Understand all on 1,2,3,4,5 and 7.
For the above question. Perhaps it should consider growth % based on rebills/converts and initals... For example ...
Site A has 100 members, at 10.00 per month, with an average of 25 new members per month and average membership retention rate of 80%. (using easy math here).
It would project 12 months
Month 1: 100*10.00 + 25*10.00 = 1,250.00 (members * $ + new * $) $ = the average income earned per member each month (because some may have different price ranges).
Month 2: 125 (members) - 12.5 (80% retention) + 25 (new memberships) = 137.5 * 10.00 = 1375.00
Month 3: 137.5 - 17.1 + 25 = 145.4 * 10.00 = 1454.00
and so on....
This was a quick 5 minute idea on, the members, average memberships per month and retention rates. The numbers will probably always be changing number based on overall averages, so the above is more of a static example.
I currently have an excel that averages my retention rates, average membership income earned, conversion rates based on traffic and page views, average rebills, average conversions, average initial bills. I have not figured out the best formula to use to project yet, but haven't tried all that hard. Biggest issue I have right now is I have to import by hand each membership billed (initial, rebill, conversion), all traffic data and a few other points. KVS has all the data I need currently within the script to generate everything I use for my excel sheets.
Just a thought... a quick on page line graph with a few statistical averages and projections may do the trick.