Popularity, winning and the birthday paradox

The most popular blog so far on this site was one of the first – it dealt with winning, and made the point that win or lose, it’s important to recognise that the way you prepared was more important than the outcome. You can read it here.

It’s ironic, because I don’t think it was the best blog I have written (process), but if you measure the success of your blog by the amount of people who read it (which I don’t), this particular blog is the winner (outcome). I find myself coming back to the same point in a different way today.


It’s a mathematical fact that if there are 23 people in a room, the chances are higher than 50/50 that two of them will have the same birthday. It’s known as the birthday paradox – because it’s counter-intuitive, but completely true. In fact, if you fill the room even further and put 75 people in it, there is now a 99.9% chance that 2 of those 75 people will have the same birthday. You can read about the math behind this here.

I presented this fact to a friend of mine recently, and he didn’t believe me. He set out to prove me wrong, and so asked 23 people who happened to be in the same hotel bar as us for their birthdays. None had the same birthdays, and so he claimed victory.

But here is the thing – his social experiment, while fun, proved nothing. The sample size was too small. It’s like using the results of one coin toss to disprove the statement that there is a 50/50 chance of a coin landing on heads every time you toss it.

As the old saying goes – there is nothing certain in life, bar death and taxes. Everything else is a series of probabilities.

If you’re going for a job interview, no amount of preparation you can do will make it a certainty that you will get the job. You can increase your chances by preparing well-crafted answers, researching the panel of interviewees, and dressing appropriately, but no matter how well-prepared you are, there is always a chance that a more suitable, equally-prepared candidate will be waiting to go in when you are finished.

That’s why process is more important than outcome. Process is under your control, outcome is not. Keep improving your process and you will increase your chances of a favourable outcome.



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