# Can excel count concurrent events given start and end times ?

G

#### Guest

Hi there. I have a spreadsheet with thousands of phone call records. Each
has a start time, and end time and of course, therefore, a duration. I want
to get excel to tell me how many concurrent calls there are.

How do I do it ?

Charlie

First question - of these thousands of phone calls, are they all on the same
day or are numerous days represented on the sheet?

If more than one day is represented on the sheet, is the DATE of the call
recorded as part of the start/end time of the call or somewhere else on the
same row with the start end time?

You're essentially asking Excel to take each date and compare it to all
other dates and tell you how many others were going on at the same time -
that's not going to work well if multiple days are involved unless you can
distinguish the dates.

It might be better if you set up a group of time ranges, down to whatever
granularity you need and ask what calls were concurrent on a given day during
those time periods.

Yesterday I stared at this for about an hour trying to figure it out.
since it is an important aspect of your solution. I made some
assumptions about "down to the minute" granularity and tried to
develop a way to determine calls originating during a particular
minute and calls that were ongoing during a particular minute, and
couldn't get the logic down, and then couldn't devote more time to it.

The best I can figure right now is to calculate calls in progress
during a particular time frame by listing for each call the start and
then use IF statements to determine if a call is in progress during a
given time period. If TRUE then return 1 in a given cell, and at the
bottom of the column sum all the 1s. That's not very elegant, tho,
hopefully one of the resident geniuses can respond with a better
method.

Assuming you have call data with start date/time and end date/time
(i.e. start date/time + duration), one way of doing this is to create
TWO records for every call record. One record to contain START date/
time and an indicator set to "S", and the second to contain END date/
time and an indicator set to "E".

Merge the two sets of records together and sort by date/time in
ascending sequence. If the S/E indicator is in column C, and assuming
first record is in row 2, then in column D row 2 add the formula:

=IF(C2="S",D1+1,D1-1)

and replicate this formula downwards to all other records (cell D1
should be initialised to 0). Column D should then contain the number
of simultaneous calls at any one time. You can easily determine the
maximum number (using the MAX function) AND the number of times that
this number, and every lower number, was reached (using the COUNTIF
function).

Hope this helps.

Pete

Assuming you have call data with start date/time and end date/time
(i.e. start date/time + duration), one way of doing this is to create
TWO records for every call record. One record to contain START date/
time and an indicator set to "S", and the second to contain END date/
time and an indicator set to "E".

Merge the two sets of records together and sort by date/time in
ascending sequence. If the S/E indicator is in column C, and assuming
first record is in row 2, then in column D row 2 add the formula:

=IF(C2="S",D1+1,D1-1)

and replicate this formula downwards to all other records (cell D1
should be initialised to 0). Column D should then contain the number
of simultaneous calls at any one time. You can easily determine the
maximum number (using the MAX function) AND the number of times that
this number, and every lower number, was reached (using the COUNTIF
function).

Hope this helps.

Pete
15 Years later your post is still helping people. Thanks Pete, just what I wanted.