Economics : The Black Swan: The Impact of the Highly Improbable

The Black Swan: The Impact of the Highly Improbable

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Bestselling author Nassim Nicholas Taleb continues his exploration of randomness in his fascinating new book, The Black Swan, in which he examines the influence of highly improbable and unpredictable events that have massive impact. Engaging and enlightening, The Black Swan is a book that may change the way you think about the world, a book that Chris Anderson calls, a delightful romp through history, economics, and the frailties of human nature. See Anderson s entire guest review below. Guest Reviewer: Chris AndersonChris Anderson is editor-in-chief of Wired magazine and the author of The Long Tail: Why the Future of Business Is Selling Less of More. Four hundred years ago, Francis Bacon warned that our minds are wired to deceive us. Beware the fallacies into which undisciplined thinkers most easily fall--they are the real distorting prisms of human nature. Chief among them: Assuming more order than exists in chaotic nature. Now consider the typical stock market report: Today investors bid shares down out of concern over Iranian oil production. Sigh. We re still doing it. Our brains are wired for narrative, not statistical uncertainty. And so we tell ourselves simple stories to explain complex thing we don t--and, most importantly, can t--know. The truth is that we have no idea why stock markets go up or down on any given day, and whatever reason we give is sure to be grossly simplified, if not flat out wrong. Nassim Nicholas Taleb first made this argument in Fooled by Randomness, an engaging look at the history and reasons for our predilection for self-deception when it comes to statistics. Now, in The Black Swan: the Impact of the Highly Improbable, he focuses on that most dismal of sciences, predicting the future. Forecasting is not just at the heart of Wall Street, but it’s something each of us does every time we make an insurance payment or strap on a seat belt. 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. He calls them Black Swans, which is a reference to a 17th century philosophical thought experiment. In Europe all anyone had ever seen were white swans, indeed, all swans are white had long been used as the standard example of a scientific truth. So what was the chance of seeing a black one? Impossible to calculate, or at least they were until 1697, when explorers found Cygnus atratus in Australia. 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. In full disclosure, I m a long admirer of Taleb s work and a few of my comments on drafts found their way into the book. I, too, look at the world through the powerlaw lens, and I too find that it reveals how many of our assumptions are wrong. But Taleb takes this to a new level with a delightful romp through history, economics, and the frailties of human nature. --Chris Anderson

Das Paris Hilton Prinzip - Eine Folgeerscheinung der modernen Medienlandschaft sind Paris Hilton Berühmtheiten. Eine hohe Dosis Narzismus und ein Talent zur Selbstdarstellung sind die einzig nennenswerten Eigenschaften. Der Autor wird in hymnischen Kritiken als Übergenie gefeiert. Er ist bestenfalls ein Paris Hilton Genie (PHG). Er macht aus seiner Methode auch kein Hehl: My major hobby is teasing people who take themselves & the quality of their knowledge too seriously & those who don t have the courage to sometimes say: I don t know.... (You may not be able to change the world but can at least get some entertainment & make a living out of the epistemic arrogance of the human race). Er präsentiert dem Leser eine Karikatur eines bekannten Denkers bzw. einer anerkannten Theorie und zieht sie dann mit schauts her, wie bin ich doch gescheit durch den Kakao. Wobei er davon ausgeht, dass der Leser bestenfalls eine sehr oberflächliche Ahnung vom Thema hat. Z.B. wird Plato als Sinnbild eines öden und unfruchtbaren Schubladen-Denkens hingestellt. Tatsächlich war er ein höchst origineller Denker. Sein Gastmahl ist die vergnügliche Beschreibung eines Saufgelages. Enpassant werden zentrale Begriffe des abendländischen Denkens eingeführt. L.Wittgenstein wird so ganz nebenbei abgefertigt. Der Riese PHG steht auf den Schultern dieser Zwerge. Besonders hat es PHG die Normalverteilung angetan. Er nennt sie Great Intellectual Fraud (GIF). Zunächst ist die Normalverteilung ein sehr elegantes Mathematisches Model. An der Mathematik kann selbst ein PHG nicht herummeckern. Das ist von zeitloser mathematischer Schönheit. Besonders verdammenswert ist laut PHG die Verwendung der Normalverteilung für das Börsenspiel. Tatsächlich ist PHG noch in den Windel gelegen, da wusste man schon, dass Börsenkurse nicht Normalverteilt sind. Die Black-Scholes Optionenformel geht von der Normalverteilung aus. Natürlich wussten auch Black-Scholes, dass die Kurse nicht Normalverteilt sind. Wegen der mathematischen Eleganz der Normalverteilung kann man aber unter dieser Annahme eine einfache Formel ableiten. Bei einer realistischeren Annahme wäre es ein obskurres Wissenschafts-Paper gewesen, mit dieser Annahme war es eine Revolution im Derivate-Handel. Den Anwendern/Händlern sind die Beschränkungen der Formel natürlich bewußt. Sie korrigieren die Abweichungen von der Normalverteilung mit dem Volatility-Smile. Die tatsächlich spannende Frage ist, ob die Korrektur richtig ist. M.E. fürchten sich die Händler sogar zu stark. Die Erkenntnis, dass es unvorhergesehene Ereignisse mit grossen Auswirkungen gibt, ist nicht besonders neu. Ein klassisches Modell dazu ist die Poisson-Verteilung. Das berühmteste Beispiel für diese Verteilung stammt von L.v.Bortkewitsch: Die Anzahl der von Hufschlag Getöteten in der Preussischen Armmee. Es gibt zahlreiche Börsenmodelle, die die Normal- mit der Poissonverteilung kombinieren (Levy-Prozess). Ab und zu trifft die Börse ein schwerer Hufschlag. Unklar ist nur, wer das Pferd ist. Der Ausdruck Schwarzer Schwan wird im Buch Gebetsmühlenartig wiederholt. PHG berichtet ganz Stolz, dass er Mr. Schwarzer Schwan geworden ist und ihm alle (un-)möglichen Schwarzer-Schwan Produkte geschenkt werden. Er hat aber nicht einmal diesen Begriff erfunden sondern vom Sir Karl ausgeliehen. Man kann das Buch aber auch gegen den Strich lesen. Wenn PHG über einen Denker oder eine Theorie besonders herfällt, dann kann das nicht so schlecht sein. Das beste am Buch ist der Hinweis, man sollte seine Zeit nicht mit unnützer Lektüre verplempern. Ich habe den Hinweis schnell angewandt und das Buch zugeklappt. Keine Antwort weiss ich allerdings auf die Frage, ob man Zeit für die Besprechung schlechter Bücher aufwenden sollte.

Enjoyable explanation of why (nearly) all mathematical models of financial markets are wrong - As a PhD student in Economics interested in financial markets I have read NN Taleb s book (The Black Swan), then Riccardo Rebonato s (Plight of the Fortune Tellers: Why We Need to Manage Financial Risk Differently, 2007) and Benoit Mandelbrot s ((Mis)behaviour of Markets: A Fractal View of Risk, Ruin and Reward, 2005). All books contain the same message: the assumptions underlying modern risk management models are wrong (and yes, this has something to do with the financial crisis). All books are worth reading, but if you know one, you know the others. Which leaves you with the question of which book to read.Here is my recommendation: For economists and people with a mathematical background, I would suggest Mandelbrot. The story is very nice, and his explanations original. He was the first to suggest that stock prices resemble fractals, and not random walks. Since he had a co-author, the book is a good read, given some prior knowledge. For those without some intermediate knowledge of Economics or mathematics or both, I would suggest Riccardo Rebonato s book. It has a clear structure and is easy to understand. Still, it does the job and gets the point across. Now, for those who think they know a bit of philosophy, economics, mathematics and the universe in general, it s The Black Swan that I would recommend. Taleb is getting at the subject from a philosophical point of view, of course based on mathematics, and the story unfolds in a hilarious way. Taleb is smart and has a lot of knowledge of things that matter and things that don t. It s funny to see him bark at different groups of scientists (economists, philosophers,..). I have found no instance where his disappointment at people/theories is misplaced. Being outside the scientific establishment has its advantages.

Great book!! - I recommend this book without restriction to every conscious reader. Having read his first book Fooled by randomness, I must say that this book is not as concise as the previous in making his point. This book has a more personal touch, where more of his character shines through. With respect to his first book, this one seems more mature as far as the formulation of his thoughts is concerened. I have the feeling that he wrote everything he wanted to write, whereas in the first, I had the feeling that he just rushed through the material. I do not want to write a short summary, because his ideas may have a big impact to everyone. In fact, everyone should have read this book. For its ideas can change the way one looks at the world and the things that happen everyday...

u won t regret it!! - THE BLACK SWAN is a highly acclaimed piece of work from the writer of the stellar FOOLED BY RANDOMNES. Taleb is a philosopher of randomness, and before becoming a writer he worked on Wall Street as a senior trader. This book explores our inherent yet primerily ignored relationship with Black Swan theory, first concieved by David Hume. I encourage anyone who is remotely intersted in society, philosophy, politics or discussion to pick up this book and they won t regret it!! I d also recommend reading the mesmerising and highly evocative novel The Fates by Tino Georgiou.

Exposes the Flawed Assumptions of the Bell Curve Nudists, Those Who Always Decide by Using Normal Distribution Models - Do you agree that being hit with a tsunami has a totally different effect from a normal high tide? If so, you ll be glad that Professor Taleb has decided to point out that all tsunamis (low probability, high impact events) need special attention, even if they occur infrequently. His advice: Minimize exposure to large potentially harmful events while taking maximum exposure to large potentially helpful events.I was particularly thrilled to see that Professor Taleb points out the foolishness of economists in preparing theories without checking the data to see if the theories work in practice . . . the greater foolishness of the Nobel committee granting prizes for such work . . . and the greatest foolishness of relying on the advice of such economists.Why all the fuss? Many phenomena display high predictability and the differences from the average usually don t make all that much difference to you and me (that quality is captured by a statistical display called a bell curve where most cases cluster near the average and vary symmetrically from the average). But in some cases, there are rare events that change the reality so strongly (like a tsunami can do on the negative side or a selection as an Oprah book of the month can do on the positive side) that it would be the height of foolishness to ignore the possibilities.When it comes to assets, wealth, book sales, athlete pay, and lots of other places where there is lots of competition, there are geometric rewards for a few while the mass do poorly. These are long-tail events (the way statisticians talk about lots of variation from the norm). But almost all human decision making assumes that there is little variation from the norm.The book concentrates on helping you understand why such a potentially harmful bias exists (brain structure plays a large role). We also assume a continuance of what s in front of us, even when there s obvious evidence to the contrary.I was pleased to see these descriptions. I constantly run into the same problem with executives who are subject to stalled thinking and don t see opportunities right under their noses to accomplish 20 times as much. I liked Professor Taleb s points about overcoming our ignorance of antiknowledge . . . our tendency to discount what we haven t experienced or measured. I frequently see executives estimate that the best anyone will ever do at a level that someone already exceeded in 1880. In fact, in many important areas such as herbal health remedies, our actual knowledge is receding very rapidly, turning into antiknowledge.To help break you free of how you think now, he uses a metaphor (a black swan -- is that really a swan?) and new terms (Mediocristan -- where the bell curve is the right way to think about things and Extremistan -- where powerful in effect black swans lurk). I found this tendency to be both helpful and not. It made it clearer to me what he was talking about the first time, and then made things seem muddier after that.I suspect that for most people, the metaphor itself will be the biggest problem. Do you really care about black swans, per se? I don t. I think Professor Taleb would have done better to use two metaphors (one positive -- perhaps like formation and attraction of wealth to the Bill and Melinda Gates foundation and the foundation s effects on world health, and the other negative -- perhaps like a tsunami) than to focus on one that is mostly about definitions (black swan).If you agree with Professor Taleb s main points, you will probably want to get lots of advice about how to do so. He s specific only in regard to two areas (wealth management and book publishing opportunities). That s a shame. Perhaps he will write a future book that will go more into solutions.I was surprised to see that the book pretty much ignores the scenario work that many organizations use to identify the large impact, unlikely occurrence events and to devise strategies that work better under all possibilities. If that subject interests you, I suggest that you read books like The Art of the Long View and Inevitable Surprises by Peter Schwartz, Scenarios by Kees van der Heijdan, and The Irresistible Growth Enterprise by Carol Coles and me.I was pleased to see that Professor Taleb also feels that many black swans can become grey swans by employing new prediction methods (although we cannot predict specifics, we can often predict up or down reasonably well in some situations). That has been my experience is seeing that Modern Portfolio Theory makes no sense in unsettled market conditions while more refined methods built stock-by-stock can be quite predictive over the short run in identifying over and under performers, even during unsettled market periods.Check your models before you use them each day. Otherwise, you ve just checked into work without your brains intact.Keep your eyes and ears open whenever you are away from bell curves!




The Black Swan: The Impact of the Highly Improbable