Originally posted by Palynka Pseudo-science? What are you talking about? Probability theory is a branch of mathematics.
what is its purpose? to tell someone if the odds are favorable enough for him to undertake an action that might end unfavorable? if someone puts a bulet in a six shooter and puts it to your head saying "if you survive i will give you a million dollars" would you do it? what if there were 2 bullets? i wouldn't. probability deals with the situations where you say the risks are
outweighed by the rewards and you will go ahead with the action.
perhaps pseudo science is bit harsh of a name for it. name a situation that absolutely needs probability and if i can offer no counter proposal i will cry uncle.
Originally posted by Wheely Go back and try it for yourself. The link ATY posted is a flash game that demonstrates the question. Play it for a while and you will see, if you always change your guess, you will win around 75% of the time.
To me it is fairly clear and if you start playing around with math it just makes it look more complicated than it is. The math always ignores the ...[text shortened]... door which contains the salt thereby adding an element of certainty in the math of probability.
that proves nothing. in a coin flipping game you have theoretically 50% chance of head. yet you might end up with a series of 99% tails.
in my view the first choice doesn't matter as there is no outcome. only the second choice where you are asked to choose between two doors. the fact that is formulated"would you like to change?" doesn't matter. you are presented with a 50% chance of getting it right.
An even more (for me) counter-intuitive experiment is the following:
Imagine there are two envelopes, and all you know is that one has the double of the amount of the other one. You choose one, open it, look at how much is in it and you're then given the opportunity to switch.
In this case, your expected value is always higher if you switch.
Originally posted by Zahlanzi what is its purpose? to tell someone if the odds are favorable enough for him to undertake an action that might end unfavorable? if someone puts a bulet in a six shooter and puts it to your head saying "if you survive i will give you a million dollars" would you do it? what if there were 2 bullets? i wouldn't. probability deals with the situations where yo ...[text shortened]... on that absolutely needs probability and if i can offer no counter proposal i will cry uncle.
Certainty is a rare commodity in any decision regarding the future.
Whenever there is uncertainty, there are probabilities. You might stick your head in the sand and try to ignore them, but it won't go away just because you do.
Originally posted by shavixmir I guess that sort of makes sense.
So, basically with a 2/3 chance of choosing salt to start with and then being shown that another door has salt behind it, you have 1/3 chance of a porche if you don't change, yet a 1/2 chance of a porche if you do change?
That's pretty bizarre.
Thank you. I think I get it now.
No; you have a 2/3 chance if you do change, because you had a 2/3 chance of picking salt in the first place.
Originally posted by Zahlanzi that proves nothing. in a coin flipping game you have theoretically 50% chance of head. yet you might end up with a series of 99% tails.
in my view the first choice doesn't matter as there is no outcome. only the second choice where you are asked to choose between two doors. the fact that is formulated"would you like to change?" doesn't matter. you are presented with a 50% chance of getting it right.
Yes, and theoretically you could flip a coin for two hours every day for ten years and only ever get tails but you wont.
I tell you what, you play ATY's game for a five minute period, as many times as you like and if you win less than 51% of the time after any of your five minute attempts I'll buy you a crate of beer,
Alternatively, flip a coin, just ten times and if you manage to get tails each time I'll send you a new coin.
Originally posted by Wheely Yes, and theoretically you could flip a coin for two hours every day for ten years and only ever get tails but you wont.
I tell you what, you play ATY's game for a five minute period, as many times as you like and if you win less than 51% of the time after any of your five minute attempts I'll buy you a crate of beer,
Alternatively, flip a coin, just ten times and if you manage to get tails each time I'll send you a new coin.
WOW! I got ALL LOSSES after 956 tries. Where's my beer?
Originally posted by Palynka Certainty is a rare commodity in any decision regarding the future.
Whenever there is uncertainty, there are probabilities. You might stick your head in the sand and try to ignore them, but it won't go away just because you do.
people try and should do the right choice, not the choice with the most chances of success.
tell me of a situation where it is necessary to calculate the probability before making a decision. if a doctor tells me i have cancer and i will croak in 1 month and that there is a treatment that will give me 5% of survivability, i will freaking take the treatment. i will take it if it is 1%. or 90%. if the maintenance dude tells a pilot that something on the plane is broken and the plane has a 1% chance of crashing, that pilot better sit his posterior on the ground.
i wouldn't base my decision on probability but rather on possibility. maybe there are exceptions where calculating probabilities is necessary. or my examples are exceptions where it isn't necessary.
i want certainties. and when i don't have certainty i try to do the choice that seems the right one at the time. because it would be foolish to do the less intelligent action just because it has more chances of success.
Originally posted by Wheely Yes, and theoretically you could flip a coin for two hours every day for ten years and only ever get tails but you wont.
I tell you what, you play ATY's game for a five minute period, as many times as you like and if you win less than 51% of the time after any of your five minute attempts I'll buy you a crate of beer,
Alternatively, flip a coin, just ten times and if you manage to get tails each time I'll send you a new coin.
what i am trying to say is that on paper the coin has 50% chance of landing on heads. but if you do a finite series of tosses, the coin might land on heads from 0% to 100%. experiment and theory are two different notions in probability.
Originally posted by Zahlanzi when i don't have certainty i try to do the choice that seems the right one at the time. because it would be foolish to do the less intelligent action just because it has more chances of success.
If you don't consider the chances of success, then you are the fool. The "intelligent action" must ALWAYS consider such chances.
But it's only normal that you think that way. People unfortunately tend to dislike what they do not understand.
Originally posted by Palynka Human trials of medical drugs. Do you want more?
you mean a drug that might cure cancer? if you have cancer, do you care if it has a 15% chance or 1% chance or 90% chance? at what probability of success would you refuse the drug? and if someone else would refuse the drug at a different number?
Originally posted by Palynka If you don't consider the chances of success, then you are the fool. The "intelligent action" must ALWAYS consider such chances.
But it's only normal that you think that way. People unfortunately tend to dislike what they do not understand.
so if you see a girl drowning you calculate your chances of success? where would you consider jumping in after her? would it matter that you calculate 1% or 99%? not jumping means 100% death for her. jumping has some chance. for me it is irrelevant what that chance is because i would jump after her even though i am not such a good swimmer. at least in this case it is the possibility of success that matter, however remote it is.
people have bet fortunes on coin flips which is 50-50. card counters in las vegas massage the odds and bet big when they think the odds of getting the needed cards are close to something, only to lose everything. russian roulette might end on the first pull of the trigger. possibility in my opinion trumps probability. of course there are exceptions, which you didn't produce yet.
Odds... can someone explain?
07 Aug '08 07:38
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