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#1 2007-03-12 07:39:40

amygdala
Member
Registered: 2007-03-12
Posts: 3

simple question about statistics

I apologise in advance for my total idiocy with this one but its been a while since i did statistics and i`ve lost my book on it...

Here is the problem..

I survey a series of records (say 80) looking to see if a piece of information is recorded in them. I find that it isn`t recorded in any of them ie 0%.

6 months later i survey another series of different records..( say 90) and find that the information is recorded in 9 of them . ie. 9%.

So what is the % improvement in recording this piece of information...i know it isn`t 9%.

If the first survey had shown 1% recorded the info it would be a 900% improvement i think, but seeing as 0% was the initial result how do you calculate the improvement?

I`m sure this kind of thing was simple for me a few years ago! but as they say `if you don`t use it you lose it`

Amygdala.

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#2 2007-03-12 09:38:04

lightning
Real Member
Registered: 2007-02-26
Posts: 2,060

Re: simple question about statistics

answer these they'll get you brain going
please use hide tags
[math]50%of 100=     50%of36=      1%of100=
25%of 100=     25%of36=     1%of200=
10%of 100=     10%of30=     1%of300=


Zappzter - New IM app! Unsure of which room to join? "ZNU" is made to help new users. c:

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#3 2007-03-12 09:44:19

amygdala
Member
Registered: 2007-03-12
Posts: 3

Re: simple question about statistics

50%of 100=  50   50%of36=  18    1%of100= 1
25%of 100=  25   25%of36=    9 1%of200= 2
10%of 100=   10  10%of30=     3 1%of300= 3

err thats not really that difficult but i would like an answer to my question.

amygdala

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#4 2007-03-12 12:18:52

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: simple question about statistics

I'd agree with you that you can't find an answer.

Percentage increase is defined as

.

So normally, it would be fairly easy to just plug in the new and old values to get your answer, but in this case that would involve a division by 0 and so it can't be done.


Why did the vector cross the road?
It wanted to be normal.

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#5 2007-03-12 16:23:57

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,711

Re: simple question about statistics

It is an increase of 9 Percentage Points (Note the word Points)

But as a pure percentage increase, mathsyperson is right.


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#6 2007-03-12 18:06:31

George,Y
Member
Registered: 2006-03-12
Posts: 1,379

Re: simple question about statistics

How many times is 9 as much as 0?
No. This problem is incorrect. "Times" is usually used to measure the relative scale between two values. 0 means vanity, nothing, so it isn't a value at all. The difference between 0 and 9 is not only that the latter is somewhat larger than the former, but also that nothing Vs something.
Something:Something=Ratio,Percentage
Something, Nothing-no need to compare. The improvement is substantial, not increamental.


X'(y-Xβ)=0

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#7 2007-03-12 23:24:12

amygdala
Member
Registered: 2007-03-12
Posts: 3

Re: simple question about statistics

Thanks for the help...i think that clarifies it! Basically i cant describe the improvement in terms of a `percentage improvement` ie 50% improvement or 75% improvement...but i could say there has been a 9% point improvement.

Amygdala

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#8 2007-03-13 22:37:39

George,Y
Member
Registered: 2006-03-12
Posts: 1,379

Re: simple question about statistics

amygdala wrote:

but i could say there has been a 9% point improvement.

Smart answer!


X'(y-Xβ)=0

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