We have often discussed the possible benefits of prediction markets for reducing bias. One key element that could be particularly useful is a conditional prediction market, where betting claims are based on outcomes conditional on some factor we want to evaluate. Robin recently mentioned the possible benefit from
Subsidizing real-money prediction markets and real-money conditional prediction markets = BULLSHIT IDEA
Should Google subsidize the Lunar X Prize contract on InTrade?John Salvatier,Our good friend Bo Cowgill might have already re-created those prediction markets on Googles internal prediction exchange at a marginal cost of zero US dollar. No nee...
Blogged and flogged.
I'll miss my posting privileges here. I really will :-(
Now, if only Intrade worked in the United States without requiring a bank transfer...
Why not Democrat and Republican? Those are the two major parties. What about third parties?
I suspect the intention was to make the probabilities ("Dem presidency" and "non-Dem presidency") add up to be exactly the same as the probability of any kind of presidency.
"Democratic" is the system of Democracy. Democrat is a political party in America. Although I'm sure the DNC loves how people conflate the two.
I don't think it's a conflation; it's simply a word with more than one meaning. The word Republican is the same: it also has a meaning distinct from the name of a party.
(1) Column headings:"Dem pricenon-Dem priceDem normnon-Dem norm"
Why not Democrat and Republican? Those are the two major parties. What about thirdparties?
(2) "non-Democratic administration"
Being argumentative for the sake of argumentation isn't productive.
Robin: Silas, as I explained before,
Where? Would you mind pointing me to the first comment you made in that discussion, in which you understood what I was proposing, and correctly stated what you meant? Because that was kind of an issue back then.
we expect that on election day most of the causal direction of the correlation is from the vote to the consequences, while for most days before there are large causal forces in both directions.
Well, you certainly *hope* so, but then, the market has usually largely incorporated expectations about the winner before election, making the signal really really small, and allowing the random influences to dominate.
Let me take a gander at Peter McCluskey's shock futures market. Is it consistent with my theory that bidders will assume that other random forces will determine the election day correlation?
Yep, that's betting on a coin flip alright!
Also, we want a market estimate as useful as possible right up until the election, but just before the election the overall correlation price would be dominated by the previous correlation history.
Yes, so in the unlikely event that the correlation of "probability of democratic win" and "oil futures" is very far from the unknown noise-filtered, manipulation-filtered election day correlation, this metric will have inaccurate results.
If you really think the election day's correlation is that much more important, then you can say:
"Silas, that's a really good idea, but to account for election day's more relevant information, the metric should treat election day as 30 days of price history for purposes of determining the correlation that resolves the bet."
Then, you give stronger weight to election day, but still incorporate all the available information and dilute irrelevant influences!
(And do you really imagine I had not considered your obvious variation when I chose my design?)
I invite anyone to read the thread and decide if Robin's responses indicate that he had considered the idea before.
P(Robin responds to misunderstandings of my idea | Robin has considered my idea before) = lowP(Robin responds to misunderstandings of my idea | Robin has not considered my idea before) = high
I doubt Peter makes a profit on this batch. That would require a lot of trading with that small a spread.
But in principle you are right. There's got to be some sweet spot of volume and good guesstimation of the initial line where this is profitable even with the fairly small bid/ask.
If a somewhat larger spread would still invite interest in the market, it should be fairly easy to make it profitable as long as transaction costs to the market maker are low (much smaller than the spread).
Without knowing anything about the trading algorithm Peter is using, I suspect that subsidize is probably the wrong word for what he's doing. Market-making is a very common trading strategy that can be highly profitable if done correctly, even without knowing much about the actual value of what you're trading. I'd assume that the algorithm adjusts the bid and ask prices whenever a trade is made, meaning that if the initial market is wrong, the algorithm will correct it. If there's enough trading volume, Peter will make enough from the bid/ask spread of 2.5 to cover any losses from the initial market being incorrect.
Props to Peter for taking on the risk in order to get the market going, and more props if he ends up making a profit. Anyone interested in setting up a prediction market based on whether Peter McCluskey comes out ahead?
Silas, as I explained before, we expect that on election day most of the causal direction of the correlation is from the vote to the consequences, while for most days before there are large causal forces in both directions. Also, we want a market estimate as useful as possible right up until the election, but just before the election the overall correlation price would be dominated by the previous correlation history. (And do you really imagine I had not considered your obvious variation when I chose my design?)
Silas: Sorry to hear that.
Robin: That claim definitely demands some serious acknowledgment. It sure does sound like Silas proposed a better system for extracting info from markets.
When I told my father the current price for McCain on Intrade, he wanted to bet on him, but his bank blocked the credit card transfer.
(My father predicts that Obama will win the popular vote but lose the electoral vote, guessing that he'll sweep the blue states and lose enough red states, but barely.)
Silas, if you improve my ability to understand the present and predict the future, the yes, I will definitely award you proportionate appreciation and respect.
Peter: Silas, it's too late to change the existing contracts, and I'm not about to subsidise more contracts for this election.
Were you able to understand how I wasn't asking you to change the existing contracts or subsidize others, but rather, proposing to subsidize my own superior ones that have better safeguards than "I will watch carefully possible manipulation"?
I can't agree that the claims I'm subsidizing have been a success yet. Note that NONDEM.PRES-GOVT.DEBT is priced as if it could be expired above 100, but the rules say the maximum expiry price is 100. That's a clear sign that there hasn't been enough trading to make the price of that claim reasonable.A few of the "Impact of Next Pres." claims have traded. I bought and sold 2 contracts of PRES.McCAIN+LESS.CRIME in June. I'm not sure what time period the Intrade volume figures cover.Gwern, "over $10 billion" and "over 2000" mean that you divide debt changes by $10 billion and divide troop levels by 2000 to get the corresponding contract price.Silas, it's too late to change the existing contracts, and I'm not about to subsidise more contracts for this election. I will watch carefully for possible manipulation, and will consider better ways of minimizing manipulation risks if I subsidise similar contracts in the future. I think the rest of your arguments have been adequately answered. I certainly encourage you to subsidise additional contracts.Jason, two of the contracts will expire at zero when the election is settled. I will lose nearly $8000 on those. For the others, it's unpredictable.
What I find most pleasing about this design is that it avoids the awkward construction that Richard alludes to, and at the same time spurs trade by virtue of the changing denominator. Excellent.
I think the actual subsidy is much smaller although it did seem that over $1000 was given away at inception by setting the initial prices at 50.