If one randomly chooses a standard coin in circulation anywhere in the world, and flips it, what is the probability that it lands heads?
(Note: I actually don't know the answer to this question, which makes it a bit interesting: how many coins actually have heads? Maybe there are coins with heads on both sides?)
Resolves to MKT, meaning resolves to whatever the market probability is at the time of close.
The market close will be a date chosen uniformly at random between 9/24 and 9/26 (inclusive), to help avoid issues with last-minute trading. Here is a possible procedure I may use (subject to change): On each day, I will generate a random integer between 1 and the number of days remaining, and if the generated number is 1 then I will close the market. The time I perform this procedure on each day will be arbitrary, and I will not perform any trading immediately before or after carrying out this procedure.
Motivation: There are many ambiguous, hard-to-resolve questions that people have created on Manifold that use a "self-resolving" mechanism of resolving to the market probability. However, there are many concerns about how well such mechanisms work and how reliable they are especially against price manipulation.
This experiment is similar to other recent experiments, but with the answer expected to be close to 50% instead of close to 100% or 0%. The hypothesis I wish to test is whether that makes a big difference to the accuracy of the market.
Some examples of other markets using self-resolution are in the group https://manifold.markets/group/selfresolving
Sep 17, 7:53pm: What is the probability that a coin flip lands heads? [Resolves to MKT] → What is the probability that flipping a random coin anywhere in the world lands heads? [Resolves to MKT]
1,000
3.00The close window has arrived (9/24 to 9/26). I will use the next random value generated on https://drand.love/ - round # 2286490. Taking the hexadecimal value and converting it to an integer, and dividing by 16^hex_length, will provide a random real number between 0 and 1. If this is less than 1/3 then the market will resolve now.
(See https://www.cloudflare.com/leagueofentropy/ for info about this distributed public randomness beacon).
Note in case anyone places a bet in between when I post this comment and when I actually resolve - in case the RNG says to resolve, I will resolve to the value as of the time of this comment.
I'm just posting all this detail the first time because this is a new procedure.
Copying some notes from the market description for reference:
The market close will be a date chosen uniformly at random between 9/24 and 9/26 (inclusive), to help avoid issues with last-minute trading.
So on each day, the probability of close is 1/(number of days remaining, inclusive).
The time I perform this procedure on each day will be arbitrary, and I will not perform any trading immediately before or after carrying out this procedure.
To help prevent the author (me) from gaming it.
One issue with this procedure: Despite spending an hour on it, I wasn't able to set up drand-client to retrieve past RNG values. So it would be kind of hard for anyone to actually verify the value. Still better than just using a local RNG because at least in principle anyone can verify it.
https://en.wikipedia.org/wiki/Obverse_and_reverse
https://en.wikipedia.org/wiki/Currency_in_circulation
Euro area has a lot of coinage in circulation, and looks like many of them do not depict heads.
@jack the obverse side of a coin is often called "heads" even if it doesn't depict an actual human head
@Yev I agree, but the text of the market description strongly implies that the question is about whether a head is depicted. The question is ambiguous and I declare that my authorial intent was to ask about whether a head is depicted, but in the spirit of resolve-to-mkt I leave it up to the market to resolve this ambiguity.
Here is some data on number of various european coins (and bills) in circulation: https://www.ecb.europa.eu/stats/policy_and_exchange_rates/banknotes+coins/circulation/html/index.en.html
There have been some studies on the dynamics of coin flips: https://statweb.stanford.edu/~cgates/PERSI/papers/dyn_coin_07.pdf.