Design an A/B test for a search ranking change
Last updated: November 11, 2025
Quick Overview
Design an experiment to test the impact of a redesigned homepage. Include sample size calculation, metrics, and analysis plan.
82
4
1,395 solved
Design an experiment to test the impact of a redesigned homepage. Include sample size calculation, metrics, and analysis plan.
This statistics question from Reddit's Onsite tests your ability to apply mathematical reasoning to practical problems. The interviewer expects precise definitions, correct methodology, and awareness of assumptions and limitations.
What the Interviewer Expects
- Set up the problem formally with proper notation
- Apply the correct statistical test with clear justification
- Interpret results with appropriate caveats and confidence levels
- Discuss practical significance vs statistical significance
- Identify potential confounders and how to address them
Key Topics to Cover
How to Approach This
- Define your hypotheses (H0 and H1) clearly before performing any test.
- Calculate required sample size BEFORE running an experiment, using power analysis.
- Remember the Central Limit Theorem: sample means become approximately normal with large n.
- Watch for Simpson's paradox. Always segment data by key dimensions.
- Distinguish between statistical significance and practical significance.
Possible Follow-up Questions
- How would you handle multiple comparisons?
- What if the sample size is very small?
- How would you explain this result to a non-technical audience?
- What assumptions does this test make, and how would you validate them?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Browse Statistics QuestionsSample Answer
Problem Formulation
To evaluate the impact of a redesigned homepage on user engagement, we can formulate this as an A/B test. We define the null hypothesis (H0) as "there is no difference in user engagement metrics betwe...
Solution Approach
To determine the sample size, we must consider the following:
- Effect Size: Estimate the minimal difference in means we want to detect. For instance, if we expect the redesigned homepage to incr...
Submit Your Answer
