The winning ad set is determined by comparing the cost per result of each ad set. The ad set with the lowest cost per result, such as cost per website purchase, is calculated in Facebook's attribution system.

Based on the data from the test, Facebook simulates the performance of each variable tens of thousands of times to determine how often the winning outcome would have won.

Once a winner is determined, you'll receive a notification in Ads Manager and an email will be sent to you with the results.

Learn more: About split testing

* Nguồn: Facebook