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Marketing

A/B Testing

Split Testing

Portrait of Robert Klimant, co-founder of Roelu Studio
Robert KlimantCo-founder

What is A/B Testing?

A/B testing, also called split testing, is a method of comparing two versions of a page, element, or user flow by showing each to a random portion of visitors and measuring which one performs better against a defined goal. The test runs until enough data accumulates to declare a winner with statistical confidence. The winner becomes the new default, and the next hypothesis queues up. It is the engine of disciplined conversion optimization.

Why it matters

Most website debates end with the loudest voice or the highest title in the room. A/B testing replaces that with evidence. The CEO thinks the hero should say one thing, the CMO thinks another — run both, let the visitors decide. Done seriously, it kills the bad habit of redesigning the homepage every six months because someone got bored. It also exposes the truth that most changes do nothing, and a few do a lot. Knowing the difference is worth more than another agency pitch. Teams that test consistently compound small wins into double-digit conversion lifts over a year.

How it works

A team picks one variable to test — a headline, a CTA color, a form length, a pricing layout. Tools like PostHog, VWO, or Optimizely split incoming traffic between the original (A) and the variant (B). Both versions run simultaneously, so seasonality and traffic mix do not skew the result. Once the test reaches statistical significance — usually a few thousand visitors per variant, depending on baseline conversion — the winner gets rolled out to 100 percent of traffic. Tests with no clear winner are still useful: they tell you the variable does not matter, and the team can move on to something that does.

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