Figured it out myself and posting this in case it's useful to other folks:
This is my data table:
No. Date of Call Time of Call Type of Call
1 1 Jan 2am 1
2 1 Jan 3am 2
3 2 Jan 1am 1
4 2 Jan 4am 2

Where Type of Call 1 = Defect
2 = Query
I've had to use numbers in column "Type of Call" in order to get a scatter
diagram which showed the calls spread over the 24-hours for each Type of
Call.
So, X Values = C1:C4
Y Values = D1:D4
and the resulting graph looks something like this

2 | * * *
1 | * * * * * *
0 |
--------------------------------------
0:00h 1:00h 2:00h 3:00h

"Melissa" wrote:

I am using Excel 2000.
I would like to create a scatter plot of Types of Calls received throughout
the day. The end result is for me to see at what time of day are the various
types of calls concentrated in. Thus, the X-axis would be the 24-hour range,
starting from 00:00hr on left-end to 00:00hr on right-end.
I don't know what should be on Y-axis. but I do want my scatter dots to be
differentiated by Call Types.

What is the best way for me to structure my data table, i.e. what columns do
I need?
I suppose at the minimum, I need these columns:
1. Call Type (e.g. Defect; Query)
2. Time of Call
3. Date of Call

I do not require the date of the call to be displayed in the scatter plot
but I do want to sum up all the calls received over the week for each hour of
the day.

Thanks.