm | In Articles | Post Comment

If you toss a coin and want it to come up heads then start with it heads up. 51% of the time it will come up heads. This remarkable result was discovered by a mathematician Persi Diaconis and you can hear an interview with him here (then click on All Things Considered audio link) where he talks about the lack of randomness of coin tossing.

It turns out that any randomness is just due to sloppy humans who toss coins differently every time. So all those text books on tossing coins are wrong and until now nobody had noticed!

See also Science News articles:

Toss Out the Toss-Up: Bias in heads-or-tails
Heads or Tails?