A/B test significance

Two-proportion z-test for conversion-rate experiments: rates, lift, z-score, p-value, and a 0.05 verdict.

Variant A (control)

Variant B

Pooled two-proportion z-test, two-sided p-value. No correction for peeking or multiple variants.

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How to use

  1. Enter visitors and conversions for variant A.
  2. Enter the same for variant B.
  3. Read the z-score, p-value, and significance verdict.

What it supports

Two-sided z-test on independent proportions, α = 0.05. Needs at least 1 visitor and 0–all conversions per variant; p is exact-normal (no continuity correction). Not for A/A tests, sequential peeking, or more than two variants. z and p display to at most 4 and 6 decimal places respectively.

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