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DoorDash·Data Scientist·Technical Phone Screen·Senior

SeniorPrefer not to say
May 2026Los Angeles

Summary

DoorDash data science interview, one big case question about a metric drop in the LA market. The whole thing was a single sprawling problem with six sub-parts that kept going deeper. Felt like a marathon.

Questions Asked (6)

Q1

Successful orders per day in the LA market has dropped over the past two weeks compared to the prior four-week baseline. How would you first verify the decline is real and not caused by data pipeline issues, seasonality, or a mix shift?

Product Analytics & MetricsRoot Cause Analysis
Author's notes

This is where I spent too long.

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AI HintsAI Generated

Suggested Approach

Start by validating the data pipeline and metric definition to rule out instrumentation or ETL issues, then decompose the decline by isolating seasonality and mix shift effects. Use statistical tests and cohort analyses to confirm the decline is real and identify its drivers before jumping to conclusions.

Pro tip: Always check if the decline is uniform across all sub-segments or concentrated in specific ones—a uniform drop often signals a data issue, while a concentrated drop points to a real behavioral or operational change.

1. Validate Data Pipeline and Metric Definition

Check for data freshness, completeness, and consistency across sources. Verify that the metric 'successful orders per day' is defined and calculated identically in both periods, and look for any recent changes in logging or ETL jobs.

2. Isolate Seasonality Effects

Compare the two-week decline against the same period in previous years or use seasonal decomposition (e.g., STL) to adjust for weekly and yearly patterns. If the decline persists after seasonal adjustment, it's likely not just seasonality.

3. Decompose by Mix Shift

Break down the metric by key dimensions (e.g., customer segment, restaurant type, order channel, geography) to see if the decline is driven by a change in the mix of orders rather than a true drop in each segment.

4. Run Statistical Tests for Significance

Use hypothesis testing (e.g., t-test, Mann-Whitney U) or control charts to determine if the decline is statistically significant and not due to random variation. Consider confidence intervals and effect size.

5. Cross-Validate with External and Internal Benchmarks

Compare with other markets, overall company trends, or external industry data to see if the decline is LA-specific. Also check if similar declines appear in other metrics (e.g., sessions, conversion) to infer if it's a real behavioral shift.

Key Points to Mention

  • Data pipeline validation: check for missing data, duplicate records, and changes in logging.
  • Seasonality adjustment: use time-series decomposition or year-over-year comparisons.
  • Mix shift analysis: segment by customer, restaurant, channel, and geography to detect composition changes.
  • Statistical significance: apply appropriate tests and consider multiple comparisons.
  • Metric definition consistency: ensure 'successful orders' is defined the same way across periods.
  • Cross-validation: compare with other markets and metrics to rule out isolated data issues.

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

Q2

Give one plausible hypothesis for the drop from each side of the marketplace: the customer side, the restaurant side, and the dasher side.

Root Cause AnalysisProduct Analytics & Metrics
Author's notes

Liked this part.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the metric and time frame of the drop, then structure your answer around the three sides of the marketplace. For each side, propose one plausible hypothesis that is specific, testable, and grounded in common marketplace dynamics. Briefly explain how you would validate each hypothesis to show analytical rigor.

Pro tip: Acknowledge that a single drop often has interconnected causes across sides, but since the question asks for one per side, pick hypotheses that are distinct and avoid overlap. This demonstrates you can isolate variables while understanding systemic effects.

1. Clarify the scenario

Ask clarifying questions about the metric (e.g., orders, active users), the magnitude and duration of the drop, and whether it's global or segmented. This ensures your hypotheses are relevant.

2. Customer side hypothesis

Propose a plausible reason for reduced customer activity, such as a new competitor promotion, a recent app update causing friction, or seasonal demand shift. Explain the mechanism.

3. Restaurant side hypothesis

Propose a plausible reason for reduced restaurant participation or order fulfillment, such as increased commission fees leading to churn, or supply chain issues affecting menu availability.

4. Dasher side hypothesis

Propose a plausible reason for reduced dasher supply or productivity, such as a change in pay structure, increased gas prices, or a new competing delivery platform offering better incentives.

5. Validation approach

Briefly outline how you would test each hypothesis using data (e.g., cohort analysis, A/B tests, external benchmarks) to confirm or rule out causes.

Key Points to Mention

  • Marketplace dynamics: interdependencies between customers, restaurants, and dashers.
  • Specificity: hypotheses should be concrete and testable, not vague.
  • Data validation: mention metrics or experiments to confirm hypotheses.
  • External factors: consider seasonality, competition, and macroeconomic trends.
  • Internal changes: recent product updates, pricing changes, or policy shifts.
  • Segmentation: consider if the drop is uniform or affects specific geographies or user groups.

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

Q3

If all three hypotheses seem to be contributing to the decline, how would you quantify the impact of each one on the overall drop in successful orders?

Product Analytics & MetricsRoot Cause Analysis
Author's notes

Blanked a bit here.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the metric definition and the time period, then propose a decomposition framework that isolates each hypothesis's contribution to the decline. Use a combination of causal inference methods (e.g., difference-in-differences, propensity score matching) and sensitivity analysis to quantify the impact of each factor.

Pro tip: Emphasize that quantifying impact requires a counterfactual—what would have happened if the factor were absent—and that you'd validate assumptions with robustness checks and business context.

1. Define the metric and scope

Clarify what 'successful orders' means (e.g., completed orders, on-time deliveries) and the time frame and segments affected. Ensure alignment on the decline magnitude and data sources.

2. Formalize hypotheses and causal model

Translate each hypothesis into a measurable variable (e.g., delivery time, restaurant availability, Dasher supply) and map their relationships in a causal diagram (DAG) to identify confounders and mediators.

3. Choose quantification method

Select appropriate methods such as regression with interaction terms, difference-in-differences, or mediation analysis to estimate each factor's marginal contribution while controlling for others.

4. Estimate and decompose impact

Run models to estimate the effect of each factor on the decline, then decompose the total drop into attributable components (e.g., using Shapley values or sequential attribution).

5. Validate and communicate

Perform sensitivity analyses, check for interactions, and validate with holdout or A/B test data if available. Present findings with confidence intervals and business implications.

Key Points to Mention

  • Counterfactual reasoning: what would have happened without each factor?
  • Control for confounders and avoid omitted variable bias
  • Use of causal inference techniques (DiD, propensity scores, instrumental variables)
  • Decomposition methods like Shapley values or mediation analysis
  • Sensitivity analysis and robustness checks
  • Business context and actionable insights for stakeholders

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

Q4

Walk through the funnel you would build to diagnose this drop. What metrics would you track at each step and how would you pinpoint where the biggest loss is occurring?

Product Analytics & MetricsRoot Cause Analysis
Author's notes

This felt like the core of the question and I think I did okay.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scenario—what drop, over what time period, and for which user segment—then structure your answer around a standard funnel (e.g., acquisition, activation, engagement, retention, monetization) and specify the key metrics at each stage. Emphasize a systematic diagnostic process: segment the data, compare time periods, and use statistical tests to isolate the largest drop-off and its root cause.

Pro tip: Always tie the funnel to the specific business model (e.g., for DoorDash, focus on order funnel: app open → store view → add to cart → checkout → order placed → delivery completed) and mention that you'd validate findings with A/B tests or holdout groups before recommending action.

1. Clarify the problem and scope

Ask clarifying questions to understand the drop: which metric, time frame, platform, and user segment. Define the funnel stages relevant to the product (e.g., for DoorDash: app open, search, store page view, add to cart, checkout, order placed, delivery).

2. Map metrics to each funnel stage

Assign key metrics to each stage: e.g., DAU/MAU for acquisition, conversion rates between stages, average order value, delivery time, and retention rates. Ensure metrics are actionable and aligned with business goals.

3. Analyze drop-offs and segment

Calculate conversion rates at each step and identify the largest drop. Segment by dimensions like device, geography, user cohort, and time to see if the drop is concentrated in a specific group.

4. Pinpoint root cause with statistical methods

Use statistical tests (e.g., t-test, chi-square) to compare periods and segments. Investigate external factors (e.g., seasonality, competitor actions) and internal factors (e.g., app changes, pricing) to isolate the cause.

5. Validate and recommend actions

Propose hypotheses and validate with A/B tests or holdout groups. Recommend targeted fixes and define success metrics to monitor post-intervention.

Key Points to Mention

  • Funnel stages specific to DoorDash (e.g., app open → search → store view → add to cart → checkout → order placed → delivery completed)
  • Key metrics per stage: conversion rates, drop-off rates, time between steps, average order value, delivery time
  • Segmentation by user cohort, device, geography, and time to identify concentrated drops
  • Statistical significance testing to avoid false positives
  • Root cause analysis techniques: cohort analysis, funnel visualization, hypothesis testing
  • Validation via A/B tests and monitoring post-change

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

Q5

Based on the likely root causes you've identified, what product or operational changes would you propose?

Product Sense & IdeationProduct Strategy
Author's notes

I suggested a few things: dynamic dasher incentives when supply dips in specific zones, better ETA confidence intervals shown to customers before checkout, and smarter restaurant availability surfacing so closed restaurants don't show up.

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AI HintsAI Generated

Suggested Approach

Start by briefly recapping the root causes you identified, then propose changes that directly address each cause, prioritizing by impact and feasibility. Structure your answer around a clear framework that connects each change to a measurable outcome and considers trade-offs.

Pro tip: Tie every proposed change to a specific metric it should move (e.g., order completion rate, delivery time) and acknowledge potential second-order effects, showing you think like an owner, not just an analyst.

1. Recap root causes

Briefly restate the key root causes you identified earlier to ground your proposals in evidence. This ensures your changes are clearly linked to the problem.

2. Prioritize causes by impact

Rank the root causes based on estimated impact on the key metric and ease of implementation. This helps you focus on the most critical changes first.

3. Propose product changes

Suggest specific product features or modifications that directly address the prioritized causes. For each, explain how it solves the problem and what metric it should improve.

4. Propose operational changes

Recommend process or policy adjustments (e.g., dasher incentives, restaurant partnerships) that complement product changes. Highlight how they work together.

5. Define success metrics and trade-offs

Specify how you would measure the success of each change and discuss potential trade-offs or risks. This shows a balanced, data-driven approach.

Key Points to Mention

  • Direct linkage between each proposed change and the root cause it addresses
  • Prioritization based on impact vs. effort (e.g., using an impact/effort matrix)
  • Specific metrics to track (e.g., order completion rate, delivery time, customer satisfaction)
  • Consideration of trade-offs (e.g., cost, complexity, potential negative side effects)
  • Cross-functional collaboration (e.g., with engineering, operations, marketing)
  • Iterative testing approach (e.g., A/B tests, pilot programs) to validate changes

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

Q6

Pick one of your proposed improvements and design an A/B test for it. Cover the unit of randomization, primary metric, guardrail metrics, experiment duration, and any interference, power, or bias concerns.

A/B Testing & ExperimentationProduct Analytics & Metrics
Author's notes

I picked the dasher incentive idea and immediately ran into the randomization problem.

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AI HintsAI Generated

Suggested Approach

Choose a concrete improvement from your earlier proposals that is testable and relevant to DoorDash, such as a new dasher incentive or a checkout flow change. Structure your answer by walking through each required element—randomization unit, primary metric, guardrails, duration, and concerns—while tying them back to the specific improvement and DoorDash's marketplace dynamics.

Pro tip: Demonstrate awareness of DoorDash's two-sided marketplace by addressing interference between consumers, dashers, and merchants, and propose mitigation like cluster randomization or switchback tests. Also, mention practical constraints like novelty effects and the need for a pre-experiment power analysis.

1. State the improvement and hypothesis

Briefly describe the chosen improvement and articulate a clear, testable hypothesis about its impact on a key metric.

2. Define randomization unit and metrics

Specify the unit of randomization (e.g., user, dasher, store) and justify it. Identify the primary metric (e.g., conversion, order volume) and guardrail metrics (e.g., delivery time, cancellation rate).

3. Determine experiment duration and sample size

Explain how you would calculate the required sample size and duration, considering baseline rates, minimum detectable effect, and power. Mention accounting for weekly seasonality.

4. Address interference, power, and bias concerns

Discuss potential interference (e.g., network effects, cannibalization), power limitations, and biases (e.g., novelty, selection). Propose mitigation strategies.

5. Conclude with success criteria and next steps

Summarize what results would lead to a launch decision and mention any follow-up analyses or iterations.

Key Points to Mention

  • Unit of randomization: justify choice based on improvement (e.g., user-level for consumer-facing changes, dasher-level for incentives) and consider cluster randomization if interference is likely.
  • Primary metric: align with business goal (e.g., order completion rate, gross bookings) and ensure it's sensitive to the change.
  • Guardrail metrics: include marketplace health metrics like delivery time, dasher utilization, and customer satisfaction to detect negative side effects.
  • Experiment duration: account for weekly cycles, novelty effects, and sufficient power; typically 1-2 weeks minimum.
  • Interference: address two-sided marketplace effects (e.g., dasher supply affecting consumer experience) and propose designs like switchback or geo-based tests.
  • Power and bias: mention pre-experiment power analysis, avoid peeking, and control for multiple testing if using multiple metrics.

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