Expert Political Judgment: How Good Is It? How Can We Know? (Paperback)

~ Philip E. Tetlock (Author)

Editorial Reviews

Review

"... the best lesson of Tetlock's book may be the one that he seems most reluctant to draw: Think for yourself". -- Louis Menand, The New Yorker

"He discovered that the accuracy of an expert's predictions decreased the greater the person's self-confidence, celebrity and depth of knowledge" -- Michael Kesterton, The Globe & Mail

"Tetlock demonstrates in meticulous academic detail that most expert forecasters are no better than the rest of us". -- James Harkin, The Guardian

"Tetlock discovered that specialists were no more reliable than non-specialists at guessing what is liable to happen next". -- Stephen McGinty, The Scotsman

"Tetlock dismisses the comforting notion that public life is 'a marketplace of ideas". -- Nick Cohen, The Observer

"Tetlock's findings are disconsoling for anyone who believes that expertise confers reliable forecasting powers. -- Paul Monk, Financial Review

"The bottom line is that experts are no better at making predictions than dart-throwing monkeys". -- Ellen Goodman, The Boston Globe

"The results of his painstaking research are complex, nuanced, and contingent". -- John T. Jost, Science

"You have been a world-class sap for years. Why? For listening to the economic and political forecasts of experts". -- Geoffrey Colvin, Fortune --This text refers to an out of print or unavailable edition of this title.

Review

It is the somewhat gratifying lesson of Philip Tetlock's new book . . . that people who make prediction their business--people who appear as experts on television, get quoted in newspaper articles, advise governments and businesses, and participate in punditry roundtables--are no better than the rest of us. When they're wrong, they're rarely held accountable, and they rarely admit it, either. . . . It would be nice if there were fewer partisans on television disguised as "analysts" and "experts". . . . But the best lesson of Tetlock's book may be the one that he seems most reluctant to draw: Think for yourself.
(Louis Menand The New Yorker )

Before anyone turns an ear to the panels of pundits, they might do well to obtain a copy of Phillip Tetlock's new book Expert Political Judgment: How Good Is It? How Can We Know? The Berkeley psychiatrist has apparently made a 20-year study of predictions by the sorts who appear as experts on TV and get quoted in newspapers and found that they are no better than the rest of us at prognostication.
(Jim Coyle Toronto Star )

Tetlock uses science and policy to brilliantly explore what constitutes good judgment in predicting future events and to examine why experts are often wrong in their forecasts.
(Choice )

[This] book . . . Marshals powerful evidence to make [its] case. Expert Political Judgment . . . Summarizes the results of a truly amazing research project. . . . The question that screams out from the data is why the world keeps believing that "experts" exist at all.
(Geoffrey Colvin Fortune )

Philip Tetlock has just produced a study which suggests we should view expertise in political forecasting--by academics or intelligence analysts, independent pundits, journalists or institutional specialists--with the same skepticism that the well-informed now apply to stockmarket forecasting. . . . It is the scientific spirit with which he tackled his project that is the most notable thing about his book, but the findings of his inquiry are important and, for both reasons, everyone seriously concerned with forecasting, political risk, strategic analysis and public policy debate would do well to read the book.
(Paul Monk Australian Financial Review )

Phillip E. Tetlock does a remarkable job . . . applying the high-end statistical and methodological tools of social science to the alchemistic world of the political prognosticator. The result is a fascinating blend of science and storytelling, in the the best sense of both words.
(William D. Crano PsysCRITIQUES )

Mr. Tetlock's analysis is about political judgment but equally relevant to economic and commercial assessments.
(John Kay Financial Times )

Why do most political experts prove to be wrong most of time? For an answer, you might want to browse through a very fascinating study by Philip Tetlock . . . who in Expert Political Judgment contends that there is no direct correlation between the intelligence and knowledge of the political expert and the quality of his or her forecasts. If you want to know whether this or that pundit is making a correct prediction, don't ask yourself what he or she is thinking--but how he or she is thinking.
(Leon Hadar Business Times )

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Product Details

• Paperback: 352 pages
• Publisher: Princeton University Press (July 31, 2006)
• Language: English
• ISBN-10: 0691128715
• ISBN-13: 978-0691128719
• Product Dimensions: 9 x 6 x 0.9 inches
• Shipping Weight: 13.6 ounces (View shipping rates and policies)
• Average Customer Review: 4.3 out of 5 stars  See all reviews (18 customer reviews)
• Amazon.com Sales Rank: #37,884 in Books (See Bestsellers in Books)

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Customer Reviews

Most Helpful Customer Reviews

20 of 22 people found the following review helpful:

5.0 out of 5 stars A classic of Political Science & Cognitive Psychology, January 5, 2007

By	Dr. Frank Stech (Glenndale, MD USA) - See all my reviews (REAL NAME)

Tetlock shows conclusively two key points: First, the best experts in making political estimates and forecasts are no more accurate than fairly simple mathematical models of their estimative processes. This is yet another confirmation of what Robyn Dawes termed "the robust beauty of simple linear models." The inability of human experts to out-perform models based on their expertise has been demonstrated in over one hundred fields of expertise over fifty years of research; one of the most robust findings in social science. Political experts are no exception.
Secondly, Tetlock demonstrates that experts who know something about a number of related topics (foxes) predict better than experts who know a great deal about one thing (hedgehogs). Generalist knowledge adds to accuracy.
Tetlock's survey of this research is clear, crisp, and compelling. His work has direct application to world affairs. For example he is presenting his findings to a conference of Intelligence Community leaders next week (Jan 2007) at the invitation of the Director of National Intelligence.
"Expert Political Judgment" is recommended to anyone who depends on political experts, which is pretty much all of us. Tetlock helps the non-experts to know more about what the experts know, how they know it, and how much good it does them in making predictions.

11 of 14 people found the following review helpful:

5.0 out of 5 stars Careful, Plodding, Objective, September 22, 2006

By	Peter McCluskey (Mountain View, CA USA) - See all my reviews (REAL NAME)

This book is a rather dry description of good research into the forecasting abilities of people who are regarded as political experts. It is unusually fair and unbiased.
His most important finding about what distinguishes the worst from the not-so-bad is that those on the hedgehog end of Isaiah Berlin's spectrum (who derive predictions from a single grand vision) are wrong more often than those near the fox end (who use many different ideas). He convinced me that that finding is approximately right, but leaves me with questions.
Does the correlation persist at the fox end of the spectrum, or do the most fox-like subjects show some diminished accuracy?
How do we reconcile his evidence that humans with more complex thinking do better than simplistic humans, but simple autoregressive models beat all humans? That seems to suggest there's something imperfect in using the hedgehog-fox spectrum. Maybe a better spectrum would use evidence on how much data influences their worldviews?
Another interesting finding is that optimists tend to be more accurate than pessimists. I'd like to know how broad a set of domains this applies to. It certainly doesn't apply to predicting software shipment dates. Does it apply mainly to domains where experts depend on media attention?
To what extent can different ways of selecting experts change the results? Tetlock probably chose subjects that resemble those who most people regard as experts, but there must be ways of selecting experts which produce better forecasts. It seems unlikely they can match <a href="http://hanson.gmu.edu/ideafutures.html">prediction markets</a>, but there are situations where we probably can't avoid relying on experts.
He doesn't document his results as thoroughly as I would like (even though he's thorough enough to be tedious in places):
I can't find his definition of extremists. Is it those who predict the most change from the status quo? Or the farthest from the average forecast?
His description of how he measured the hedgehog-fox spectrum has a good deal of quantitative evidence, but not quite enough for me check where I would be on that spectrum.
How does he produce a numerical timeseries for his autoregressive models? It's not hard to guess for inflation, but for the end of apartheid I'm rather uncertain.
Here's one quote that says a lot about his results:

Beyond a stark minimum, subject matter expertise in world politics translates less into forecasting accuracy than it does into overconfidence

7 of 9 people found the following review helpful:

5.0 out of 5 stars brilliant and encouraging, October 24, 2006

By	reader (Syracuse NY) - See all my reviews

Amazon Verified Purchase

Why isn't this book on the front page of every newspaper everywhere? The author makes a cogent argument that informed amateurs are as good as "experts" in seriously important fields from investing to politics. He provides experimental evidence that this is the case. This is the hypothesis that a bunch of farmers and merchants tested when they sat down and organized the United States of America. This is the hypothesis that every smart investor proves when he meets or beats hedge funds spending millions on experts and computer power. A very empowering book. Well-written, well-argued, well-referenced. I dare you to read this one and not give it to a friend.