* Subject: Survival deviation-a very important logical concept *)

In 1941, the Second World War was in full swing.
One day, Professor Abraham Wald, a famous statistician at Columbia University)
An unexpected visitor, the Battle Commander of the Royal Air Force.
"Professor Ward, every time the pilot leaves for bombing,
What we are most afraid of hearing is: "Call the headquarters, I'm playing !』
Please help us improve this difficult problem that is critical to the lives and deaths of pilots !」

Ward took the emergency study and he was commissioned to analyze information about German Ground Artillery hitting the coalition bomber.
We recommend how to strengthen the body armor in order to reduce the chance of being shot down by artillery. However, according to
In aviation technology, the body armor can only be partially strengthened. Otherwise, the body is too heavy, which may lead to difficulties in takeoff and slow control.
Ward described the bullet points of the Coalition bomber as two comparison tables,
Ward's research found that the wing is the most vulnerable to being hit,
The cockpit and tail of the pilot are the least hit parts.
Ward's detailed data analysis satisfied the Royal Air Force.

However, there was a heated debate at the Conference on the study results report.

"Professor Ward's research clearly shows that the wing of a coalition bomber,
The bullet holes are dense and easy to play. Therefore, we should enhance the armor of the wing .」
Ward said politely but firmly, "General, I respect your professionalism in flight,
But I have totally different opinions. I suggest Strengthening the armor of the pilot cockpit and the rear engine, Because there
At least bullet holes are found .」
In a stunned and Skeptical View, Ward explained: "the samples I analyzed only include the smooth return to the base.
Bomber.
From the statistical point of view, I think that the bombers that have been repeatedly hit the wing still seem to be able to return safely and fly.
The host rarely finds the point of impact, but it is not really not normal,
However, once it gets hit, it will not be able to return .」 The commander retorted:
"I really admire Professor Ward's lack of flight experience, so he dared to make such bold inferences. For me personally
When I went to execute the task, I also suffered from many serious attacks on the wing. If I hadn't been a veteran of flight technology, I was lucky,
The machine has been destroyed for a long time, so I still strongly advocate that the wing armor should be strengthened .」 The two opinions are deadlocked.
The Minister of the Royal Air Force is suffering.

Should he believe in the combat-experienced General Apsara, or should he believe in an independent statistician?
Unable to conduct further research due to the urgent situation, the Minister decided to accept Ward's suggestion and immediately strengthen the cockpit.
Protection Armor with tail engine. Shortly afterwards, the proportion of the Coalition bomber was significantly reduced. To
Confirm the correctness of the decision. After a while, the British military used the staff behind the enemy to collect some crashes.
The wreckage of coalition aircraft in Germany, where they were shot, was as expected by Ward, mainly concentrated in the cockpit.
With the engine location.
Invisible bullet marks are the most fatal

At first glance, it was quite reasonable for the combat commander to strengthen wing armor, but he ignored the fact that the bullet points
Is a type of material with serious bias.
Because the most critical information is actually on the plane that was shot down,
However, these planes cannot be observed. As a result, the wings are covered with bullet marks, instead, the most powerful part of the plane.
The Air Force combat commander almost made wrong decisions because he paid too much attention to the "visible" bullet marks.
There are two points worth noting in this case.
A dead or captured person cannot give comments
First, collecting more information will not improve the quality of decision-making. The source of the bullet marks is serious.
If you try to collect more information, I am afraid it will only be a more profound misunderstanding.
Second, it is impossible to improve the quality of decision-making by bringing together more pilots with rich combat experience to provide professional opinions.
These pilots are part of the process of generating biased data. They are all pilots of safe return flights, although possible
But they are not the "martyrs" of the cockpit or engine 」.

Simply put, the more they stare at the bullet marks that are "visible", the farther they are from the truth.

There are so-called "garbage in, garbage out" in the information field 」,
If the premise (or hypothesis) is incorrect, then the beautiful statistical formula or method, and more information cannot let the subsequent
The inference is correct.
In management practices and daily life, many key materials, like the above-mentioned bomber cases, Will
"Failed" but not observed.

Professor Liu shunren of Taiwan University, in his book "winning ",
Bias. If a 70-year-old man
On TV,
He has to smoke a pack of cigarettes and chew a pack of betel nuts every day to live. Please remember that "no one can talk on TV ".
Events.
In the same way, it is not the old people who live in the same region who eat or drink something, but the health care product.

Let's look at another example of money fraud (this has evolved to the E-Mail version)
On June 18, January 2, you received an anonymous letter saying that the market will rise this month. As a result, the market will rise, but you
I don't agree, because we all know that there is a lunar January effect.
(In the past January S, the stock price has risen, fallen, and decreased ).
In February 1, you received another letter saying that the market would fall. This time, I spoke to the letter again.
.
I received another letter in May March 1, in the same situation. In July, you were very interested in the foresight of the anonymous.
Invite you to invest in an overseas fund.
So you took out all your savings and invested it. Two months later, the money was like a steamed stuffed bun and you couldn't go back.
You cried on the shoulder of your neighbor. He told you that he also received two mysterious emails, but sent them to the second one.
It stops.
He said that the predictions for the first round are correct, but those for the second round are incorrect.
What is this?
The tricks of scammers are that they find 10 thousand people in the phone book and send half of them a bullish email.
People, the market outlook bearish letter to the other half.
A month later, five thousand people will receive the correct predictions, and then target these five thousand people.
After another month, the remaining two thousand five hundred people received the correct prediction, so that the remaining five hundred people remained on the list, of which
Two hundred people will be cheated,
Therefore, scammers can earn millions of dollars as long as they spend thousands of dollars on postage.
Make some changes.
A scammers pretend that they want to recruit members and tell you that you can join a general member first.
VIP member. What makes this change more clever is that scammers can make money from the very beginning, and VIP members will also help scammers.
Establish a reputation to prove how accurate the scammers are: the deviation between the active users (segment vorship bias ).

As long as the information is not circulated, others do not know how accurate this fake investment teacher is.