A 24-year-old man with moderate intellectual disability (IQ 42) is brought to the PMHNP by his group home staff for evaluation of increasing aggression, self-injurious behavior (head-banging), and disrupted sleep over the past three weeks. Staff report that these behaviors represent a significant change from his baseline. He has limited verbal communication and uses a combination of gestures and a picture exchange system. His current medications include risperidone 1 mg twice daily, which was initiated two years ago for aggression. The PMHNP considers the most appropriate initial assessment approach. Which of the following best reflects evidence-based practice for evaluating behavioral changes in individuals with intellectual disability?