
47
5
System Control Points
Where to Aim the
Silver Bullets
During WWII, statistician Abraham Wald was asked to help the British decide
where to add armor to their bombers.After analyzing the records, he recom-
mended adding more armor to the places where there was no damage! [30]
The expert’s advice was based on the insight that airplanes with damage
to important parts probably never returned to their airbases. On the other
hand, only those with relatively inconsequential types of damage were the
ones that managed to return. Contrary to the initial intuition, the armor—
that is, control over potential damage—had to be applied to parts that stayed ...