Looks fine, but maybe try this variation

=AVERAGE(IF((Sheet1!A$2:A$5310=Sheet2!A2)*(Sheet1 !B$2:B$5310<=Sheet2!B2),Sh
eet1!I$2:I$5310))

--
HTH

Bob Phillips

(replace somewhere in email address with gmail if mailing direct)

"Jason" wrote in message
...
I am trying to average time for multiple entries over a year. I have about
10,000 records with the date and a total time. On my next sheet I have the
start date and end date for each week of that year columns A&B
respectivly.
The formula below returns a result but it is wrong. I ran an average for
the
first week to conform it and it is off by more than 20 seconds. Can anyone
show me what I did wrong. Thank you


{=AVERAGE(IF(Sheet1!A$2:A$5310=Sheet2!A2,IF(Sheet 1!B$2:B$5310<=Sheet2!B2,Sh
eet1!I$2:I$5310)))}