Compare 30-day retention by channel, not just signups
The channel with the most signups is often the one with the worst retention. Score channels on people still here at day 30.
Step 4.1.4
Time: 2h
Done when
List each channel with its signups and how many were still active on day 30. Every channel has both numbers; a channel under 10 signups is marked too small to read. (Proof: a list of the items.)