I'm trying to calculate average customer lifetime value of a membership site.
The data available to me is unfortunately either incomplete or very simplistic (or else I don't know how to extract the information needed).
Let's say I can find the total number of signups the site has ever had, plus the number of current members, how can deduct from that the average lifetime of a member?
Not really - you're missing a lot of key information. Most importantly, you don't know how long people stay around because you don't know when each person came and left.
Take a simple example and you'll see why:
Both of these are equally possible:
This is a simplistic example of course but multiply all the numbers by 1000 and it may be more realistic.