Intelligence Testing and Cut-off Scores

Assessment methods provide data to the clinician, however, the clinician must decide how to use the data in making a decision or recommendation with regard to the client. The assessment data do not make the decision for the clinician, rather the data are used by the clinician in making the decision. The process of clinical decision-making requires the clinician to apply the data to clinical “decision rules or guidelines.” For example, one guideline may be that if a clinician believes that their client, as a result of a mental illness, poses a substantial and imminent risk of harm to self or others then that clinician is obligated to pursue available means to have the client hospitalized. If a client reports suicidal ideation then the clinician must apply this information to their “decision rule” to determine if hospitalization is warranted. Also, the criteria determining an intellectual disability indicates a significantly below-average performance on a standardized test of intelligence, the presence of functional impairments, and onset prior to age 18. The criterion for establishing significant impairment in intelligence is frequently established as a score below 70 on a standardized test of intelligence.