Are some randoms more random than others?

[tinkthank]

Heh thanks.
I always wondered: If there is a 1% chance of an event happening, and you looked at 100 possible event-worlds, what are the chances of it happening once? If it is 1/100 + 1/100 ..., wouldnt that make it 100/100? Does that mean there is a 100% chance of it happening? That just sounds absurd to me. Obviously, "chances are" that it will happen, but what the heck does that mean? (Is my question clear or must I be more precise?)

[Endoperez]

Happening once or atleast once? That is a world of difference... Interesting question, anyway.

[PDF]

Originally posted by tinkthank:
Heh thanks.
I always wondered: If there is a 1% chance of an event happening, and you looked at 100 possible event-worlds, what are the chances of it happening once? If it is 1/100 + 1/100 ..., wouldnt that make it 100/100? Does that mean there is a 100% chance of it happening? That just sounds absurd to me. Obviously, "chances are" that it will happen, but what the heck does that mean? (Is my question clear or must I be more precise?)

eheh, probabilities... Your additive method only works with very small chances/small number of occurences, but in this case it's faulty.
A 1% chance event has an *average* chance of NOT occurring (at all) of (1-0.01)^100, that's 33.6%, so chance of occuring *at least once* is 66.4 %
However the average *number* of occurence is 1 (ie it will sometimes occur 0 time, other 1 time, or more, but average still is 1%*100 = 1)

[tinkthank]

I dont know.
I'll put it this way.
If you flip a coin, there is a 1/2 chance it will come up heads. If you flip it twice, there is a 2/2 chance you will get heads in one out of those two times -- right? So I think that means "once"?
But it would be absurd to say there is a 100% chance of you getting heads, so I must be confused somewhere, or maybe it is a language thing.

[Graeme Dice]

Originally posted by tinkthank:
I dont know.
I'll put it this way.
If you flip a coin, there is a 1/2 chance it will come up heads. If you flip it twice, there is a 2/2 chance you will get heads in one out of those two times -- right?

No. There is a 1/2 chance you will get heads the first time, and a 1/2 chance you will get heads the second time. Past results have no effect on the future results for a coin.

[tinkthank]

OK, but I thought that statistics were also used over time to consolidate possible worlds?

[archaeolept]

OK, but I thought that statistics were also used over time to consolidate possible worlds?

ok, but then, in this case, there are 4 equi-probable possible worlds:

1. first toss heads, second toss heads
2. first toss heads, second toss tails
3. first toss tails, second toss heads
4. first toss tails, second toss tails.

Thus, each of the 4 possible outcomes has a 25% probability; and the chance that heads will be tossed at least once is 75%, as that would be 3 of the 4 possible worlds.



[ March 11, 2004, 15:16: Message edited by: archaeolept ]

[PDF]

Originally posted by tinkthank:
OK, but I thought that statistics were also used over time to consolidate possible worlds?

You're confusing "probability" and "average", and forget to .. forget past
So for example :
If I plan to flip a coin 2 times, what I know is that heads has a 50% chance of coming out, so in average will appear 1 time out of the 2.
Now this is different from the probability to see *at least once* heads, which is the inverse of the chance to never see it (50 % of 50% = 25%), so 75%
But suppose heads comes up the 1st time. Now for the second time our previous expectations are obsolete, and again heads has a 50% of showing up.
Even if heads comes up 99 times ina row it has STILL a 50% chance of coming up next time - even if AT START the chance of that particular series was very tiny (0.5^99 = nada approx ).
Clearer ?

[ March 11, 2004, 15:29: Message edited by: PDF ]

[Peter Ebbesen]

Originally posted by tinkthank:
I dont know.
I'll put it this way.
If you flip a coin, there is a 1/2 chance it will come up heads. If you flip it twice, there is a 2/2 chance you will get heads in one out of those two times -- right? So I think that means "once"?
But it would be absurd to say there is a 100% chance of you getting heads, so I must be confused somewhere, or maybe it is a language thing.

No. The coin no memory.

You are committing the same error that makes people bet on lottery combinations that have not won yet.

The universe does not care that the coin came down heads or the lottery 1-2-3-4-5-6-7 Last time.

Hehehe. This is nearly the right time to introduce tinkthank to the Monty Hall problem

[tinkthank]

OK thanks, think I got it now. I knew that events dont remember past events, and have heard of the casion fallacy, but I didnt know what it meant in statistics terms. Thanks guys. Actually, Arceolept's explanation was the most clear to me.