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Out of Stock: Remove the Button or Notify Me A/B Test

An out-of-stock label explains why a product cannot be bought.

  • Product page
  • Back-in-stock notification signup rate

Variant A vs Variant B

Two alternatives; neither is the incumbent.

Changed
Options
Page
Product page
Difference
changed

Hypothesis

Replacing the purchase control with a stock-alert option also gives interested visitors a way to hear back. Sign-ups describe use of this new path; assess its value through later purchases and notification complaints.

How to run this test

Primary metric

Back-in-stock notification signup rate

Measure signups per eligible assigned visitor. The status-only arm has no signup path, so this metric describes demand captured by the added mechanism.

Other metrics

  • Purchase rate after restockAfter the product returns to stock, compare purchases among all eligible assigned visitors over the same follow-up window.
  • Alternative product page visit rateMeasure visits to alternative product pages among assigned visitors who see an alternative-product link.
  • Notification complaints and unsubscribesAmong users who consent to notifications, track complaints and unsubscribes over the same follow-up period.

What to check before and during the test

  • ComparisonCompare an out-of-stock status label with one defined back-in-stock notification option.
  • ChannelChoose one notification channel and consent flow before launch.
  • AlternativesKeep alternative-product recommendations the same.
  • Stock timingIf shown, use the same accurate availability estimate in both arms.
  • DeviceCheck notification signup completion on mobile and desktop.

Setup mistakes to avoid

  1. 1Do not present an uncertain restock date as definite; label estimates clearly.
  2. 2Do not change the notification format and alternative recommendations together.
  3. 3Ask only for information needed to send the stock notification.
  4. 4Do not add urgency claims that are not supported by live inventory.
  5. 5Change the out-of-stock action only; leave price, images and product details as they are.