[nirvana]

I found this one on bit coins: http://longbets.org/611/

Nobody has taken the other side of it. I'm skeptical (but intrigued) by bit coins, but I wouldn't take the other side of this bet, simply because bit coins have just started out and aren't yet a "fully mature form of money". That is to say, its a lot easier for a penny stock, or any other cheap commodity, to double (or outperform by 2 orders of magnitude) a global currency or form of money that has millions of owners, and relatively stable value.

[bermanoid]

I wouldn't take the other side of this bet

You should be more than happy to take this bet, at any amount that he's willing to offer. I know I would be, as long as it was denominated in USD.

Let's say the wager was $10k - if you buy about $198 worth of BTC at the start of the bet, you're guaranteed to come out ahead by at least $9,802, regardless of what happens. Do the math if you don't believe me - that's a bet I'd be happy to take...

If the bet was in terms of Bitcoins instead, then I'd be a lot more hesitant - you could still hedge against an unbounded loss by buying the BTC up front, but if the price of BTC went down by more than 50% you'd end up losing USD even though you won the bet (also if the price went up by a factor of more than 100 but less than 101, which is unlikely enough to mostly ignore), so you'd need to be somewhat of a BTC bull to be comfortable with that.

Edit: I see now that Longbets mandates that proceeds go to charity, which means that if you followed my strategy you'd be making a donation in some cases since you don't see winnings from the bet. I suppose that changes things a little bit, but even so, I'd happily throw in $198 of my money to make sure with 100% certainty that $10k went to charity.

Which makes it extra scummy if it's true that the offerer of this bet won't accept any challengers...

[jessriedel]

The problem with longbets is that you can post a challenge without being required to accept a bet. I emailed the organization and they helpfully confirmed this.

>[Me:] "Must the makers of predictions (eventually) accept a challenger? I get the impression that several of these predictions are dubious yet have been sitting for awhile without forming a bet. It seems against the spirit of the site to allow predictors to grand stand without having to put their money where their mouth is."

>[Them:] "Predictors put their money where their mouth is by paying $50 to be published. They do not, however, have to accept challenges to their Predictions."

If it were up to me, they'd also allow bets with odds other than 50-50. Still, I think it's a great site.

[bermanoid]

The problem with longbets is that you can post a challenge without being required to accept a bet.

That's pretty shady, especially since it sends a misleading message to see a bet being offered with no challenger - without knowing about that part of the policy, I'd assume that meant nobody had the balls to take them up on the bet, not that they themselves didn't have the balls to accept any challengers!

Longbets should be removing bets from public display if too many reasonable challenges have been submitted without an acceptance. I'd leave it to them to decide what "reasonable" means, maybe something like falling within a certain range of amounts (perhaps making the offerer specify this beforehand?), with argument content that passes a cursory review.

I'd at least suggest that they manually review "bets" that pass a certain threshold of page views and/or challenge requests, and tried to determine whether the bets were proposed in good faith or not, up to and including interacting directly with the people offering the bet and asking them for explanations about why the challengers didn't meet their requirements.

[nialo]

Just posting some sort of list of unaccepted challenges would solve most of this problem with relatively little effort, and seems like a large improvement.

[bdr]

I tried to take the opposing side of this bet. My challenge was not accepted.

[gwern]

One of the problems with that prediction, I found when recording it on PredictionBook ( http://predictionbook.com/predictions/2972 - I do this for most LBs. There aren't that many) is that it's not clear what is being increased relative to what.