Monday, July 06, 2009

Justin Fox on CNBC

I saw a snippet of Justin Fox discussing his misleadingly titled book, 'The Myth of the Rational Market', and he continues to not admonish those who praise the book but haven't read it. Market Haynes summarizes the theory of efficient markets thusly:
One of the longest held economics theories is called the Efficient Markets Hypothesis, basically it says the market's always right...

That's just wrong. It is a straw man argument, like saying Republicans hate poor people, that Black-Scholes caused the failure of LTCM, or that Value-at-Risk is a panacea: only naive critics say these things.

I think Fox may realize this, but I also think it is possible that amidst all his study, he doesn't really understand the ideas in play. After all, in that same interview, his big note of a regulatory reform that might help is Glass-Steagall, which is about as related to this crisis as the deregulation of Airlines (they both involved deregulation). For in his book, he notes the failure of beta as related to the Efficient Markets Hypothesis (the EMH), but it is not clear how. I guess the nuance of the theory, how any test is a joint test of a market model and the EMH, is too subtle for either his audience, or Fox. For example, the CAPM could be true while the EMH false, and the EMH could be true and the CAPM false. So, tying the CAPM into his book is really confusing unless you explain why and how it failed.

I still like the book, which is much less tendentious than how presented in any of his TV appearances. But not as an exposition of the EMH debate, rather, as a supplement. There's good stuff in there, just don't expect to be clear on whether markets are efficient or not.

1 comment:

Anonymous said...

I had to look up the word "tendentious" since you used it in 2 of the last 3 posts. Keep the vocabulary zingers coming!