Calculate expected value for A/B test results
Last updated: July 9, 2025
Quick Overview
Given the following scenario about revenue per session, calculate the the sample size needed.
Oracle
July 9, 202532
6
2,794 solved
Given the following scenario about revenue per session, calculate the the sample size needed.
This statistics question from Oracle's Technical Screen 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 design a follow-up experiment based on these results?
- What assumptions does this test make, and how would you validate them?
- What if the sample size is very small?
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Browse Statistics QuestionsSample Answer
Problem Formulation
To calculate the sample size needed for an A/B test comparing two groups (Group A and Group B), we need to define the following parameters:
- Null Hypothesis (H0): There is no difference in reve...
Solution Approach
To calculate the required sample size (n) for each group, we can use the following formula for sample size in A/B testing:
[ n = \left( \frac{(z_{\alpha/2} + z_{\beta})^2 \cdot (\sigma_A^2 + \sigma_...
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