What is Survivor Bias?
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Hundreds of bunnies released into a valley
Over the next couple of decades hawks and other predators eat the bunnies EXCEPT the brown ones who blend in well with their surroundings
Years later you do a survey of the valley and seeing only brown bunnies in the valley the assumption is that the people that released bunnies in the past only released brown ones
That is survivor bias, we get a bias based on what we can directly observe. Similar to how people talk about how old building last longer because look at all these 600 year old building around the country…. but what about every other building other than those ones that did not survive till now
“nobody in my family ever wore seatbelts and we all made it ok” does not account for all the others that died because they didnt wear their seatbelts.
Here’s my example: Common saying: “They don’t build cars like they used to.”
Rational: Look at all the old cars people collect. Must mean they made them to last.
They are basing it on the old cars they see and notice. These cars survived as they were collectable and they were taken care of or restored.
They are not taking into account the millions of cars that were manufactured but are now scrap metal. They did not survive. But people don’t notice the ones that did not survive.
Another example: Elon Musk (or any other successful person) tells in an interview that the secret to success is getting up at 5am/meditation/something else. Our natural response is to say “this is a great idea!” And follow this advice.
The problem is the survivorship bias, as you don’t know how many people got at 5 am and meditated in total, and how many of them got successful. In other words, their success may have nothing to do with these factions, and you may not become successful by waking up at 5am and meditating.
Example of understanding survivorship bias: Examining planes coming back from bombing runs and adding armor to the LEAST hit areas of the planes on average.
The fact my mom thought I was overreacting, thinking its risky for my cousin to live out it the bush in Quebec, because if her kids got hurt they could die simply because they are far away from healthcare services. Her attitude in this regard is due to the fact she grew up in rural Quebec and never had any issues with 6 brothers and sisters.
Cue both of my kids having anaphylactic allergic reactions at 1 year old and 3 years old. So, my kids would both have died if they would have waited hours for treatment. My mom goes quiet when I bring that up. My cousin and her husband and three kids are all doing well.
You only see the successful Actor, Athlete, and Directors, not the thousands that failed.
George Lucas saying that all you have to do is believe in yourself and you too can be a mega movie director would be survivor bias.
Let’s say you want to know how to be successful at a task.
You could interview people who were successful at said to find out what they did, and this would be a valid method… but you’re potentially missing a ton of information that would only be available if you interviewed the ones who weren’t successful (for example, what did the failures do that the victors also did, and thus can’t be the determining factor of success)
Survivor Bias is the result of not looking at those failures. In some cases, it’s because you can’t look at the failures (you can’t ask a failed lion tamer what they did wrong if they were eaten), hence the name. In other cases, it’s because the failures are hard to notice. The guy who failed to get their business off the ground so they could quit their job is probably still employed at whatever job, and thus won’t be an obvious statistic to measure.
People saying safety precautions aren’t needed because “we didn’t have those as kids and turned out fine.”
We come to conclusions based only on what we see and not what we don’t.
For example, people say “When I was a kid, we didn’t wear seatbelts and we grew up fine!” while ignoring the fact that thousands of kids died because they weren’t wearing seatbelts when the car they were in crashed.
Or “My grandpa smoked a pack a day and lived to be 96”, while ignoring the fact that many many people who smoked died much younger…but they only see the survivor, their grandpa.
Relevant nowadays is people who say that they know many people who weren’t vaccinated and caught COVID-19 and it was no big deal…completely ignoring the number of people who died of it, but they only see the “survivors” and base conclusions on that.
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