"Survivorship Bias" 3D.gif
*A rare, signed, higher resolution and non-watermarked version of this image is available for download at: https://creary.net/digitalart/@jaichai/abraham-wald-bullet-holes-in-planes-and-survivorship-b
Wald was born in 1902 in the then Austria-Hungarian empire.
After graduating in Mathematics he lectured in Economics in Vienna.
During World War Two, Wald was a member of the Statistical Research Group (SRG) as the US tried to approach military problems with research methodology.
For example, they mapped out the patterns of bullet damage from the returning aircraft and showed the most common areas that were hit by the firepower of enemy anti-aircraft weaponry.
The US military’s conclusion was quick and simple: the wings and tail are obviously vulnerable to receiving bullets.
We need to increase armour to these areas.
Wald stepped in.
His conclusion was surprising: don’t armour the wings and tail.
Armour the engine.
(https://mcdreeamiemusings.com/blog/2019/4/1/survivorship-bias-how-lessons-from-world-war-two-affect-clinical-research-today)
In other words, the army incorrectly based their assumptions on the surviving aircraft.
Wald on the other hand, posed this plain yet pivotal question to army decision makers:
"Since the defense against incoming enemy planes basically blankets the sky with sheets of anti-aircraft artillery, I wonder where all the 'missing' bullets from our patterns went?"
Answer:
They hit the aircraft that DIDN'T make it home!
That's why he recommended reinforcement in the areas that WEREN'T hit on the returning aircraft.
Imagine that?
About Survivorship Bias -
Survivorship Bias (also known as Survival Bias or Immortal Time Bias) is an error in logic from concentrating on the people or things that made it past some selection process or time frame and overlooking those that did not, typically because of their lack of visibility.
Oftentimes, this can lead to incorrect conclusions.
RE: WW II Aircraft and Bullet Holes
If the aircraft were reinforced in the most commonly hit areas, this would've been the result of "Survivorship Bias" ; that is, the crucial data from fatally damaged planes was being ignored.
Bottom Line:
Those hit in other places did not survive.
See: https://www.nafcu.org/musings-cu-suite/planes-armor-and-survivorship-bias
Submitted FYI.
May you and yours be well and loving life today.
In Lak'ech, JaiChai
(JaiChai 8 May 2022. Simultaneous multi-site submissions posted. All rights reserved.)
