Survivorship Bias and our Perception of the World

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By Anas Namouchi


If we were to seek out the reasons behind the success of Uber, Facebook, or Google, we will come to find them numerous. A sit-down with Elon Musk would surely be a remarkable experience. After all, he is a symbol of success in today’s culture. He, and many others similar to him, ought to know the right path to greatness. Or do they? 

In 1941, Abraham Wald challenged the decision of his colleagues regarding how to properly armor bomber airplanes. His decision saved hundreds of lives. Wald was working among data scientists and mathematicians to analyze data from World War 2 and bring forth decisions that will give the United States military a technical advantage in the field. A problem the Air Force frequently faced is how to armor airplanes. Too much armor and the plane would not take off, too little and the tiniest damage is fatal. A common strategy is to place armor where the planes are most fragile, and a study analyzed where returned aircrafts took the most damage. A graph, that is now extremely popular, was drawn depicting this information, and it appeared that most damages were taken at the tip of the wings and towards the middle of the aircraft. Air force commanders saw it fit to armor these particular areas. After all, this means planes will be taking less damage. More of them will resist the heavy fire. Needless to say, Wald saw that this was a huge mistake. He brought to their attention how areas you’d expect to be extremely sensitive, for example, the cockpit, did not record any damage. He noted how airplanes were returning when harmed in these areas, meaning they can indeed sustain this damage. Instead, armor should be added where no damage is recorded. These areas proved most sensitive since aircrafts hit there did not return. This phenomenon is known as survivor bias. It occurs when the observed data only takes into account the “surviving” samples. The data viewed here is not representative of the population. This particular example only considers damage on airplanes that returned rather than all airplanes. Wald was able to recognize this and spare the lives of hundreds of pilots. A more intriguing story, however, takes place after the war. The story behind Abraham Wald’s noble accomplishment was neither recorded nor published, it rather came up as an anecdote in the eighties when these war mathematicians had gathered for an award ceremony. The story was almost not brought up and we can only admire the irony behind how the most accurate and famous depiction of the survivorship bias almost didn’t survive. It makes us wonder how many other anecdotes were not brought up, how much wisdom was lost simply because its owners thought of it as axiomatic. But how does all of this relate to human perception? While the logic behind the commanders’ initial decision is flawed, we cannot deny it is based on sound human intuition. As humans, we tend to seek out the wisdom of those who have succeeded and pay attention to where they have struggled most even though they represent a slim portion of the population. Those who fail rarely get the chance to share their input. To us, they carry the shame of their failure. They are unfit to offer proper advice. “Successful people have the monopoly over the advice industry” stated David McRaney. Human nature dictates that we attribute the value of advice solely to how successful a person is. Survivorship bias states that while this advice is indeed valuable, it is necessarily incomplete. The result is a flawed perception of success in the long run. We will romanticize the careers of entrepreneurs and performers since we get to see how fortunate those who succeeded are. We think that since X “made it” following a certain career path, it would be wise to do the same. The survivorship bias dictates the opposite. The more glamorous the end result is, the tougher the path is. 

It is not that successful people will fail to give us proper advice, it is that they collectively fail to accurately represent the missteps we must avoid in our journey. We should consider numerous points of view and keep in mind how unbiased our outlook is when we approach.