Interpret a statistically significant lift of 2% from an experiment

Last updated: March 2, 2026

Quick Overview

An experiment shows a 3% lift with p=0.08. What conclusions can you draw? What are the caveats?

Compass
Analytics & Experimentation
Data Scientist
Compass
March 2, 2026
Data Scientist
Phone Screen
Analytics & Experimentation
Medium

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4,981 solved


An experiment shows a 3% lift with p=0.08. What conclusions can you draw? What are the caveats?

Analytics questions at Compass evaluate your ability to define metrics, design experiments, and derive actionable insights from data. This Phone Screen 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
Funnel analysis and cohort analysis
A/B testing methodology
Long-term vs short-term metrics
Network effects and interference
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 would you do if a stakeholder wants to end the experiment early because initial results look good?
  • What if the experiment shows a positive short-term effect but you suspect a negative long-term impact?
  • How would you handle an experiment where the control and treatment groups are different sizes?
  • How would you handle seasonality in your experiment?
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