Clinical Textbook of Addictive Disorders 3rd ed - R. Frances, S. Miller, A. Mack (Guilford, 2005) WW

3. Psychological Evaluation 39several facets. Construct validity means that the psychological processes claimedto be measured are, in fact, what are being assessed. For instance, it is essentialto be confident that a poor score on a neuropsychological test of memory capacityis due to a central nervous system (CNS) disorder and is not spurious.Hence, utility of a particular instrument depends on its capacity to evaluateaccurately the process intended to be measured.In addition, psychological measures should have predictive validity; that is,the processes evaluated by the test should yield scores that predict the individual’sbehavior. For example, low scores on tests of educational aptitudeshould portend academic underachievement. High scores on tests of anxietyshould predict avoidant social behavior. These predictions should be orientedto meaningful and specific domains of functioning, such as the person’spotential to respond to a particular type of treatment or hold a certain type ofjob. Predictive validity is therefore an essential aspect of a comprehensiveassessment, because it yields information that guides selection of the particulartype of rehabilitation program that in turn impacts on long-term prognosis.Finally, it should be noted that psychological testing is warranted onlywhen the obtained data have incremental validity; that is, the test should yieldinformation beyond what can be acquired from informal interviewing or casualobservation. It is pointless to measure depression if the patient readily providesa self-report of symptoms. Psychometric procedures are most prudently utilizedin situations where the objectivity of measurement yields information that iseither too complex or too subtle to be obtained from observation or ordinaryinteraction with the client. Because it is both expensive and labor-intensive,clinicians should not request a psychological evaluation to merely confirm aclinical impression.ReliabilityOf the various types of reliability, two need to be considered here: test–retestand interrater reliability. Test–retest reliability refers to the temporal stability ofthe score. The clinical meaningfulness of test results is contingent upon itsrepeatability. Thus, any changes observed in the individual over time shouldreflect a true change in the person’s status and not be due to random fluctuationsof unknowable origin. A psychological test that has established test–retestreliability can be thus used repeatedly to monitor changes in status that occurduring the course of treatment and aftercare.The second type of reliability is interrater reliability. A test score obtainedby one clinician should ideally be the same as the test administered by another,equally skilled clinician. In this fashion, confidence can be placed in theresults. In effect, the results should not reflect the idiosyncratic interactionbetween the clinician and the client.