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DoorDash·Data Scientist·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

DoorDash data science interview with a logistics-focused diagnostic case. The question was framed as a regional manager scenario but was clearly testing structured analytical thinking, not business intuition.

Questions Asked (1)

Q1

Successful deliveries in one territory dropped by 10%. How would you diagnose the root cause? Walk through how you'd slice the data, what hypotheses you'd form, and what statistical tests you'd run.

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

This one is deceptively wide.

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AI HintsAI Generated

Suggested Approach

Start by validating the 10% drop and defining the metric precisely, then systematically slice the data across dimensions like time, geography, and delivery characteristics to isolate where the drop is concentrated. Form hypotheses about potential causes (e.g., supply, demand, logistics, external factors) and prioritize them based on data patterns. Finally, use statistical tests to confirm or rule out each hypothesis, ensuring you account for seasonality, sample size, and multiple comparisons.

Pro tip: Always quantify the impact of the drop in business terms (e.g., lost revenue, affected customers) and consider whether the drop is statistically significant and practically meaningful before diving deep. Also, check for data pipeline issues or metric definition changes first—sometimes the 'drop' is an artifact.

1. Validate and Define the Metric

Confirm the 10% drop is real by checking data quality, metric definitions, and seasonality. Ensure you're comparing apples-to-apples (e.g., same time period, same territory definition).

2. Slice the Data

Break down the metric by dimensions such as time (daily/weekly trends), geography (sub-regions, zip codes), delivery type (restaurant vs. grocery), customer segments (new vs. returning), and operational factors (dasher supply, delivery times).

3. Form Hypotheses

Based on the slices, generate hypotheses for the root cause: e.g., increased competition, dasher shortage, restaurant closures, pricing changes, app issues, or external events (weather, holidays). Prioritize hypotheses by likelihood and potential impact.

4. Run Statistical Tests

Use appropriate tests to validate each hypothesis: e.g., t-tests for comparing means, chi-square for categorical shifts, regression to control for confounders, and time-series analysis for trends. Consider A/B tests if an intervention was made.

5. Synthesize and Recommend

Combine findings to identify the most probable root cause(s), quantify their impact, and propose actionable next steps or further experiments to confirm and address the issue.

Key Points to Mention

  • Check for data quality issues and metric definition changes before assuming a real drop.
  • Segment the data by time, geography, customer type, and delivery characteristics to localize the drop.
  • Consider both supply-side (dasher availability, restaurant capacity) and demand-side (customer behavior, competition) factors.
  • Use statistical tests like t-tests, chi-square, and regression to validate hypotheses and control for confounders.
  • Account for seasonality and external events (e.g., holidays, weather) that could explain the drop.
  • Quantify the business impact and prioritize causes by potential actionable solutions.

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