# CTA Button Color A/B Test Example on the Cart Page

Page: https://alidemirbas.com.tr/en/lab/ab-test-library/tests/cta-button-color-ab-test-example-on-the-cart-page

## Hypothesis

If the button takes a color that stands out more from the design around it, visitors may notice it more easily. That could raise clicks on the cart CTA and the number of visitors who move on to checkout.

## When to run this test

Consider this test when the cart page gives you a sign that the main button does not stand out from the elements around it, such as a low click rate, a heatmap that shows the button being skipped, or session recordings of visitors looking for it. The expected behavior is that a button that is easier to notice moves more visitors on to checkout. If the problem is checkout errors, a slow page or an unclear offer, look at those first, because a color change does not replace them.

## Primary metric

**Click-through rate (CTR)**: Compare clicks on the cart CTA between visitors assigned to each color. Suggested definition: of the visitors assigned to the control or the variant who saw the CTA, the share who clicked it at least once. Repeat clicks by the same visitor count once.

## Other metrics

- **Purchase conversion rate (CR)**: Compare completed orders among all visitors assigned to each experience.
- **Checkout start rate**: Compare assigned cart visitors who proceed to checkout.
- **Cart page exit rate**: Compare the share of assigned visitors who leave the cart page.

## What to check before and during the test

- **Color**: Compare the current CTA color with one preselected, brand-approved alternative. Record both color values before launch.
- **Contrast**: Keep the label easy to read and maintain accessible contrast in both versions.
- **Keep constant**: Do not change the button label, size, position or surrounding design.
- **Tracking**: Verify CTA impressions and clicks, checkout starts and completed orders are attributed to the correct variant.
- **Device**: Review mobile and desktop separately.

## What to watch when reading the result

- More clicks alone are not a reason to ship the change. Check whether the increase carries through to checkout starts and completed orders.
- The result holds for the color pair you tested and for the cart page. Validate it again in the new context before applying it to another page or another color.
- If the difference is small or unclear, note that this sample could not measure it. Look at the size of the effect and the uncertainty around it together. You can check whether the gap could be ordinary sampling variation with the [A/B test significance calculator](https://alidemirbas.com.tr/en/calculators/ab-test).

## Frequently Asked Questions

### When should button color be a priority in CRO?

Consider a color test when usability research suggests visitors overlook the button. Low click-through alone does not establish a color problem. Check payment errors, performance and offer clarity first. Maintain readable text contrast, including the applicable WCAG text-size exceptions.

### Does a higher click-through rate make the new color a winner?

Use the predefined CTA click-through rate as the primary outcome. Check uncertainty, downstream completion and guardrails before shipping. A non-significant purchase result does not establish that the purchase effect is zero.

### Can I apply the winning cart button color across the site?

The finding concerns the tested color pair and cart context. Validate other placements before extending it. Review mobile and desktop results where the experiences differ, so an improvement on one device does not conceal harm on another.