Sticky Checkout CTA Test
Where was the friction hiding?
Wickes is a major UK DIY and home improvement retailer with a high volume of mobile web traffic. Like many retailers, the basket-to-checkout funnel on mobile was a key area of commercial focus – small friction points at this stage of the journey can have an outsized impact on revenue.
The existing mobile basket page (the control) required users to scroll past their delivery options and order summary before reaching the checkout button. On smaller screens, this meant the primary call to action was frequently out of view, creating unnecessary effort at a moment when the user’s intent to purchase was already high.
What were we trying to prove?
As UX Manager, I was approached by the Product Owner to explore whether we could meaningfully improve checkout throughput on mobile by reducing friction at the basket stage.
The hypothesis was straightforward: if we made the checkout CTA more persistently accessible – reducing the cognitive load and time required to proceed – we could increase the rate at which basket-viewing sessions converted into checkout entries, and ultimately into completed transactions.
My task was to define and help design the challenger variants that would be built and tested by our experimentation partner, Good Growth, as part of a multivariate A/B test on the live site.
How did we design the test?
We designed two challenger variants to test different approaches to reducing friction:
Challenger A introduced a sticky “Summary & Checkout” drop-up panel that remained anchored to the bottom of the screen as users scrolled, with an at-a-glance view of their basket total. This drop-up panel allowed the user to click on it to view the Checkout CTA and PayPal CTA when available, reducing the need to scroll back up to proceed.
Challenger B took a slightly different approach, surfacing a condensed “Order Summary” panel and a prominent “Checkout options” button in a sticky bottom drawer. This gave users a persistent at-a-glance view of their basket total alongside an always-accessible route to checkout. When there wasn’t the option of PayPal payment on the customer’s basket, the user only saw a “Checkout” CTA, which in one click took them straight to sign in screen of the checkout process.
A key design consideration across both variants was ensuring the prominently positioned promo code entry field wasn’t taking up too much space. In the control, this field was highly visible on mobile and desktop – and data suggested it was encouraging a meaningful proportion of users to pause their checkout journey to search for discount codes, introducing unnecessary drop-off. Therefore both challengers significantly reduced the visibility of this feature.
Good Growth built and deployed the test across mobile sessions, running from late November through mid-December 2024, with traffic split across the control and both challengers.
What did the data tell us?
The results were conclusive and commercially significant – but only on mobile, which was the intended target device. Desktop and tablet showed no significant impact, confirming the changes were appropriately scoped.
On mobile, Challenger B was declared the clear winner:
- Conversion rate to checkout increased by +6.7% (vs +2.2% for Challenger A)
- Conversion rate to transaction increased by +2.9% , which was statistically significant and conclusive
- Average order value rose by +3.1%,
- Average item value increased by +3.4%
- Revenue per session grew by +6.1%
- Promo code entry rate dropped by -93%, confirming the redesign successfully reduced this source of checkout abandonment.
The in-test revenue uplift attributable to Challenger B on mobile was approximately £56k during the test window alone, translating to an estimated £4.5 million annualised revenue uplift when projected at scale.
The recommendation to mainstream Challenger B was approved and developed.
What would I take forward?
This test reinforced something I think is easy to undervalue in UX: the commercial impact of reducing friction at high user-intent moments. Users arriving at the basket page have already done the hard work of product discovery and selection. A well-placed, persistent CTA on mobile doesn’t push them into a decision – it just removes the effort from the process.
What surprised me most was the magnitude of the promo code effect. In isolation, the -93% reduction in promo code entry rate sounds alarming, but the data told a clear story: it was a distraction, not a value-add, at that point in the journey. Removing its prominence drove higher-value, faster-completing transactions.
The desktop and tablet null results were also a useful reminder to design and test with device context front of mind. The sticky CTA pattern solved a genuinely mobile-specific problem – the need to scroll to reach a CTA on a small screen – and delivered meaningful results precisely where that problem existed. Customers rarely had more than 3 different products in their basket on desktop, so they didn’t need to scroll to see the Checkout CTA. My main learning from that null result was this: if it doesn’t solve a user problem, we don’t need to build it!
