So the number you see is AI (audience impression).
Rolling is the NET GAIN compared to the previous week (7 days ago).
For example:
9/09, Day 1: 1.000 (Total: 1.000)
9/10, Day 2: +16.000 (Total: 17.000)
9/11, Day 3: +3.000 (Total: 20.000)
9/12, Day 4: +3.000 (Total: 23.000)
9/13, Day 5: +3.000 (Total: 26.000)
9/14, Day 6: +2.000 (Total: 28.000)
9/15, Day 7: +2.000 (Total: 30.000)
Here's an example what would happen on 9/16, Day 8.
The song would lose what it had from Day 1 (7 days ago). So that's -1.000. It would add whatever AI it had on 9/15, Day 8...let's say it has 1.500. The update would show the NET GAIN, therefore it would show +0.500 (-1.000 + 1.500 = +0.500).
So you would see:
9/16, Day 8: +0.500 (Total: 30.500)
Here's an example for what would happen on 9/17, Day 9.
The song would lose what it had from Day 2 (7 days ago). So that's -16.000. It would add whatever AI it had on 9/16, Day 9...let's say it has 1.500 again. The update would show the NET GAIN, therefore it would show -14.500 (-16.000 + 1.500 = -14.500).
So you would see:
9/17, Day 9: -14.500 (Total: 16.000)
When most people talk about ROLLING, they are talking about something like what will happen on Day 9. They mean the rolling effect will take place because there is such a big difference between what happened a week ago (+16.000) and what happened this week (+1.500). The difference is -14.500 (The song loses this much AI on Day 9).
Why is the rolling effect necesarry? I mean, that's how much the song gains in a day. Why do they have to substract how much it gained a week ago?
To keep a balance on the chart and keep it flowing. I'm assuming if you didn't have a system like that the songs would just be counted by amount of spins and they wouldn't have any metric to go down by.
So glad you're not delusional. Poor everyone else in here.
and tracking week ends tomorrow...
is impressive!