the improvement obtained by adding a particular procedure or technique to an existing combination of assessment methods. In other words, incremental validity reflects the value of each measure or piece of information to the process and outcome of assessment. The standards for evaluating incremental validity depend on the goal of the assessment, such as whether one wishes to gather unique information, predict a criterion, make a diagnosis, or choose a treatment. For example, teacher observations of the daily frequency of a child’s vocal tic may not add critical information in diagnosing a tic disorder but may contribute significantly when the purpose of the assessment is to monitor treatment progress.