Calculate variance for user retention

Last updated: October 13, 2025

Quick Overview

Given the following scenario about revenue per session, calculate the the p-value.

Cruise
Statistics & Math
Data Scientist
Cruise
October 13, 2025
Data Scientist
Technical Screen
Statistics & Math
Medium

6

12

4,806 solved


Given the following scenario about revenue per session, calculate the the p-value.

Cruise values data-driven decision making. This Technical Screen 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
Confidence intervals and significance levels
Conditional probability and Bayes theorem
Power analysis and sample size calculation
Probability distributions
Regression analysis
How to Approach This
  1. Define your hypotheses (H0 and H1) clearly before performing any test.
  2. Calculate required sample size BEFORE running an experiment, using power analysis.
  3. Remember the Central Limit Theorem: sample means become approximately normal with large n.
  4. Watch for Simpson's paradox. Always segment data by key dimensions.
  5. 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?
  • How would you design a follow-up experiment based on these results?
  • What assumptions does this test make, and how would you validate them?
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Sample Answer
Setting Up the Problem

Start by formalizing the problem: 1. **Define the hypotheses**: H0 (null hypothesis) and H1 (alternative). Be precise about what you're testing. 2. ...

Solution Approach

**Compute the test statistic**: Apply the appropriate formula using the sample data. **Find the p-value**: The probability of observing a result this...


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