The Missing Bullet Holes
In WWII, returning aircraft showed dense bullet holes on the wings and fuselage but few on the engines. The military proposed reinforcing the areas with the most holes. Statistician Abraham Wald recommended the opposite. Where should the armor go?
Related problems & prerequisites
Worth solving first
- Bessel's Correction 5.0/10
- Halving the Standard Error 5.0/10
- The Taxi Cab Problem 5.0/10
Source: From Abraham Wald's aircraft-survivability work for the Statistical Research Group in the Second World War; the canonical survivorship-bias example. Statement written for AxiomIQ.