Hi there. Been trying to work this one out for a while, but have hit a brick wall. Any ideas / help would be appreciated.

From the example data below, which summarises a series of meetings that we have hosted with different firms attending, i'm trying to get a formula to work out how many unique 'Group' meetings there were.

i.e. from the data below, 4 firms attended a group meeting at 12:00 on 17/10/2007, so that needs to be counted as one unique group meeting.

I can use sumproduct and countif (or frequency) to work out how many unique values there are within one column, but I can't work out how to sum up the number of unique entries across two columns (date and time).

Please note that this needs to be done as a sumproduct because the sample data below comes from a larger data set.

Any thoughts?


A B C D
Date StartTime MeetingFormat FirmName
17/10/2007 09:00 One-on-one Firm 1
17/10/2007 10:30 One-on-one Firm 2
17/10/2007 12:00 Group Firm 3
17/10/2007 12:00 Group Firm 4
17/10/2007 12:00 Group Firm 5
17/10/2007 12:00 Group Firm 6
17/10/2007 13:30 Group Firm 7
17/10/2007 13:30 Group Firm 8
17/10/2007 13:30 Group Firm 9
17/10/2007 15:00 One-on-one Firm 10
06/03/2008 09:00 One-on-one Firm 11
06/03/2008 10:30 One-on-one Firm 12
06/03/2008 12:00 Group Firm 13
06/03/2008 12:00 Group Firm 14
06/03/2008 12:00 Group Firm 15
06/03/2008 12:00 Group Firm 16
06/03/2008 12:00 Group Firm 17
06/03/2008 13:30 Group Firm 18
06/03/2008 13:30 Group Firm 19
06/03/2008 13:30 Group Firm 20
06/03/2008 13:30 Group Firm 21
06/03/2008 15:00 One-on-one Firm 22
16/04/2008 09:00 One-on-one Firm 23
16/04/2008 10:45 One-on-one Firm 24
16/04/2008 12:00 Group Firm 25
16/04/2008 12:00 Group Firm 26
16/04/2008 12:00 Group Firm 27
16/04/2008 12:00 Group Firm 28
16/04/2008 12:00 Group Firm 29
16/04/2008 12:00 Group Firm 30
16/04/2008 13:30 Group Firm 31
16/04/2008 13:30 Group Firm 32
16/04/2008 13:30 Group Firm 33
16/04/2008 13:30 Group Firm 34
16/04/2008 13:30 Group Firm 35
16/04/2008 15:30 One-on-one Firm 36