Stripe·Data Scientist·Technical Phone Screen
- Write a single PostgreSQL query using CTEs to detect weekly chargeback spikes by country and industry. You need to compute GMV, active merchants, succeeded payment counts, a lagged chargeback rate, week-over-week change in that rate, and top merchant GMV concentration, then filter to rows where the WoW chargeback rate increase exceeds 50% and the top merchant share is below 40%. Weeks start Monday using ISO week truncation. Handle late-arriving chargebacks by joining through payment_id rather than chargeback timestamp alone.
“This one took me a minute to even parse.”