Focus is idiographic understanding of the behaviour of an individual person. Also may be used to evaluate treatment progress. Test-retest reliability yields the same results every time it is given to the same people. Interrater (inter-judge) reliability different judges independently agree on how to score and interpret a particular tool: validity the accuracy of a tool"s results. Allow the interviewer to focus on whatever topics they consider most important focus depends on theoretical orientation. Conducting the interview can be either unstructured or structured. In an unstructured interview, clinicians ask prepared questions, often from a published interview schedule (mental exam) Limitations may lack validity or accuracy individuals may be intentionally misleading. Interviewers may be biased or may make mistakes in judgment. Focus on parent-child, sibling-child, or teacher-child interactions, and on fearful, aggressive, or disruptive behaviour made by participant observers and reported to clinician.