eCPM calculation on dashboard could be better

I've been doing this for a month, and my eCPM has been all over the place. Because the revenue calculation takes days to determine, and the impression count is much faster to report, you end up with incompatible data sets with which to calculate eCPM.

Usually revenue comes in little packages, and impression count is reported continuously. So as you gain more impressions since you got paid, your eCPM appears to go way down, and when you get a new revenue package it goes up again.

My reported eCPM has fluctuated from $7 to $1, and I have no clue what it really is. Would it be better, instead of making eCPM a calculated field, to use only the impression count that led to that payment? Then you could average the amount from previous payments in a given time window.

So an eCPM data point would be 1000/impressions-since-last-payment * payment. I think this would give a much clearer idea of how you are doing.