Calculate conditional probability for user retention
Last updated: February 19, 2026
Quick Overview
Given the following scenario about user conversion, calculate the the sample size needed.
Expedia
February 19, 2026258
6
4,791 solved
Given the following scenario about user conversion, calculate the the sample size needed.
Statistics questions at Expedia test your ability to reason quantitatively and design rigorous experiments. This Technical Screen question evaluates your understanding of statistical inference and its application to business decisions.
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
- What alternative statistical method could you use here?
- How would you handle multiple comparisons?
- What assumptions does this test make, and how would you validate them?
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Problem Formulation
To assess user retention on the Expedia platform, we need to calculate the conditional probability of users returning after their initial interaction. Let:
- : the event that a user returns to...
Solution Approach
To compute , we first need to gather data from user interactions and retention statistics. We will follow these steps:
- Identify the total user base and the number of users who interact...
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