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 to diagnose traffic and measure relevance?
How to decide if users need a new feature
Design an experiment to evaluate an onboarding progress bar
Design and analyze end-to-end A/B test
Design pre-launch plan and cluster A/B test
Prove source growth is cannibalization, not incremental
Design a small-sample launch experiment in Europe
Evaluate shopping tab pre- and post-launch
Design robust metrics for a feature launch
Design causal measurement without randomization
Evaluate emoji reactions launch
Diagnose drop in shopper order acceptance
Calculate Customer Lifetime Value for Spokeo Using Models
Determine User Need for In-App Video Call Feature
Determine Discount's Effect on Conversion Rate with A/B Testing
Analyze Trade-off Between DAU Growth and Ad Revenue
Estimate Venmo Revenue and Boost User Engagement Metrics
Measure whether posts strengthen friendships
Brainstorm a business problem approach
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.