A/B Testing Interview Questions
A/B testing questions are central to data science and product analytics interviews at companies like Meta, Google, Netflix, and Airbnb.
Expect questions on experiment design, randomization units, sample size calculation, multiple comparisons, and metric selection.
Interviewers evaluate your statistical rigor, practical judgment, and ability to communicate experiment results.
Common A/B testing interview patterns
- Designing an experiment for a product change
- Calculating sample size and experiment duration
- Choosing between one-sided and two-sided tests
- Handling multiple comparisons and peeking
- Interpreting results with novelty or primacy effects
- Network effects and interference between test groups
A/B testing interview questions
Estimate sales impact from reviews causally
Diagnose a 20% retail revenue drop
Define metrics for harmful-content severity
Investigate Reasons for Higher Instagram Story Consumption
Design marketplace experiments at DoorDash
Measure free-month promotion impact
Optimize amusement park pricing, capacity, and testing
Design an experiment with marketplace network effects
Design and assess an A/B test
Analyze Causes for 10% Decline in LA Deliveries
Explain P-Value and Errors in A/B Testing
Calculate Break-even for New Credit Card Product Launch
Evaluate Key Metrics for Biker-Dasher Program Success
Evaluate a credit-card acquisition partnership
Diagnose metric drop in Ads Manager
Design causal study for reminder impact
Investigate cross-country engagement and ads experiments
Recommend Next Steps for Pirate Theme Optimization
Evaluate Facebook Groups Metrics and Test Comment-Collapsing Feature
Common mistakes in A/B testing interviews
- Not specifying the randomization unit (user vs session vs page)
- Peeking at results before reaching the required sample size
- Ignoring practical significance when statistical significance is achieved
- Not considering guardrail metrics
- Failing to account for novelty effects in short experiments
How A/B testing questions are evaluated
Structure your experiment design: hypothesis, metrics, unit, sample size, duration.
Discuss what could go wrong and how you would detect it.
Show ability to make a recommendation even when results are ambiguous.
Related analytics concepts
A/B Testing Interview FAQs
How do you determine the sample size for an A/B test?
Use a power analysis with inputs: baseline metric, minimum detectable effect (MDE), significance level (alpha, usually 0.05), and power (usually 0.80). Larger effects need fewer samples. For small MDE on rare events, you may need millions of users.
What is the difference between statistical and practical significance?
Statistical significance means the observed difference is unlikely due to chance (p-value < alpha). Practical significance means the effect is large enough to matter for the business. A statistically significant 0.01% lift may not be worth the engineering cost to ship.