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DoorDash·Data Scientist·Technical Phone Screen·Senior

Senior
Jul 2026

Summary

DoorDash data scientist interview with a product analytics case built around a geo-targeted feature launch. The core of it was interpreting a retention chart under data constraints, which sounds manageable until you're actually in it.

Questions Asked (2)

Q1

You're evaluating whether to launch a new geo-targeted feature with limited traffic data. Walk through how you'd build the business case: what data you'd need, which metrics matter, and how you'd define success.

Product Analytics & MetricsProduct StrategyA/B Testing & Experimentation
Author's notes

I started with the metrics layer and worked backward, which felt right in the moment but I think I skipped over some data availability assumptions too quickly.

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AI HintsAI Generated

Suggested Approach

Start by framing the business problem and the decision at hand, then outline the data and metrics you'd use to evaluate the feature's potential. Emphasize a hypothesis-driven approach that accounts for limited data, such as using proxies, Bayesian methods, or staged rollouts. Conclude with how you'd define success and make a recommendation.

Pro tip: Acknowledge the data limitation upfront and propose a pragmatic approach like a pilot in a few markets with a holdout group, rather than waiting for perfect data. This shows you can balance rigor with business velocity.

1. Clarify the business objective and decision

Understand what problem the geo-targeted feature solves and what decision needs to be made (e.g., launch, iterate, or kill). Align with stakeholders on the goal and constraints.

2. Identify required data and assess availability

List the data needed (e.g., historical geo-level performance, user behavior, market characteristics) and evaluate what's available versus what can be proxied or collected quickly.

3. Define success metrics and guardrails

Select primary metrics (e.g., conversion, order frequency) and guardrail metrics (e.g., delivery time, customer satisfaction) that reflect the feature's impact and potential risks.

4. Design a pragmatic evaluation plan

Propose a test design that works with limited data, such as a geo-based A/B test, switchback experiment, or Bayesian analysis with priors. Include sample size and duration considerations.

5. Synthesize findings and recommend next steps

Interpret results with confidence intervals and sensitivity analysis, then provide a clear recommendation (e.g., launch, iterate, or gather more data) with expected impact and risks.

Key Points to Mention

  • Use of proxy metrics or Bayesian methods to handle limited data
  • Importance of guardrail metrics to avoid negative side effects
  • Consideration of network effects and interference in geo-based tests
  • Staged rollout or pilot approach to mitigate risk
  • Alignment with business KPIs like ROI, market share, or customer retention
  • Statistical power and minimum detectable effect given data constraints

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

Q2

Looking at a retention curve comparing test vs. control groups, what hypotheses can you pull from it and what would you do next?

A/B Testing & ExperimentationProduct Analytics & MetricsRoot Cause Analysis
Author's notes

This part tripped me up more than I expected.

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AI HintsAI Generated

Suggested Approach

Start by describing what a retention curve shows and how to compare test vs. control. Then, systematically generate hypotheses based on the shape, magnitude, and timing of differences, and outline a plan to validate them using additional data and statistical tests.

Pro tip: Focus on the timing of divergence—early differences suggest onboarding or initial experience issues, while later differences point to long-term value or habit formation. Also, consider novelty effects and ensure your retention metric is correctly defined (e.g., day-7 retention vs. rolling retention).

1. Understand the retention curve

Explain that a retention curve plots the percentage of users still active over time. Compare test and control curves to identify if they diverge and when.

2. Identify patterns and anomalies

Look for differences in early retention (first few days), long-term retention (flattening of curve), or crossing curves. Note if the test group performs better or worse.

3. Generate hypotheses

Based on the pattern, hypothesize why the difference exists. For example, early divergence might indicate onboarding issues; later divergence might suggest changes in user engagement or value perception.

4. Validate hypotheses with additional data

Propose analyses such as segmenting by user demographics, checking engagement metrics, or running statistical tests to confirm if the difference is significant.

5. Decide next steps

If the test is positive, consider scaling; if negative, investigate root causes. Suggest further experiments to isolate the cause or improve the feature.

Key Points to Mention

  • Statistical significance and confidence intervals to ensure the difference is not due to chance.
  • Segment analysis to see if the effect varies across user groups (e.g., new vs. existing users, regions).
  • Consideration of novelty effects and seasonal trends that might confound results.
  • Alignment with business metrics like order frequency, customer lifetime value, or churn rate.
  • Potential root causes: changes in user experience, feature adoption, or external factors.
  • Recommendation for follow-up experiments or deeper dive if results are ambiguous.

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