Not tested very much but here is a start. Note that I used 20 rows only for
my experiment, so change as needed
A1: a date value as you specify
B1: =MAX(IF(Sheet1!A1:A20=A1,Sheet1!C1:C20)) as you have
B2:=MATCH(B1,Sheet1!C1:C20,0) will find the row with the same value as the
MAX. However, a reading may not be unique.
So in D1 of Sheet1 use formula =A1&C1 and copy down to end of column
(combine date and reading)
Now in C1 (Sheet2) use =MATCH(A1&B1,Sheet1!E1:E20,0) this returns the (A1 is
date, B1 is reading)
This tells us the row
For the Time use =INDEX(Sheet1!B1:B20,B2)


--
Bernard Liengme
www.stfx.ca/people/bliengme
remove CAPS in email address


"Ray Wright" wrote in message
...
I have a large dataset (about 55,000 records) that consists of instrument
readings taken at different times on different days (between 24 - 40
readings per day). The data is in the format: Col A - dates; Col B - times
(24 hour clock format); and Col C - instrument readings.



I want to extract (on another worksheet) the maximum instrument reading
per day and the time of that reading (Col A - dates; Col. B - max reading
for the date in Col A; Col. C - time of that reading). I have
successfully extracted the maximum instrument reading with the array
formula:

{=MAX(IF(Sheet1!A1:A55000=A1,Sheet1!C1:C55000))}



However, I have not been able to extract the time of the maximum reading.
Is the solution come combination of INDEX and /or MATCH and/or OFFSET?
Any help appreciated.



I am using XL2002.



Ray Wright