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Always 50/50 chance?

...

Of course, if Monty is so wasted that he sometimes chooses the door you chose (I'm not sure what consequences of this would be in the game... automatic loss? Forced to pick another door? Monty arrested for drug use?), that just messes everything up, and you might as well go home.

I'm such a nerd! ;)

It was the 70s. Who wasn't completely baked out of their gourd at that time?
 
It was the 70s. Who wasn't completely baked out of their gourd at that time?

Which is an even better reason for making the parameters of our model explicit beforehand.

When you factor in the possibility that Monty might be so doped that he simply stares at the walls muttering "Whoa man, that's heavy" without ever choosing any door, the problem becomes nightmarishly complex.
 
Definitive disproof: A human can either be immortal, or mortal. If there was a 50/50 chance, then there would be a substantial number (in the billions) of people on earth who were extremely old. But there isn't. So there's not.
 
Definitive disproof: A human can either be immortal, or mortal. If there was a 50/50 chance, then there would be a substantial number (in the billions) of people on earth who were extremely old. But there isn't. So there's not.

Whoa man, that's heavy
 
Redefining?

What else could it mean?

Empirical applications never involve infinitely many trials, so defining it that way won't really work. ...

I don't see any other way out of the infinite regress, besides invoking belief.

doesn't your argument apply equally well to irrational numbers? they seem pretty well-defined even though empirical measurements never involve infinitely many bits...
 
Redefining?

What else could it mean?

Empirical applications never involve infinitely many trials, so defining it that way won't really work. We can talk about what we imagine would happen if the trial were to be repeated infinitely often, but then we're back to belief again.

"A tossed coin will land heads with probability 1/2." If this means, "in a long sequence of tosses, it will probably land heads about half the time", then what is the meaning of that "probably"? Shall we repeat the long sequence itself many times? That won't help; there will still be a "probably" in there.

I don't see any other way out of the infinite regress, besides invoking belief.

Right. Belief. But, aren't there theories that the universe is non-infinite, incrementalized (which I guess it would have to be to be non-infinite) and filled to a degree with redundancies (such as symmetries, etc.)? If so, I think it would be possible to perfectly model the universe within the universe, and give absolute descriptions of what "will" happen.

To a degree, perhaps we could look at apparently effective predictions using things like bayesian analysis rather than default human intuition as better harnessing such symmetries/redundancies in space-time?

Thoughts? (particularly from 69dodge and others taking this discussion somewhat seriously).
 
Definitive disproof: A human can either be immortal, or mortal. If there was a 50/50 chance, then there would be a substantial number (in the billions) of people on earth who were extremely old. But there isn't. So there's not.

Here's my attempt at a definitive disproof. Reality is either binary, or it's not. If there was a 50/50 chance,then0110111101101000001000000111001101101000011010010111010000101100001000000100100100100000011001110111010101100101011100110111001100100000011010010111010000100111011100110010000001100010011010010110111001100001011100100111100100101110
 
No. Just cause something is yes or no and either or doesn't mean it's 50/50. Just cause there are only two possible outcomes doesnt mean they are equally probable.
 
The evidence? Common sense!

Two football teams are playing. Either one could win or the other but it's not 50/50 if they're not equally good. If they have the same track record and equally talented players, it's about 50/50 but if you have my college's team vs. the other guy, it's gonna be the other guy.

I could either die tomorrow or I could live but considering I'm young, healthy and don't take to sky diving, I figure I don't have nothing to worry about.

The next President of the United States could conceivably be either a woman or a man (for arguments sake, let's eliminate any possibility of a hermaphodite or a transexual) but considering that none of the major or minor candidates are women, other than Hillary, my money's on a man. In 2008, 2012 and 2016. If there were as many major women politcians in both parties as there are men, it would be closer to 50/50.
 
EVIDENCE???

I thought that this was covered ad nauseum.

- I toss a die. The outcome can either be a 6 or not a 6.
- I buy a lottery ticket. I can either win $20M or I don't win the grand prize.
- I can try to pick up a hot blonde at the club by guessing her birthday. Either she is actually born on May 2nd or she isn't.
- I wake up in the morning. I either drink a cup of coffee before work or I don't.
- The next person to knock on my door will either be an annoying newspaper salesman or it will be someone not selling me newspapers.

None of these are 50/50.
 
To a degree, perhaps we could look at apparently effective predictions using things like bayesian analysis rather than default human intuition as better harnessing such symmetries/redundancies in space-time?

one objection to "the" bayesian program is that in order to have a well oiled machine, it takes as input only human intuition.
 
one objection to "the" bayesian program is that in order to have a well oiled machine, it takes as input only human intuition.
Technically it's an objection, but that doesn't make it true.

Let me talk you through an application of Bayesian probability to computer vision, feel free to point out the point where human intuition kicks in.

We want to find all of the grass in a photo.
For tractability, we model these images as a Markov random field where each pixel is connected to it's nearest neighbours.

We set the unary potentials of each pixel by looking at the probability that a pixel of that colour, and in that location was grass by looking at the frequency of occurrences in a training set with labelled ground truth.

We form the pairwise links between pixels similarly, learning how often two pixels with a similar colour difference between them and in a similar location share the same label.
So the pairwise links look like:
[latex] P_A_s B_t = P(A_s B_t)/(P(A_s)P(B_t))[/latex]

and the unary terms:
[latex] U_A_s =P(A_s) [/latex]

We then look for the maximal solution to:
[latex] \Pi_{\forall A} (U_A_s \times \Pi _{\forall B>A} P_A_s B_t) [/latex]

Which you can normally find by running graph-cuts or TRW-S providing it's sufficiently tractable.

Now without question this is an exclusively Bayesian method, I'm talking about what the probability is that a single pixel in a single image is grass, an idea which just doesn't make sense in terms of the old frequential framework.

But still, it is an objective (no intuition used here) method for finding the closest model from a set of models and assigning a confidence to it.
 
A separate question is why probability is so counter-intuitive at the conscious, reflective level, when our brain probably does advanced probability calculations intuitively (for example, when catching a ball).
I imagine the reason statistical problems are so unintuitive is that our ancestors weren't required to deal with these sorts of conundrums in the wild. There was no evolutionary pressure in favour of this kind of abstract thought, so it didn't develop.

This 50/50 discussion reminds me of an old stockmarket scam I read about. What you do is write to a thousand rich people, predicting the state of a company's stock the next week. To half the people you say the stock will go up, to the other half you say the stock will go down. Next week, the stock will have gone up or down, so you write to the people to whom you made a correct prediction (numbering 500) and send them another set of up/down letters about the stock of another company. The next week you do the same etc. etc. At the end of the exercise, you end up with a handful of people who think you're some sort of financial genius able to predict the ups and downs of the stockmarket. They give you lots of money to invest. You put it in a suitcase and skip town. As far as I can recall, this scam is not a recent idea - more pre-war.
 
I imagine the reason statistical problems are so unintuitive is that our ancestors weren't required to deal with these sorts of conundrums in the wild. There was no evolutionary pressure in favour of this kind of abstract thought, so it didn't develop.

Well that's the easy and obvious default hypothesis we can apply to pretty much anything about humans.

I'd like to see a better and more finely articulated analysis of this particular phenomenon though.
 
Well that's the easy and obvious default hypothesis we can apply to pretty much anything about humans.

I'd like to see a better and more finely articulated analysis of this particular phenomenon though.

why be so disparaging other people's posts? Most people spend their lives thinking in words, to understand statistics you need to think in maths - it's just another type of language. And like any language, you need to spend time learning its application. You may find it counter-intuitve - it doesn't mean that counter-intuitiveness is a universal attribute.
 
Aw. I wanted to come up with more stupid events that aren't 50% sucessful. Like a marriage in Hollywood. Or a red shirt surviving an episode on the original Star Trek.

All right, this second example is complicated. I've enclosed it in spoiler tags, because the work required it's very LaTeX-heavy, and the formulas involved are lengthy. If you're into probability, give it a look-see.

The probably of a red shirt surviving an episode of the original Star Trek:

Please note the following definitions:

[latex]$S_r = \textrm{Red shirt surviving} \newline
I = \textrm{Spock saying "highly illogical, Captain."} \newline
K_s = \textrm{Kirk sleeping with some alien woman} \newline
K_k = \textrm{Kirk saying "KHHHAAAAAAAAANNNNN!"} \newline
\textrm{C} = \textrm{Chekov's constant (value: "Wessels").}$[/latex]

latex.php
 

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