Calculate conditional probability for A/B test results
Last updated: October 7, 2025
Quick Overview
Given the following scenario about revenue per session, calculate the the sample size needed.
Lyft
Statistics & Math
Data Scientist
Lyft
October 7, 2025Data Scientist
Take-home Project
Statistics & Math
Medium
19
4
1,701 solved
Given the following scenario about revenue per session, calculate the the sample size needed.
Lyft values data-driven decision making. This Take-home Project question assesses whether you can design experiments, interpret results correctly, and avoid common statistical pitfalls like p-hacking or Simpson's paradox.
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
Multiple testing correction (Bonferroni, FDR)
Regression analysis
Probability distributions
Confidence intervals and significance levels
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 explain this result to a non-technical audience?
- How would you handle multiple comparisons?
- What assumptions does this test make, and how would you validate them?
- How would you design a follow-up experiment based on these results?
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Browse Statistics QuestionsSample Answer
Problem Formulation
We aim to calculate the sample size required to detect a difference in revenue per session between two variants (A and B) in an A/B test for Lyft. Let and represent the expected re...
Solution Approach
- Determine Parameters: Define expected means and standard deviations:
- Let (average revenue per session for variant A)
- Let (average revenue per sessi...
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