Interpret a statistically significant lift of 2% from an experiment

Last updated: July 14, 2025

Quick Overview

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

Workday
Analytics & Experimentation
Data Scientist
Workday
July 14, 2025
Data Scientist
Technical Screen
Analytics & Experimentation
Medium

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1,853 solved


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

This analytics question from Workday's Technical Screen tests your ability to think critically about data. The interviewer expects you to consider confounding variables, selection bias, and the difference between correlation and causation.

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
Long-term vs short-term metrics
Metric definition and success criteria
Network effects and interference
Simpson's paradox and ecological fallacy
Funnel analysis and cohort analysis
A/B testing methodology
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 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?
  • What if you discover a bug in the logging during the experiment?
  • How would you handle an experiment where the control and treatment groups are different sizes?
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