Case Study: Turning Inventory Gaps into Revenue Wins 🛒📈
🧠 Background
Like many fast-moving eCommerce stores, our client frequently faced stock fluctuations. But when out-of-stock items were appearing at the top of product listings and flavor selectors, it created a frustrating experience for users, especially mobile users.
This A/B test emerged directly from on-site customer complaints and aimed to answer a key question:
Can we reduce friction and even improve conversion by simply reordering how unavailable products are displayed?
💡 Hypothesis
If out-of-stock items are placed at the bottom of product listings and flavor selectors, shoppers will have an easier time engaging with available products, leading to more confident decisions, higher add-to-cart activity, and increased revenue per user.
This strategy supports a core CRO principle: friction kills conversion.
🧪 Test Setup
- Test Duration: 7 days
- Traffic Split: 50/50 Control vs. Variation
- Pages Targeted: Homepage, Product Detail Pages (PDPs)
- Devices: All devices (mobile & desktop)
- Key Metrics Tracked:
- Conversion Rate
- Add-to-Cart Rate
- Revenue per User (ARPU)
- Product Page Views
🔧 Design Changes
- Homepage: Out-of-stock products moved to the end of product lists
- PDPs: Flavor variant dropdown reordered so in-stock items appear first
- No visual styling changes were made, only reordering logic was altered.
📊 Results
| Metric | Control | Variation | Uplift |
|---|---|---|---|
| Conversion Rate | 27.86% | 30.32% | +8.82% |
| Revenue per User (ARPU) | $22.65 | $27.41 | +21.01% |
| Add-to-Cart Rate | 53.4% | 56.4% | +5.74% |
📈 With a 91% probability of winning, the variation proved that something as simple as reordering content could have a measurable impact on customer experience and revenue.
🔍 Insights
🧭 Reduced Friction & Frustration
Users were no longer clicking unavailable flavors or scrolling past sold-out items. Especially on mobile, this made product exploration faster and less frustrating.
🔍 Improved Product Discovery
By focusing attention on available products, product page visits and add-to-cart interactions rose, helping shoppers find something they could actually buy on their first try.
💰 Higher Order Value
With fewer blockers in the experience, customers were more likely to confidently add higher-priced items or multiple SKUs, driving a 21% increase in revenue per user.
✅ Recommendations
- Keep the reorder logic live sitewide, as it clearly enhances usability and sales.
- Test hiding out-of-stock flavors entirely if restocks are infrequent. This could further streamline the PDP experience.
- Consider personalization, like showing “Notify Me When Back” badges for out-of-stock items with high interest or demand.
🔗 Related Reading
- Baymard: Allow Users to Purchase Temporarily ‘Out of Stock’ Products by Increasing the Delivery Time
⭐ Conclusion
This test proves that what users see first matters. By prioritizing in-stock items visually, we reduced confusion and decision fatigue, leading to a smoother path to checkout and significantly better business outcomes.
Key Takeaway: Reducing friction doesn’t always require redesign, it can start with thoughtful, strategic reordering.
📣 Let’s Talk CRO
Is your site losing sales due to small UX blockers? We help eCommerce brands turn hidden friction points into measurable growth with data-backed experimentation and smart optimizations.
👉 Get in touch today to find your next conversion win.