Explain power analysis with an example
Last updated: September 30, 2025
Quick Overview
Explain power analysis in simple terms and provide a concrete example.
Jane Street
September 30, 2025431
15
3,375 solved
Explain power analysis in simple terms and provide a concrete example.
Statistics questions at Jane Street test your ability to reason quantitatively and design rigorous experiments. This Take-home Project question evaluates your understanding of statistical inference and its application to business decisions.
What the Interviewer Expects
- Derive results from first principles when needed
- Handle complex scenarios with multiple interacting variables
- Design experiments that account for real-world complications
- Discuss advanced topics: Bayesian methods, causal inference, resampling
- Connect statistical concepts to business decision-making
- Identify subtle errors in reasoning (Simpson's paradox, survivorship bias)
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 if the sample size is very small?
- What assumptions does this test make, and how would you validate them?
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Problem Formulation
Power analysis is a statistical method used to determine the likelihood that a study will detect an effect when there is an effect to be detected. In the context of Jane Street, we can frame this with...
Solution Approach
To conduct a power analysis, we follow these steps:
- Define the Null and Alternative Hypotheses:
- Null Hypothesis (H0): There is no relationship between trading volume and profitability. ...
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