Prorating Full-Scale IQ Scores on the WAIS-IV

• Published in: Archives of clinical neuropsychology 2013-01, Vol.28 (6), p.43-44
• Main Authors: Olivier, T, Spengler, K, Sterk, V, Espinoza, K, Golden, C
• Format: Article
• Language: English
• ISSN: 0887-6177

Objective: This paper examined the relationship between prorated and full scoring methods on Full-Scale IQ scores (FSIQ) of the WAIS-IV as a result of removing Working Memory and Processing Speed Index (WMI, PSI) subtests. Method: Participants included 25 adults (M age = 31.64, SD = 14.01), mostly Caucasian (56%). Diagnoses were primarily neuropsychological (72%). Participants were administered the WAIS-IV core battery, which was scored using the standard scoring methods outlined in the manual and re-scored by removing WMI/PSI subtests to obtain prorated FSIQ scores. Results: Results of a one-way repeatedmeasures ANOVA indicated no significant differences between FSIQ scoring methods, F(3.415, 192) = 2.24, p = .082. Prorated scores were highly correlated with full FSIQ scores (r > .95); standard error for all estimates did not exceed 2.95. Conclusion: There were no significant differences between full and prorated FSIQ scores obtained by omission of either one WMI or PSI subtest or omission of one WMI and one PSI subtest. These data suggest that the WAIS-IV core battery may be shortened by the removal of up to two subtests without damaging the reliability or validity of the resulting FSIQ score or significantly increasing standard error. All prorated scores were highly correlated with FSIQ scores. This study was limited, however, because of the small sample size; perhaps significant differences between prorated and full FSIQ scores would appear in larger or more specific diagnostic samples, such as neurological and acute impairment conditions, which may cause decreased WMI and PSI scores. In such cases, removing subtests sensitive to impairment may cause artificially inflated FSIQ estimates.