A/B tests and A/B testing

In short: in an A/B test, users are randomly split between two versions of a page or element, and a chosen metric is compared, such as purchases or completed forms. Before the test, the goal is set and the required sample size is assessed; the result is not judged by the test’s duration alone.

A/B testing is a way to make well-founded decisions in the digital environment. It lets you test different solutions based not on guesses or gut feeling but on real user data. A/B tests are widely used to improve websites, online stores and digital systems — to increase conversion, improve the user experience and achieve better business results.

Put simply, A/B testing means comparing two or more solutions. Some users are shown one version, others another, and then it is analysed which one works better.

An A/B test compares two versions. They can differ in one or more elements; when several elements are changed at once, their combined effect is assessed. You can change, for example:

• the colour or text of a button
• a headline
• the page structure
• the layout of forms
• how prices are displayed
• the call to action

Users are split into groups, and each group sees a different version. During testing, specific metrics are measured, such as clicks, purchases, completed forms or time spent on the page. Based on the data obtained, a decision can be made about which version is more effective.

A/B tests help answer questions that would otherwise be hard to answer objectively. Often a design or content that seems logical from the company’s side may not be clear or convenient for users. This is exactly where A/B testing provides real value.

For websites, A/B testing helps to:

• improve the user experience
• increase the number of contact form submissions
• reduce the bounce rate
• improve how information is taken in

For online stores, A/B tests are especially important, because even small changes can directly affect sales. With A/B testing, you can:

• increase the number of purchases
• improve basket completion rates
• test how prices or discounts are displayed
• optimise the ordering process

What can be tested with A/B testing

A/B testing is not just for design. It can be used to improve almost any digital element.

The most commonly tested elements are:

• page design and layout
• texts and headlines
• button colours, sizes and texts
• form length and fields
• navigation structure
• product page content
• images and visual elements

If you want to find out the effect of changing a specific element, keep the other differences between the variants unchanged.

In larger projects, A/B testing becomes an integral part of the development and growth process. This applies especially to custom systems, online stores and platforms with high user traffic.

In such cases, A/B tests are used to:

• validate new features before full roll-out
• reduce risk when introducing changes
• test user behaviour in different scenarios
• make strategic decisions based on data

A/B testing helps avoid situations in which changes are introduced but the result is worse than before.

A/B testing is not a one-off experiment but a structured process.

It usually includes:

• defining the goal
• forming a hypothesis
• creating the variants to test
• starting the test
• collecting data
• analysing the results
• drawing conclusions and implementing changes

It is important to give the test enough time for the data to be objective and statistically significant.

A/B testing is not meant only for one-off optimisation. It is an approach that allows digital solutions to be improved continuously. Companies that use A/B tests regularly can adapt faster to user needs and market changes.

In the long term, A/B testing helps to:

• make well-considered decisions
• improve return on investment
• develop products based on data
• improve competitiveness

Related: Web design and UX/UI · UX/UI and design testing · Online store development.