"Black Swan" Author's new work: why many experts' suggestions are wrong

It is a mistake that many professionals often make things that are not observed.

Economists, lawyers, public figures ... Many people often put forward grand and general claims on how they work on the wrong premise and wishful wish. Therefore, we saw the topic of "Suggestion Experts Do not recommend" not long ago, and boarded the hot search first.

In Talb's new book "Fat Tail Effect", similar situations are also discussed.

For example, some experts cit the so -called "experience" data show that we should not worry about Ebola virus, because only two Americans died in Ebola virus in 2016. They believe that from the perspective of death, we should even worry about dying of diabetes.

However, assuming that one day the newspaper reported that it suddenly died 2 billion people, they were more likely to die from Ebola virus or smoking or diabetes?

——This is the problem that "fat tail distribution" will consider.

In the eyes of Taleb, the world we live in is full of "fat tail" incident, but people often know very little.

Tellerb is a mathematician trader on Wall Street. Because he had a war in Lebanon in his childhood, he was particularly sensitive to those small probability events that would cause catastrophic consequences. In academic, he focused on complexity and uncertainty. The study of the "Black Swan" theory he put forward has now become a well -known concept of investors.

The English version of "Fat Tail Effect" was published in 2020 and scored 9.6 points in Douban; recently, the Axin family finally translated and published this disruptive work.

In the book, Taleb told readers how to make decisions and investments based on "future mathematical expectations" instead of "naive empiricalism", and once again hit the essence of uncertainty.

Tellerb said that his main hobby is to make fun of those who pay too much attention to the quality of their knowledge, because "the more shallow people people understand the world, the easier it is to make decisions."

He admires the extreme and unpredictable of the fat tail effect, and believes that "fragile talents are eager for peace, and anti -fragile people grow up disorderly."

So, what exactly is the "fat tail effect"?

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What is "fat tail"?

To understand the concept of "fat tail", first of all, we need some statistical knowledge.

We know that many statistical distribution curves are bell -type, that is, the majority of the situation in the middle, and the probability of the extreme situation at both ends is less likely.

For the middle part of the middle, we are called "Peak", and the sides of the peak are "shoulders" and "left tail" and "right tail". They represent different distribution intervals.

For example, the height distribution of adult men across the country, the left tail represents the probability of male height than 1 meter, which is relatively small; the right tail represents men with a height of 2 meters, and the probability is relatively small. Most people are people. Falling in the middle -that is, the average height.

The tail on the left and right is relatively thin, and this situation is called "thin tail".

Under normal circumstances, this distribution is in line with the law of "normal distribution", such as human height and weight. In "Black Swan", Tellerb called this situation "average Stan". In the average Stan, the individual impact of specific events was small, and only the influence of the group was great.

In contrast, "extreme Stan". In extreme Stan, the probability of data that deviates from average far from the average value is much greater than that of the bell -shaped curve, which means that a single order will have a disruptive effect on the overall result.

How to understand this concept?

If we choose two people randomly, the sum of their height is 4.1 meters, then the probability is that the height of two people is 2.05 meters, not a person 10 cm and a 4m person. Because the distribution of height belongs to the average Stan.

However, two people are also randomly selected. The sum of their wealth is $ 36 million. So the most likely situation is that two people have 18 million US dollars each? Not, the bigger possibility is that one person has 35.999 million US dollars and the other has $ 1,000.

This is extreme Stan, and its distribution is "fat tail".

Drawing: Huaying Capital

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"Naive empiricalism"

Let experts come to the wrong conclusion

Many times, the conclusions and results of statistics are derived from the normal distribution. However, the financial market does not conform to the thin tail characteristics of the normal distribution, it is fatty tail.

In other words, the probability of extreme surge and plunge is far greater than described by the normal distribution. Therefore, a series of our common conclusions and achievements are actually not suitable for the financial market.

However, the financial academic community still makes a lot of derivation and so -called "results" that has not been practical.

However, in fact, the variables and securities returns in all economic and financial fields are thickly distributed. Tellerb counted the time sequence of more than 40,000 securities, and did not meet the thin tail distribution, which is also the biggest misunderstanding in economic and financial research.

I do n’t know or even ignore the distribution of fatty tails. It is not only exposed in the financial market, but also in the field of research involving statistics and even in daily life.

This often leads to the blind confidence of humanity and the future, and the consequence of this "blindness" is "naive empiricalism."

The so -called "experience distribution" is likely to have no experienced reference significance at all. Just like someone wants to prevent floods by building dams, childish "experience" will be based on the highest level of history, that is, the probability of higher water levels is 0. Did you find the problem here? Before becoming the highest water level, the highest water level must surpass the "highest water level" before. Therefore, statistical distribution based on "experience" has been broken.

The same is true of this year's historic high temperature. Before this year, it is difficult to imagine that summer will be so hot.

Another typical "childish empirical" case is that many epidemiologists in the United States have judged the new crowns:

In the early days of the outbreak of new coronary pneumonia, many epidemiologists who did not understand statistics compared the risk of death of new crown pneumonia with the risk of drowning in the swimming pool.

This comparison may be established for an individual (although the new crown pneumonia quickly becomes the main cause of death, and then even accounts for 80%of the causes of death in New York City), but if the "at the same time causes 1,000 people to die" conditions, drown in the swimming pool The probability is minimal.

John Hopkins University's website statistics statistics in the United States infected with deaths

This is because your neighbors infected with new coronary pneumonia, which will increase the probability of your infection with new crown pneumonia, but your neighbors drowning in the swimming pool will not increase your probability of drowning.

This is also a moral issue: when you are infected with a new crown, you have caused death greater than yourself -because you will eventually endanger the entire system.

How to use fat tail theory

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Refusing naive empiricism

After understanding this, we have to return to the answer that Talbu wants to find -how to refuse this "high -quality empiricalism" to better cope with the uncertainty in life?

It can be said that the first step to reject "childish empiricism" is to understand the fertilizer and its "tail risk"; the second step is to give up self -centered; finally to accept risk as part of life, and learn to be disorderly. growing up.

The development of scientific theory makes people more and more inclined to put forward confident conclusions about unknown things. However, this exactly leads to expert problems, risks, and serious dependence on human errors.

At the same time, our thinking happens to be a good self -deception tool: our brain is born to simplify the problem, and it is not suitable for processing complexity and uncertainty.

The opposite of common concepts, Tellerb believes more information means more illusion. The real world full of information is chaotic, random, and complex, and our intuition for things is simple -these two are not matching.

As a result, our spiritual architecture is increasingly unable to keep up with the world we live.

If you do n’t understand, you do n’t talk about response. In Taleb's philosophy, the fat tail is the most basic masonry of the bottom. "Black Swan" outlines the outline of extreme risks, and "Anti -fragile" gives the philosophical response, and "Fattail Effect" gives specific instances and mathematical derivation solutions.

In this world, the consequences of rare events are the most serious. "Knowledge" cannot be regarded as a real truth. Only those who are prepared at all times can survive.

In the "Fat Tail Effect", Taleb told people how to make decisions from the perspective of fertilizer tails by telling the distribution type of extreme events and the mathematical derivation of the essence.

Even if you skip all the formulas, you can only benefit a lot.

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