Averaging percentages
 

Greetings,
This is actually a basic mathmatical question but its a stumper for me.

Can you average a column of percentages and get a true average?
I've been told that it can't be done accurately but I never understood
the expanation.

thanks in advance
Marketing Analyzr

Averaging percentages
 

Perhaps the person who told you that should explain why it can't be done.
Excel will not include blanks cells in an average, but it will include zero
values, although they can be excluded with the array formula

=AVERAGE(IF(A1:A1000,A1:A100))

--
HTH

Bob Phillips

(replace xxxx in email address with googlemail if mailing direct)

"Marketing analyzr" wrote in message
oups.com...
Greetings,
This is actually a basic mathmatical question but its a stumper for me.

Can you average a column of percentages and get a true average?
I've been told that it can't be done accurately but I never understood
the expanation.

thanks in advance
Marketing Analyzr

Averaging percentages
 

Hi

It is all to do with weighting. If all samples are of equal size, then
an arithmetic average of the average will be correct.
If sample size is different then it will be incorrect when compared with
the weighted average.
Taking a set of simple figures

8 / 4 = 200%
6 / 2 = 300%
10 / 5 =200%
The arithmetic Average percentage would be 233% ( =(200%+300%+200%)/3)
The correct weighted Average percent would be 218%
=(8+6+10)/(4+2+5)
having given the correct weighting to the discrepancies in sample size.

--
Regards

Roger Govier


"Marketing analyzr" wrote in message
oups.com...
Greetings,
This is actually a basic mathmatical question but its a stumper for
me.

Can you average a column of percentages and get a true average?
I've been told that it can't be done accurately but I never understood
the expanation.

thanks in advance
Marketing Analyzr