What is A/B testing?
A/B testing is a method of comparing two (or more) versions of a webpage or digital asset to determine which performs better against a specific objective, such as generating more enquiries, increasing purchases or improving click-through rates.
Visitors are randomly shown two versions of the same webpage, one being the original version and one being a slightly modified version. Their behaviour whilst on the page is then measured and analysed to determine which version delivers the best results, backed by actual user behaviour data.
The changes tested can be as small as updating a headline or changing the colour of a call to action button, or as significant as redesigning an entire landing page.
By measuring the impact of each change, A/B testing allows businesses to validate ideas before fully implementing them, helping transform website optimisation from guesswork into evidence-based decision making. It shifts the conversation from hoping it will work to knowing it will work.
Why is A/B testing important?
Making significant changes to a website without testing introduces unnecessary risk. A/B testing allows businesses to validate ideas before fully implementing them, helping reduce the chances of a major change negatively impacting online performance.
Beyond reducing risk, A/B testing provides valuable insights into how users interact with your website, allowing you to continually refine the user experience.
Improved content engagement:
Understanding what resonates with your audience enables you to create more engaging content. Insights gained through A/B testing can inform future campaigns, helping you produce content that has already been proven to generate higher engagement.
Reduced bounce rates:
If visitors are leaving your website shortly after arriving, A/B testing can be part of the toolkit to help identify why. Testing different headlines, images, page layouts or introducing new copy allows you to discover what captures visitors’ attention and encourages them to stay longer. Even relatively small improvements can have a noticeable impact on reducing bounce rates.
Increased conversion rates:
Ultimately, most websites exist to encourage users to act. This can come in the shape of completing enquiry forms, downloading a guide or making a purchase; A/B testing helps identify which version of a page persuades more visitors to convert. Instead of relying on assumptions, businesses can clearly see what works for their audience and make confident, data-driven decisions.
What can you A/B test?
Almost every element of a website can be tested. Some of the most common examples include:
- CTA (Call to Action) buttons – Experiment with button text, colour, size or placement to encourage more clicks.
- Page layouts – Compare long-form pages containing more detailed information against shorter pages designed for quicker conversions.
- Forms – Test the number of fields required to determine whether shorter forms increase completion rates.
- Headlines – Compare short versus long headlines, or emotional messaging against more direct, benefit-led copy.
- Navigation – Simplify menus and navigation structures to help users find information more easily and reduce confusion.
The goal of A/B testing isn’t just making changes, but instead to understand which changes genuinely improve user behaviour.
Why A/B testing assumptions often fail
Whilst A/B testing is a powerful optimisation tool, it’s only effective when carried out correctly. Poorly designed tests can produce misleading results and lead business to make decisions that might not be right.
One common misconception is that only major bespoke website redesigns create meaningful improvements. In reality, relatively small changes can often deliver measurable increases in engagement or conversions. However, there are several common mistakes to avoid:
Testing pages with too little traffic:
Running tests on pages with very few visitors often produces unreliable results. Without sufficient data, it’s difficult to distinguish genuine improvements from what could be random variation.
Ending tests too early:
It’s tempting to stop a test as soon as one variation appears to be outperforming the other. However, ending a test before reaching statistical significance increases the likelihood of false positives. Allowing tests to run for an appropriate amount of time ensures decisions are based on evidence rather than short-term fluctuations.
Treating optimisation as a one-off project:
User behaviour evolves over time, customer expectations change and business priorities develop. A/B testing is an ongoing process of continual improvement rather than a one-time exercise.
A/B testing best practices
Successful A/B testing requires more than just changing a button colour and hoping for the best. Every test should be carefully planned, measured and documented.
Some key best practices include:
- Starting with a clear hypothesis and define exactly what you expect to happen and why before launching a test.
- Test one variable at a time. Changing multiple elements simultaneously makes it difficult to determine which change influenced the results.
- Allow enough time to test theories and avoid making decisions based on incomplete data.
- Document every experiment. Maintaining a record of previous tests helps prevent repeated experiments and builds a valuable knowledge base over time.
The goal of A/B testing is to develop a deeper understanding of how your users are using your site, helping to continually improve your website’s performance based on your findings.
Expert insights: The importance of A/B testing in the design process
We spoke to Halah, our UX Designer at Hydra Creative, to understand the process behind A/B testing:
What role does A/B testing play in the design process?
A/B testing is a way of validating a design decision using real user behaviour. For example, when there are two credible design options, an A/B test can show which one performs better when it’s put in front of real users.
A/B testing is one part of a wider design process. It does not replace user research, usability testing or professional judgement. Instead, it adds another layer of evidence and helps teams make decisions with greater confidence. It is particularly valuable when a team has a clear objective and enough traffic to produce meaningful results.
How to decide which parts of the website are worth A/B testing
Start with the business objective and the user journey, rather than choosing an element simply because it’s easy to change. The questions to ask yourself are:
- What would we like users to do at this point?
- Are there any signs that users are getting stuck or losing interest?
- What have we learned from analytics, feedback or user research?
- Could a small change here make the experience clearer or easier?
Once you have answered these questions review the analytics, any user feedback and identify areas of friction on the site, for example places where users abandon a form, struggle to find information or fail to complete an action that is important for your site.
From there, prioritise opportunities based on their potential impact, the strength of the evidence and the effort required to test them. Examples could include the wording of a call to action, the structure of a landing page, the number of fields in a form, the presentation of pricing information, or the way information is organised during a checkout or booking process.
The aim is not to test everything. It is to test changes that are connected to a genuine user need or business goal.
How many variables should you test at once and why?
For a straightforward A/B test, it is recommended that one main variable is tested at a time.
If several elements are changed at once, you may find that one version performs better, but you will not know which change caused the improvement. Keeping the test focused makes the results easier to interpret and turns them into useful evidence that can guide future design decisions.
It’s also important to define the variable carefully. For example, testing an entirely redesigned page against the existing page may tell you which page performs better but will not necessarily explain why.
There are more advanced approaches, such as multivariate testing, where several combinations are tested at the same time. However, these usually require significantly more traffic, more time and a carefully planned testing strategy.
Taking the guesswork out of website optimisation
Your website is often the first interaction potential customers have with your business, making first impressions count.
At Hydra Creative, award winning digital marketing agency, we’re passionate about creating websites that combine creativity with proven UX and UI best practices. Through thoughtful design and data driven optimisation from A/B testing, we help businesses make informed decisions that improve user experience, increase conversions and maximise website performance.
If you’re looking to get more from your website, we’d love to help you uncover the insights that drive meaningful results. Contact our website designers today for an initial consultation.
