Robert McNamara, former US Secretary of Defence, talking about early US bombing missions in WWII:
The U.S. was just beginning to bomb. We were bombing by daylight. The loss rate was very, very high… The loss rate was 4% per sortie, the combat tour was 25 sorties — it didn’t mean that 100% of them were going to be killed but a hell of a lot of them were going to be killed.
4% loss rate per sortie, 25 sorties per tour… so the theoretical chance of dying for those guys was actually 100%.
Not good odds.
What were the actual odds of a given serviceman dying on over the course of 25 such sorties?
Thankfully my smart friend Nick Fyson knows the answer: 64%.
1 – chance_of_surviving_every_
sortie = 1 – ( 1 – 0.04 )^25 = 0.639603283
Still not good odds. Thanks Nick!
From the Errol Morris documentary The Fog Of War: 11 Lessons From The Life Of Robert McNamara. You can find the full transcript of the film on Errol Morris’s website.