Cohort Retention & Power-User Curve

Goal: analyze cohort retention and power-user curve. Data: GA4 users and events, subscription logs if applicable. Steps: 1) Build weekly cohorts by first_visit; 2) Compute W1–W12 retention; 3) Plot power-user curve (events per user per week); 4) Segment by acquisition channel. Output: retention heatmap + target cohort improvements.