Missing

My recent leisure reading is about the life and time of Abraham Wald, who was famous for, amongst his other contributions to mathematics and decision theory, the story of the missing bullet holes.

To put it simply, Wald was a mathematician born in the then Austria-Hungary Empire and moved to the States when Nazi took over his country (around the same time with Captain Georg von Trapp of The Sound of Music). He had most of his academic career at the Columbia University.

During World War II, Wald was involved in a project to minimize bomber losses to enemy fire. In short, the US Navy conducted a study of the damage done to aircraft that had returned from missions. The original idea was to add armor to the areas that showed the most damage. In contrast, Wald argued that reinforcement should be made in the areas where the returning aircraft had least bullet holes, since those were the areas that, if hit, would cause the plane to be lost.

Simple, eh? The actual calculation is a lot more complicated. For fans of pure mathematics, you may like to go through Wald's original report, which is a 90-page text available at http://www4.ncsu.edu/~swu6/documents/A_Reprint_Plane_Vulnerability.pdf