Anyone who thinks that betting market prices are rational will not bet on them. Why would you tie up your capital (even for a few weeks) and pay fees if the prices are fair?
Can you elaborate? I’m not sure what the point of disagreement is here.
For a big market like this, on an exchange like Betfair, my rough mental model is that there is a combination of recreational/compulsive gamblers, more serious professional/wannabe professional gamblers, and (given that the US election captures the attention of a great portion of the world) people who don’t bet for a living but will keep an eye on the market and take any obviously profitable bets on offer.
So a lot of the bets that get matched will be between unserious players (who either don’t care or don’t think carefully about whether the price is rational) and serious players (who do). Others will be matched within the group of serious players, who of course can disagree with each other about the ‘correct price’. But if there’s a mispricing obvious enough that you or I can detect it just by reading 538 or Less Wrong, and large enough to be hugely +EV after transaction and opportunity costs, my default assumption is that it will probably self-correct before I get a chance to take advantage. Not all the money in the market is rational, but there are rational bettors with enough capital to keep the prices roughly where they should be.
edit to clarify why I’m focusing on Betfair: I don’t know a lot about Predictit, but I believe it heavily limits the amount any individual user can bet. In isolation, that could be enough to allow it to stay surprisingly irrational for surprisingly long. But I assume its prices for any significant market will stay relatively close to those of a big exchange like Betfair, because of the easy arbitrage opportunities when they diverge. And the 65-66c you quote is very close to the Betfair price of about a day ago (though the latter has since tightened to the equivalent of about 62c).
At least a couple of people have downvoted this without replying. One of the things I usually like about LW and similar spaces is that good-faith comments get a reply, not just a silent dismissal.
I get that the comment is not exactly punchy or brilliantly written, but I was trying to do the right thing and explain some of my own assumptions, rather than write the equivalent of ‘wat?’ and leave deluks917 to do all the work of bridging our communication gap.
Anyone who thinks that betting market prices are rational will not bet on them. Why would you tie up your capital (even for a few weeks) and pay fees if the prices are fair?
Can you elaborate? I’m not sure what the point of disagreement is here.
For a big market like this, on an exchange like Betfair, my rough mental model is that there is a combination of recreational/compulsive gamblers, more serious professional/wannabe professional gamblers, and (given that the US election captures the attention of a great portion of the world) people who don’t bet for a living but will keep an eye on the market and take any obviously profitable bets on offer.
So a lot of the bets that get matched will be between unserious players (who either don’t care or don’t think carefully about whether the price is rational) and serious players (who do). Others will be matched within the group of serious players, who of course can disagree with each other about the ‘correct price’. But if there’s a mispricing obvious enough that you or I can detect it just by reading 538 or Less Wrong, and large enough to be hugely +EV after transaction and opportunity costs, my default assumption is that it will probably self-correct before I get a chance to take advantage. Not all the money in the market is rational, but there are rational bettors with enough capital to keep the prices roughly where they should be.
edit to clarify why I’m focusing on Betfair: I don’t know a lot about Predictit, but I believe it heavily limits the amount any individual user can bet. In isolation, that could be enough to allow it to stay surprisingly irrational for surprisingly long. But I assume its prices for any significant market will stay relatively close to those of a big exchange like Betfair, because of the easy arbitrage opportunities when they diverge. And the 65-66c you quote is very close to the Betfair price of about a day ago (though the latter has since tightened to the equivalent of about 62c).
At least a couple of people have downvoted this without replying. One of the things I usually like about LW and similar spaces is that good-faith comments get a reply, not just a silent dismissal.
I get that the comment is not exactly punchy or brilliantly written, but I was trying to do the right thing and explain some of my own assumptions, rather than write the equivalent of ‘wat?’ and leave deluks917 to do all the work of bridging our communication gap.
https://www.lesswrong.com/posts/y8RWtNBiksbSzm9j4/bet-on-biden?commentId=ENYJswSZy2DgrntEh seems like an ok guess.
I have a much higher confidence in this being a good bet than in any particular theory of why people are betting on Trump.