Calculate probability for coin flips
Last updated: May 29, 2026
Quick Overview
Given the following scenario about revenue per session, calculate the the sample size needed.
Datadog
May 29, 20262
12
3,490 solved
Given the following scenario about revenue per session, calculate the the sample size needed.
Statistics questions at Datadog test your ability to reason quantitatively and design rigorous experiments. This Onsite 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
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 alternative statistical method could you use here?
- What if the sample size is very small?
- How would you handle multiple comparisons?
- How would you explain this result to a non-technical audience?
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Problem Formulation
We are tasked with determining the necessary sample size to assess the impact of a new feature on revenue per session for Datadog. We define:
- Null Hypothesis (H0): The new feature does not have...
Solution Approach
To calculate the required sample size (n), we will use the formula for sample size in a one-sample t-test:
n = ((Zα/2 + Zβ)^2 * σ^2) / δ^2
Where:
- Zα/2 is the critical value for a two-tailed test a...
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