Abraham Wald and the Missing Bullet Holes

The statistician Abraham Wald is credited with telling the military to armour the parts of its bombers that showed no bullet holes. The advice sounds backwards until a reader asks which planes were never seen.

Abhishek Leela Pandey15 Oct 20261 min readGRE1 question ↓
A returning wartime bomber on an airfield at dawn, its wings and fuselage pocked with small bright holes while its engines gleam untouched.

During the Second World War, analysts counted the holes in every bomber that returned from a mission and found that bullet holes were concentrated on the wings and fuselage, while the engines had far fewer. Military planners therefore proposed adding armour to the wings and fuselage, since these were the areas most often hit by enemy fire.

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