8 ms·

This is incredibly puzzling. Is there a minimum number of rotations per coin flip to consider it valid? If looks like the bias was not evenly distributed acro

This is incredibly puzzling. Is there a minimum number of rotations per coin flip to consider it valid? If looks like the bias was not evenly distributed across people. How did you protect your experiment from skilled bad actors who could influence the data with a few bad/skilled flips? Did strangers on the internet fare any differently than in-person attempts from trusted people?

morelisp 3y ago
Why do you think this is puzzling? This bias has been analytically and dynamically predicted for years.
- hurtuvac78 3y ago
  Because I find it counter-intuitive. And because I am not aware of scientific development in this field. @bradrn on this thread kindly extracted the description of the proposed physical model from inside the paper, it is helpful: https://news.ycombinator.com/item?id=37830265 https://news.ycombinator.com/item?id=37830265
fbartos 3y ago
We told people that the coin has to flip at least once (which would bias it for the opposite site). Whenever instructing people, I tried to explaining that the coin flip should look like you were trying to determine an outcome of a bet. You can find the complete experimental protocol here: https://osf.io/hkv8p https://osf.io/hkv8p Also, I wish I had (any) budget to hire proffesional skilled tossers haha.
- cantrevealname 3y ago
  I assumed that the 1% bias was entirely due to coins that did not undergo any rotation at all. However, reading that you told people that the coin has to flip at least once, I think I assumed wrongly. It sounds like the bias is due to coins that have undergone an integral number of 360-degree rotations (not zero rotations). But what exactly is the physical mechanism causing this bias? It's easy to understand why zero rotations would introduce a bias, but I can't easily picture a reason for a bias toward an integral number of 360-degree rotations. Is there a simple and intuitive way you can explain the physical reason?
  - fbartos 3y ago
    It's not about the number of rotations at all. I doubt that you can control it at all even after dozens of hours coin flipping (I did more than 20h and I can't eveb guess how many rotations the coin made) Diaconis, Holmes, and Montgomery (2007) proposed a physical model of coin flipping that introduces the bias as a result of wobblines (i.e., off-axis rotation in the flips). Diaconis, P., Holmes, S., & Montgomery, R. (2007). Dynamical bias in the coin toss. SIAM Review, 49(2), 211-235. https://doi.org/10.1137/S0036144504446436 https://doi.org/10.1137/S0036144504446436

morelisp 3y ago

Why do you think this is puzzling? This bias has been analytically and dynamically predicted for years.

hurtuvac78 3y ago
Because I find it counter-intuitive. And because I am not aware of scientific development in this field. @bradrn on this thread kindly extracted the description of the proposed physical model from inside the paper, it is helpful: https://news.ycombinator.com/item?id=37830265 https://news.ycombinator.com/item?id=37830265

fbartos 3y ago

We told people that the coin has to flip at least once (which would bias it for the opposite site). Whenever instructing people, I tried to explaining that the coin flip should look like you were trying to determine an outcome of a bet. You can find the complete experimental protocol here: https://osf.io/hkv8p https://osf.io/hkv8p Also, I wish I had (any) budget to hire proffesional skilled tossers haha.

cantrevealname 3y ago
I assumed that the 1% bias was entirely due to coins that did not undergo any rotation at all. However, reading that you told people that the coin has to flip at least once, I think I assumed wrongly. It sounds like the bias is due to coins that have undergone an integral number of 360-degree rotations (not zero rotations). But what exactly is the physical mechanism causing this bias? It's easy to understand why zero rotations would introduce a bias, but I can't easily picture a reason for a bias toward an integral number of 360-degree rotations. Is there a simple and intuitive way you can explain the physical reason?
- fbartos 3y ago
  It's not about the number of rotations at all. I doubt that you can control it at all even after dozens of hours coin flipping (I did more than 20h and I can't eveb guess how many rotations the coin made) Diaconis, Holmes, and Montgomery (2007) proposed a physical model of coin flipping that introduces the bias as a result of wobblines (i.e., off-axis rotation in the flips). Diaconis, P., Holmes, S., & Montgomery, R. (2007). Dynamical bias in the coin toss. SIAM Review, 49(2), 211-235. https://doi.org/10.1137/S0036144504446436 https://doi.org/10.1137/S0036144504446436