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Previously: About Justin Wolfers’-s column
Justin Wolfers’- Freakonomics post (which suggests that BetFair would have a better predictive power if US traders could use it).
Justin Wolfers gives his views about the (now past) differences between the probabilistic predictions given by InTrade on the 2008 US presidential elections…- and the ones generated by the other real-money and play-money prediction exchanges. One hypothesis: US political insiders can’-t access BetFair, legally, and thus can’-t arbitrage. (But they can trade legally on the Iowa Electronic Markets, NewsFutures, Inkling, and HubDub, one could retort.)
Emile Servan-Schreiber’-s hypothesis still holds.
Or else —-your own hypothesis is welcome.
P.S.: The latest news is that InTrade now gives Barack Obama slightly above John McCain.
Via David Pennock of Odd Head fame
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Gary Becker:
[…] I believe that online political prediction markets, and other online prediction markets as well, should be legal in the United States and elsewhere, even if the amounts bet were quite large. There is no important substantive difference between such online betting markets and the Chicago Mercantile Exchange and other exchanges that allow individuals and organizations to take positions on movements of stock indexes, housing price indexes, and prices of other derivatives. A distinction is sometimes made between political betting markets and derivative markets since participants in derivative markets may be hedging other risks that they face. Yet this distinction has little substance since if larger bets were allowed in online political markets, groups whose welfare depended greatly on political outcomes would make greater use of these markets. For example, if a Republican presidential win would mean greater spending on military weapons, companies in the arms business might hedge their risks by betting on Barack Obama.
If large bets were allowed, some wealthy groups may bet a lot on their candidates in order to exert bandwagon influences on public opinion through their large bets affecting market odds. If so, these markets likely would become less reliable as predictors of outcomes, and hence would have less influence on opinions. To a large extent, therefore, these markets would be self correcting, although online political markets might place various other restrictions on bets, as is common in derivative and other exchanges.
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Richard Posner:
[…] There is an interesting question whether prediction markets should be thought of as “-gambling” and perhaps prohibited. As a matter of policy, that would be a mistake, even if one thinks that gambling should be prohibited. The prediction markets are markets for speculation, rather than for game-playing or risk-taking. Slot machines, card-playing, roulette wheels, and other conventional forms of gambling do not generate socially valuable information. Speculation does. Commercial speculation serves to hedge commercial risks and bring prices into closer phase with value. Political, cultural, etc. prediction markets also yield socially valuable information. The outcome of elections is important to companies and even individuals for whom particular public policies are important- they may wish to make adjustments to avert or exploit looming political change. Politicians too need to have as sharp a sense as possible about the effects on the electorate of their and their opponents’- strategies. Apparently they can get more accurate information from the prediction markets than from the public opinion pollsters.
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As I write this, Intrade gives the advantage to McCain over Obama and has the Republican party even with the Democratic party to win the election, whereas all the other prediction markets, meaning IEM, Betfair, and the NewsFutures play-money kind still favor a Democrat in the White House. That disconnect prompted Chris to wonder aloud whether Intrade is faster than the other markets to incorporate the latest polls, perhaps because of its “-bigger liquidity”-.
That’-s an interesting reaction on several levels.
First, reactivity and accuracy are not to be confused for one another. Given that market prices are supposed to be more accurate and more stable that fickle U.S. raw polls (Berg et al, 2008), one should not necessarily be impressed by the market that is quickest to mirror the latest polls. I very much doubt that traders in the “-other”- markets have not heard about the latest polls giving McCain an edge. Rightly or wrongly – it is too soon to tell – they just gave those polls less weight that the Intrade traders apparently did.
Second, the argument from “-bigger liquidity”- is not receivable. Recently, Paul Tetlock analyzed Tradesports data in depth and found that more liquidity may in fact make the market dumber. He concludes: “-In both sports and financial prediction markets, the calibration of prices to event probabilities does not improve with increases in liquidity- and the forecasting resolution of market prices actually worsens with increases in liquidity.”-
My personal theory is that Intrade has a hair-trigger Republican bias which is not found in the other markets, because Intrade appeals to, and is marketed to, the more Republican-leaning segments of the U.S. population. In my opinion, the Intrade/Tradesports Republican bias was already evident in the 2004 election, as this analysis shows.
Of course, I may be completely wrong. In any case, I find today’-s dual disconnect between the polls and most of the markets, on the one hand, and between Intrade and the other markets, on the other hand, to be two very interesting data points that should be duly recorded so we can come back to them later, with hindsight.
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#1. Explainer On Prediction Markets
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Prediction markets produce dynamic, objective probabilistic predictions on the outcomes of future events by aggregating disparate pieces of information that traders bring when they agree on prices. Prediction markets are meta forecasting tools that feed on the advanced indicators (i.e., the primary sources of information). Garbage in, garbage out…- Intelligence in, intelligence out…-
A prediction market is a market for a contract that yields payments based on the outcome of a partially uncertain future event, such as an election. A contract pays $100 only if candidate X wins the election, and $0 otherwise. When the market price of an X contract is $60, the prediction market believes that candidate X has a 60% chance of winning the election. The price of this event derivative can be interpreted as the objective probability of the future outcome (i.e., its most statistically accurate forecast). A 60% probability means that, in a series of events each with a 60% probability, then 6 times out of 10, the favored outcome will occur- and 4 times out of 10, the unfavored outcome will occur.
Each prediction exchange organizes its own set of real-money and/or play-money markets, using either a CDA or a MSR mechanism.
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More Info:
– The Best Resources On Prediction Markets = The Best External Web Links + The Best Midas Oracle Posts
– Prediction Market Science
– The Midas Oracle Explainers On Prediction Markets
– All The Midas Oracle Explainers On Prediction Markets
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#2. Probabilistic Predictions = Charts Of Prediction Markets
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Put your mouse on your selected chart, right-click, and open the link in another browser tab to get directed to the prediction market page of your favorite exchange.
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2008 US Elections
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InTrade
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2008 US Electoral College
2008 Electoral Map Prediction = InTrade – Electoral College Prediction Markets = Probabilistic predictions for the 2008 US presidential elections based on market data from InTrade Ireland = electoralmarkets.com
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– This is a dynamic chart, which is up to date. Click on the image, and open the website in another browser tab to get the bigger version.
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#1. Explainer On Prediction Markets
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Prediction markets produce dynamic, objective probabilistic predictions on the outcomes of future events by aggregating disparate pieces of information that traders bring when they agree on prices. Prediction markets are meta forecasting tools that feed on the advanced indicators (i.e., the primary sources of information). Garbage in, garbage out…- Intelligence in, intelligence out…-
A prediction market is a market for a contract that yields payments based on the outcome of a partially uncertain future event, such as an election. A contract pays $100 only if candidate X wins the election, and $0 otherwise. When the market price of an X contract is $60, the prediction market believes that candidate X has a 60% chance of winning the election. The price of this event derivative can be interpreted as the objective probability of the future outcome (i.e., its most statistically accurate forecast). A 60% probability means that, in a series of events each with a 60% probability, then 6 times out of 10, the favored outcome will occur- and 4 times out of 10, the unfavored outcome will occur.
Each prediction exchange organizes its own set of real-money and/or play-money markets, using either a CDA or a MSR mechanism.
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More Info:
– The Best Resources On Prediction Markets = The Best External Web Links + The Best Midas Oracle Posts
– Prediction Market Science
– The Midas Oracle Explainers On Prediction Markets
– All The Midas Oracle Explainers On Prediction Markets
–
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#2. Probabilistic Predictions = Charts Of Prediction Markets
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Put your mouse on your selected chart, right-click, and open the link in another browser tab to get directed to the prediction market page of your favorite exchange.
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InTrade
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2008 US Electoral College
2008 Electoral Map Prediction = InTrade – Electoral College Prediction Markets = Probabilistic predictions for the 2008 US presidential elections based on market data from InTrade Ireland = electoralmarkets.com
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– This is a dynamic chart, which is up to date. Click on the image, and open the website in another browser tab to get the bigger version.
BBC News:
According to Tom Snee of the Iowa Electronic Market, at Iowa University, futures markets need more hard information than they get in the veepstakes, to reliably predict a result.
Markets are very good at predicting elections, he says – but not choices being made inside Barack Obama’-s or John McCain’-s head.
Thank God for the BBC.
Thank God for the Iowa Electronic Markets.
Shame on John Delaney —-over 3 generations of Delaneys.
Other than Tom Snee (the IEM spin doctor), Chris Masse and Justin Wolfers are the only prediction market analysts to have sent out warnings about the VP-candidate prediction markets.
Via our good friend Mike Linksvayer: —- Implied Prices for Presidential Decision-Aid Markets —- Implied Prices for Presidential Decision-Aid Markets
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My good Doctor Robin Hanson,
Please, refresh my memory:
– Are your experimental, conditional prediction markets offered by the Iowa Electronic Markets or by InTrade Ireland?
Additional question for our Master Of All Universes:
– Who has done more for web-hosting experimental prediction markets, overall: the Iowa Electronic Markets or InTrade Ireland?
Thanks for providing me with some answer(s) on those 2 important questions.
Best Regards,
Signed: Chris “-GadFly”- Masse
PostScriptum: When the CFTC refreshes its webpage that indexes the comments to its concept release on “-event markets”-, you will see that that issue has been raised by some “-gadfly”-. 
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Overall, his input is very brainy.
It’-s a major contribution to the general discussion about prediction markets.
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Please, allow me to disagree on one thing he said.
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Robin Hanson:
One proposed distinguishing criteria includes the size of an individual trader’-s stake, and the number of traders. The Iowa Electronic Markets are limited on both of these parameters. Such limits do succeed in preventing large hedging markets from masquerading as info-motivated event markets. But they do little to prevent generic gambling markets from masquerading as info-motivated event markets.
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I have a fundamentally different view. What is important is not what Robin Hanson thinks of TradeSports-InTrade, BetFair-TradeFair, and HedgeStreet —-and what their motivation(s) are.
What is important is whether those prediction exchanges do generate trustworthy and accurate probabilistic predictions. Period.
They do or they do not. Period.
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And guess which prediction exchange has been more than willing to host Robin Hanson’-s conditional prediction markets: Hint: it’-s not the Iowa Electronic Markets.
Did Robin Hanson tell that to the CFTC?
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UPDATE: Robin Hanson’-s comment, posted below this post.
Chris, I did not take the CFTC call for comments as asking for what I would choose if I were king. I instead took it as them asking for help negotiating treacherous political waters. Part of the reality of their difficult situation is that the public, and hence Congress is quite wary that new rules might in effect legalize general gambling. Convincing the public that betting markets provide accurate predictions is not enough to convince them to legalize such markets in general. If there is any doubt, if I were king I would in fact legalize general gambling.
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