# Possibility and probability

Posted by Ward on October 07, 2004

In Reply to: Possibility and probability posted by Henry on October 04, 2004

: : HI,

: : Can anyone out there tell me what does this phrase or saying mean...

: : "Possibility and probability are two different things"

: : OR

: : "Probability and possibility are two different things"

: : Thanks

: : Abhishek

: It's not a phrase I'm familiar with. I think it may refer to planning for the future.

: It's possible but not probable that there will be an earthquake tomorrow. I'm not taking any precautions.

: It's possible and probable that Mount St Helens will erupt in the future. I'll be taking my holidays somewhere else!

In my useage, possible tends to establish two categories ......something is possible or it's not. Probable is used when there is a conceivable gradation or some measure of statistical certainty of the occurance of a particular event. (A good coin, when flipped, will produce heads and tails with a probablity of 50% of each)

There can be a high probability of a certain thing happening -- this suggests a likelyhood of more than 50% that it will occur. Something must be possible to have a probability established for it. Impossible things have zero probability of happening.(A two headed coin will never show up tails -- it's impossible)

- Possibility and probability
**Lotg***07/October/04*