The paper shows some significant evidence that human coin flips are not as fair as I would have expected (plus probably a bunch of people would agree with me). There’s always some probability that this happened by chance, but this is pretty low.

Of course, we should be able to build a really accurate coin flipping machine, but I never would have expected such a bias for human flippers.

This is why science is awesome and challenging your ideas is important.

Edit: hopefully this is not too wrong a place, but Lemmy is small, and I didn’t know where else I could share such an exciting finding.

  • wmassingham@lemmy.world
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    1 year ago

    tl;dr:

    The standard model of coin flipping was extended by Persi Diaconis [12] who proposed that when people flip a ordinary coin, they introduce a small degree of ‘precession’ or wobble—a change in the direction of the axis of rotation throughout the coin’s trajectory. According to the Diaconis model, precession causes the coin to spend more time in the air with the initial side facing up. Consequently, the coin has a higher chance of landing on the same side as it started (i.e., ‘same-side bias’).

    “Higher chance” being 50.77% to land on the same side it started from. But this varies by person; apparently some people introduce more precession than others. But even if you could figure out how to do it reliably, I wouldn’t bet the farm on it.

      • Veltoss@lemmy.world
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        1 year ago

        Crazy how simple and obvious that seems after you see it, but I never would have suspected it if someone did it right in front of me.

        • Jessica@lemmy.blahaj.zone
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          1 year ago

          I tried for a few minutes, before my son got bored and wanted to move on 😜. If you do learn it, let us know!

          • PetDinosaurs@lemmy.worldOP
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            1 year ago

            How old is your son? I imagine I’ll do the same, but this is the only magic trick that I’ve really wanted to learn. My son has some fine motor delays so he won’t be able to do this.

            I realized that I’ve interacted with you a few times here, so I ended up looking at your comment history. We seem to share a lot of similar characteristics.

            I noticed that you’re trans and had a Q&A. I’m cis-het and I missed that session. I hope that we’ll interact again. I want to understand T as well as I understand LGB. I just don’t know anyone T.

            • Jessica@lemmy.blahaj.zone
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              1 year ago

              My boy is about 15 now. I miss the times when magic was, well, magic. I love the times we have now, and look forward to the future as well. But, I’d be lying if I said that I didn’t miss my little boy.

              If you have any Q’s, ask away. I may do another AMA soon, for fun.

    • PetDinosaurs@lemmy.worldOP
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      1 year ago

      I’m curious why you don’t think this is significant?

      This is a pretty high house edge (or whatever you want to call it) for a game that seems the most fair as possible.

      No casino games are that fair.

      As is discussed elsewhere in this thread, you could probably practice and get that higher.

      • beeng@discuss.tchncs.de
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        1 year ago

        Where are coins flipped multiple times in order to gain such value from doing so? I can only think of 2up being played in Australia, 1 day per year and they don’t flick it with their thumb, so…

        Where is the “house” gaining so much?

        • PetDinosaurs@lemmy.worldOP
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          1 year ago

          You can bet on dice and coin flips.

          “I bet you a dollar that my coin flip will come up heads?”

          This research suggests that this is not only profitable, but can be improved upon.

          Edit: so weird. Why would such a simple and correct statement be controversial? I would’ve thought that betting on heads or tails was not this far out of fair coin odds.

          • Snowplow8861
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            1 year ago

            I think the question is, where can you bet on a single coin flip? Maybe because I’m Australian, there’s only one day a year you can bet on a (two) coin flip legally here. Everyone else seems to generally understand that coin flips aren’t fair for gambling and therefore is illegal.

            If this paper was like ‘this is how corruption in sports…’ rather than ‘this is like that magician cup and balls trick’ then I’d understand your concern.

            But like you said, you don’t even have a coin in the house, so the practical side is day to day, perhaps not even once a year, not only are you not deciding on a coin flip, even if you were, you’d (or whomever was flipping it for you) have to learn a technique to see it affect you.

            • PetDinosaurs@lemmy.worldOP
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              1 year ago

              Aside from National Lampoon Vegas Vacation, it would be in back alleys. It’s not a commercial game because it’s not exciting enough and it would be easy enough to fool with a machine (also the paper at hand). I just didn’t expect it to be so biased for actual people flipping coins.

              I seem to have confused people. I just thought there was a different understanding and didn’t want to explain gambling.

              What I meant to express in “the house always wins” is that in games of chance, you’re always at a disadvantage. That’s how the house is statistically guaranteed to make money when played at a large scale.

              Roulette has red, black, and the green one.

              A “fair coin” is a mathematical abstraction. There’s zero probability that actual coin flips are “fair”, in the mathematical sense. What I was expressing was the fact that this is way larger of an effect than I expected and, over time, this effect will change things that use coin flips.

              • Snowplow8861
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                1 year ago

                To be honest I think we have different cultural values here. The way I read this and the way you read it is clearly different. I’m disappointed by how little I had my expectations changed, while you had them moved more.