The Wisdom of Crowds

Several years ago I wrote about prediction markets like Intrade.com. As the U.S. Presidential election cycle heats up I find I am drawn back to this special kind of bookmaking operation on the Internet. You can see a long list of Presidential election predictions on the Intrade site.

The phrase The Wisdom of Crowds is the title of a book by James Surowiecki, a staff writer for The New Yorker. In 2004 Surowiecki wrote that large groups of average individuals can predict outcomes with greater precision than smaller groups of experts. Intrade.com is a real-life, functioning demonstration of this claim.

First, a quick refresher. Anyone can start an account on the Intrade web site. You add a modest amount of money to your account using a credit card. Then you go to a specific event/market which predicts some outcome. The outcome is easy to verify, eventually. For example, there is a market for the outcome that President Obama is re-elected as president in 2012. Eventually that outcome will either be yes or no. As I write this on November 12, 2011 the prediction for this event is 52.1%. If I think it is likely that Obama will be re-elected I can buy a share in this event for $5.21. If I am right, and hold on to this share until the election I will receive $10.00 – a profit of $4.79.  If I am wrong, and hold on to the share I lose my $5.21. If events alter my prediction, I can either buy more shares for the positive outcome or sell my shares.

Here is a graph of this particular prediction and how the Intrade investors have evaluated the President’s chances.

Intrade.com - Probability of President Obama being Re-ElectedIntrade.com – Probability of President Obama being Re-Elected

You can click on the graph to see more information on this prediction. You can see that Intrade investors have gotten more pessimistic about the President’s chances over the last six months. An important thing to note is that anyone can play in this market. It is not a poll of political experts or those horrid talking heads we hear/see on broadcast media.

A Competitive Market

For my microeconomics students this is an example of a special form of a competitive market. There are many sellers (almost 2,000 to date) and an equal number of buyers. They all have approximately the same amount of information (no insider trading advantage in this case.) It is very easy to enter this market, and to leave it. There are few market imperfections – no monopoly, no obvious cartel.  If we assume, like Adam Smith did 240 years ago, that buyers and sellers will act in their own self-interest (making as much money as possible) then the market price will reach an equilibrium. That equilibrium price will change as new information arrives. For example, when Rick Perry forgets which federal agency he wants to close, some people may judge that Obama’s chances of re-election are slightly higher. They will bid the price up from $5.21 (52.1%) to something higher.

As an exercise consider Surowiecki’s claim that this large number of regular investors will more accurately predict the final outcome that a panel of experts.

Economic Models and Forecasting

Recently, I’ve been thinking a lot about how pointless economic models are.  A good portion of this is probably due to being in a college microeconomics class (which uses Mankiw’s book, which Vox picks apart here.).  What passes for mainstream economics is nothing more than gussied-up tautologies and pretty models that don’t actually prove anything.  What irks me most is how the proponents of the mainstream view—in this case my professor and Mankiw’s textbook—act so certain about everything they assert.

For example, Mankiw devotes a chapter to the actions of a monopoly in the free market, complete with very precise mathematical models.  Yet, this entire chapter is utter B.S. because all the models in the world don’t change the fact that said models are based entirely on assumptions and tautologies, and stupid tautologies at that.  The models, then, only say what the programmer thereof tells them to say.  This isn’t science; it’s an appeal to personal authority, writ large.

In the same vein, an economic prediction is only going to be as accurate as the assumptions upon which it is based.  The reason why so many mainstream pundits missed the housing bubble is not because they lacked computational power with which to build their macroeconomic models; it’s because their assumptions about the housing market and banking industry were wrong.  They thought housing growth could be sustained forever, or that the current housing growth was organic instead of government-subsidized, or that the government would be able to subsidize housing forever, etc.

Trying to build on assumptions of arbitrarily-defined variables being correlated to one another is a recipe for failure, as is evidenced by decades of repeatedly doing so.  The time has come to put away the pretentious belief in the need for mathematically precise models; this isn’t physics, after all.  Ultimately, the foundation of economics must be built on understanding Man as an economic actor.  This paradigm shift cannot come soon enough.

Economics and the Return of History?

In Friday’s edition of NY Times, David Brooks wrote a very interesting column (link) discussing the state of economics. Although subtle and rigorous in its assertions I doubt that the field of economics needs a fundamental change in the philosophical origins of economic methodology. I agree with the author that economists often ignore the notion of moral philosophy and history in economic analysis but that doesn’t mean that old textbooks on classical microeconomics need to be disposed. The author points out the role of economic forecasters who often appear on the TV, essentially trying to forecast economy’s future path. Econometrics, which constitutes time-series forecasts on which most economic projections are based, is a real discipline to which numerous new scientific articles are devoted, published mostly in The Econometrics Journal and Econometrica. In his famous 1983 article (link) Let’s take the con out of econometrics, Ed Leamer wrote how econometric modeling can be misused if a researchers ditch the true role and significance of assumptions. A prominent example is the study of death penalty on crime deterrence. As you can read in more detail in Leamer’s article, one study found out that each capital punishment deters more than 9 murders while another one found out that each additional capital punishment causes more murders.

The contradicting evidence doesn’t imply the falsification of the scientific method in economics. It merely reveals the hidden difference in how economists set assumptions regarding the behavior of individuals, firms and countries. David Brooks pointed out that economists failed to predict the recent financial crisis. However, many economists (myself included) pointed out the true dangers of an over-leveraged economy and monetary easing which led to subprime mortgage crisis and the consequential aftermath.

Many of us have had clear evidence, models and studies that showed how an over-leveraged financial sector can induce a significant economic downturn. However, many policymakers ignored the evidence of the behavior of the financial system which could be easily compared with chaos theory in mathematics. In my recent paper on Iceland’s financial crisis I showed that the depository banks’ overall leverage and indebtedness in the small country was growing exponentially, beyond the limit of capital adequacy.

As Paul Krugman recently noted, lessons from the Great Depression were not learned because people forgot it too quickly. Although mainstream economics, as every field within economic science, needs some major cures, I disagree with author’s assertion that economics is not a real science but a moral philosophy. True, economics is not exact science because human behavior is not as experimental as particle analysis in physics but economics tries to resemble the scientific methodology through models, data, statistical inference and evidence. In fact, new interdisciplinary fields within economics are emerging such as behavioral economics, neuroeconomics and transport economics in which economic analysis is combined with other disciplines such as law, psychology, sociology and neuroscience.

The limits of mathematical recourse in economics were already discussed by economic thinkers such as John Maynard Keynes. And agreeably, mathematical reasoning is bounded by economic reasoning. However, from the real point of view, we need models to address human behavior mostly because, as F.A Hayek noted, it’s too complex to capture its essence in a scientific entirety. If the necessity of assumptions, models and evidence were not the case, hardly any lessons would be learned from the episodes of crises, booms, busts and periods of economic advancement in human history.