Interpret a statistically significant lift of 2% from an experiment

Last updated: April 22, 2026

Quick Overview

An experiment shows conflicting results. What conclusions can you draw? What are the caveats?

Postmates
Analytics & Experimentation
Data Scientist
Postmates
April 22, 2026
Data Scientist
Take-home Project
Analytics & Experimentation
Medium

32

3

4,568 solved


An experiment shows conflicting results. What conclusions can you draw? What are the caveats?

Analytics questions at Postmates evaluate your ability to define metrics, design experiments, and derive actionable insights from data. This Take-home Project question tests your end-to-end analytical thinking.

What the Interviewer Expects
  • Design a rigorous experiment with proper randomization and sample size calculation
  • Define primary and guardrail metrics with clear rationale
  • Address novelty effects, network effects, and interference
  • Segment results appropriately and identify heterogeneous treatment effects
  • Propose follow-up analyses when results are ambiguous
Key Topics to Cover
A/B testing methodology
Segmentation and heterogeneous effects
Simpson's paradox and ecological fallacy
Guardrail metrics
Funnel analysis and cohort analysis
How to Approach This
  1. Define success metrics carefully. A good metric is measurable, actionable, and aligned with business goals.
  2. Run experiments long enough to account for novelty effects and weekly seasonality.
  3. Use funnel analysis to identify where users drop off for maximum optimization impact.
  4. Segment results by key dimensions (platform, country, user cohort) to catch hidden patterns.
  5. Consider network effects and interference between treatment and control groups.
Possible Follow-up Questions
  • What if you discover a bug in the logging during the experiment?
  • What if the experiment shows a positive short-term effect but you suspect a negative long-term impact?
  • What would you do if a stakeholder wants to end the experiment early because initial results look good?
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