Interpret a statistically significant lift of 2% from an experiment
Last updated: December 31, 2025
Quick Overview
An experiment shows a 3% lift with p=0.08. What conclusions can you draw? What are the caveats?
Supabase
Statistics & Math
Data Scientist
Supabase
December 31, 2025Data Scientist
Technical Screen
Statistics & Math
Medium
40
5
1,589 solved
An experiment shows a 3% lift with p=0.08. What conclusions can you draw? What are the caveats?
Statistics questions at Supabase test your ability to reason quantitatively and design rigorous experiments. This Technical Screen question evaluates your understanding of statistical inference and its application to business decisions.
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
Power analysis and sample size calculation
Causal inference basics
Hypothesis testing (H0, H1, p-values)
Bayesian vs frequentist inference
Conditional probability and Bayes theorem
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?
- What alternative statistical method could you use here?
- 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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Browse Statistics QuestionsSample Answer
Problem Formulation
To analyze the results of the experiment, we set up the null hypothesis (H0) and the alternative hypothesis (H1):
- H0: There is no lift in the metric being measured (lift = 0%).
- H1: There ...
Solution Approach
- Hypothesis Testing: We will use the p-value to determine if we can reject the null hypothesis. Since p = 0.08 > 0.05, we fail to reject H0.
- Confidence Intervals: To understand the lift'...
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