I would use SUMPRODUCT for this but since you are otherwise happy with your
array formula:
=IF(ISERROR(=AVERAGE(IF('Summary Days'!$D$3:$D$65536="2A",(IF('Summary
Days'!$K$3:$K$65536=38,(IF('Summary Days'!$O$3:$O$1500<"0",'Summary
Days'!$O$3:$O$1500))))))),""<=AVERAGE(IF('Summary
Days'!$D$3:$D$65536="2A",(IF('Summary Days'!$K$3:$K$65536=38,(IF('Summary
Days'!$O$3:$O$1500<"0",'Summary Days'!$O$3:$O$1500)))))))

That is
=IF(ISERROR(your_formula),"", your-formula)

best wishes
--
Bernard V Liengme
Microsoft Excel MVP
www.stfx.ca/people/bliengme
remove caps from email

"Rebekah" wrote in message
...
I have multiple columns of data in another sheet and am using this formula
(entered as an array) to provide an average based on conditions, one
column
reads "2a", and another reads "38" etc.

i thought that by by entering the IF formula to include "<0", this would
count all the data and return a zero value for a blank or zero value. (I
certainly hope this is making sense to somebody!!!)

=AVERAGE(IF('Summary Days'!$D$3:$D$65536="2A",(IF('Summary
Days'!$K$3:$K$65536=38,(IF('Summary Days'!$O$3:$O$1500<"0",'Summary
Days'!$O$3:$O$1500))))))

This formula works if in all columns there is a value above zero, but
returns "#DIV/0!" if not. This would be ok if my table wasn't presenting
data for a fixed period....
Please help!!!