You may not know the name Abraham Wald, but he has a very valuable lesson you can apply to problem solving, engineering, and many other parts of life. Wald worked for the Statistical Research Group…

One of Wald’s ways to approach problem was to look beyond the data in front of him. He was looking for things that weren’t there, using their absence as an additional data point. It is easy to critique things that are present but incorrect. It is harder to see things that are missing. But the end results of this technique were profound and present an object lesson we can still draw from today. //

The Army Air Corps noticed that after a mission, bullet holes were not distributed uniformly across the aircraft. The fuselage took nearly 2 bullet holes per square foot on average, and the fuel system took almost as much. But the engines took just a bit more than one bullet per square foot. The Army wanted to know how much more armor to put on the parts of the plane that were taking the most bullets.

Wald had a different point of view. Instead of putting armor on the fuselage, Wald wanted to add armor to the engines, even though they appeared to be taking fewer hits. Why? Because the samples the Army measured were from planes that returned. Wald surmised that the planes with many bullet holes to the engines were not coming home. The extra armor belonged not on the part of the plane that could survive a lot of bullets, but to the part of the plane that couldn’t.

As a result, extra engine armor appeared on warplanes from that point forward. Once you understand the logic, Wald’s insight seems obvious. But it defies many people’s idea of common sense to protect the part of the plane taking the least damage. //

For software, hardware, and most other fields, it is much easier to look at what’s present and critique it than it is to decide what’s totally missing. In Wald’s case, everyone was looking at the hole densities without thinking why the density wasn’t uniform to start with