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TECH TALK: Black Swan: Reviews

June 6th, 2007 · No Comments

Here is what the Economist has to say about Nassim Talebs The BlackSwan:

Nassim Nicholas Taleb, a professor of the sciences of uncertainty (who gave us known unknowns), has no time for the charlatans who think they can map the future. Forget the important things: we can’t even get it right when estimating the cost of a buildingwitness the massively over-budget Sydney Opera House or the new Wembley Stadium.

The problem is that almost all forecasters work within the parameters of the Gaussian bell curve, which ignores large deviations and thus fails to take account of Black Swans. Mr Taleb defines a Black Swan as an event that is unexpected, has an extreme impact and is made to seem predictable by explanations concocted afterwards. It can be both positive and negative. Examples include the September 11th 2001 attacks and the rise of the internet. Smaller shocks, such as novels and pop acts whose popularity explodes thanks to word of mouth, can also be Black Swans.

This is what The Wall Street Journal wrote:

The power-law distribution, by contrast [to the bell-curve distribution], would seem to have little to recommend it. Not only does it disproportionately reward the few, but it also turns out to be notoriously difficult to derive with precision. The most important events may occur so rarely that existing data points can never truly assure us that the future won’t look very different from the present. We can be fairly certain that we will never meet anyone 14-feet tall, but it is entirely possible that, over time, we will hear of a man twice as rich as Bill Gates or witness a market crash twice as devastating as that of October 1987.

The problem, insists Mr. Taleb, is that most of the time we are in the land of the power law and don’t know itIf we accept Mr. Taleb’s premise about power-law ascendancy, we are left with a troubling question: How do you function in a world where accurate prediction is rarely possible, where history isn’t a reliable guide to the future and where the most important events cannot be anticipated?
Mr. Taleb presents a range of answers–be prepared for various outcomes, he says, and don’t rush for buses–but it’s clear that he remains slightly vexed by the world he describes so vividly. Then again, beatific serenity may not be the goal here. As Mr. Taleb warns, certitude is likely to be found only in a fool’s (bell-curve) paradise, where we choose the comfort of the “precisely wrong” over the challenge of the “broadly correct.” Beneath Mr. Taleb’s blustery rhetoric lives a surprisingly humble soul who has chosen to follow a demanding and somewhat lonely path.

Niall Ferguson wrote in The Telegraph:

Taleb’s central point, then, is that we are too much influenced by instinct, history, Plato and Gauss. We assume the entire world is “Mediocristan”, whereas in reality large swathes of it are “Extremistan”.
The trouble is that it is much harder to live with this insight than to live without it. As Taleb’s critics in the financial world will tell you (and he himself admits), merely insuring yourself against fat tail events does not constitute a profitable trading strategy. Knowing that world wars can happen roughly twice a century is like knowing that a student can run amok roughly once a decade: it doesn’t allow you to predict which diplomatic/personality crisis will be the lethal one.

For practical purposes, it turns out, we humans prefer to work with predictions and forecasts, even when they are nearly always wrong. We prefer to regard financial markets as casinos (what Taleb calls “the ludic fallacy” that odds are always calculable), even when they clearly aren’t. And we resist paying excessive insurance premiums to cover ourselves against very remote contingencies.

Tomorrow: Mediocristan and Extremistan

TECH TALK Black Swan+T

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