Add metrics for user churn

[hollomancer]

Feature

Why is this feature being added?

We need a way to measure user churn. Being able to measure our retention is critical, in order to know whether we're improving our ability to keep users active in Slack.

What should your feature do?

As staff, I want to see the number of inactive users per day, as well as the number of new joiners per day, so that I know “How many people joined the OC and did/did not join Slack?”

[hollomancer]

What further detail can I add to this?

[apex-omontgomery]

Per day you'd want :

1. Number of users who logged into website
2. Number of users who logged into slack
3. Number of users who did not log into slack
4. Number of users who signed up for website
5. Number of users who signed up for slack.

Details:

1. first one but we only retain 2 signins which can occur on same day.
2. This one is available using the slack api, and we can get historical data.
3. This could be done by querying slack user count on each day and use 2 for a simple delta.
4. This one is fairly easy to get with our current database.
5. Again this one we can also find but we don't have the data stored.

I'd also suggest tracking the number of slack users who went from billable = yes to billable = no, and the opposite as it would show users leaving and users returning. Additionally the slack metric for number of days active in the last 30 days.

[hollomancer]

User churn statistics - We get a lot of that from Slack analytics, but unfortunately it is not exposed in the Slack API that I know of.

I think that one should be split off into maybe a separate OC project, because I can see a lot of Slack workspaces benefiting from better usage analytics, that are exposed and not hidden behind Slack's API. Might be our first open source 'product'?

[apex-omontgomery]

Are the above KPI still the desired goal?