Guys and gals,

Apologies for this being simple to some, but what I want to do sounds simple
in theory. I've got to make a spreadsheet to track when talks were given and
how many attended, and this data will be broken up into periods of the year.
So far, I've got something like this

Talk Title......Date Given......Number attendees

On another worksheet I've used a sumproduct to work out how many talks took
place in one period (eg. 1/3/2005-28/3/2005) but now I want to be able to
take the number of attendees and correlate it with specific periods. Below is
an example of the sumproduct calculation:

=SUMPRODUCT(--('Talk Log'!C4:C61=C4),--('Talk Log'!C4:C61<=D4))

As you can see, it works out how many talks took place in specific periods
(C4 and D4 just have dates in them), what I need to do is take the dates
mentioned and add up the number of people who went on the talks, any
ideas???????? Thanks for even reading this by the way!