What is Survivorship Bias?

Survivorship bias is a tendency to get carried away by a rare success story without considering similar examples of failure. Everyone loves the story of a survivor or a winner. Nobody cares about the person who failed.

1. Think about it

“Many of the successful people dropped out of college and started their own company.” How does the statement sound? Doesn’t it seem like the few people who dropped out of college, go on to build an amazing product?

Why One Third of Tech Billionaires Are The College Dropouts

Well, think again. For every college drop out who turned out successful, a big number of dropouts end up unsuccessful. But those stories will never reach you because the internet loves the story of a survivor. Such a phenomenon is termed as the survivorship bias.

Have you also considered the other side? How many people who are successful did not drop out of college? In a study made over about 12,000 successful individuals, more than 94% completed college or attended an elite school.

The fraction of successful people who were dropouts is tiny. But such stories spread on the media while the normal stories don’t. Similarly, you only hear about Neil Armstrong talking about “One small step for man one giant leap for mankind.” You do not hear about the others.

2. What is survivorship bias?

Survivorship bias happens in everyday life when you hear a story of a person or a method that succeeded. Due to the internet and the media, the success story can reach a ton of people in no time. For every such success story, there will be another person who tried something similar and failed.

For example, when Mark Zuckerberg dropped out of college, some other students would have also dropped off. But you never heard about them because they did not achieve the success of Facebook.

The survivorship bias is the flaw of your brain due to which you look at the most obvious information and generalize it. You forget to take into account other factors and the failed cases before convincing yourself. The stories of success get all the attention while those of failure slip away in silence.

3. Real world examples: World War 2 Airplanes

During World War 2, the bombing planes were returning with damage on various parts making them difficult to reuse. The airforce knew that they needed armor but did not know where to add it. If you look at the pictures, what would you decide? Where would you add the armor?

Where would you add the armor?

Did you decide to add armor on the wing and tail to save the planes? If you did, you failed to consider the planes which never returned. You decided to add armor to areas that could take damage without crashing. When the damage was on the other areas such as engines, the planes never returned.

By analyzing the data of only the survivors, you would make the wrong decision. The right decision would be to add armor in the areas like the engine which shows no damage in the pictures.

During the war, many such incorrect decisions were made. Statistician Abraham Wald performed the necessary research on survivorship to reach the right decision.

4. Note

When I create new apps, I research and try out existing apps from other developers. Not only learning from high-ranking apps, but also learning from low-ranking apps to avoid survivorship bias.

I am a developer loves animals and hippopotamus. I create free application to help users reduce time cost to have more freetime. I am shaping the future of the world for sure, because some of my users could become global influencers.
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