title: Comparison of Predicted-difference, Simple-difference, and Premorbid-estimation methodologies for evaluating IQ and memory score discrepancies.
abstract: Discrepancies between WAIS-III and WMS-III scores for a group of 39 males and 48 females with a history of TBI were examined using three methodologies: Predicted-difference, Simple-difference, and Premorbid-estimation methods. Overall, the Predicted-difference method tended to classify the fewest individuals as impaired based on statistical rarity of discrepancies (11-16% classified as impaired), while the regression-based Premorbid method tended to classify the fewest individuals as impaired based on clinical rarity of discrepancies (4-8% classified as impaired). Degree of agreement is reported and was substantial. The only comparison between methods to reach statistical significance was the Predicted-difference method classifying subjects as impaired at a higher rate than other methods for Auditory Delayed memory index (Cochran's Q = 7.00, P < .05). Findings suggest a combination of estimates of premorbid functioning and regression-based predicted scores is optimal for interpreting IQ/memory score discrepancies. Clinical implications are discussed.
authors.affiliation: Central Michigan University, Mt. Pleasant, MI 48859, USA. reid.skeel@cmich.edu
authors.forename: Reid L
authors.initials: RL
authors.lastname: Skeel
authors.forename: David
authors.initials: D
authors.lastname: Sitzer
authors.forename: Tammie
authors.initials: T
authors.lastname: Fogal
authors.forename: Janet
authors.initials: J
authors.lastname: Wells
authors.forename: Brick
authors.initials: B
authors.lastname: Johnstone
mesh_terms: D000328:Adult; D020208:Brain Injury, Chronic / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D004522:Educational Status; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007360:Intelligence; D008297:Male; D008569:Memory Disorders / Q000145:classification / Q000175:diagnosis* / Q000523:psychology; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D011932:Reading; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results; D012153:Retention, Psychology; D014888:Wechsler Scales / Q000706:statistics & numerical data*