Does Pinning a Mobile Checkout CTA Improve Conversion?
Hypothesis
On a mobile multi-step checkout/enrollment flow with a long verification page, users may struggle to find the primary action when they reach the bottom. Making the primary CTA persistently visible should reduce friction and improve progression to the confirmation step.
Test Results
Key Learning
Sticky mobile CTAs can compress time-on-page meaningfully (~15% faster) without sacrificing engagement signals — users converted at a directionally higher rate AND moved through the page faster, suggesting reduced hesitation rather than rushed clicks. The result was shipped via 90/10 holdout monitoring rather than traditional 50/50 A/B inference — the high baseline (~85%) and limited mobile traffic made full A/B underpowered, so the team chose a holdout-validated rollout as the deliberate methodology. Bayesian P(variant > control) was ~0.90, supporting the directional ship call. Worth noting: external research flags sticky CTAs as context-dependent — they help when the primary action is buried below the fold, but can hurt on shorter pages where the original CTA is already visible.
How to Apply This to Your Site
This experiment demonstrated that does pinning a mobile checkout cta improve conversion? can improve conversions. The test was run on a checkout page in the energy & utilities industry.
Before you test: Consider that cta tests typically require adequate traffic to reach statistical significance. Run your test for at least 2 full business cycles to account for weekly traffic patterns.
This result reached 95% statistical confidence, meaning there is a very low probability the observed effect was due to chance. Results at this confidence level are generally considered reliable for making business decisions.
What Was Tested
Mobile-only test on a verification step with a high baseline conversion rate (~85%) where the primary CTA was anchored at the bottom of a long page. The variant pinned the CTA to the bottom of the viewport on scroll.
Methodology
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