Doctor SpinMedia & PsychologyBehavioral PsychologySurvivorship Bias — Abraham Wald and the WWII Airplanes

Survivorship Bias — Abraham Wald and the WWII Airplanes

Don't let the success of others dictate your strategy.

Survivorship bias is a tricky bias to deal with.

During World War II, the Allies studied Nazi damage to their fighter planes. Their study resulted in this dotted illustration:

Survivorship-Bias - Missing Bullet Holes - Abraham Wald
This aircraft seems to suffer from some mysterious condition.

The analysis of these damages resulted in the idea that the Allied Forces should reinforce their fighter planes in the areas showing the densest clusters of red dots.

A statistician by the name of Abraham Wald disagreed. Instead, he suggested that they reinforce surfaces with no red dots.

Wald was right, of course. By studying planes that somehow returned home, the red-dotted areas indicated non-fatal damaged regions.

If it had been possible to study all the planes shot down and destroyed by the Nazis, the research team would likely have found an inverse pattern.

The Fallacy of Survivorship Bias

This is an excellent example of a particular fallacy — survivorship bias.

During World War I, the military forces increased the issuing of helmets for soldiers. The number of wounded soldiers skyrocketed, but this wasn’t because helmets somehow made it easier for more people to get hurt.

The helmets ensured fewer people died and showed up in the column for “wounded” soldiers. Progress of a kind, no doubt.

We’re fascinated by successful people and successful brands in popular culture and business. We want to know how they think and how they act. But few think to study those who tried — but never turned out to be successful.

It bears repeating; correlation does not equal causation.

Inverting your data sets is more causative and provides more powerful clues to your analysis.

Cover photo by Jerry Silfwer (Prints/Instagram)


Jerry Silfwer
Jerry Silfwer
Jerry Silfwer, aka Doctor Spin, is an awarded senior adviser specialising in public relations and digital strategy. Currently CEO at KIX Index and Spin Factory. Before that, he worked at Kaufmann, Whispr Group, Springtime PR, and Spotlight PR. Based in Stockholm, Sweden.
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