Toss Out the Toss-Up: Bias in heads-or-tails

By Erica Klarreich, 15:50 PM April 15, 2008

If you want to decide which football team takes the ball first or who gets the larger piece of cake, the fairest thing is to toss a coin, right? Not necessarily.

A new mathematical analysis suggests that coin tossing is inherently biased: A coin is more likely to land on the same face it started out on.

"I don't care how vigorously you throw it, you can't toss a coin fairly," says Persi Diaconis, a statistician at Stanford University who performed the study with Susan Holmes of Stanford and Ri...

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