Take a look at the sumif and countif functions. sumif/countif will give you
an average.
HTH,
Gary Brown

"Kaine" <Kaine@discussions.microsoft.com> wrote in message
news:7FD45235-D0D7-4415-A915-0CBE914BD7BD@microsoft.com...
> Does any one know an easy way to convert a series of weekly data into
> their
> respective monthly averages.
>
> I have a large range of data in weekly format:
> 1/2/99 3.54
> 8/2/99 5.41
> 15/2/99 2.10
>
> through to...
> 25/2/05 4.10
>
> How can i get that data into a table which looks like:
> 1999 2000 ....... 2005
> Jan 5.12 1.24 ...... 5.28
> Feb 2.14 3.54 ....... 1.79
> Mar etc etc
> ....
> Dec 2.45 4.8 ........ #NA
>
> The monthly average table needs to look up the respective months in the
> weekly data and average them into the corresponding cell (ie Jan-1999
> equals
> 5.12 from the 4 or so weeks of data).
>
> I am thinking vlookup function, but am unsure how to add average when
> looking up a series of dates in a lookup function.
> I already have a similar table which looks up the week number of the date
> and puts the corresponding weekly data into the table against its week
> number.
>
> The weekly data may also have returned #na for graphing purposes, is there
> anyway i can accommodate this in the formula.
>
> I would appreciate some help.