Explain p-value with an example
Last updated: July 21, 2025
Quick Overview
Explain p-value in simple terms and provide a concrete example.
Cloudflare
July 21, 20255
5
3,744 solved
Explain p-value in simple terms and provide a concrete example.
Cloudflare asks this during the Take-home Project to assess your experimentation skills. They want to see how you define success metrics, design controlled experiments, and interpret results with appropriate statistical rigor.
What the Interviewer Expects
- Define clear success metrics aligned with business goals
- Propose a basic experimental design with control and treatment groups
- Interpret results correctly and draw reasonable conclusions
- Identify obvious confounding variables
Key Topics to Cover
How to Approach This
- Define success metrics carefully. A good metric is measurable, actionable, and aligned with business goals.
- Run experiments long enough to account for novelty effects and weekly seasonality.
- Use funnel analysis to identify where users drop off for maximum optimization impact.
- Segment results by key dimensions (platform, country, user cohort) to catch hidden patterns.
- Consider network effects and interference between treatment and control groups.
Possible Follow-up Questions
- How would you handle interference between treatment and control?
- How would you handle an experiment where the control and treatment groups are different sizes?
- What would you do if a stakeholder wants to end the experiment early because initial results look good?
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