Tag Archives: prediction markets

Can the prediction markets survive without the over-selling from John Delaney and his little fanboys?

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Emile Servan-Schreiber:

[…] The classic first line of defense in these cases is to remind people that market “predictions” are really just probabilities, so any one outcome cannot invalidate the approach. The argument is sound and backed up by loads of data. But it would of course be much more convincing if we, as an industry, would remember to show at least as much humility when our market “predictions” appear correct instead. If you’re going to spread the idea that your market called all 50 states in the last U.S. presidential election because each correct outcome was predicted with over 50% chance, then you can’t hide behind probabilities when an 80% prediction comes to naught, as in Obama’s NH collapse. […]

Emile Servan-Schreiber makes a good point &#8212-see also Panos Ipeirotis, in the same vein.

But the over-selling is the reason [*] why InTrade (and not NewsFutures) has managed to infiltrate so many US media. If you suppress the magical touch, then InTrade is just a forecasting tool of convenience &#8212-for those too busy to look at the polls.

Give me one reason why the political analysts should follow InTrade instead of the polls, then?

What is the true nature of the prediction markets? How to use the prediction markets? Who should use the prediction markets? For what benefits? Once you have the answer to these 4 questions, you can tackle the next two problematics: How to market the prediction markets without over-selling them. How to report news thru the prism of the prediction markets while respecting their true probabilistic nature.

Welcome to the version #2 of the prediction market industry. Quite a horse of another color, now.

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[*] UPDATE: The over-selling aspect is the topping over the real-money and the liquidity dimensions. The over-selling aspect wraps all that.

NewsFutures Emile Servan-Schreiber has two lines of defense for the prediction markets.

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And a slam at the InTrade fanboys:

[&#8230-] The classic first line of defense in these cases is to remind people that market “predictions” are really just probabilities [*], so any one outcome cannot invalidate the approach. The argument is sound and backed up by loads of data. But it would of course be much more convincing if we, as an industry, would remember to show at least as much humility when our market “predictions” appear correct instead. If you’re going to spread the idea that your market called all 50 states in the last U.S. presidential election because each correct outcome was predicted with over 50% chance, then you can’t hide behind probabilities when an 80% prediction comes to naught, as in Obama’s NH collapse. [&#8230-]

Excellent point, my Lord.

[*] Note that Midas Oracle is stuffed with phrases like &#8220-probabilistic predictions expressed in percentages&#8221-, and full of charts showing these probabilities.

Go reading his second point, now.

[&#8230-] capturing the consensus opinion in a much finer and dynamic way than all the amorphous media buzz [&#8230-]

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TECHNICAL NOTE:

Because NewsFutures is a strictly hierarchical company, I assume the piece is from EJSS, even though our smart man did not sign it. Bad Karma. Anonymous texts have no weight on the Internet.

On the Internet, nobody knows you’re a dog.

Author Profile&nbsp-Editor and Publisher of Midas Oracle .ORG .NET .COM &#8212- Chris Masse&#8217-s mugshot &#8212- Contact Chris Masse &#8212- Chris Masse&#8217-s LinkedIn profile &#8212- Chris Masse&#8217-s FaceBook profile &#8212- Chris Masse&#8217-s Google profile &#8212- Sophia-Antipolis, France, E.U. Read more from this author&#8230-

Read the previous blog posts by Chris. F. Masse:

  • Good news: The BetFair blog now features a prediction market column. — Bad news: Their columnist is an anonymous writer with long hair… and dubious skills.
  • Once again, a BetFair spin doctor misunderstands the prediction market approach.
  • Grandizer
  • Tss… Tss… Surely, you are joking Doctor Giberson.
  • Comments are still open on Midas Oracle.
  • “I am much more aligned with InTrade than you are, Chris.”
  • And the award for the most technology advanced software vendor goes to… the envelope, please…. QMARKETS in Israel. … [Cheers and applauses in the crowd.]

Prediction Markets 101

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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 advanced indicators (like polls and surveys). 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 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.

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Any comment, Michael Giberson? :-D

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Credits given to:

– Chris Masse-.

– Justin Wolfers.

– Robin Hanson.

– Jason Ruspini.

– Caveat Bettor.

– John Tierney.

– Jonathan Kennedy.

– Mike Giberson.

– Eric Zitzewitz.

– Cass Sunstein.

– Steve Roman,

– Nigel Eccles.

– The Everyday Economist.

– Adam Siegel.

– George Tziralis.

– Leighton Vaughan-Williams.

– Emile Servan-Schreiber.

– &#8220-Thrutch&#8220-.

– Panos Ipeirotis.

Prediction Markets 101 – Chapter One: Interpreting The Probabilistic Predictions

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&#8220-Thrutch&#8221-:

Probabilities, Prediction Markets, and Popular Fallacies

With Hillary&#8217-s surprise victory over Obama in the New Hampshire primary, pundits everywhere are decrying the allegedly &#8216-wrong&#8217- odds that prediction markets like Intrade were displaying prior to the announced results. (As just one example, Barry Ritholtz weighs in with his &#8216-explanation&#8217- of : &#8220-Why Opinion Markets Fail&#8220-.)

At one point the betting markets were implying over a 90% probability for Obama to win. Does this mean they were &#8216-wrong&#8217-? No it does not. It is impossible to judge whether a given probability is/was correct based on the outcome of a single event.

A 90% probability simply implies that, if you encounter a series of events each with a 90% probability, then 9 times out of 10, the favored outcome will occur- and 1 time out of 10, the unfavored outcome will occur. Those like Ritholtz who are now calling the prediction markets &#8216-wrong&#8217- are implying the following: if the probability is 90% for an outcome to occur, then that outcome should occur every time. In other words, if the odds are 90% in favor of something &#8212- it should happen 100% of the time! But this is obviously fallacious. If the outcome occurs 100% of the time, then the correct probability to assign to it would be 100% &#8212- not 90%.

To validly assess the accuracy of prediction markets, one needs to aggregate all the situations where the odds were 90%, and then calculate whether the favored outcome indeed occurred 90% of the time. (And do the same with each level of probability.) This &#8212- and only this &#8212- will tell you how accurate prediction markets tend to be.

Barry Ritholtz:

As every good prognosticator knows, if you couch your forecasts in probabilities, the innumeric will never know you were wrong. It&#8217-s a cheap trick for the easily fooled.

Imagine if instead of a &#8220-THE END IS NEAR&#8221- sign, every loon carried a sign that proclaimed:

THERE IS A 57% CHANCE THAT THE END IS NEAR!!!

The fact that this didn&#8217-t happen &#8212- and the 43% probability did &#8212- doesn&#8217-t mean this forecast was accurate. It merely meant that the person had proferred two possibilities and one of those two occurred. But the math remains unverified.

Neat trick: By your definition, PREDICTION MARKETS CAN NEVER BE WRONG, so long as they maintain a 1% possibility of the alternative outcome.

That&#8217-s hardly a satisfying defense&#8230-

Author Profile&nbsp-Editor and Publisher of Midas Oracle .ORG .NET .COM &#8212- Chris Masse&#8217-s mugshot &#8212- Contact Chris Masse &#8212- Chris Masse&#8217-s LinkedIn profile &#8212- Chris Masse&#8217-s FaceBook profile &#8212- Chris Masse&#8217-s Google profile &#8212- Sophia-Antipolis, France, E.U. Read more from this author&#8230-

Read the previous blog posts by Chris. F. Masse:

  • Good news: The BetFair blog now features a prediction market column. — Bad news: Their columnist is an anonymous writer with long hair… and dubious skills.
  • Once again, a BetFair spin doctor misunderstands the prediction market approach.
  • Grandizer
  • Tss… Tss… Surely, you are joking Doctor Giberson.
  • Comments are still open on Midas Oracle.
  • “I am much more aligned with InTrade than you are, Chris.”
  • And the award for the most technology advanced software vendor goes to… the envelope, please…. QMARKETS in Israel. … [Cheers and applauses in the crowd.]

Columbia Journalism Review not much convinced by Wall Street Journals Justin Wolfers

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No GravatarTo say the least.

[&#8230-] Unfortunately, by the eve of the New Hampshire primary, Wolfers was back in the Journal, writing this time that the newspaper’s own prediction market, WSJ Political Marketplace, run by Intrade, was showing that New Hampshire might be the “death knell” for Clinton and a couple other candidates. After a bet like that, in Vegas they’d say, &#8220-craps.&#8221- 

Humm&#8230- I don&#8217-t like this CJR piece, but it shows that many in the non-business press are skeptical of prediction markets.

Read the previous blog posts by Chris F. Masse:

  • I get a kick each morning out of spying on the rich, famous, and powerful people updating their LinkedIn profile and connections. (Go to “InBox”, and click on “Network Updates”.)
  • ??? BetFair bet-matching logic ???
  • Eliot Spitzer has simply demonstrated once again that those who rise to the top of organizations are very often the most demented, conflicted individuals in any group.
  • Business Risks & Prediction Markets
  • Brand-new BetFair bet-matching logic proves to be very controversial with some event derivative traders.
  • Jimmy Wales accused of editing Wikipedia for donations.
  • What the prediction market experts said on Predictify

GIGO and prophets, tears and markets

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Prediction markets failed to accurately predict the unexpected effect a few tears had on the New Hampshire primaries- and some analysts rushed to blame the tool and undermine its reliability and applicability. Let me restate some fundamentals and my view, in a snapshot:

  • Markets are not prophets, prophets do not exist.
  • A mechanism&#8217-s forecastability should not be judged against a virtual fool-proof prophet- we&#8217-d better compare it with other existing or widely-used mechanisms and -to my partial and context-bound knowledge- markets outperform all those.
  • Markets are the only tool that intrinsically suggests their probability of failure. If Obama&#8217-s stock is traded at 70 cents, this suggests that there is a 30% probability of Obama losing- I&#8217-d say markets are by character modest and no fanfare has any place in describing their suggestions.
  • Markets are primarily an aggregation/meta mechanism- as such, garbage-in-garbage-out effects are expected to happen, so we&#8217-d need to keep focus on minimizing garbage rather than blaming the market/compiler.
  • Maturity of the mechanism and its use, as long as trading volume (in real-money intrade for example), have not yet reached a fully efficient level (more on this to come soon), but these result in significant profit opportunities, so I expect things to just keep getting better.

cross-posted from my blog

Who did best in explaining the prediction markets to the lynching crowd?

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After the New Hampshire fiasco, 16 18 people came to defend the prediction markets, so far. So far, the best takes are from:

  1. George Tziralis
  2. Robin Hanson
  3. Jonathan Kennedy
  4. and I&#8217-ll give the 4th spot to a combo, mixing takes from John Tierney, Adam Siegel (surprisingly pertinent &#8211-I bet he is on a fish diet, post Christmas :-D ), and Steve Roman.
  5. UPDATE: &#8220-Thrutch&#8220-, Emile Servan-Schreiber and Panos Ipeirotis.

AWOLs (so far): PMIA, AEI-Brookings, InTrade, TradeSports, BetFair, TradeFair, NewsFutures, Emile Servan-Schreiber, Jed Christiansen, Koleman Strumpf, Bo Cowgill, Richard Borghesi, Chris Hibbert, David Perry, Ken Kittlitz, Paul Tetlock, David Pennock, Mike Linksvayer, Brent Stinsky, David Yu, Mark Davis, David Jack, James Surowiecki, Tyler Cowen, Greg Mankiw, Donald Luskin, John Delaney [*], etc.

[*] Steve Bass tells us that John Delaney&#8217-s pre-NH CNBC appearance was awesome. I was up that day, waiting for that CNBC segment, but failed to spot it. If somebody sends me the YouTube link, I&#8217-ll publish it here.

Prediction Market Industry Association = useless, so far

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We have witnessed a backlash against the prediction markets just after the Hew Hampshire fiasco. Some bloggers and journalists picked on the prediction markets (InTrade, that is), even though both the polls and the pundits were awfully wrong too. [*] Here are the persons who participated in the pro-PM side of the debate:- Robin Hanson at Overcoming Bias (the best pro-PM piece so far, although his phrasing is a bit too long and a bit too complicated for the average citizen)-

– Justin Wolfers in the Wall Street Journal (who did not convince Felix Salmon, who in tun did not convince me :-D )-

– Chris Masse at Midas Oracle (see Tim Harford&#8217-s new post to discover how irrational Chris Masse really is :-D )-

– Jason Ruspini in a comment here-

– Caveat Bettor on Caveat Bettor–

– and John Tierney in the New York Times (a special case I&#8217-ll blog about soon).

[UPDATE: Jonathan Kennedy.]

[UPDATE: Mike Giberson.]

[UPDATE: Eric Zitzewitz.]

[UPDATE: Cass Sunstein.]

[UPDATE: Steve Roman,]

[UPDATE: Nigel Eccles.]

[UPDATE: The Everyday Economist.]

[UPDATE: Adam Siegel of Inkling Markets.]

[UPDATE: George Tziralis.]

[UPDATE: Leighton Vaughan-Williams.]

[UPDATE: Emile Servan-Schreiber of NewsFutures.]

[UPDATE: “Thrutch“.]

[UPDATE: Panos Ipeirotis.]

[UPDATE: Sean Park.]

[UPDATE: Lance Fortnow.]

[UPDATE: Jed Christiansen.]

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[*] For why the polls were wrong, see: The New York Times, Zogby, Rasmussen, Gallup&#8230- [Thanks to Emile Servan-Schreiber of NewsFutures for one link.]

HSX CO-FOUNDER MAX KEISER IS BREWING A PREDICTION MARKET TV SHOW.

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No GravatarMax Keiser in a comment here:

As far as a PM-based TV show… Watch this space. I should have some news on that front by the first week of Feb.

Fantastic.

Previous blog posts by Chris F. Masse:

  • NUCLEAR SCANDAL: HubDub allow their traders to bet on celebrities’ death.
  • APRIL FOOL’S DAY: This year, again, CNET makes fun of the wisdom of crowds.
  • Play-money prediction exchange HubDub is a phenomenal success.
  • BetFair Australia’s spin doctor tells all about their payments to the horse race industry.
  • Meet Jeffrey Ma (at right on the photo), the ProTrade co-founder, and whose gambling life is the basis of the upcoming movie, 21.

Five Reasons the Prediction Market Critics Are Wrong.

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1. It really was an upset – As it has been pointed out elsewhere, the Clinton victory was a surprise to everyone. Favorites can lose. But so what? Ordinarily, that’s not a market flaw or a reason to doubt the odds shown in the market.

Justin Wolfers article in the WSJ had the best summary:

Against this background, it is no exaggeration to term the result truly historic. Not that there haven&#8217-t been more dramatic upsets or come-from-behind wins that carried more significance &#8212- this was just an early primary, albeit a pivotal one. But in terms of unpredictability, or at least the failure of everyone to predict it, it may have no modern match.
…
Historical comparisons are already being drawn between the New Hampshire primary and the famous 1948 presidential race…Yet the magnitude of the Clinton surprise is arguably even greater&#8230-Thus, Sen. Clinton&#8217-s victory on Tuesday was more surprising than President Truman&#8217-s in 1948.

Given the above, were the Clinton prices on Intrade very far off? It&#8217-s not obvious that they were.

2. Pundits/Critics are NOT traders – If I believe a contract should be trading around 30 and I see it trading at 7, it would make my day. As a trader, seeing a contract that is clearly mispriced is a good thing. Traders who remember the French politician Le Pen’s strong showing in 2002 vs his polls or who read Steve Sailer’s blog should not be surprised that people are dishonest with pollsters. However, to a pundit, an isolated incident of mispricing means the entire concept of prediction markets is faulty.

Since NH results, pundits have been asking, “Are prediction markets flawed?” The traders who make and move the market don’t believe so- they are trading more than ever. In any case, there were no postings on the 7th of January about how wrong the prediction markets are, only after-the-fact postings demonstrating perfect 20/20 hindsight. Traders, not critics, will determine the success of the prediction markets.

Let us not forget that pundits have an agenda too. For some, especially political ones, they need to present themselves as being able to offer insight that no one else has. Since prediction markets allow events to be quantified in real time, the pundits have less to add. This makes critics especially eager to take some of the shine off prediction markets and make themselves look smarter by comparison.

Additionally, there is a contingent of commentators and bloggers with an anti-market bias who delight in seeing any market based tool be wrong. They will be the first to loudly smear PM errors but no where to be found when the market turns out to be right.

3. PMs are not polls – This common mistake is exemplified by this quote from the Chicago Tribune, “The New Hampshire primary was a reminder that prediction markets, where bettors are putting money on the line, can have no more value than opinion polls, where participation costs nothing.” This critic missed the point and doesn&#8217-t realize he is comparing apples and oranges.

Most commentators have focused on the accuracy of the market prices without touching on the underlying purpose of the market: speculation and hedging. Even if the polls are no more accurate than the market, they still can’t be used for trading functions.

4. Regulations have hurt the accuracy and liquidity of PMs – The inconvenience of opening a trading account at Intrade has excluded many Americans from participating. What is the cost of accuracy to the PMs? Surowiecki’s The Wisdom of Crowds lists four factors necessary for a wise crowd: diversity of opinion, independence, decentralization, and aggregation. At least two of these have been highly restricted due to regulations. Even so, the market is usually more accurate than the polls. None of the critics has pointed out that with so many potential traders cut off from trading, the market is surely excluding informed participants.

5. “Serious people who study or work with these markets are not in the &#8216-markets are magic&#8217- camp” – Prediction markets are like other financial markets: fat tails, black swans, bubbles, “manipulations” etc. These are all visible in housing, equities, and fixed income markets as well and no one speculates about the end of those instruments. As Eric Zitzewitz pointed out, the “markets are magic” crowd is just a strawman and not a logical basis to attack prediction markets.

Digg Link:

http://digg.com/business_finance/Top_Five_Reasons&#8230-