I hear about survivorship bias, and I hear examples like “Bill Gates dropping out of college is survivorship bias”. I don’t really know how they correlate, or how to think of things with that in mind.
In: Culture
It means that you only hear about the ones that got lucky.
If someone tells you that motorcycle helmets are overrated because he has been riding for 30 years without one and that he has never had a problem, that may be true, but all the motorcycle riders that died because they weren’t wearing a helmet are no longer around to say otherwise.
When evaluating a certain dangerous behavior you have to make sure that you don’t just pay attention to the few lucky examples that made it, but also to the ones that have perished.
Another classic example is the story of the (now) successful business owner that had to mortgage his house, max out his credit cards and borrow money from friends to keep his company going, and now he’s a millionaire. There are enough of those stories around, so people may get the impression that this is a winning strategy.
But chances are that for every success story like this, there are many more people who did the same, failed, went bankrupt and they’re now delivering pizza for a living. That’s because the media is only doing profiles on the ones that became successful, not the ones who failed.
Survivorship bias is the idea that if we only look at the remaining subjects, it may skew our data. For instance, when armoring planes in WW2, the RAF (I think it was the RAF anyway) always added armor onto their airplanes in places where they found bullet holes. This did their planes very little good. Why? Because the airplanes that they were looking at were the survivors. If an airplane lands with a bullet hole in the wing, then that hole must not have done too much damage. If no airplanes land with bullet holes in the fuel tank, then the fuel tank is likely a critical component that needs armor.
Survivorship bias is coming to conclusions based on what limited data survived or only on examples of people who succeeded.
If you look at a collection of arrowheads you would think that every arrowhead was made from stone, but the dominance of stone arrowheads in our collections isn’t due to stone arrowheads being the only type. There are a few examples of wooden arrowheads but wood decays over time so very few have *survived* for us to find.
For things like “these traits make people successful” they often list traits that successful people have as though those traits are what lead to the success, but that ignores that there are far more people with those traits who have failed. The vast majority of new businesses will fail within 5 years, and those that survive may have done something right but are more likely to have just been lucky. If you look at a bunch of lucky samples and try to find a trend you’ll draw bad conclusions because you’ve ignored the identical samples that didn’t turn out the same and aren’t around for you to study.
There are 1000’s of college dropouts every year. Even looking specifically at those who drop out to start a business, only a tiny fraction become fabulously successful in spite of that, but those are the ones you hear about. You don’t hear about the ones who ran up credit card debt before his business fizzled out, and he couldn’t afford to return to school so now he works for Geek Squad at Best Buy, or ended up managing a Denny’s. Because you hear about the ones who best survive, it creates a bias thinking it’s easier to succeed even without a degree than it actually is.
Survivorship bias is basically looking at something successful and assuming that the success is because of successful strategy, without taking into account how likely the strategy is to be successful.
If you only talk to lottery winners you might get the idea that spending your entire salary on lottery tickets is a great idea, but if you talk to everyone who buys a lottery ticket you will realize that most of them don’t win.
If you look at bill gates you might get the idea that dropping out of college is a good strategy for success, but if you talk to most college dropouts you will quickly realize that so is not the case.
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