task Cohorts & retention · hard

Next-month retention by signup cohort

Group shoppers into cohorts by signup month. A shopper is retained if they placed a non-cancelled order in the calendar month after their signup month. Return cohort_month, cohort_size, retained and retention_pct.

what to return

Columns

cohort_monthcohort_sizeretainedretention_pct in this order

Rows

2 rows · any order

Watch for

cohort_month is YYYY-MM; cohort_size counts every shopper who signed up that month, even those who never ordered.

Only include cohorts whose following month ends on or before 2025-03-31 (later months aren't fully observed).

retention_pct is 0–100 with 2 decimals.

Skill

Build a cohort retention table with a maturity rule. Refresher: Dates & monthly analysis →

expected result

Your query should return exactly these columns and values. Run it and compare.

data you can query

Sample rows from each table. Each column shows its type underneath; → marks a link to another table.