re: Time to discuss the Monty Hall problem (strategy and game show)

So do we get to the intergalactic space travel age or not? Is that curve exponential?

This is like watching a couple fat chicks playing with each other.

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Sooooooo Genro says it, it's gold.

I say it, I'm an idiot.

Got it.

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Glad you understant.

Genro, every higher level mathematician, and all emperical evidence say it, but no you're probably right.

Lemme guess, you don't think time is relative either?

So, does the plane take off?

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This thread is pulled out and dusted off once every year. And the discussion never changes.

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Yeah, it's pretty sad how many people feel the need to chime in arguing it's 50-50 because if they know one thing about probability it's that past trials don't affect future trials.

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Do people not realize that you simply copied/pasted all of this post from one of the threads linked on Google?


FWIW, I used to argue with my Stats professer daily in grad school about this. I always held the belief that the question and the way the game is set up are two different things. Since you know one of the bad doors will be removed, I always believed my odds to be 50/50 to begin with (or to be more clear...33% compared to 33% of the other door. It's not that the removed bad door's probablity is switched ONTO the remaining door, but rather that your initial odds are against you.

Like someone said, it's about avoiding losing rather than the odds that you picked the right door. The best explanation I got of this was to imagine 100 envelopes in front of you, with a $100 bill in one of them. You choose one and then the host removes 98 empty ("bad door") envelopes. So now, you're left with two envelopes. The one you chose and the remaining one. Odds are, you didn't choose the correct one, and by a long shot (1% chance that you picked correctly versus the assumed 99% chance that the remaining envelops is the right one). So you switch.

That's always been the way I look at it. Well, that and my Stats professor was one of the smartest people I know, so I'd trust his judgment and switch every time.

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i get what you're saying, and i understand the stats behind it, but if he's always removing a goat, in the end you're left with a 50-50 decision. i really wonder what the difference is between either keeping or switching and just flipping a coin at that point

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But it isn't 50-50, because you aren't faced with the choice of picking one door or another, you are faced with the choice of one door or two doors.

Imagine it this way:

You pick your door, and then before opening any doors the host says "Change of plan, now you can either keep your door or have BOTH of the other two doors. Do you want to keep your door or have the other two?"

You know that if you pick two doors, you have a 2/3 chance of having the car behind one of your doors. So you go with two doors. You and the host and math know that there is a 100% chance that at least one of your 2 doors contains a goat.

The hosts then says "I will open this door that you picked, which contains a goat"

This changes nothing at all because you already knew that one of your doors contained a goat. The odds are still 2/3 in your favor.

By switching in the original format of the game, you effectively got to pick two doors instead of one.