The study will evaluate the effectiveness of a standardized EEG method with the intended clinical users in the intended clinical settings with the intended population (patients who would typically receive a clinician's evaluation for ADHD). Multiple sites will be examined to provide a sample of patients across numerous communities with different demographics. The goal is to evaluate if the predictive accuracy of EEG will not be inferior to that of a widely-used and extensively validated ADHD scale in the prediction of ADHD in the intended use population as evaluated by Best Estimate Diagnosis.