Subscriptions
Cohort retention
Cohort retention measures what share of customers acquired in a given period are still active after each subsequent period, tracked separately per acquisition cohort.
It is the correct primary view because it separates effects a blended rate hides. An improving product with worsening acquisition quality can produce a flat overall churn number while both trends are large.
Cohorts should be cut by acquisition channel as well as date. Customers acquired through a heavy first-order discount retain differently from organically acquired ones, and blending them makes both unreadable.