Senior interview questionAsked at DoorDash · interview write-up
Predict whether a delivery will be late at order-creation time: define the target, build a leakage-free time-based split, and choose features and metrics.
Model answer
Target: delivered later than the promised time plus a tolerance agreed with the business. Features may only use what's known at order creation: store prep history, current queue, nearby courier supply, distance, weather, time. Anything later, like actual pickup time, is leakage.
Split by time: train on earlier weeks, validate on later ones, with a gap so labels and aggregates don't overlap, and compute aggregates point-in-time. Metrics: PR-AUC for the rare class, calibration if the probability feeds ETAs, and recall at the alert volume ops can handle.
Practise the rest
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