It's the end of college graduation season, and across the country recent graduates are expected to listen to countless successful people as they give their parting advice in commencement speeches.
If you're not exactly relishing the thought of listening to a political has-been or B-level actor impart their wisdom while severely hungover, you're not alone.
In fact, there's a very good statistical reason why you should probably take a healthy serving of salt with whatever you hear, and it's called survivor bias.
Survivor bias is a type of selection bias, where a study focuses on people that survived some process, overlooking those who didn't survive, which skews the results.
For an example of survivor bias from the finance industry, just look at mutual funds. From Investopedia:
For example, a mutual fund company's selection of funds today will include only those that have been successful in the past. Many losing funds are closed and merged into other funds to hide poor performance.
It's the same reason that dating sites are able to say they have a higher success rate than they actually do — mostly because they pretend the quitters never joined — and that even though many mathematicians say Alice in Wonderland inspired a love of math, the book isn't a surefire way to mint a mathematician.
It's the same thing with people. For example, let's say you looked at 100 commencement speeches, 90% of which encouraged you to do as the speaker did and follow your dreams.
You might conclude then that following your dreams is a surefire way to succeed, as 9 in 10 very successful commencement speakers all encourage doing so.
But you've got a selection bias here.
Since universities typically invite only successful people to speak at these events, you don't know several things, like the failure rate of all people who followed their dreams.
For every Senator talking about their success in front of a bunch of college kids, t here are lot of Amy's Baking Companies out there that followed their dreams but aren't invited to the commencement..
This isn't to say that universities shouldn't invite successful people to speak at these events.
Nor is it to say that all college addresses should be followed by a brief disclaimer that past performance is not indicative of future results.
It's just worthwhile to remember that the skills that these people recommend aren't guarantees of success, and because being highly successful is by definition exceptional, they're probably the exception rather than the rule.
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