That Random Coin Toss? Not So Random Afterall...

from the a-weaker-man-might-be-moved-to-reexamine-his-faith dept

One of my all-time favorite scenes in a play and movie, is the scene in Tom Stoppard's Rosencrantz & Guildenstern Are Dead where every coin toss comes up heads, leading to a bit of a philosophical discussion on probability. Of course, the randomness of the coin toss is the quintessential example of a random event and is used regularly for a variety of situations in which randomness is required, let alone expected. Except... it turns out the common wisdom may be wrong. Paul Kedrosky has the news of a test that showed that if you ask people to try flip a coin and get more heads than tails, they will, and not by a small margin either. In the test, 13 people were asked to flip a coin 300 times, trying to get as many heads as possible. All 13 participants got more heads than tails. Seven out of the thirteen had statistically significant margins of heads over tails (meaning almost certainly not a matter of chance). The highest was one individual had 68% of the coin flips land heads. In other words, a coin toss isn't particularly random.

Filed Under: coin toss, random


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  1. identicon
    Brandon, 14 Dec 2009 @ 6:45am

    Re: Re: Defining Randomness

    So like you said, for random things, A: Past outcomes do nothing to help predict future outcomes.
    This principle is nowhere to be found in the coin toss scenario. This may not sound intuitive, but I can predict with nearly 100% certainty based on past coin flipping data that the coin will land on either heads or tails. (the randomness only comes in, as I explained before, if something else happens, like the coin lands on its side or is hit by a stray bullet and destroyed). A coin toss is almost perfectly predictable.

    Something is not random if you can known all the possible outcomes and their chances of occurring. Randomness involves unknown outcomes (or at least unknown probabilities for known outcomes)

    The problem is dependent on defining randomness, and sadly the conventional definition of randomness is very based on statistically non-random events such as casino gambling and coin tosses, and not on the kind of randomness thats found in the chaos of nature.

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