After a long break, I am back with a post in line with the 'Questions without answers' theme.
Why is an expected result, observed just once, believed to be more probable than an unexpected one occurring multiple times?
I have never seen a teller at a bank recheck the number of currency notes if the counting machine shows 100. But if it shows a 98, the teller rechecks until the machine shows 100.
Isn't the probability of a 98 note bundle becoming 100 same as the probability of 100 note one becoming 98?
Guess the world is just "optimistic".
How close is reality to expectations?
8 comments:
haha Thats because of general human tendency (Greed!).
One will never think of returning an extra paise he gets by chance, but hits hard when he gets it less !!
I am not sure it is Greed. Because not checking the 100 note bundle doesn't qualify as greed. He may get a paise less by not rechecking.
Its more about getting the 'expected' value which makes people happy and they don't even verify if it is indeed a true positive.
In that case its good to be optimistic. If we go on rechecking things, it might inculcate a kind of phobia !!
So you are saying it is good to be optimistic and WRONG (sometimes) than taking extra effort to find out if it is equally correct?
I dont suggest to keep rechecking, but to give equal weightage. If you check two times to confirm something is really wrong, u have to do the same to check if something is really correct, right?
And a request to the anonymous commenters : please put in a sign or a nickname at the end of the comment..at least a fake one. I am not even sure if the first and the second anon comment is from the same person :(
Here is the nick name for the anonymous on this particular post:
- VANITHA.
Thanks, that made life a lot easier. Guessing is a dangerous game, u don't know !!
> "Isn't the probability of a 98 note bundle becoming 100 same as the probability of 100 note one becoming 98?"
duh . . . of course not!!
first of all, i don't think the counting machine is as open to over-counting as it is to under-counting, right? notes stick together leading to under-counting. how the hell does the poor machine over-count?
second of all, you don't have stacks of 98 notes. if you did have 98 stacks as well as 100 stacks *and* the machine was equally prone to making errors both ways, then you can be sure that the teller would check atleast twice for the same number to appear. i'm sure you'd agree.
> "I dont suggest to keep rechecking, but to give equal weightage."
by definition, when you 'expect' something, you're attaching more weight to its occurrence. so the 1/2 probability doesn't apply anymore.
-w
yup, I totally agree. Would have helped me if I had asked the teller my doubt :), Over-counting does not seem to be as probable as under-counting, while the possiblity of over-counting can only be attributed to a mechanical failure.
Thanks for enlightening, that din't strike me at all :(.
Regarding the second part, that is my doubt, actually. How close is what you expect, to the reality. Is attaching extra probability correct.
Attaching more probability to the expected results would deviate u farther from reality if there are any false positives.
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