Midas Oracle .ORG » 2008 US presidential elections

SXSW: Nate Silver explains how he approached political forecasting for the 2008 US presidential elections. – [VIDEO]

Chris F. Masse — Tue, 09 Mar 2010 10:57:12 +0000

In part #2, he speaks about the books he is writing:

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Flawed New Hampshire polls = Non-accurate New Hampshire prediction markets

Chris F. Masse — Tue, 28 Apr 2009 16:50:15 +0000

The most comprehensive analysis ever conducted of presidential primary polls:

“a handful of methodological missteps and miscalculations combined to undermine the accuracy of predictions about presidential primary winners in New Hampshire and three other states.”

Via Mister the Great Research Scientist David Pennock –who is an indispensable element of the field of prediction markets.

As I blogged many times, prediction markets react to polls… See the addendum below… – [UPDATE: See also Jed's comment.] – Prediction markets should not be hyped as crystal balls, but simply as an objective and continuous way to aggregate expectations. So, if you think of it, their social utility is much smaller than what the advocates of the “idea futures”, “wisdom of crowds” or “collective intelligence” concepts told us. Much, much, much, much smaller… They all make the mistake to put accuracy forward. (By the way, somewhat related to that issue, please go reading the dialog between Robin Hanson and Emile Servan-Schreiber.)

Addendum

California Institute of Technology economist Charles Plott:

What you’re doing is collecting bits and pieces of information and aggregating it so we can watch it and understand what people know. People picked this up and called it the “wisdom of crowds” and other things, but a lot of that is just hype.

New Hampshire – The Democrats

The Hillary Clinton event derivative was expired to 100.

New Hampshire – The Republicans

The John McCain event derivative was expired to 100.

Nate Silver of FiveThirtYeight.com on “The Interview Show” —recorded November 5th, 2008

Chris F. Masse — Fri, 17 Apr 2009 20:12:14 +0000

Nate Silver of fivethirtyeight.com on “The Interview Show,” recorded November 5th, 2008:

Nate Silver on November 3rd, 2008:

Nate Silver on August 21, 2008:

The hype is over. The party is over. — Part II

Chris F. Masse — Fri, 23 Jan 2009 21:33:11 +0000

Since the 2008 US presidential election, no more posts on prediction markets at Freakonomics.

Previously: Part I

The hype is over. The party is over.

Chris F. Masse — Fri, 23 Jan 2009 20:57:48 +0000

With respect to the 2008 US presidential elections, the prediction markets just mirrored the polls (and took a losing bet on Missouri). In hindsight, most of the media coverage about prediction markets prior to November 4, 2008, was pure hype —based on the luck that InTrade got in the 2004 US presidential elections.

Previously

Erik Snowberg on the prediction markets about the 2008 US presidential elections

Chris F. Masse — Fri, 23 Jan 2009 17:27:55 +0000

Andy Eggers:

So to sum up, I liked the use of prediction markets to estimate the conditional general election probability for a candidate at a point in time, and I think it’s worth getting some estimates of how particular events moved this probability. I think at this stage the conclusions are a bit underdeveloped and oversold, considering how many factors are at play and how unclear it is what information each primary introduced. But I look forward to future revisions.

The paper: PDF file

Prediction markets compute facts and expertise quicker that the mass media do.

Chris F. Masse — Wed, 21 Jan 2009 15:49:15 +0000

Political prediction markets react (with a small delay) to political polls —just like the political experts and the mass media do, too. Hence, in order to discover their true social utility, the prediction markets (which are tools of intelligence) should not be compared to the polls (which are just facts) but to the similar meta intelligence mechanisms (the averaged probabilistic predictions from a large panel of experts, or the averaged probabilistic predictions from the political reporters in the mass media, or else). My bet is that, in complicated situations (such as the 2008 Democratic primary), the prediction markets beat the mass media (in terms of velocity) —even though the prediction markets are not omniscient and not completely objective (but who is?).

You might remember the research article that I have blogged about:

Learning in Investment Decisions: Evidence from Prediction Markets and Polls – (PDF file) – David S. Lee and Enrico Moretti – 2008-12-XX

In this paper, we explore how polls and prediction markets interact in the context of the 2008 U.S. Presidential election. We begin by presenting some evidence on the relative predictive power of polls and prediction markers. If almost all of the information that is relevant for predicting electoral outcomes is not captured in polling, then there is little reason to believe that prediction market prices should co-move with contemporaneous polling. If, at the other extreme, there is no useful information beyond what is already summarized by the current polls, then market prices should react to new polling information in a particular way. Using both a random walk and a simple autoregressive model, we find that the latter view appears more consistent with the data. Rather than anticipating significant changes in voter sentiment, the market price appears to be reacting to the release of the polling information.

We then outline and test a more formal model of investor learning. In the model, investors have a prior on the probability of victory of each candidate, and in each period they update this probability after receiving a noisy signal in the form of a poll. This Bayesian model indicates that the market price should be a function of the prior and each of the available signals, with weights reflecting their relative precision. It also indicates that more precise polls (i.e. polls with larger sample size) and earlier polls should have more effect on market prices, everything else constant. The empirical evidence is generally, although not completely, supportive of the predictions of the Bayesian model.

You might also have watched Emile Servan-Schreiber’s videos. Emile is a smart man, and those videos are truly instructive.

In the first part (the lecture), our good doctor Emile Servan-Schreiber sold the usual log lines about the prediction markets —blah blah blah blah blah.
In the second part, Emile Servan-Schreiber took questions from the audience in the room. “Aren’t political prediction markets just following the polls?”, asked one guy. Emile’s answer was long and confused. However, in my view, Emile actually did answer that question (before it was ever asked) in his preceding lecture when, at one point, he made the point that the media were slower than the prediction markets to integrate all the facts about the 2008 Democratic primary, around May 2008. That is the right answer to give to a conference attendee who enquires about prediction markets “following” the polls. Both the mass media and the prediction markets do follow the polls (since the polls are facts that can’t be ignored), during political campaigns. Let’s compare the prediction markets with the mass media, instead, and let’s see who’s quicker to deliver the right intelligence..

Lance Fortnow gives a good insight about the relationship between polls and prediction markets (see his last paragraph).

Yesterday the Electoral College delegates voted, 365 for Barack Obama and 173 for John McCain. How did the markets do?

To compare, here is my map the night before the election and the final results. The leaning category had Obama at 364. The markets leaned the wrong way for Missouri and Indiana, their 11 electoral votes canceling each other out. The extra vote for Obama came from a quirk in Nebraska that the Intrade markets didn’t cover: Nebraska splits their votes based on congressional delegations, one of which went to Obama.

Indiana and Missouri were the most likely Republican and Democratic states to switch sides according to the markets, which mean the markets did very well this year again. Had every state leaned the right way (again), one would wonder if the probabilities in each state had any meaning beyond being above or below 50%.

Many argue the markets just followed the predictions based on polls like Nate Silver’s fivethirtyeight.com. True to a point, Silver did amazingly well and the markets smartly trusted him. But the markets also did very well in 2004 without Silver. [Chris Masse's remark: In 2004, Electoral-Vote.com (another poll aggregator) was all the rage.] One can aggregate polls and other information using hours upon hours of analysis or one can just trust the markets to get essentially equally good results with little effort.

The polls are facts. Prediction markets are meta to facts. Prediction markets are intelligence tools. Let’s compare them with similar intelligence tools.

Lance Fortnow’s post attracted an interesting comment from one of his readers:

to provide an exciting collection of political and other prediction markets.

These markets are as much a “prediction” tool as a wind vane or outdoor thermometer are. They moved up and down according to the daily trends, with very little insight of the longer place phenomena underlying them.

When the weather was hot (Palin’s nomination announcement) the market swinged widely towards McCain, while ignoring the cold front on the way here (the economic recession + Palin inexperience).

The value of weather forecast is in telling us things we didn’t know. We don’t need to trade securities to believe that if McCain is closing on the polls then his chances of wining are higher (duh!), which is what the markets did. We need sophisticated prediction mechanisms to tell us how the worsening economic conditions, the war in Iraq and Palin ineptitude (which in pre-Couric days wasn’t as well established) will impact this election, today poll’s be damned.

Looking at the actions by the republican teams, who were trying to read past the daily trend all the way to November 4th, it is clear that they thought all along they were losing by a fair margin. Because of this is they choose moderate, maverick McCain, went for the Palin hail mary fumble^H^H^H^H^H pass and the put-the-campaign-on-hold move.

A full two weeks before the election the McCain team concluded the election was unwinnable, while the electoral college market was still giving 25-35% odds to McCain.

As highlighted in bold, the commenter says two things:

The prediction markets are just following the polls.
The prediction markets have a minimal societal value.

My replies to his/her points:

That’s not the whole truth. The polls are just a set of facts, whereas the prediction markets are intelligence tools that aggregate both facts and expertise. The commenter picks up a simple situation (the 2008 US presidential election) where, indeed, anybody reading the latest polls (highly favorable to Barack Obama) could figure out by himself/herself what the outcome would be (provided the polls wouldn’t screw it).
That’s true in simple situations, but that’s wrong in complicated situations (such as the 2008 Democratic primary).

The emergence of the social utility of the prediction markets will come more clearly to people once we:

Highlight the complicated situations;
Code the mass media’s analysis of those complicated situations, and compare that with the prediction markets.

APPENDIX:

A graph with a data point for each state, with the horizontal axis representing the polling data and the vertical axis representing the Intrade contract price

Chris F. Masse — Mon, 05 Jan 2009 07:39:50 +0000

Via Andrew Gelman

On November 3, 2008:

Are prediction markets useful?

Chris F. Masse — Wed, 26 Nov 2008 15:55:08 +0000

According to Alan Abramowitz, John Tierney has been “greatly exaggerating the accuracy of the betting markets.” “They follow the polls. That’s it.”

My comment to Alan Abramowitz and John Tierney:

“They follow the polls. That’s it.”

Yes, they follow the polls. No, that’s not it.

Traders also dig the news of the day and make anticipations about the outcome. For instance, towards the end of the 2008 Democratic primary, the polls and the mass media were still giving Hillary Clinton a very good standing, whereas the prediction markets (informed by a bunch of political experts who did the counting of the delegates and super-delegates) were telling us that she was as toasted as Lehman Brothers in the middle of the credit crunch crisis.

Are prediction markets useful? If John Tierney wants to answer this question, he should pick up a prediction market and put it in the social context of that day. Some prediction markets are more useful than others. In the case of the 2008 Democratic primary (a complicated matter), the prediction markets sided with the best informed political experts against the mass media and the polls. So to speak, they were an umpire. In that case, we see the emergence of a social utility. We now have the case for the media citing more the probabilities of the liquid (play-money and/or real-money) prediction markets.

Previously: #1 – #2 – #3 – #4 – #5

External Link: Club of Growth

“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).”

Chris F. Masse — Tue, 25 Nov 2008 16:39:31 +0000

Dixit Nigel Eccles in a comment.

at least parity with the poll

I agree with the above.

their superiority over the pundits

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

John Tierney linked to that Huffington Post that listed the pundits’ 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.