Product: CTA Button Optimization
Hypothesis
If we test a similar change on our product pages as Bol.com rejected, we should be cautious
Test Results
Key Learning
Problem: The primary call-to-action on the product isn't converting at its potential — design, copy, or placement may be the bottleneck.
What was tried: Bol.com rejected this UI change (Jan 2, 2023). Rejection suggests the change underperformed the control
Why it failed: Not every CTA change improves conversion. Users may have preferred the original because it was clearer, more familiar, or better positioned.
How to Apply This to Your Site
This test showed that product: cta button optimization hurt conversions. The change was tested on a product page page in the e-commerce industry. Avoid replicating this exact approach — instead, consider testing the opposite direction or a more subtle variation.
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.
What Was Tested
After detecting some success with a more padded button, Bol continued their a/b test iteration. The Dutch online retailer ran an experiment with an even wider add-to-cart button on their product pages.
Methodology
Build On These Learnings
Save your own experiments, spot winning patterns across your test history, and stop repeating what's already been tried.
Related Experiments
Listing: Visible Payment Options
Context: The primary call-to-action on the listing isn't converting at its potential — design, copy, or placement may be the bottleneck.
Does Pinning a Mobile Checkout CTA Improve Conversion?
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.
Listing: Filled Or Ghost Buttons
Context: The primary call-to-action on the listing isn't converting at its potential — design, copy, or placement may be the bottleneck.
Does Adding a Shopping CTA to the Main Navigation Drive Plan Views?
A CTA's click rate is not its conversion contribution. This test surfaced one of the most consistently underweighted patterns in CRO: behavioral diagnostics almost always tell a more honest story than the topline. The aggregate result looked like a tiny non-significant lift (+1%); the diagnostic revealed that of every 100 button clicks, only 6 reached the next funnel step. Two failure modes converged: (1) copy intent mismatch — the chosen label read as 'create account' rather than 'shop,' so a large share of clicks came from users trying to log in / manage their account from support and customer pages; (2) extra modal step before the destination page added friction without value. The aggregate lift was partially cannibalization from higher-converting paths. The transferable pattern: when introducing a global navigation element, validate the click→conversion ratio per source page, not just the topline. High clicks from low-intent pages creates a false signal of engagement that can mask poor performance.