Monday, August 24, 2020

Survivorship Bias

From Wikipedia:
"During World War II, the statistician Abraham Wald took survivorship bias into his calculations when considering how to minimize bomber losses to enemy fire. The Statistical Research Group (SRG) at Columbia University, which Wald was a part of, examined the damage done to aircraft that had returned from missions and recommended adding armor to the areas that showed the least damage, based on his reasoning. This contradicted the US military's conclusions that the most-hit areas of the plane needed additional armor. Wald noted that the military only considered the aircraft that had survived their missions; any bombers that had been shot down or otherwise lost had logically also been rendered unavailable for assessment. The holes in the returning aircraft, then, represented areas where a bomber could take damage and still return home safely. Thus, Wald proposed that the Navy reinforce areas where the returning aircraft were unscathed, since those were the areas that, if hit, would cause the plane to be lost. His work is considered seminal in the then-nascent discipline of operational research."
What brought this to mind was a discussion on Facebook, prompted by my quipping about music:
Man, I just {LISTENED_TO_ALBUM/WENT_TO_CONCERT} by {$GROUP_FROM_MY_TEENS/EARLY_TWENTIES} and they still kicked ass just like they did when they were new. 
{$GROUP_LIKED_BY_KIDS_WHO_SHOULD_GET_OFF_MY_LAWN} just won't have that same kind of staying power."
Part of that phenomenon is that as people age, we're less likely to form strong emotional connections to specific pieces of music the way we were when we were younger, and part of it is that the music that gets remembered from the good ol' days is just the good stuff that's survived the sieve of time.

The year 1968, for instance, had huge chart hits from The Beatles and The Rolling Stones, but also from 1910 Fruitgum Company and Tiny Tim.

The airwaves had plenty of crap in my teens and early twenties, but I prefer to forget that. Say what you will about the Kids These Days, but they aren't listening to Milli Vanilli...of course, as it turned out, neither were kids back then.

Survivorship Bias is baked right into a lot of hobbies that interface with older things. “Man, they really knew how to build [cameras/pocket knives/watches/revolvers] in the old days!” is skewed by the fact that only the well-built stuff has survived. The handgun counter at the hardware store in a hypothetical Old West town had Colts and Smith & Wessons and Remingtons, and plenty of cheaply-made Victorian equivalents of Hi Points and Jennings, too.

Above you can see an 1875-vintage Colt New Line in .38 rimfire and a janky Red Jacket No.3 in .32 rimfire

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