Why Account-Level Reporting Lies
Account level shows averaged ROAS. 4.2x looks fine. Cohort level reveals that week-1 buyers have a 5.8x ROAS while week-8 buyers are down to 2.1x. Only then do you see that the audience is running out. Account average had you blind.
How Cohort Allocation Works
Track each weekly cohort: ROAS trajectory, LTV, repeat rate. Weak cohorts trigger adjustments (audience swap, hook refresh). Top cohorts trigger a scaling push. Budget allocation follows cohort performance, not campaign performance.
A pet box brand introduced cohort reporting and lifted 6-month retention from 38% to 71%. Weak cohorts were reactivated with a care push; top cohorts were upsold with a loyalty tier pitch.
Setup Effort and ROI
Cohort reporting requires an engineering layer: export CRM or Klaviyo data into BigQuery, define weekly cohorts, and use Looker Studio as the front end. Setup takes 4 to 6 weeks, with ROI visible in the first cohort wave.
„Cohort reporting is not an optimization tool. It's a truth tool.”