2009-03-13, 12:56 AM
DarkPwnage Wrote:Is this like statistics mumbo-jumbo or something that everyone is saying? It makes about as much sense as that scene from 21 with the 3 doors and he says that his odds of having the right door after one of the 3 is revealed is then magically 66%.
I guess Calculus doesn't help with understanding beyond the most basic probability.
Well, given 3 doors, 2 are empty, 1 has a prize, when you're picking the door, your odd is 1/3 of getting the prize.
When a door has been revealed, as empty, your odd is still 1/3, because when you picked that door, that's your odd.
If you get to re-pick, your odd will be 1/2. Since you get to swap, your odd is now the reverse of what you had before, ie 2/3.
That's conditional probability. When you make your choice, that's your odd. Knowing further information without allowing you to make a choice does NOT improve your odds.
There's a game calls "deal or no deal" in Australia, the idea is you have 26 suitcases, and you pick 1 at the start and there's an eliminating process. The max prize is 200k. Your odd at getting the 200K is 1/26 even if there're 5 suitcases left and the 200K is still available.
In the baby situation, if you're looking at the point of view of the babies, then each baby has a 1/2 chance of becoming a boy. If you're looking at it from the point of view of the mother, giving birth to 2 babies, the nurse tells her one of them is a boy, then, statistically, to the mother, the next announcement from the nurse has 1/3 chances that she'll get another boy.
Nowaday, they go get ultra-sounds tho.