Survivorship Bias

What Is the Survivorship Bias in Simple Terms?

Survivorship bias is the tendency to draw conclusions by focusing only on the people, things, or cases that remained visible or "survived" a selection process, while overlooking those that were lost, failed, or disappeared. As a result, we end up with a distorted picture of reality.

Survivorship Bias in Real Life

1. The classic example of survivorship bias comes from World War II. The initial idea was to reinforce the areas of returning warplanes that had been hit by enemy fire.
   
   However, these planes had made it back despite being hit in those areas. The planes that did not return were presumed to have been hit in different, more critical areas.
   
   As a result, the parts that actually needed reinforcement were the areas that showed little or no damage on the returning planes because aircraft hit there were less likely to survive and return.
2. Many people admire the idea of dropping out of college to start a business. They point to famous entrepreneurs who became multimillionaires or billionaires after leaving college, believing that a college degree is less important than it appears.
   
   However, this is an example of survivorship bias. We hear about the small number of dropouts who achieved extraordinary success, but not about the much larger number who also left college and did not become successful entrepreneurs.
   
   Because those unsuccessful cases receive little attention, focusing only on the famous success stories can give a misleading impression of how likely that outcome really is.
3. People often say that things were better decades ago, that buildings were built better, music was better, movies were better and products lasted longer.
   
   In reality, we mainly see the buildings that were well constructed because many poorly built ones have been demolished or replaced. Likewise, we remember the great songs from the past because they continued to be played and appreciated, while the countless mediocre or forgettable songs have largely been forgotten.
   
   As a result, we often compare the very best of the past with everything that exists today. This creates the impression that quality has declined, even though every era has produced both exceptional and mediocre work.

Conclusion

Judging only the survivors will often give us a false perception of reality. To truly understand the full picture, we must also take into consideration those who did not make it.