Get correct percentage

[Conax]

Hello,

This is actually a general programming question but I don't know which
newsgroup best to put it so please pardon me.

I've always been looking for the best way to get an accurate percentage
statistics.

For example, in a election scenario:

Person A gets 33 votes
Person B gets 33 votes
Person C gets 34 votes
Person D gets 35 votes

Total votes = 33 + 33 + 34 + 35 = 135
Percent for A = 0.244.... = 0.24 = 24%
Percent for B = 0.244... = 0.24 = 24%
Percent for C = 0.251... = 0.25 = 25%
Percent for D = 0.259... = 0.26 = 26%

Then add up the percentage values: 24 + 24 + 25 + 26 = 99
(where it should be 100)


So, does anybody have a way to get around this problem? How should I
calculate the percentage for each person so that the percentage will add up
to 100 in the end?

Thanks for your help
Happy New Year
Conax

 

[Mark Schupp]

What you are seeing is rounding error. You can reduce the effect by using
more precision:

Percent for A = 0.244 = 24.4%
Percent for B = 0.244 = 24.4%
....

If that is not good enough then you should add the same disclaimer that
pollsters use to the effect that the results will not necessarily add up to
100% due to rounding error.

 

[Invotion]

I think your percentages are accurate, but you simply
have to decide exactly how accurate you want them. Then
it becomes a decision of when (or if) to round. Any time
you round you will have a margin of error + or - a
certain amount.

Say you have 3 items with equal percentages. They could
each be represented as any of the following:

33%
33.3%
33.33%
33.333%
etc...

The more numbers to the right of the decimal, the greater
your degree of accuraccy.

Sincerely,
Invotion Engineering Team
Advanced Microsoft Hosting Solutions
http://www.Invotion.com

 

[Conax]

Thanks for your replies Mark and Invotion.

I was hoping someone would have a logic to somehow display percentage
without decimal points and yet can add up to 100%. But I am probably asking
too much, and should live with what you have suggested.

Thanks again for your help!

Regards
Conax

 

[Mark Schupp]

You could determine the difference from 100% and arbitrarily increase or
decrease some of the individual values. I wouldn't, but you could.

 

[Don Verhagen]

Thanks for your replies Mark and Invotion.

I was hoping someone would have a logic to somehow display percentage
without decimal points and yet can add up to 100%. But I am probably asking
too much, and should live with what you have suggested.

[start sacarasm]
Yes, unfortunately none of have a suggestion for changing the laws of
mathametics. It's like asking to split up $3 between 2 people without using
cents.
[end sacarasm]

Don

 

[Dave Anderson]

Yes, unfortunately none of have a suggestion for changing
the laws of mathametics. It's like asking to split up $3
between 2 people without using cents.

Imagine the ramifications if you could do it...

Assuming i/j (or even 100*i/j) is an integer for each integer i and j, we
should be able to represent every rational number exactly (in binary as well
as in decimal). This, in turn, would imply a trivial solution to the
Discrete Log Problem, meaning we could trivially factor arbitrarily large
numbers. That would render RSA encryption (among other things, like
Diffie-Hellmann key exchanges) immediately obsolete.

Bye-bye public key encryption...


--
Dave Anderson

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