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 Successful Sign-ups from Super Bowl QR Code Ad
Define metrics for new market expansion success
Design an experiment for thermal bags
Analyze time series and design validation experiment
Determine Metrics to Evaluate Notification Impact on Users
Frequent Traveler Case
How to test account ranking change
Investigate why an advertiser’s spend decreased
Determine if players prefer local creators without experiments
Design Experiments to Measure Promotion Scheduling Impact
How would you use propensity score matching here
Diagnose sustained drop in executed trades
Investigate ride declines and test free trials
Diagnose and reverse an adoption-rate decline
Design experiment for homepage tab replacement
Design and analyze email deliverability experiment
Explain Multi-Armed Bandit Principles
Design and Analyze A/B Test for Cashback Program
Diagnose Search Issues with Relevant Metrics and Solutions
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.