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Identify Key Drivers of Delivery Decline in Los Angeles

DoorDashData Scientist · Technical Screen
HardData ScientistTechnical ScreenAnalytics & Experimentation

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This interview question evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer for Identify Key Drivers of Delivery Decline in Los Angeles states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

Scenario

DoorDash sees a 10% drop in the number of completed deliveries in Los Angeles week-over-week.

Question

How would you identify, attribute, and quantify the key drivers behind the 10% delivery decline in LA?

  1. List the potential root causes and propose testable hypotheses across the supply, demand, merchant, product, external, and measurement dimensions.
  2. Outline an analytical plan to test each hypothesis — the data you would examine, the segmentation/cuts you would apply, and the method you would use.
  3. Quantify and attribute the −10% to its contributing drivers (e.g., via funnel/marketplace decomposition).
  4. If controlled experiments (A/B tests) are infeasible, describe the alternative approaches you would use to establish causal inference and validate your findings.
Hints

Think funnel analysis, supply vs. demand decomposition, segmentation by time/location/cohort, seasonality, competitor impact, and synthetic-control or time-series causal methods (DiD, BSTS/CausalImpact, event study, IV).