Explain Simpson's paradox with an example
Last updated: May 5, 2026
Quick Overview
Explain Simpson's paradox in simple terms and provide a concrete example.
Zillow
Statistics & Math
Data Scientist
Zillow
May 5, 2026Data Scientist
Onsite
Statistics & Math
Easy
21
4
4,656 solved
Explain Simpson's paradox in simple terms and provide a concrete example.
This statistics question from Zillow'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
- State the correct formula or theorem with clear definitions
- Apply the concept to the given scenario step by step
- Interpret the result in plain language
- Identify assumptions and when they might be violated
Key Topics to Cover
Causal inference basics
Probability distributions
Bayesian vs frequentist inference
Multiple testing correction (Bonferroni, FDR)
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 assumptions does this test make, and how would you validate them?
- How would you design a follow-up experiment based on these results?
- What if the sample size is very small?
- How would you explain this result to a non-technical audience?
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