numeric
Sample size for a 2% lift
Experimentation & A/B Testing · Design & Power · medium · Original Uplift question · 8 min
Baseline conversion is 10%. You want to detect a relative lift of 20% (10% -> 12%) with 80% power at a two-sided alpha of 0.05. Using the standard approximation n = 16 * p * (1 - p) / delta^2 with p = 0.10 and delta = 0.02, how many users per arm do you need? Answer in users, rounded to the nearest whole user.
Evaluation criteria
- Uses the correct method or distribution
- Shows the calculation
- Rounds as the prompt asks
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Source
Original Uplift question based on a common interview pattern.
Your answer
users per arm
Commas, currency symbols and a trailing percent sign are fine. Answers within ±1 users per arm of the expected value are accepted.
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