## 6703Re: [webanalytics] Re: basic math question - percentages

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• May 31 5:46 PM
Technically both are correct, however it is more common the refer to the difference between two %s as "percentage points difference". In banking, the difference is referred to as "basis points", where 1 basis point= 1/100 of 1%. So, 1%=100bp, and 0.2% = 20bp.

Hakim

Andrew Edwards <aedwards@...> wrote:

>I'm no math genius but I am pretty sure the *increase* between 1% and
>1.2% is 20%. It might also be  called (uncharitably) an additional 0.2%
>overall on total percentage of conversions, but then you're confusing
>the word "additional" with the notion of  "increase by percentage".
>
>--Andrew Edwards
>
> Ted Callier wrote:
>
>>On Wed, 31 May 2006 19:38:39 -0000
>>"matpflum" <matpflum@...> wrote:
>>
>>
>>
>>>I have always struggled with the logic behind this seemingly simple
>>>question. Doesn't it make more sense to say that if the conversion
>>>rate was 1% in March and is 1.2% in April, that the rate increased
>>>by .2% and not 20%?  So it's a simple subtraction.  I'm not a
>>>mathematician, but I think that it is wrong to compute a percentage
>>>of a percentage because the percentages were calculated off of
>>>different bases.  Are there any mathematicians who can explain which
>>>way is correct? Thanks.
>>>Maureen
>>>
>>>
>>
>>If you want to show the difference by doing a substraction, this is
>>called "percentage point", .2 percentage points(not .2% !) in your
>>example.
>>
>>If you use percentages, you can apply them to percentages w/o problems
>>as long as both measure the same thing, conversion in your example.
>>
>>So conversion increased by 20%, or .2 percentage points, from 1% in
>>March to 1.2% in April.
>>
>>And as you have no reason to believe me, see youself what Wikipedia has to say:
>>http://en.wikipedia.org/wiki/Percentage and http://en.wikipedia.org/wiki/Percentage_point
>>
>>
>>
>>
>>
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>
>
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