## 6715Re: [webanalytics] Re: basic math question - percentages

Expand Messages
• Jun 1, 2006
• 0 Attachment
Hi all,

IMHO

If the conversion rate went from 1% to 1.2% which means that the conversion
rate went up by 20%, it's ok to state that. It just depends, as long as the
opther party understands what you are saying

LOL

MM

On 6/1/06, Peter Michael Sopp <peter.sopp@...> wrote:
>
> I'm just a poor sociologist not a mathematician. Nevertheless I'm hoping
> I could clarify the points already mentioned by others.
> The main point is to understand that the result of a substraction is a
> difference and not a percentage.
> The difference is April - March, so 1% - 1.2% = 0.2%-points. The result
> of a substraction is always a absolute number and never a percentage!
> To calculate the percentage growth or percentage increase you need a base:
> (April-March)/March = simple growth rate. Now you can multiply it by 100
> and you get 20% (= growth rate in percent: The difference of the
> percentages is related to the percentage of March).
> Let's give an interesting example:
> a1t1 = absolute number of visitors in March
> a2t1 = absolute number of buyers in March
> (a2t1/a1t1)*100)
> a1t2 = absolute number of visitors in April
> a2t2 = absolute number of buyers in April
> (a2t1/a1t1)*100)
> Now the following could happens: The number of visitors as well as the
> number of buyers decrease. Nevertheless the growth rate is positive
> because relativly more visitors has converted to buyers in April as in
> March.
> For example: In March you have a simple conversion rate of
> (10/1000)*100 = 1% and in April (6/500)*100=1.2%.
> The conclusion is - well that's up to you!
> Peter
>
> matpflum schrieb:
> > I have always struggled with the logic behind this seemingly simple 0
> > 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
> >
> >
> >
>
>
>
>
>
> ---------------------------------------
> The Web Analytics Forum
> Founded by Eric T. Peterson (www.webanalyticsdemystified.com)
> Moderated by the Web Analytics Association (
> www.webanalyticsassociation.org)
> Email moderators at: webanalytics-moderators@yahoogroups.com