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Diagnose and reduce cold-food refund costs

Last updated: Mar 29, 2026

Quick Overview

This question evaluates data science competencies in analytics, experimentation, and causal inference, including cost modeling, diagnostic analysis, policy design, offline counterfactual evaluation, and rollout decision-making.

  • hard
  • DoorDash
  • Analytics & Experimentation
  • Data Scientist

Diagnose and reduce cold-food refund costs

Company: DoorDash

Role: Data Scientist

Category: Analytics & Experimentation

Difficulty: hard

Interview Round: Technical Screen

DoorDash faces an ongoing high cost from 100% refunds on cold-food complaints. Design a plan to reduce monetary impact while preserving customer trust. Be specific: (a) Decompose cost into volume × complaint rate × refund amount and define a primary success KPI (e.g., average cold-food refund cost per order) plus guardrails (e.g., re-order rate, CSAT, complaint re-open rate, fraud flags). (b) List at least five diagnostic analyses you would run to identify drivers (e.g., lateness vs. promised time, store prep time vs. travel time, order value, distance, courier wait at pickup, cuisine, packaging/thermal-bag usage, weather, time-of-day, repeat complainers). (c) Propose a tiered refund policy where refund percentage is a function of lateness and order value; specify exact thresholds (e.g., <10 min late = 0%, 10–29 min = 50%, ≥30 min = 100%; cap at $X; exclude alcohol/ice cream, etc.) and justify with CX and fraud trade-offs. (d) Describe an offline policy evaluation using historical orders and refund logs to estimate savings and risks: cohorting, counterfactuals for orders that would newly receive partial refunds, selection bias (who complains), mislabeling of reasons, and censoring. (e) Provide a rollout strategy (city-level holdouts, sequential ramp, kill switch) and a pre-registered decision rule to ship (e.g., ≥8% cost reduction with no degradation on guardrails beyond set MDE thresholds).

Quick Answer: This question evaluates data science competencies in analytics, experimentation, and causal inference, including cost modeling, diagnostic analysis, policy design, offline counterfactual evaluation, and rollout decision-making.

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DoorDash logo
DoorDash
Oct 13, 2025, 9:49 PM
Data Scientist
Technical Screen
Analytics & Experimentation
4
0
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Case: Reducing Cost of Cold-Food Refunds While Preserving Trust

Context

DoorDash currently issues 100% refunds for all "cold-food" complaints, which drives significant cost. Design a data-driven plan to reduce the monetary impact while protecting customer trust and long-term usage.

Tasks

(a) Define the cost model and success metrics

  • Decompose total cost into volume × complaint rate × refund amount. Propose a primary success KPI (e.g., average cold-food refund cost per order) and guardrail metrics (e.g., re-order rate, CSAT, complaint re-open rate, fraud flags).

(b) Diagnostics to identify drivers

  • List at least five concrete diagnostic analyses to uncover drivers (e.g., lateness vs promised time, store prep time vs travel time, order value, distance, courier wait at pickup, cuisine, packaging/thermal-bag usage, weather, time-of-day, repeat complainers).

(c) Tiered refund policy

  • Propose a tiered policy where refund percentage is a function of lateness and order value. Specify exact thresholds (e.g., <10 min late = 0%, 10–29 min = 50%, ≥30 min = 100%; caps; exclusions like alcohol/ice cream). Justify trade-offs for customer experience and fraud risk.

(d) Offline policy evaluation

  • Describe how to evaluate the policy on historical orders and refund logs. Cover: cohorting, counterfactual refund computation (including orders that would newly receive partial refunds), selection bias (who complains), mislabeling of reasons, and censoring of outcomes.

(e) Rollout and decision rule

  • Provide a rollout strategy (city-level holdouts, sequential ramp, kill switch) and a pre-registered decision rule to ship (e.g., ≥8% cost reduction with no degradation on guardrails beyond set MDE thresholds).

Solution

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