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#off-topic
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2015-08-29
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pupeno09:08:58

Long shot. Does anybody know the prediction market game? I’m trying to run it with a few friends and I forgot the scoring mechanism.

luxbock10:08:48

@pupeno that sounds interesting. Can you elaborate more on it?

pupeno10:08:54

@luxbock: yeah, it’s a game to play with a big group of people over several hours or a weekend. You set up a deadline, like Saturday at midnight and then people can come up with markets such as “A randomly chosen person will be able to name every country in Africa” “At least one person will be too drunk to stand up” “There will be more men than women in the room” and people bet using probability on yes/no, like 10/90, 50/50, 40/60, etc.

pupeno10:08:43

At the deadline, the scores are calculated, but I don’t remember the formula, which is critical. The formula rewarded you betting against the last person than bet, so if someone bet 99/1 and you bet 1/99 and you won, you had the maximum amount of points, but if your bet was the same, you got 0 points.

pupeno10:08:03

So, it’s not only the probability of the outcome that drives betting, but the other present bets.

pupeno10:08:25

Anybody can come up with markets and things get weird, like “Yes will win in this market"

pupeno10:08:47

“The majority of the markets will be yes"

pupeno10:08:06

“John will select yes in this market"

pupeno10:08:46

When we played, the markets were hanged on the wall and eventually we had markets referring to the markets on the left and right. A bunch of us, late one night, moved them around.

pupeno11:08:29

@luxbock: here’s a blog about it: http://rationality.org/2014/06/14/in-the-game-of-markets-you-win-or-you-lie/ but sadly, it doesn’t have the scoring formula.

luxbock11:08:11

@pupeno thanks that's great, will have to try it sometime

luxbock11:08:45

Me and my friends like playing a game where you come up with similar questions and you bet not on what the answers are but what some third person thinks that they are

luxbock11:08:38

You come up with the question and the person to you want to ask, and then you play a game of rock, paper, scissors and the loser has to set the line and the winner chooses over/under