Monty Hall

[plonq]

I have almost reached the point where I won't even discuss this one with most people because I am tired of having them dig in their heals and argue "it's 50/50" in the face of solid evidence to the contrary. Here is a video that explains it fairly well, and failing that, a short summary that illustrates it better than anything I've seen in awhile.

Watch on YouTube

For the Monty Hall problem, just remember there are two different ways you can choose a goat door initially (where you'll win if you swap and lose if you don't), and only one way you choose a car (where you'll lose if you swap and win if you don't).

1. choose goat A, Monty Hall opens door to goat B --> SWAP, win car
2. choose goat B, Monty Hall opens door to goat A --> SWAP, win car
3. choose car, Monty Hall opens door to goat (A or B) --> SWAP, lose car

That's 2 out of 3...

Speaking of foster cats (I wasn't, but I shall) somebody needs to come and adopt this cat sooner rather than later. She is starting to settle in and act like she owns the place. Click on the cut tag below and try to tell me that you don't have room in your house for this cat.

Comments

[fuzzytoedcollie.livejournal.com]

Looks like you've got a World of WarCat flooped down there...*grin*

[plonq.livejournal.com]

I have a couple of cats in the game too. I have way too many pets, actually. I'm desperately short on bag space, yet I have a kitten, bombay cat, rat, worg pup, dragonling, and mana wormling that I can pull out whenever I need a pet to follow me around.

Those bag spaces should be counted as available IMO. I should be able to open the bag, shove a handful of ogre giblets to the worg pup and say, "Here, hold this."

[elynne.livejournal.com]

I would, but I've been forced to sign papers saying that I won't adopt any more cats to the household. :( :( Kittttyyyy!!! (and WoW!!!!!)

[plonq.livejournal.com]

She has bobbed ears, so she wouldn't count as a whole cat if you adopted her. =)

[elynne.livejournal.com]

I'm pretty sure my housemates would still kill me. :P ;)

[furahi.livejournal.com]

What has atara tell you about trying to explain this problem? ;)

[plonq.livejournal.com]

She understands the underlying principle in the theorem now, so I don't think she will object as strongly if I bring this up again in the future.

[mwalimu.livejournal.com]

For people who don't buy the explanation in the video, I like offering the following alternate explanation. If there are not 3, but 100 doors, and Monty opens 98 of them before offering the chance to swap, it should be much more obvious that swapping is the correct strategy.

[plonq.livejournal.com]

Ugh. I've extended the example to 1,000,000 doors. "So after Monty has opened the other 999,998 doors you'd still keep your original door?!"

"Dur, but there's only two doors now, so the odds are 50/50."

I explained to one person that claiming it was 50/50 at this point is the same as claiming that they had even odds of winning the lottery every time they bought a ticket. "I mean, it's either going to be your numbers, or every other combination of numbers that is not yours. It's 50/50. You should be winning the jackpot with every second ticket you buy!"

[pierrekrahn.livejournal.com]

How did I know that you were going to post this video as soon as I saw it on VideoSift? lol