Lottery Post Journal

Flipping a coin is not so random after all

It turns out that flipping a coin has all sorts of non-randomness:

Here are the broad strokes of their research:

  1. If the coin is tossed and caught, it has about a 51% chance of landing on the same face it was launched. (If it starts out as heads, there's a 51% chance it will end as heads).
  2. If the coin is spun, rather than tossed, it can have a much-larger-than-50% chance of ending with the heavier side down. Spun coins can exhibit "huge bias" (some spun coins will fall tails-up 80% of the time).
  3. If the coin is tossed and allowed to clatter to the floor, this probably adds randomness.
  4. If the coin is tossed and allowed to clatter to the floor where it spins, as will sometimes happen, the above spinning bias probably comes into play.
  5. A coin will land on its edge around 1 in 6000 throws, creating a flipistic singularity.
  6. The same initial coin-flipping conditions produce the same coin flip result. That is, there's a certain amount of determinism to the coin flip.
  7. A more robust coin toss (more revolutions) decreases the bias.

The paper.


  • ...and don't forget two-headed coins! :)

    By truecritic, at 9:42 AM

  • These tests were done with multiple tosses of the coin. I learned a few years ago that if you flip a coin only once in your entire lifetime, there will be a 50/50 chance. But if you continually flip the coin, it will always try to balance itself out. In other words, if a coin was flipped heads 5 times in a row, most people have been taught in Universities that it still has a 50/50 chance. But this has been proven false. The more the same outcome of the event, the more it will lean towards change. This is a new theory on odds, not by me, but a report I bought from a math professor.

    So, if you saw black on roulette for 15 times in a row, people have been taught that it has a 50/50 chance on the 16th. But what would you bet on?....Red or black. Red of course.

    By joker17, at 1:57 PM

  • If I saw 15 blacks in a row, I would bet on black, not red. In wagering, it makes more sense to go with what's hot. IMHO.

    By Todd, at 2:49 PM

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