The Birthday Paradox

So I am sitting in my class for computer networks today listening to a guest speaker talk about security. I won't bore you with all the encryption stuff, but there was one mind-boggling fact she brought up. If you have 23 or more people in a room, chances are two have the same birthday.

I thought, there's no way. But we had 25 people in our lecture so we decided to have a little experiment. She had everyone born in January list off their birthdays -- no matches. Then she had everyone born in February list off their birthdays and two were born on the 13th. It worked.

Coincidence? I actually did the statistical probability of this (being a nerd and all) and found it was correct. When you have 23 people in a room, 50% of the time there will be a birthday match.

Don't believe me? Take a look at the article in HowStuffWorks.com. And for those of you with some math capabilities here's the actual proof.

The next time you are in a room with more than 23 people, try it out.

Comments

Jess said…
Wow, Buddy. You just assumed a whole new level of extreme nerdiness.

Did I mention that you never cease to amaze me?
Pops said…
I mean this with affection my friend, but uh...

Nerdiest Post Ever.

Keep up the good work.
Robert said…
Score! Maybe I should change the title. Or even better, I could take after pops' narcissist scale and post up a nerd scale...
Pops said…
Yeah, but the Narcissus Scale is just some shit I make up. I'm afraid your Nerd Scale would have to have some kind of freaky goddamn equation behind it whereby we are able actually to quantify the amount to which each post inhibits your ability to dance and makes girls run the other way.
Robert said…
Now that's an idea! I could even write up a computer program to do the math equations and probabilities for me. However, since I already know how to swing dance I may have to use a different variable to derive a post's nerdness.

Hmmm...I'll have to think on that.
Jess said…
But you're not worried about the chasing away of the women? Hmmm....

It's good to know my place, I suppose.
Darlene said…
Would this theory work 23 people you knew online?
Robert said…
Jess: I don't need any more women when I have you. You're my only. I'm glad you've put up with the nerdiness this long.

MST: Hope your socks are feeling satisfied.

Ollie: I don't see why it wouldn't work. If you can get 23 people to participate online -- go for it. Tell me how it goes afterward.
Natty said…
wow, I love stuff like this.

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