Monday, September 18, 2017

Survivorship bias

You know, there are some things that seem so apparent when someone says it but never as clear when it happens in real life. Take this 'survivorship bias' for example. It is a widely prevalent logical fallacy. Like all logical fallacies, this too is one of those things which you nod wisely when you hear of it while going about committing it with gay abandon.

"You know I think that jumping off the sixth floor is not at all fatal"
"Why do you say so?"
"Well, everyone I have met, who has jumped, is still alive"

I was flabbergasted. I mean, come on, faced by something like that too many questions jostle your mind for you to be coherent. How many such people could he have met? How did he meet even one? AND how on Earth did he expect to meet someone who had NOT survived?

THAT is the easiest example of the 'Survivorship Bias". If the only people you meet after something like that are the ones who survived, how can you draw a conclusion from that?

By now, you are all nodding and finding it funny that ANYONE could draw a conclusion like that. Let us try another one on you.

"I think you can easily make money playing on the stock markets."
"Yup! I met some twenty people in a stock market seminar who knew nothing about it before and have been making money on it for the past five years."

Nice. You are the next Warren Buffet. But...if 80 other people had also started off at the same time and become bankrupt do you expect to meet them at a seminar on the stock markets? Obviously, you did not also pursue your research with the beggars at the traffic lights. (Exaggeration, of course, but then separating a writer and exaggeration IS tough!) Could it be survivorship bias...those who survived and thrived DESPITE not knowing anything about the stock markets?

"Bill Gates is a school drop-out and look at him. I think your chances of being hugely successful is better without education."

Really? AND how many school dropouts have you studied other than Gates?

"To become a successful writer you do not need to know good English. Or even be a reader..."

Ye Gods! Now, go back to the first example and STOP laughing at THAT guy!


  1. This reminds me about an news item I had read about drug clinical trial biases as well. That stock market bias is so right on dot..hehe.

    1. This is one of the most prevalent biases in use in arguments :) Like, you tell someone the benefit of education and he will pop Bill Gates out at you :)