What it means
Show version A to half your audience and version B to the other half, change one thing, and measure the difference. It converts arguments about copy, creative, or layout into evidence.
Why it matters
Compounded over a year, a disciplined testing cadence is how conversion rates climb without more traffic.
Common mistakes
- Calling a winner before reaching statistical significance.
- Testing too many changes at once, so you cannot tell what worked.
- Stopping the moment the result looks good (peeking).
- Running tests with too little traffic to ever reach significance.