Interpret a statistically significant lift of 2% from an experiment
Last updated: December 20, 2025
Quick Overview
An experiment shows conflicting results. What conclusions can you draw? What are the caveats?
Redfin
December 20, 202527
5
217 solved
An experiment shows conflicting results. What conclusions can you draw? What are the caveats?
This statistics question from Redfin's Technical Screen 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
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 if the sample size is very small?
- What assumptions does this test make, and how would you validate them?
- How would you explain this result to a non-technical audience?
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Browse Statistics QuestionsSample Answer
Problem Formulation
To interpret the statistically significant lift of 2% from an experiment, we first need to define what 'statistically significant' means. Typically, this involves a hypothesis test where:
- **Null Hy...
Solution Approach
To derive the conclusion from the experiment, we must follow these steps:
- Calculate the lift: Compare the control and experimental groups.
- Conduct a hypothesis test: Use a t-test or z-te...
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