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DoorDash·Data Scientist·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026Remote

Summary

DoorDash data science interview focused on a classic ops debugging scenario. One question, but it had a lot of layers and I felt like I was barely scratching the surface by the time they moved on.

Questions Asked (1)

Q1

Driver wait times at restaurants spiked last week compared to the prior week. How would you debug this, and if you confirm restaurant understaffing is the cause, what would you do about it?

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

I jumped straight to restaurant-level breakdowns and forgot to first sanity-check whether the spike was even real, like ruling out a logging bug or a change in how wait time is measured.

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AI HintsAI Generated

Suggested Approach

Start by validating the metric and checking for data pipeline issues, then segment the spike by time, geography, restaurant, and driver cohorts to isolate the root cause. If understaffing is confirmed, propose a data-driven solution such as dynamic incentives or staffing recommendations, and design an experiment to measure impact.

Pro tip: Frame your answer around the scientific method: hypothesis, test, and iterate. Mention that correlation doesn't imply causation and that you'd rule out alternative explanations like weather or app changes before concluding understaffing.

1. Validate the Metric and Data

Check if the spike is real by verifying data quality, pipeline integrity, and metric definitions. Ensure no logging errors or changes in data collection occurred.

2. Segment and Explore

Break down wait times by dimensions like time of day, region, restaurant, and driver tenure to identify patterns. Look for correlations with other metrics like order volume or restaurant prep times.

3. Form and Test Hypotheses

List potential causes (e.g., understaffing, increased demand, app issues) and use data to test each. For understaffing, check if restaurants with higher wait times have lower staff levels or longer prep times.

4. Confirm Understaffing and Quantify Impact

If understaffing is likely, quantify its effect by comparing wait times at understaffed vs. adequately staffed restaurants. Use statistical methods to estimate the contribution.

5. Propose and Test Solutions

Suggest interventions like dynamic driver incentives, restaurant staffing recommendations, or order throttling. Design an A/B test to measure the impact of the chosen solution.

Key Points to Mention

  • Data validation: check for logging errors, pipeline issues, or metric definition changes.
  • Segmentation: analyze by time, geography, restaurant, and driver cohorts to isolate the cause.
  • Hypothesis testing: rule out alternative explanations like weather, promotions, or app updates.
  • Understaffing confirmation: correlate wait times with restaurant staffing levels or prep time metrics.
  • Solution design: propose dynamic incentives, staffing alerts, or order throttling based on data.
  • Experimentation: A/B test the solution to measure effectiveness and avoid unintended consequences.

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