What is the difference between a cohort retention chart and churn rate?
Churn rate is a single percentage that averages behavior across every active customer in a period, which blends new cohorts and old cohorts together. A cohort retention chart separates those cohorts and shows the retention curve of each one as it ages. Churn rate is a scalar, cohort retention is a trajectory. The chart catches deterioration in newer cohorts that a blended churn rate hides until the base turns over.