Sunday, October 28, 2007

The Black Swan

I recently finished the audiobook "The Black Swan - The Impact of the Highly Improbable" by Nassim Taleb. It currently has 3.5 of 5 stars from 199 Amazon reviewers. Taleb is a philosopher, mathematician, analyst who used these talents successfully on Wall Street as a "quant" and later as a hedge fund manager. Taleb's personal home page is here.

If nothing else, I was happy to learn more about what a quant was. These are the PhD egg heads that analyze mounds of economic and market data for use in devising trading strategies. The Wall Street brokerage firms employ them by the truck load and pay the good ones a ton of money. I've heard of them, but little more.

Taleb uses the black swan theory in his discussion of why people are so bad at predicting the future. Here is an excerpt from a review by Chris Anderson:

Our brains are wired for narrative, not statistical uncertainty. And so we tell ourselves simple stories to explain complex things we don't--and, most importantly, can't--know. ... The problem, Nassim explains, is that we place too much weight on the odds that past events will repeat (diligently trying to follow the path of the "millionaire next door," when unrepeatable chance is a better explanation). Instead, the really important events are rare and unpredictable. ... Nassim argues that most of the really big events in our world are rare and unpredictable, and thus trying to extract generalizable stories to explain them may be emotionally satisfying, but it's practically useless. September 11th is one such example, and stock market crashes are another. Or, as he puts it, "History does not crawl, it jumps." Our assumptions grow out of the bell-curve predictability of what he calls "Mediocristan," while our world is really shaped by the wild powerlaw swings of "Extremistan."

I found the book to be a bit of a mess. At times he is clever and descriptive in his discussions and arguments, and at others he is confusing, taking unnecessary tangents, and including a few rambling egotistical diatribes (IMNSHO). I didn't toss it out because it actually had a compelling message. One that I had an interest in hearing. The text is laced with all sorts of new words like: mediocristan (the land of bell curves), extremistan (where chaos reigns), empiricism, erudite, epistemic arrogance, empirical skepticism, Platonism, and the narrative fallacy. For those interested, Taleb has posted a glossary of black swan terminology. He calls himself a skeptical empiricist.

I would recommend this book only to those who have read about it from several sources and are still not dissuaded by the subject. Translation: if you can read the reviews and comments about the book, and still retain an interest in the subject, then you'll probably enjoy the book.

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