- Jun 2 10:43 AMStephane,

I am glad you brought that point up. Besides the math logic and

terminology, that was actually my point in asking the question. You

could see conversions going from 1.0% to 1.2% and proudly announce

that there was a 20% increase in conversions. But what if the goal

is 1.5% - the 20% good news has to be taken with a grain of salt. It

drives me crazy when the marketing types take only the 20% increase

(or whatever the biggest number is), spin that to upper management,

and before you know it, somebody is wildly happy about a 20%

conversion rate. Because I have gotten burned by this in the past

(and it seems you have also), I favor reporting on "differences" in

these instances and not percentage increases.

Maureen

--- In webanalytics@yahoogroups.com, "S.Hamel" <shamel67_news@...>

wrote:>

number and

> Ho boy do I love Web analytics and this newsgroup!

>

> I have seen so many times people running around with a single

> spreading wrong interpretations... Your example is a gem that

should be

> printed in all Web analytics manuals. What's important is the

interpretation

> of the numbers, not the numbers themselves. This exemlpe also

highlight how

> important it is to look at the numbers from various angles. In your

example,

> the average sales price could be the same, say 25$, but the

revenues for the

> month would be 40% lower! (10*25$ vs 6*25$)

people

>

> That's why a web analytics solution doesn't do any magic, it's the

> using them that makes all the difference! :)

hoping

>

> Cheers,

> Stephane

>

> ----- Original Message -----

> From: "Peter Michael Sopp" <peter.sopp@...>

> To: <webanalytics@yahoogroups.com>

> Sent: Thursday, June 01, 2006 4:56 AM

> Subject: Re: [webanalytics] Re: basic math question - percentages

>

>

> > I'm just a poor sociologist not a mathematician. Nevertheless I'm

> > I could clarify the points already mentioned by others.

is a

> > The main point is to understand that the result of a substraction

> > difference and not a percentage.

result

> > The difference is April - March, so 1% - 1.2% = 0.2%-points. The

> > 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

as 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

> > pt1 = percentage buyers March (buyers related to visitors:

> > (a2t1/a1t1)*100)

> > a1t2 = absolute number of visitors in April

> > a2t2 = absolute number of buyers in April

> > pt2 = percentage buyers April (buyers related to visitors:

> > (a2t1/a1t1)*100)

> > Now the following could happens: The number of visitors as well

> > number of buyers decrease. Nevertheless the growth rate is

positive

> > because relativly more visitors has converted to buyers in April

as in

> > March.

simple 0

> > 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!

> > Hope this was helpful

> > Peter

> >

> > matpflum schrieb:

> >> I have always struggled with the logic behind this seemingly

> >> 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

percentage

> >> mathematician, but I think that it is wrong to compute a

> >> of a percentage because the percentages were calculated off of

which

> >> different bases. Are there any mathematicians who can explain

> >> way is correct? Thanks.

> >> Maureen

> >>

> >>

> >>

> >

> >

> >

> >

> >

> > ---------------------------------------

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> > Moderated by the Web Analytics Association

> > (www.webanalyticsassociation.org)

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> > Yahoo! Groups Links

> >

> >

> >

> >

> >

> >

> >

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