Measuring improvement or decline on the WAIS-R in inpatient psychiatry

Psychologists in inpatient psychiatric settings sometimes are asked to assess whether patients improve or decline in intellectual functioning. The impetus for this referral question may be a perceived change in psychiatric status, an acute neuropathological event, e.g., a head injury, or a suspicion of an early dementing process. For this study, data from 100 inpatients who completed the WAIS-R on two separate admissions were used to calculate confidence bands for measurement error surrounding test-retest difference scores. The analysis indicated that, if the retest interval is three months or less, significant practice effects must be factored into the interpretation of difference scores. A table for the interpretation of difference scores at different testing intervals is provided