Cause
In 1941, during World War II, Abraham Ward, a professor of statistics at Columbia University, accepted a request from the military to use his professional knowledge in statistics to give advice on how aircraft should be better protected to reduce the chance of being shot down by artillery fire. Professor Ward analyzed and studied the relevant data after Allied bombers were attacked and found that the wings are the most vulnerable position to attack in the entire aircraft, but the tail is the least attacked position. Therefore, Professor Ward concluded that “we should strengthen the protection of the tail”, but the US military commander believed that “the protection of the wings should be strengthened because this is the most vulnerable position to be hit.”
Professor Ward insists on the following:
- The sample of this statistics only covers the bombers that returned from Ping An and crashed without being hit;
- The bomber that was hit on the wing many times seemed to be able to return safely;
- The reason why there are fewer bullet holes on the tail of the aircraft is not that it is really difficult to be shot, but that once it is shot, the possibility of returning safely and surviving is very slim. The military finally adopted the professor’s suggestion and strengthened the protection on the tail of the aircraft, and it was later confirmed that this decision was completely correct.
Survivor bias means: You only looked at the characteristics that survivors satisfy, This does not lead to a convincing conclusion.
Which applications
For example, success study
Many people study how celebrities become successful and write a biography to sell to you. They are not successful themselves, but they make a lot of money by relying on the books they learned from success.
Is success learning useful?
Here, survivorship bias can easily occur.
For example: Bill Gates (Microsoft), Steve Jobs (Apple), Zuckerberg (Facebook), Ellison (Oracle), These people are all successful and super rich, so what characteristics do they have in common? Their common characteristic is that they all dropped out of college. So some people say that if I drop out of college, I can be as successful as them? Have you ever seen those dropouts who didn’t make it? There were a lot of people who might have dropped out too, but he didn’t succeed. So this one is a typical survivor bias.
Summary
It is unrealistic to read a biography of Steve Jobs and think that I have become Steve Jobs, and to think that I have become a stock god after reading a biography of Buffett.
In fact, there are many such examples in life. We always focus on the survivors and winners, but ignore the losers.