Velocity + Inaccuracy

No Gravatar

One bit of criticism about my pamphlet (The Truth About Prediction Markets) goes like this: Velocity without accuracy is dumb.

That is not true.

Let&#8217-s imagine, for the sake of the exercise, that Barack Obama does not pick up Kathleen Sebelius to head HHS. The velocity argument remains valid: Fed by the vertical media (in this case, Yahoo News republishing the Associated Press), the prediction markets integrated expectations (informed by facts and expertise) much faster than the mass media did.

Any argument about the velocity of the prediction markets cannot be contradicted. No way.

Prediction markets didnt revolutionize decision-making -and will never do. However, they are a nice condiment to the classic forecasting toolkit.

No Gravatar

I have spent several hours re-reading the 2004 AEI-Brookings book, &#8220-Information Markets&#8221- (by which they mean &#8220-prediction markets&#8221-). It is a collection of un-enlightening research articles &#8212-except for the IEM article, which is outstanding, both on the factual and theoretical sides.

In the conclusion of their introduction, Robert Hahn and Paul Tetlock wrote that they want their readers to contemplate the idea that prediction markets could make a &#8220-big&#8221- difference and &#8220-revolutionize public- and private-sector decision-making&#8221-. Well, 4 years later, it is clear that those big dreams didn&#8217-t pan out. Not a single mass media outlet has praised the public prediction markets for their work on the 2008 US presidential election (I am taking about a post-mortem analysis about Election Day, not the primaries). Not a single one. (Not even Justin Wolfers.) And the number of corporations using enterprise prediction markets is still minute. The thinkers who wrote this book (&#8220-Information Markets&#8221-) all made the mistake to put the emphasis on accuracy instead of efficiency. That was the foundation flaw. We should reset and reboot the field of prediction markets.

Previously: The truth about prediction markets

Velocity is such a potent argument. Why dont we use it more, for Christs sake?

No Gravatar

I am re-reading a 2007 scientific article from Region Focus’ Vanessa Sumo:

– Ask The Market – Companies are leading the way in the use of prediction markets. The public sector may soon follow. – (PDF)

Here is what I see on the frontpage:

– &#8220-one or two weeks in advance&#8220-

– &#8220-even up to five weeks in advance&#8220-

Marketing-wise, velocity is a much more potent argument than the argument on accuracy. Who cares about an added accuracy of +2.7% (and that&#8217-s debated)? If any, that&#8217-s peanuts.

You cannot make a case against velocity. Impossible.

UPDATE: Put the PDF link in the address box of your browser (as opposed to clicking on it, or right-clicking on it).

The truth about prediction markets

No Gravatar

Come to the wonderful world of collective intelligence, wisdom of crowds, and prediction markets!&#8230- The sun shines bright, the market-generated predictions are vastly superior to the polls as election predictors, and the track record of the public prediction markets stretches as far as the eye can see. There are opportunities aplenty in the field of prediction markets, and the trading technology is cheap. Every working enterprise can have its own internal prediction exchange, and inside every exchange, a set of enterprise prediction markets that correctly predicts the future of business, which their happy, all-American CEO listens to. Life is good in the magic world of prediction markets&#8230- it&#8217-s paradise on Earth.

Ha! ha! ha! ha!&#8230- That&#8217-s what they tell you, anyway&#8230- &#8212-because they are selling an image (just as Bernie Madoff did). They are selling it thru their vendor websites, vendor conferences, vendor-inspired articles in blogs, newspapers and magazines, and interviews of vendor data-fed professors in the media.

The prediction market technology is not a disruptive technology, and the social utility of the prediction markets is marginal. Number one, the aggregated information has value only for the totally uninformed people (a group that comprises those who overly obsess with prediction markets and have a narrow cultural universe). Number two, the added accuracy (if any) is minute, and, anyway, doesn&#8217-t fill up the gap between expectations and omniscience (which is how people judge forecasters). In our view, the social utility of the prediction markets lays in efficiency, not in accuracy. In complicated situations, the prediction markets integrate expectations (informed by facts and expertise) much faster than the mass media do. Their accuracy/efficiency is their uniqueness. It is their velocity that we should put to work.

Here&#8217-s now our definition of prediction markets:

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 represents the imputed perceived likelihood of the partially uncertain future outcome (i.e., its aggregated expected probability). A 60% probability means that, in a series of events each with a 60% probability, the favored outcome is expected to occur 60 times out of 100, and the unfavored outcome is expected to occur 40 times out of 100.

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 enable us to attain collective intelligence. 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. The event derivative traders are informed by the primary indicators (i.e., the primary sources of information), like the polls, for instance. These informed speculators then execute their transactions based on their anticipations about the future &#8212-anticipations that will be either confirmed or infirmed.

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

PS: I am updating a bit the content of this webpage, over time &#8212-so as to finesse the message.