Tuesday, October 15, 2013

Bravo, Mr Fama!

So Eugene Fama was finally awarded the Nobel Prize in Economics, along with Lars Hansen and Robert Shiller. All of them are thoroughly deserving. I suspect in part that the committee might have felt like a parent finally caving to their child's demand for chocolate - it was easier to give Fama the prize than keep dealing with the implicit mockery when his name topped the list of prospective prize winners year after year after year.

I've written about the excellence of Mr Fama before. What I will note, however, is the interesting nature of the prize. It was awarded to the three economists for "for their empirical analysis of asset prices". Both Hansen and Shiller did their most famous work in this area - the Generalized Method of Moments in the case of Hansen, and the excess volatility of prices with respect to dividends in the case of Shiller.

But curiously, Fama's most famous work is developing the idea of market efficiency - that an efficient capital market is one where prices fully reflect all available information. This can work at several levels - weak form, which covers all past price and volume information, semi-strong form, which covers all public information, and strong form, which covers all information, both public and private.

Simple, right? But people hadn't thought about it in that way.

Market Efficiency was a Nobel Prize worthy insight. More importantly, it was a Nobel Prize worthy insight even if markets are not, in fact, efficient. This is because the concept of market efficiency crucially changed the way the debate was framed and the evidence understood. The people that bang on about how markets obviously aren't efficient because of the 87 crash, or the financial crisis, or whatever, still implicitly accept the framework that Fama laid down. It is very difficult to conceive of what asset pricing would look like without Fama.

Of course, people confuse the real contribution of market efficiency with the related point that markets are actually mostly efficient (which Fama has made statements in support of, though by no means universally or dogmatically). But this is the secondary part - the real genius is the idea, regardless of whether efficiency is 'true' or not. The better way of phrasing the question is how efficient markets are, rather than the boo-hiss pantomime of 'all efficient' or 'all inefficient'.

If you come up with a brilliant idea simple enough for people to understand, they'll dismiss it as obviously wrong and unimportant. If you're like Lars Hansen and do something totally brilliant that nobody outside economics will ever understand the importance of, people will assume that your reputation is deserved.

And hence they didn't give Fama the prize for market efficiency directly - they gave it for his body of work on empirical asset pricing. Which is fair enough, as it gets to the main point. By including Shiller, they also added someone whose work tends to suggest that markets may not be efficient, although again by performing novel tests to examine this question. Don't get me wrong, Shiller is a totally deserving recipient. But it still seems to me that Fama's work is the most central of the three, in the same way that Leonid Hurwicz was arguably the most central in the mechanism design prize of 2007. It seems like the addition of a behavioral person in the empirical asset pricing prize was partly a way of saying that the committee doesn't necessarily think markets are efficient (a totally fair opinion), and also, along with the prize label, to insulate themselves somewhat against clowns who misunderstand the importance of market efficiency.

Still, this is all by the by. A great day for Chicago.

It's been a while since anyone has been inducted into the Shylock Holmes Order of Guys Who Kick Some Serious Ass, but Eugene Fama is most deserving of the honour. Congratulations! Apparently some guys in Sweden rate your work too, but that's not so important.

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