# The meaningfulness item on math probability

• A
• boby
boby
TL;DR Summary
All probability numbers that calculated , depending on the subject ,have a boundary of meaningfulness,...
Hello,
In probability math,because of math's nature that is merely quantitative and not
a qualitative, for any case,it give you just a number; so, I think for every cases,
there should be a boundary probability number that is " meaningfulness " just
for that specified case and out of that boundary is not meaningful and that is just
a meaningless number.

Thanks,

Summary:: All probability numbers that calculated , depending on the subject ,have a boundary of meaningfulness,...

Hello,
In probability math,because of math's nature that is merely quantitative and not
a qualitative, for any case,it give you just a number; so, I think for every cases,
there should be a boundary probability number that is " meaningfulness " just
for that specified case and out of that boundary is not meaningful and that is just
a meaningless number.

Thanks,

I think this is getting more at statistics than probability theory.

• FactChecker
Mentor
Summary:: All probability numbers that calculated , depending on the subject ,have a boundary of meaningfulness,...

Hello,
In probability math,because of math's nature that is merely quantitative and not
a qualitative, for any case,it give you just a number; so, I think for every cases,
there should be a boundary probability number that is " meaningfulness " just
for that specified case and out of that boundary is not meaningful and that is just
a meaningless number.

Thanks,
Yes. Probabilities greater than 1 or less than 0 are not meaningful.

• sysprog
Homework Helper
Gold Member
We are left to guess at what you mean by "meaningful". Do you want to exclude outliers in a sample of data? Do you want to exclude rare events, no matter how significant they may be if they do happen? I agree that really surprising data points should be examined closely to see if something went wrong in the experiment or if they are things that are valid, but you hadn't thought of them before. Please describe what you mean.

boby
Yes. Probabilities greater than 1 or less than 0 are not meaningful.
I mean that there are many cases in which, when we calculate and get a probability ratio number like that; P(A),but
in real for Pa(A) less than P(A),the absolute and certain answer is Pa(A) .

sysprog
I mean that there are many cases in which, when we calculate and get a probability ratio number like that; P(A),but
in real for Pa(A) less than P(A),the absolute and certain answer is Pa(A) .
What does "Pa(A) less than P(A)" mean?

Mentor
I mean that there are many cases in which, when we calculate and get a probability ratio number like that; P(A),but
in real for Pa(A) less than P(A),the absolute and certain answer is Pa(A) .
I am not sure I understand what you are saying. It sounds like maybe you think probabilities should have a lower threshold. But that would make the probability density function unnormalized.

Could you be more descriptive and explicit? Perhaps with a concrete example.

Last edited:
• sysprog
zinq
Partly for difficulties with the English language and possibly for other reasons, I am not able to understand what question is being asked.

• Dale
boby
I meant that ; sometimes we get a probability ratio of for example of : 1/ 5 ∧ 23 from a calculation
but,in fact,a number of; 1/ 5 ∧ 8 for that is perfectly the absolute answer.

I meant that ; sometimes we get a probability ratio of for example of : 1/ 5 ∧ 23 from a calculation
but,in fact,a number of; 1/ 5 ∧ 8 for that is perfectly the absolute answer.
Can you give a specific example? Say you have five driferent cards and you draw one, then put it back, shuffle, repeat twenty three times. The probability to get the same card is (1/5)^23. What is wrong with this answer and what is "prefectly the absolute answer"?

Mentor
I meant that ; sometimes we get a probability ratio of for example of : 1/ 5 ∧ 23 from a calculation
but,in fact,a number of; 1/ 5 ∧ 8 for that is perfectly the absolute answer.
This is incorrect. It will lead to unnormalized probability density functions.

SSequence
I am not learned about probability (at all), but here would be my interpretation of the question.

Let's try to think about something like a fair coin toss. However, we could add something like a 'boundary condition' saying that when we run a trial run of coin toss then in the "running average" the ratio of heads (divided by total no. of trials) can't drop below 0.3 for example.

So if we run the trial 100 times and get 30 heads and 70 tails. Then before we even run the next trail we know that a head will occur because otherwise the ratio drops below 0.3

Perhaps this might be something closer to what OP was saying ... just a guess.

Homework Helper
Gold Member
I meant that ; sometimes we get a probability ratio of for example of : 1/ 5 ∧ 23 from a calculation
but,in fact,a number of; 1/ 5 ∧ 8 for that is perfectly the absolute answer.
If the calculation was done correctly, and the assumptions are correct, then there is no other "in fact" answer.

EXAMPLE: Suppose there is a jar with 5 balls, labeled A, B, C , D, E. You randomly (blindly) select one ball from the jar and replace it, 23 times. The probability of getting all A's is 1/5 ^ 23. There is no other answer.

That being said, there certainly are errors that can be made in a calculation of probability. A calculated probability of 1/5^23 might be wrong, where 1/5^8 is correct. Is there a particular situation that you are worried about?

• Dale
boby
All the above answers are very significant but ;
As you know that we faced to a few cases(events),in our real life daily,that their occurrences are inevitable
but their math probabilities are still get you numbers that show uncertains!

Mentor
We are now on post 15 and I still don’t have any idea what you are talking about. This thread is closed.

If you post anything else please make a sincere effort to be clear in your description of the question and when you respond please do so by quoting the person you are responding to and directly addressing their post. Also, please review the forum rules, including the rules on proper grammar.