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Uber·Data Scientist·Technical Phone Screen·Senior

Senior
May 2026

Summary

Uber DS interview with a meaty experimentation question around surge pricing push notifications. The whole thing was basically one big causal inference puzzle and it went deeper than I expected.

Questions Asked (1)

Q1

Design an experiment to measure the causal impact of surge pricing push notifications on resolving driver supply shortages at airports. Cover your success metrics, how you'd set up the A/B test at the driver level, how you'd handle spillover between treatment and control, and how you'd actually establish causality.

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

This one had layers.

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AI HintsAI Generated

Suggested Approach

Start by defining the causal question and the primary metric (e.g., driver supply shortage resolution rate), then design a driver-level randomized experiment with careful consideration of spillover effects. Use techniques like cluster randomization or spatial separation to mitigate interference, and analyze with methods that account for spillover, such as difference-in-differences or instrumental variables, to establish causality.

Pro tip: In marketplace experiments, spillover is the norm, not the exception. Proactively address it by randomizing at a level where interference is minimized (e.g., airport clusters) and measure both direct and indirect effects to avoid underestimating the treatment effect.

1. Define the causal question and metrics

Clearly state the treatment (surge pricing push notifications) and the outcome (driver supply shortage resolution). Choose primary metrics like time-to-resolve shortage, number of drivers responding, and secondary metrics like driver earnings and rider wait times.

2. Design the experiment with spillover in mind

Randomize at the driver level, but account for spillover by using cluster randomization (e.g., by airport or time block) or by measuring spillover explicitly. Consider a two-sided experiment where control drivers are also monitored for changes due to treatment drivers' behavior.

3. Implement and monitor the experiment

Ensure proper randomization, sample size calculation, and power analysis. Monitor for compliance and potential interference during the experiment, and collect data on driver responses and supply metrics.

4. Analyze with causal methods

Use difference-in-differences, instrumental variables, or causal forests to estimate the treatment effect while adjusting for spillover. Compare treated vs. control groups and assess heterogeneity in treatment effects.

5. Validate and interpret results

Check for robustness, conduct sensitivity analyses, and ensure that the results are not driven by confounding factors. Interpret the causal impact in the context of business goals and potential policy implications.

Key Points to Mention

  • Randomization unit: driver-level vs. cluster-level to handle spillover
  • Spillover effects: how treatment can affect control drivers (e.g., via shared airport supply)
  • Primary metric: driver supply shortage resolution rate or time-to-resolve
  • Secondary metrics: driver earnings, rider wait times, acceptance rates
  • Causal inference methods: difference-in-differences, instrumental variables, or switchback experiments
  • Sample size and power analysis to detect meaningful effects

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