Due the manner in which the MRC audits Session statistics and CUME, these numbers cannot be tallied over multiple dayparts or multiple intervals to give a unique tally for the combined timeframes.  The reason is that the CUME number (and the Session numbers) needs to be specific and unique to the specific connections in a specific day, week, or month and they must also be unique to a given daypart. 

So, looking at a specific example, the CUME number in the Webcast Metrics reports is unique only to the selected daypart and interval.  Since the numbers MUST be unique they can't be summed.  If, for example, you were to try to sum the Mid-6a M-F CUME number with the M-F 6a-Mid number those would not, and should not equal, the Cume number that is reported when you run the report M-F 12a-12Mid.

So, let’s say that 100 people start their session between Mid-6A giving you a unique CUME of 100 for the entire daypart.  If 50 of them stop listening at 5:45AM.  That leaves 50 already connected when the second daypart starts at 6AM.  And let’s expand that to say that 200 people make new connections and stay connected for at least 1 minute from 6a-mid.  That’s 250 for that specific daypart. 

But when we pull the individual reports for all of the individual dayparts we get the following:

Mid-6A = 100 – total unique IP’s that listened during this specific daypart

6a-Mid = 250 – Total unique IP’s that listened during this daypart

But if we run a 12a-12Mid report the Cume is reported as 300 because these are the unique IP’s that connected during the entire time frame.  We don’t get 350 which is the sum of the two segmented dayparts.

We hope that helps.  Please let us know if you need any further assistance whatsoever.