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
How would you define and use retention metrics?
Design measurement to detect fake accounts
Measure causal impact of YouTube ads
Analyze Transactions for Risk and Implement Mitigation Strategies
Diagnose Checkout Rate Drop: Steps and Analyses
Evaluate the Health of Facebook Groups
Measure Ultrafast Delivery's Impact Using Synthetic Control Method
Evaluate a new ranking model
Diagnosing a drop in total ads revenue
Estimate impact of global launch without holdout
Measure and Improve Listing Quality with Key Metrics
Measure App Store success and debug funnel anomaly
Evaluate Impact of New Roblox Homepage Tab
Quality and frequency control for push notifications
Design A/B Test for Search Feature Effectiveness
Decompose and optimize delivery operational costs
Experiment on increasing order notifications
Design an ETA experiment under interference
Design experiments for payments, search, and promotions
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.