A/B Proportion Test
Compare two independent conversion rates using a two-sided pooled z test.
Your numbers
B minus A
Requires independent fixed-horizon samples and sufficiently large expected cell counts. Repeated peeking changes error rates.
Scenario comparison
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Formula
z=(pB−pA)/√[p̂(1−p̂)(1/nA+1/nB)]
Compare two independent conversion rates using a two-sided pooled z test.
Worked example
- A conversions
- 100
- A visitors
- 1000
- B conversions
- 130
- B visitors
- 1000
- B minus A
- 3 percentage points
- Two-sided p-value
- 0.0354884504665
- z statistic
- 2.10274060562
- Relative lift
- 30 %
Scope and limitations
Requires independent fixed-horizon samples and sufficiently large expected cell counts. Repeated peeking changes error rates.
Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.
Check your units and assumptions before relying on a result. Changing a label does not convert a currency or physical unit.
Formula version: 10785dd5de02 · Example checked: