Thursday, January 15, 2009

Let's make a deal...

One of the advantages of my job is being surrounded by domain experts in all kinds of different fields. Consequently, most every day something I wouldn't have encountered or thought about is brought to my attention and I learn something interesting.

I'd like to share today's with you. It's called the "Monty Hall Problem" or "Let's make a deal."

You are a contestant on a game show and there are three doors. Behind two of the doors are goats. Behind one of the doors is a car.

You will choose a door and the game show host will open another, revealing a goat, and then ask if you want to switch from your original selection. Does switching improve your odds of winning the car?

Although it's counter-intuitive, switching does improve your chances. In fact, instead of a ~33% chance of winning the car, you have a ~66% chance.


Seriously. Try it.
Play the Game

Now, to understand why it works, watch this video.

Or... in short...
"Basically, if you choose to "swap" you are betting that your original guess was wrong, and you will win everytime your original guess was wrong. Your original guess is going to be wrong 2/3 of the time, therefore you'll win 2/3 of the time by swapping." - semiauto25


Anonymous said...

amazingly though, everytime I switched I lost and everytime I did not I won

gravy said...

Ah... but this game assumes I want a car...