Car or Goat game

[Martyn]

Who on earth came up with that last lot of nonsense faaip?

I would love to play cards against him / her, the ignorance of probability is astounding

[The Subhuman]

Who on earth came up with that last lot of nonsense faaip?

I would love to play cards against him / her, the ignorance of probability is astounding

yes I copied and pasted the wrong bit, that was a response to a better explanation.

[The Subhuman]

nice to get some discussion going here though..even if I'm apparently wrong..(still don't get it btw trying to find out why ..)

[YorkshireSquare]

because at no point is it a one in three choice, and even if it were a true one in three choice it no longer is after the reveal

At the beginning there are three doors, two with goats behind and one with a car.

If you had to pick one door, would it be a 1/3 choice there is a car behind it?

[Twiggster]

Then again - I've eaten goat, but never contestant or show host. Tasty?

[YorkshireSquare]

Then again - I've eaten goat, but never contestant or show host. Tasty?

They look a bit rubbery to me!

[Twiggster]

They look a bit rubbery to me!

or plastic?

[HarryofOz]

I have to admit that when I first came across this problem, I didn't get it right.

This Wiki page explains it pretty well

http://en.wikipedia.org/wiki/Monty_Hall_problem

Especially looking at the table in section 4.1 which says the same as Meeta said in his opening post.

Evidently the key is knowing which door you selected and that the host would deliberately reveal the goat behind the other door. Without knowing those facts the odds are the same for switching and not switching which is what they appear to be when first looking at the problem.

[drsdadsotherson]

I argued that it was 50:50 at first as well. The first choice and the second choice seem to be independent events, but the deliberate removal of one goat then skews the probabilities that previously existed in the initial choice.

It goes against common sense because it requires you to see that the cause and effect are the wrong way round in time. The cause of the changed probaility of picking a goat occurs after the effect of your initial choice... The probability that you chose the car remains the same, while the proability you chose a goat increases, which means that statistically you have the better chance of winning by switching, and it's all because of the effect of something that you have not done yet.

Brian Cox would love this one!

[Martyn]

I argued that it was 50:50 at first as well. The first choice and the second choice seem to be independent events, but the deliberate removal of one goat then skews the probabilities that previously existed in the initial choice.

It goes against common sense because it requires you to see that the cause and effect are the wrong way round in time. The cause of the changed probaility of picking a goat occurs after the effect of your initial choice... The probability that you chose the car remains the same, while the proability you chose a goat increases, which means that statistically you have the better chance of winning by switching, and it's all because of the effect of something that you have not done yet.

Brian Cox would love this one!

Not quite DDOS. The probability that your original choice was a goat was 0.67 before the opening of the door by the host, and remains 0.67 after the opening of the door.

The real lack of independence comes in the choice of door for the host to open. People assume that he can open any door he likes but in fact two thirds of the time (when you picked a goat initially) his choice is forced. Only when you originally chose a car does he have an independent choice of door

[Gino 1959]

Brian Cox would love this one!

Especially one of the goats washed down with a nice Chianti.

[Stout LUFC]

I like goats cheese on toast...

[oneshortplanck]

everyday's a school day!

lets not kid our selves, butt i think it is a matter of perspective.

if ewe didn't know there would be a reveal, then i now agree that it is a 2/3; your emotionally in the game for both rounds thinking there a 1 in 3, then you get to switch....

if you know the host will offer the switch right from the onset, then its 1/2; the only choice that matters is the second one, you are not bothered which door opens in the first round because you know the real choice comes later, the host just herds you in the right direction...

[MeeTa]

everyday's a school day!

lets not kid our selves, butt i think it is a matter of perspective.

if ewe didn't know there would be a reveal, then i now agree that it is a 2/3; your emotionally in the game for both rounds thinking there a 1 in 3, then you get to switch....

if you know the host will offer the switch right from the onset, then its 1/2; the only choice that matters is the second one, you are not bothered which door opens in the first round because you know the real choice comes later, the host just herds you in the right direction...

Think you may need to read some more about this, you haven't understood how this game works.

[Martyn]

Let's try a variant - you choose one card from a pack of 52, hoping for the Ace of Spades.

I then take the remaining 51 and discard 50 of them, face up. The Ace of Spades is not among the discards. We now have 1 card each. Do you think it is a 50/50 chance that you are holding the Ace? If you do, please can I play cards with you?

[MeeTa]

Let's try a variant - you choose one card from a pack of 52, hoping for the Ace of Spades.

I then take the remaining 51 and discard 50 of them, face up. The Ace of Spades is not among the discards. We now have 1 card each. Do you think it is a 50/50 chance that you are holding the Ace? If you do, please can I play cards with you?

Haha i somehow doubt the people who cant understand the car or goat game is going to get any wiser on your example...

[MeeTa]

I knew i had seen this problem before, and i found where.



Heres to problem explained in the american cop show Numb3rs. Think he managed to explain it quite well..

[rab_rant]

I would just take the goat if they threw in a pair of wellingtons.

[oneshortplanck]

Think you may need to read some more about this, you haven't understood how this game works.

contrary, i understand it quite well,
what i question is when does the game start?
plus i wanted to use some goat puns

[Twiggster]

contrary, i understand it quite well,
what i question is when does the game start?
plus i wanted to use some goat puns

Goat puns are aaaaalways welcome. Sorry to be so Gruff.