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DoorDash·Data Scientist·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

DoorDash data science interview with a product analytics case centered on a real operational problem. The question was meaty and covered a lot of ground, which I wasn't fully prepared for.

Questions Asked (1)

Q1

DoorDash is seeing a surge in complaints about food arriving cold. How would you diagnose the root cause, what metrics would you track, and how would you design an A/B test to validate a fix?

Root Cause AnalysisProduct Analytics & MetricsA/B Testing & Experimentation
Author's notes

This question is three questions stitched together and I didn't realize that until I was halfway through the diagnosis part.

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AI HintsAI Generated

Suggested Approach

Start by segmenting the problem to identify where cold food complaints concentrate (e.g., by restaurant, dasher, region, time, order type). Then define a metric tree that connects delivery time components to food temperature, and design an A/B test that isolates a specific intervention with clear success metrics and guardrails.

Pro tip: Emphasize that temperature is a proxy for delivery time and handling; use existing data to triangulate the root cause before jumping to solutions. Also, consider that a fix might involve trade-offs (e.g., faster delivery vs. cost) and design the experiment to measure both impact and cost.

1. Segment and Explore

Break down complaints by dimensions like restaurant, dasher, region, time of day, order size, and delivery distance to find patterns. Use funnel analysis to see where delays occur (e.g., food prep, dasher wait, transit).

2. Define Metrics

Establish a metric tree: top-level metric (e.g., % orders reported cold), driver metrics (delivery time, time to accept, wait time at restaurant, transit time), and guardrail metrics (customer satisfaction, cost per delivery).

3. Hypothesize Root Cause

Based on segmentation, form hypotheses (e.g., long dasher wait times at restaurants, inefficient routing, lack of insulated bags). Prioritize by impact and feasibility.

4. Design A/B Test

Choose a specific intervention (e.g., incentivizing dashers to use insulated bags, optimizing dispatch). Randomize at the order or dasher level, define control and treatment, set sample size and duration, and specify primary and guardrail metrics.

5. Analyze and Iterate

Analyze results for statistical significance and practical impact. Check for heterogeneous treatment effects and guardrail metrics. If successful, consider rollout; if not, iterate on hypotheses.

Key Points to Mention

  • Segmentation by restaurant, dasher, region, time, and order characteristics to localize the issue.
  • Metric tree linking delivery time components (prep, wait, transit) to food temperature.
  • Use of proxy metrics (e.g., delivery time) when direct temperature data is unavailable.
  • A/B test design with proper randomization unit (order vs. dasher), sample size calculation, and guardrail metrics.
  • Consideration of trade-offs: faster delivery may increase cost or reduce dasher utilization.
  • Importance of checking for novelty effects and ensuring experiment validity (e.g., no contamination between groups).

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.