Graying Out vs Hiding Out-of-Stock Products A/B Test

This comparison is worth planning when out-of-stock products fill a noticeable part of your category lists; session recordings of shoppers tapping grayed-out cards and backing out, site search clicks that land on sold-out items, or support tickets saying products are always sold out all point to it. If hiding wins, shoppers reach in-stock products faster; if graying wins, the wider assortment keeps them browsing. If the real issue is wrong stock data, fix that first, and check that the gray arm shows unavailable items as clearly not purchasable and that neither arm switches on a “show in-stock only” filter the shopper did not choose.

Category-page purchase rate

Compare purchases among category visitors assigned to the two out-of-stock display approaches.

Also track

• Product detail click-through rateCompare visits to in-stock product pages between arms.
• Category-page exit rateTrack exits among visitors who see the category page.
• Back-in-stock signup rateTrack this only if a “notify me” flow already exists; do not add a new signup flow.
• Listing load timeCheck whether stock-status and label handling affects load time.

• DisplayShow the same out-of-stock products in gray in one arm and hidden in the other.
• Keep constantKeep the order, filters and stock data for available products the same.
• PurchasesCompare purchases among all eligible visitors assigned to the category-page experience.
• Out-of-stock shareRecord the share of products out of stock; eligibility should be comparable between arms.
• Existing flowIf a back-in-stock notification already exists, keep it the same in both arms.

1. 1The category-page purchase rate is what picks an option; product detail click-through, category-page exits and listing load time explain why it moved. More product page visits without a change in purchases are not enough to choose an option. To see how hiding affects category browsing, track detail visits and exits in the hidden arm through the whole test and report them.
2. 2This result reflects only this category and the stock situation during the test, so do not carry it straight to categories with a different out-of-stock share. Keep the position of grayed-out items and the sorting rule fixed throughout, or you cannot tell whether the difference came from the display or the order.
3. 3If stock levels or the out-of-stock share are unbalanced across arms, do not interpret the result; first check caching, assignment and whether traffic split between the arms as planned. If the split holds, enter each arm's visitors and purchases in the A/B test significance calculator to see whether the gap is beyond chance. If the result stays inconclusive, extend the test long enough to cover different stock periods.