WWII wing reinforcement case
It is said that such a thing happened during the Second World War. With the development of the war, the Allies represented by Britain and the United States began to carry out air raids on the German mainland. Although Germany was at the end of the crossbow and the air force that once dominated the world was exhausted, ground anti-aircraft artillery still posed a serious threat to the Allied aircraft. A large number of aircraft were injured, shot down and suffered heavy losses.
In order to reduce the probability of the aircraft being shot down, it is necessary to strengthen the key parts of the fuselage accordingly. The staff conducted a comprehensive inspection of the aircraft returning from the war. They found that almost all aircraft had bullet marks on the belly, but the wings were barely hit by gunfire. So the military decided to reinforce the belly portion of the aircraft to deal with the enemy's dense bullets.
However, Abraham Wald, a professor of statistics at Columbia University, gave completely different advice: it is the wings that need to be strengthened, not the belly! His reason is that although the abdomen of the aircraft under inspection was full of bullet marks and serious injuries, this did not affect the final safe return of the aircraft.
What can ensure the return is obviously not the injured belly, but the relatively intact wing. But why not find a large number of aircraft with damaged wings? The reason is simple: it is not that the wing is less likely to be hit or stronger than the belly, but that the aircraft that was shot in the wing has been unable to return home and was shot down!
The pilot confirmed that the statistician's view is correct. A shot in the belly of an airplane has little effect on flight, but if the wing is hit, the probability of a safe return is almost zero! Those planes that can be inspected are just lucky to have escaped the catastrophe of the wing.
In the end, the military adopted the experts' recommendations and made reasonable reinforcements of the wings of the participating aircraft. Sure enough, the number of planes shot down was greatly reduced.
Survivor bias
This story reveals an important psychological concept: survivor bias. Let ’s look at a few short paragraphs about survivor deviation:
On the eve of the Spring Festival, a TV reporter interviewed many passengers on the train. Everyone said that they had bought the train tickets. The problem of the hard-to-find tickets for the Spring Festival transport has been significantly improved!
Why are adults as picky as children? Because what you eat and do is decided by the adults!
Why do e-commerce companies selling parachutes have a 100% positive rating? Because the owner of all the parachutes that have failed has no chance to give a bad review!
These paragraphs all involve survivor deviation, which makes people laugh, and also makes us more intuitively understand what is survivor deviation: a "attribution" error that occurs in the cognitive process. That is to use the conclusions of a specific environment and background to speculate on the situation of the broader environment. Even if the conclusion in a specific environment is objective and true, it is often not universal and comprehensive in other scenarios or in a larger environment. For example, the same is a passenger, everyone on the train has bought a ticket, does not mean that everyone who needs to buy a ticket has already bought a ticket.
Since it is a paragraph, of course, I strive to be easy to understand, funny first, and inevitably have the suspicion of exaggeration. But whether the real examples in life that are not funny are affected by the survivor's deviation may not be so clear.
For example, in the U.S. presidential election in 1936, "Literary Digest" magazine conducted a telephone survey of 1.4 million people, showing that candidate Alf Langdon would win the election. How credible is this survey? Papyrus was found in the artifacts of ancient Egypt, but it was not found in other Mediterranean civilizations in the same period, such as Phoenicia, Ancient Greece, and Ancient Rome. It can be shown that papyrus was widely used in Egypt and not used in other Mediterranean civilizations during this period. ?
Visible is bright
What is invisible is downcast
Let ’s temporarily put aside these two long-term and slightly professional questions and see the nature of the survivor ’s deviation. Some people gave an explanation for the reason for this cognitive error:
On the one hand, we need to give a reason to the success of others (or our own failure). Because we all tend to find some traits in the survivors to convince ourselves, every survivor is not accidental, otherwise there is no way to explain the question "Why are survivors not me".
On the other hand, people always think that what they have experienced is the only truth. When you encounter a bear in the forest, you must pretend to die, because the bear does not eat dead animals. I am afraid that this statement is well known, and I am convinced that it is because those who have personally experienced the terrible encounter with bears tell us.
In fact, they can tell us this "experience" only because they survived, and those who took the same approach, but ultimately failed to escape doom, can no longer tell us what actually happened. Therefore, "survivor deviation" is also called "dead people can't speak"!
Let us look at a simple example. A grassroots star was a mass actor at the entrance of Beiying Factory. Later, he had the opportunity to cooperate with a famous director and became a big name. So many people who are also grassroots gathered at the entrance of Beiying Factory, hoping that they could one day turn around gorgeously, follow the path that star walked, and finally set foot on the peak of life. These dreaming people are affected by the survivor deviation.
The star ’s path to fame is indeed at the entrance of Beiying Factory, but what really makes him shine. In addition to the geographical coordinates of the entrance of Beiying Factory, there are a lot of other factors: his personality, character, ability , Opportunities, performance ...
Assuming that the result of one thing is caused by 10 reasons, not only is it difficult for us to deduce all 10 reasons from the result clearly, but also often only recognizes one of the reasons and subjectively considers this reason As the only reason. This is similar to many talent shows: why do everyone think the entertainment industry is very glamorous? Because the people we know are all well-known actors, but we ignore the vast majority of small actors who are not famous.
The dead cannot speak, and the loser has little say. What can be seen is bright, but what is invisible is downcast. The streets are full of entrepreneurs. What we remember is the bloody Ma Yun and Liu Qiangdong, just because they are the "survivors" of this era of the Internet economy.
There is no single, versatile "success method" in this world. There is no essential difference between successful people who talk about "successful learning" and survivors of the rest of Xiongkou, because we cannot hear more losers. , Just like not hearing the warning of the poor man who finally fell into bear's mouth.
Avoid survivor bias
In project management activities, we must also pay attention to avoid falling into the trap of survivor deviation.
On the one hand, we should pay attention to the study of project management theory. Experience is important, but experience always contains too many background factors. These specific background factors often affect the effective copying of experience: helping others to gain successful experience may not have the same effect on our own actual activities.
What's more, always take the special as the general. For example, a certain project is handled well by the project manager ’s up-and-down relationship; a certain project has no plan at all, as long as the leader personally takes charge, he can do it all; The above situation may really exist objectively, but like the survivors who escaped from Xiongkou, copying to other projects may not be true.
Unlike experience, theory is more like the "concentration" and "essence" of experience. After summarizing and refining a large amount of experience, what is sorted out is more universal principles and rules. Without the constraints of specific background, the reproducibility of the theory is greatly improved. Adhering to the correct theory and actively shielding those "noise interferences" that are taken for granted will enable our concrete work to get more valuable and well-founded help.
On the other hand, in project management activities, we must learn to observe and think about problems from multiple perspectives and in all directions. We must not only attach importance to the work of correct theory and successful experience, but also ignore the lessons learned from failure.
Every negligence, every mistake, may have an adverse effect on the current work, or even a substantial loss. If we only solve and correct the problem itself, instead of analyzing and summarizing the lessons with a serious attitude, the same mistakes may still happen again in the follow-up work, leaving us repeatedly tripped over by the same and similar stones.
Finally, let us look at the previous two difficult questions. The survey of the US election in 1936 was a telephone survey, and the telephone in the 1930s in the United States was still a patent for a few rich people, so although there are up to 1.4 million survey data, these rich people are not American voters. As an effective representative, Roosevelt won 46 out of 48 states, overwhelmingly defeated Republican candidate Alf Langdon, and became the 32nd President of the United States.
The archaeological work on ancient Egypt found papyrus but not elsewhere. In fact, because the climate in ancient Egypt was drier, the dry climate allowed the papyrus to be preserved. The climates of the other three places-Phoenicia, Ancient Greece, and Ancient Rome are more humid than ancient Egypt, and the ancient papyrus has long since disappeared!
