A/A testing, also known as split-split testing, is a type of testing where two groups of users receive the same experience in order to validate the accuracy of a testing method or tool. In other words, it is a control test where both the control group and treatment group receive the same experience to determine if any difference between the two groups is due to the tool being used or to chance. A/A testing is used to ensure that a testing method is working correctly and to identify potential sources of error before conducting a more meaningful A/B test.