Tag Archives: polls

Still, as noted, it was a good election for [the] prediction markets and another piece of evidence of their superiority over the pundit[s] (and at least parity with the poll).

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Dixit Nigel Eccles in a comment.

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at least parity with the poll

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I agree with the above.

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their superiority over the pundits

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What documented evidence do you have about that, mister the cocky entrepreneurial Scotsman?

John Tierney linked to that Huffington Post that listed the pundits&#8217- predictions about the total number of electoral votes that each presidential candidate would take. But I disagree with that way of predicting the electoral college and assessing these predictions. With this completely flawed method, if you are damn wrong on a state and damn wrong (in the opposite way) about another state that has the exact same number of electoral votes, then you are a bright genius worth the Nobel prize of forecasting. Gimme a break. Enough with that voodoo way of assessing predictions about the electoral college. Do the assessment state by state.

InTrade and HubDub got lucky that their 2 mistakes (so to speak, in a non-probabilistic way) on Missouri and Indiana (both with 11 electoral votes) canceled themselves perfectly. IT WAS PURE LUCK. If their 2 mistakes had been made in the same direction (say, betting on Obama with the outcome going eventually to McCain), and/or their 2 mistakes had been done on 2 very dissimilar states (say, one with 6 electoral votes and the other one with 27 electoral votes), then we would have had reporters and bloggers bashing the prediction markets for the whole month of November.

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It wasnt about the predictions.

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Let&#8217-s not confuse media visibility with utility. Aside from the depressed Obama-to-win prices on one exchange, prediction market and polling aggregation results for the 2008 election were essentially the same using squared errors. Despite his insane schematics, Emile Servan-Schreiber has a good point about capturing the interest of the public, something that nerdy academic and libertarian-types aren&#8217-t necessarily good at. An Obama-backing baseball statistician out of Daily Kos nailed that part this year, a year where people were especially skeptical of markets, not to mention unregulated &#8220-offshore&#8221- ones. Likewise, if you put down the lens of considering markets as commission generators, you&#8217-ll see the value of contracts tied to social and cultural outcomes. Of one the biggest assets of prediction exchanges is media goodwill, which should be fostered by distilling information on subjects like global development and art prices.

Other things to keep in mind:

  • This year happened to have a lot of favorite-longshot States, which turned-out to be favorable to 538&#8217-s error relative to markets.
  • Prediction markets register information in real time. Since the difference in error is small, this is important.
  • Markets are more flexible, and useful in situations where you don&#8217-t have a rich data set and obvious statistical analyses. Elections are just one type of question. Even if you have data, it might be less expensive to set up a new contract than to undertake the analysis.
  • And of course, prediction markets have functions aside from forecasting, and provide incentives for uncovering new information.

2008 US electoral college: What I am betting on.

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PollTrack:

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I like the way they color this electoral college map &#8212-with 5 colors only (simplicity is good). It is very clear and usable, I believe. You can see 6 states in gray (&#8221-too close to call&#8221-). I am heavily betting on Barack Obama for Florida and North Carolina. There will be a good payoff, next Tuesday &#8212-maybe. :-D

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Price for Alabama - Florida at intrade.com

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Price for New Jersey - Rhode Island at intrade.com

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Who will win Florida in the 2008 Presidential Election?

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Who will win North Carolina in the 2008 Presidential Election?

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Explainer On Prediction Markets

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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 60 times out of 100, the favored outcome will occur- and 40 times out of 100, 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 &#8212-with or without an automated market maker.

Prediction markets produce dynamic, objective probabilistic predictions on the outcomes of future events by aggregating disparate pieces of information that the traders bring when they agree on prices. These event derivative traders feed on the primary indicators (i.e., the primary sources of information), like the polls, for instance. (Garbage in, garbage out&#8230- Intelligence in, intelligence out&#8230-) Armed with these bits of information, the speculators then trade based on their anticipations, which will be either confirmed or infirmed. Hence, the prediction markets (which are more than just an information aggregation mechanism) are a meta forecasting tool.

The value of a set of prediction markets consists in the added accuracy that these prediction markets provide relative to the other forecasting mechanisms, times the value of accuracy in improved decisions, minus the cost of maintaining these prediction markets, relative to the cost of the other forecasting mechanisms. According to Robin Hanson, a highly accurate prediction market has little value if some other forecasting mechanism(s) can provide similar accuracy at a lower cost, or if very few substantial decisions are influenced by accurate forecasts on its topic.

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More Info:

– The Best Resources On Prediction Markets = The Best External Web Links + The Best Midas Oracle Posts

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More Charts Of Prediction Markets

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Is InTrade being manipulated? Why does InTrade give a discounted probability for Barack Obama as US president?

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A quick link panorama.

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#1. Is InTrade being manipulated?

– Nate Silver shows that there are abrupt downward pressures on the Barack Obama event derivative, while we also see some abrupt upward pressures on the Hillary Clinton event derivative.

However, you can see by yourself that InTrade is resilient enough and does a great job of going back to normal [*], after just a few hours of trading:

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– At Portfolio, blogger Zubin Jelveh blows the incidents out of proportion.

– Professor Lance Fortnow has a more careful analysis and notes that the price of the Barack Obama bounces back quickly enough.

– Quick thought: Maybe the media should use an average of event derivate prices for the last 5 work days&#8230- so that the abrupt perturbations would be eliminated.

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[*] UPDATE:

Professor Eric Zitzewitz:

I’m not sure you can conclude from Silver’s graphs that the market goes “back to normal.” You can conclude that it moves back in the opposite direction of the impact those large trades. Back when the Hillary for President market looked like it was being manipulated, it appeared that the manipulator was both placing a large purchase and then placing limit orders to provide price support and slow down the reversion of the price.

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UPDATE: Are we witnessing manipulation attempts on the &#8220-Florida to vote Republican&#8221- prediction market at InTrade?

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#2. Why does InTrade give a discounted probability for Barack Obama as US president?

– As you remember, Emile Servan-Schreiber of NewsFutures believes that it&#8217-s a Republican conspiracy all over.

– Professor Justin Wolfers puts up an hypothesis: it&#8217-s legally impossible for US traders to arbitrage on BetFair.

– InTrade put up a crappy excuse: the industry is still too &#8220-young&#8221-. How lame. How stupid. The industry was younger in the previous elections, where arbitrage opportunities didn&#8217-t exist according to professors Justin Wolfers and Eric Zitzewitz (see their 2004 paper and their other publications).

– Blogger Zubin Jelveh swallows the InTrade P.R. line, and adds another crappy InTrade P.R. line: More arbitrage opportunities are being exposed in open air because much more observers are hunting down arbitrage opportunities in 2008 than in previous elections. That&#8217-s a second blatant cretinery, uncorrected by the Portfolio blogger. Re-read Justin Wolfers&#8217- blog post. Professor Justin Wolfers states that:

The current variation in price is larger than I have ever seen in my years of studying prediction markets. The forces of arbitrage that would typically eliminate these differences have been handicapped by the legal restrictions preventing U.S.-based traders from using overseas markets.

– Finally, professor Lance Fortnow says nothing about the arbitrage opportunities between InTrade and BetFair, but does offer some technical points about the issue of polls versus the prediction markets, centered around the question of state correlations. Read on.

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UPDATE: Eric Crampton (a Canadian exiled in New Zealand) says he has managed to turn a buck by arbitraging between InTrade and iPredict New Zealand. He also makes 2 theoretical points. Go read it.

UPDATE: Greg Mankiw just linked to Nate Silver.

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2008 US Presidential and Congressional Elections Prediction: The Sarah Palin effect has partially evaporated, but its remains point to a close race, come Tuesday, November 4, 2008.

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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&#8230- Intelligence in, intelligence out&#8230-

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. Objective 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 = 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.

Is Intrade out on a limb?

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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 &#8220-bigger liquidity&#8221-.

That&#8217-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 &#8220-other&#8221- 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 &#8220-bigger liquidity&#8221- 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: &#8220-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.&#8221-

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&#8217-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.

2008 US Elections Prediction: John McCain is now the favorite at InTrade, while all the other prediction exchanges still have Barack Obama ahead. Is InTrade quicker to incorporate the latest polls because of the bigger liquidity of its prediction markets?

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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&#8230- Intelligence in, intelligence out&#8230-

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.

2008 US ELECTORAL MAP PREDICTION: The 2008 US elections thru the prism of the prediction markets – 2008 US presidential and congressional elections – US President Prediction + US Congress Prediction – Barack Obama vs. John McCain

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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&#8230- Intelligence in, intelligence out&#8230-

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.

–

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.