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.
All psychological tests have some degree of error and this reduces the accuracy of a score. Therefore, it cannot be established with certainty that an individual has a specific IQ of 69, 70, or 71, rather, there is a certainty of a score within a particular range, accounting for error. This application of data to clinical decisions is referred to as “clinical validity”—is the decision clinically valid? Clinicians must carefully assess their confidence in their decision as well as the consequences of an error in clinical judgment as a result of ever-present measurement error.
This week you are asked to take a position with regard to a current legal standard. Review this week’s Learning Resources and analyze the Virginia v. Atkins ruling in which the Supreme Court has determined that it is unconstitutional to execute an individual who has an intellectual disability. In its decision the court stipulated that one criterion is an IQ score below 70. Consider the use of this “cut-off” score in formulating this type of decision. Remember, this is not a discussion about the death penalty; rather, it is a discussion about the use of specific cut-off scores in making clinical, administrative, or legal decisions.
With these thoughts in mind:
Post by Day 4 an argument for or against the use of cut-off scores in diagnoses that might affect court decisions. Use the current literature to support your response. Then, justify an alternative solution to this issue using the Learning Resources and current literature to support your response. Finally, explain one way cut-off scores might be applied in clinical practice.