Skip to main content
Log In | Register

TR Memescape


Topic: Monty Hall (Read 277 times) previous topic - next topic - Topic derived from Direct Down Wind Fast...

0 Members and 1 Guest are viewing this topic.
  • Brother Daniel
  • Global Moderator
  • predisposed to antagonism
  • 605

  • 160

Monty Hall
On another forum there was the 3 doors question.
There was a guy that could not accept the switching doors strategy.
And he was able to reword the question in such a way that anyone new to the thread would agree with him.
But of course he wasn't asking the original question.
The Monty Hall problem?

There was a substantial thread about that in the early days of TR.

The now-canonical answer (that switching doors is the best strategy) is based on an assumption that wasn't in the problem as originally worded.  It's a reasonable assumption, but it's still an assumption.

If someone questions the switching-doors strategy, one of the standard responses is to challenge the questioner to write a simple simulation to test the problem out.  In order to make it possible to write that simulation, most people end up making the canonical assumption without even thinking about it.  So of course they end up with the canonical answer.

It isn't hard to come up with other scenarios, also consistent with the problem as originally worded, where switching doors is not the best strategy.
  • Last Edit: June 07, 2016, 07:01:11 PM by Brother Daniel

  • 758

  • 61

Re: Monty Hall
Reply #1
(If this post gets any responses at all, it will be a derail.  Then I can try to test out my mod powerz by splitting off the resulting derail to a new thread.)

On another forum there was the 3 doors question.
There was a guy that could not accept the switching doors strategy.
And he was able to reword the question in such a way that anyone new to the thread would agree with him.
But of course he wasn't asking the original question.
The Monty Hall problem?

There was a substantial thread about that in the early days of TR.

The now-canonical answer (that switching doors is the best strategy) is based on an assumption that wasn't in the problem as originally worded.  It's a reasonable assumption, but it's still an assumption.

If someone questions the switching-doors strategy, one of the standard responses is to challenge the questioner to write a simple simulation to test the problem out.  In order to make it possible to write that simulation, most people end up making the canonical assumption without even thinking about it.  So of course they end up with the canonical answer.

It isn't hard to come up with other scenarios, also consistent with the problem as originally worded, where switching doors is not the best strategy.

This guy was way beyond that.
He was in Humber territory only with probability.

Imagine you are on the show but it's Mean Monty.
He always shows you the car if you pick a door with a goat.
You pick door 1.
What is the probability that the car is behind door 1?
Mean Monty opens door 2, and shows a goat.
What is the probability that the car is behind door 1?

The guy was sure that things had to happen behind the doors for the probability to change.

And it was mostly people who knew the show that made the  canonical assumption.
Or should I say that it was mainly people who did not know the show that did not make it.

  • Brother Daniel
  • Global Moderator
  • predisposed to antagonism
  • 605

  • 160

Re: Monty Hall
Reply #2
mod knote:  This derail was pretty harmless, but I decided to split it off anyway (from the DDWFTTW thread), just for the sake of learning how to split a thread.

  • 758

  • 61

Re: Monty Hall
Reply #3
The helpful handyman scenario didn't help him out either.
I forget how I worded it then.

But imagine that your wife's brother's best friend's father is the set decorator and wants to help you.
He will know which door the car is behind but can't be there when you play.
So what he will do is use a backdrop with one palm tree behind each door if the car is behind door 1.
And two palm trees if behind door 2, and three palm trees if it is behind door 3.

You choose door 1, Monty shows you door 2, and you see 3 palm trees.
Should you switch?

I think that scenario was put to him, maybe not quite as clear cut but close enough as to make no never mind.


And your welcome.  (check the wayback depository thread)
I'm not even going to check if someone beat me to it and I didn't see it. ( I almost put one unmatched parenthesis)


  • Brother Daniel
  • Global Moderator
  • predisposed to antagonism
  • 605

  • 160

Re: Monty Hall
Reply #4
The guy was sure that things had to happen behind the doors for the probability to change.
Poor guy was probably very confused about a lot of things.
And your welcome.  (check the wayback depository thread)
I'm not even going to check if someone beat me to it and I didn't see it. ( I almost put one unmatched parenthesis)
Heh.  Yeah, there was some good stuff here and there, on the old TR.  (And thanks for keeping the parentheses balanced.)