Split testing

What is split testing?

Split testing, also known as A/B testing, is a method where you compare two or more versions of a webpage, app interface, or marketing element to determine which one performs better. The core idea is straightforward: create variations of your content, show them to similar audiences, and measure which version achieves your goals more effectively. For example, you might test different headline text on a landing page to see which generates more sign-ups. Split testing removes guesswork from optimization decisions by providing concrete data about what actually works with your audience.

How does split testing work?

Split testing begins with forming a hypothesis about what might improve performance. You then create a control version (your current design) and at least one variation that incorporates your proposed change. When users visit your site or open your email, they're randomly assigned to see either the control or a variation. The testing tool tracks how users interact with each version, collecting data on metrics like click-through rates, time on page, or conversions. After gathering sufficient data to achieve statistical significance, you analyze the results to determine if your variation outperformed the control. If it did, you can implement the winning version with confidence that it will improve overall performance.

What are the different types of split testing?

A/B testing compares two versions that differ in just one element—like a button color or headline. This straightforward approach makes it easy to identify exactly what caused any performance differences. Multivariate testing examines multiple variables simultaneously, testing different combinations to find the optimal mix. For instance, you might test different headlines, images, and call-to-action buttons all at once to see which combination works best. Sequential testing (also called bandit testing) dynamically allocates more traffic to better-performing variations during the test, maximizing conversions while you learn. Each approach has its place depending on your goals, timeline, and available traffic.

When should you use split testing?

Split testing delivers the most value when making high-impact decisions or when you have competing ideas about what might work best. Use it when redesigning key conversion pages like landing pages or checkout flows. Test email campaigns to improve open rates and click-throughs. Split test paid advertising elements like headlines and images to increase ROI. Product features and user experience changes benefit from testing before full rollout. The best candidates for testing are elements that directly impact business goals and have sufficient traffic to gather meaningful data quickly. Avoid testing minor elements with little potential impact or during seasonal anomalies that might skew results.

How do you measure split testing success?

Measuring split testing success starts with defining clear objectives tied to business goals. Primary metrics often include conversion rate (the percentage of visitors who complete your desired action), click-through rate, revenue per visitor, or average order value. Look beyond surface metrics to understand the full impact—a button that gets more clicks but leads to fewer purchases isn't truly successful. Statistical significance is crucial; most tools calculate this for you, typically aiming for 95% confidence that your results aren't due to random chance. Consider test duration as well—run tests long enough to capture weekly cycles in user behavior, but not so long that external factors contaminate your data. The ultimate measure of success is implementing changes that create lasting improvements in your key performance indicators.