I have an experimental data set that yields a timestamp. I need to
categorize each entry according to which experiment group it belongs
to . Can I use vlookup to seek a value between two date/time stamps.
If not, any other suggestions to do this.
.e.g.

If my lookup table is thus
begin time stamp end time stamp experiment group
10/20/08 06:55:30 10/20/08 07:04:10 G1
10/20/08 07:05:10 10/20/08 07:07:30 G2
10/20/08 07:10:30 10/20/08 07:13:20 G3

My original data table is
Time stamp data1
10/20/08 7:01:30 1.2
10/20/08 7:11:55 1.5
10/20/08 7:06:40 0.98

I need to add a column of 'experiment group' to the original data
table which will be G1, G3, G2 respectively for the 3 row based on the
lookup table.

Thanks in advance.

Assuming your lookup table is range A1:C3 and your original table is A16:B18
you could put this formula in cells C16:C18.

=VLOOKUP(A16,$A$1:$C$3,3)

Tom