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DefinitionA/B testing

A/B Testing

A/B(n) testing is a method that compares two or more versions of a web page, an application, an algorithm, advertising banners, etc., to determine which performs best.

An experimental method that involves comparing two or more versions (A, B, C, etc.) of a digital element – web page, application, algorithm, advertising banner, email, etc. – in order to determine which version performs best according to one or more defined metrics (conversion rate, clicks, revenue, engagement...).

The different variants are randomly presented to users, then analyzed using rigorous statistical methods (frequentist or Bayesian) to ensure that the observed results are significant and reliable.

Unlike correlative or retrospective analyses, A/B testing makes it possible to establish a causal relationship: it precisely isolates the impact of a change on user behavior, while controlling for external variables.

The A/B(n) approach is at the core of Conversion Rate Optimization (CRO) strategies, as it enables:

  • continuous improvement of a site or product's performance,
  • limiting risks associated with untested deployments,
  • prioritizing changes that bring measurable value,
  • validating decisions on empirical and data-driven grounds.

In practice:

  • An A/B test compares two variants (A vs B),
  • An A/B/n test can compare three or more versions (A vs B vs C...), while maintaining random distribution and consistent statistical analysis.

This method is commonly used in e-commerce, SaaS, media, or mobile app contexts, and is integrated into tools such as AB Tasty, Optimizely, VWO, Google Optimize (former), or Dynamic Yield.

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