Gary L. Canivez

Long-Term Stability of the Wechsler Intelligence Scale for Children--Third Edition.

Long-term stability of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV; Wechsler, 2003) was investigated with a sample of 344 students from 2 school districts twice evaluated for special education eligibility at an average interval of 2.84 years. Test-retest reliability coefficients for the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), Processing Speed Index (PSI), and the Full Scale IQ (FSIQ) were .72, .76, .66, .65, and .82, respectively. As predicted, the test-retest reliability coefficients for the subtests (Mdn = .56) were generally lower than the index scores (Mdn = .69) and the FSIQ (.82). On average, subtest scores did not differ by more than 1 point, and index scores did not differ by more than 2 points across the test-retest interval. However, 25% of the students earned FSIQ scores that differed by 10 or more points, and 29%, 39%, 37%, and 44% of the students earned VCI, PRI, WMI, and PSI scores, respectively, that varied by 10 or more points. Given this variability, it cannot be assumed that WISC-IV scores will be consistent across long test-retest intervals for individual students.

Investigation of the Factor Structure of the Wechsler Adult Intelligence Scale—Fourth Edition (WAIS-IV): Exploratory and Higher Order Factor Analyses

The present study examined the factor structure of the Wechsler Adult Intelligence Scale--Fourth Edition (WAIS-IV; D. Wechsler, 2008a) standardization sample using exploratory factor analysis, multiple factor extraction criteria, and higher order exploratory factor analysis (J. Schmid & J. M. Leiman, 1957) not included in the WAIS-IV Technical and Interpretation Manual (D. Wechsler, 2008b). Results indicated that the WAIS-IV subtests were properly associated with the theoretically proposed first-order factors, but all but one factor-extraction criterion recommended extraction of one or two factors. Hierarchical exploratory analyses with the Schmid and Leiman procedure found that the second-order g factor accounted for large portions of total and common variance, whereas the four first-order factors accounted for small portions of total and common variance. It was concluded that the WAIS-IV provides strong measurement of general intelligence, and clinical interpretation should be primarily at that level.

Construct validity of the WISC-IV with a referred sample: direct versus indirect hierarchical structures.

The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) is one of the most frequently used intelligence tests in clinical assessments of children with learning difficulties. Construct validity studies of the WISC-IV have generally supported the higher order structure with four correlated first-order factors and one higher-order general intelligence factor, but recent studies have supported an alternate model in which general intelligence is conceptualized as a breadth factor rather than a superordinate factor (M. W. Watkins, 2010, Structure of the Wechsler Intelligence Scale for Children-Fourth Edition among a national sample of referred students, Psychological Assessment, Vol. 22, pp. 782-787; M. W. Watkins, G. L. Canivez, T. James, K. & R. Good, in press, Construct validity of the WISC-IVUK with a large referred Irish sample, International Journal of School and Educational Psychology). WISC-IV core subtest data obtained from evaluations to assess learning difficulties in 345 children (224 boys, 121 girls) were examined. One through four, first order factor models and indirect versus direct hierarchical models were compared using confirmatory factor analyses. The correlated four-factor Wechsler model provided good fit to these data, but the direct hierarchical model showed statistically significant improvement over the indirect hierarchical model and correlated four-factor model. The direct hierarchical model was judged the best explanation of the WISC-IV factor structure, with the general factor accounting for 71.6% of the common variance while the first order factors accounted for 2.4-10.3% of the common variance. Thus, the results with the present sample of referred children were similar to those from other investigations (G. E. Gignac, 2005, Revisiting the factor structure of the WAIS-R: Insights through nested factor modeling, Assessment, Vol. 12, pp. 320-329; G. E. Gignac, 2006, The WAIS-III as a nested factors model: A useful alternative to the more conventional oblique and higher-order models, Journal of Individual Differences, Vol. 27, pp. 73-86; P. Golay, I. Reverte, J. Rossier, N. Favez, & T. Lecerf, 2012, Further insights on the French WISC-IV factor structure through Bayesian structural equation modeling. Psychological Assessment, advance online publication; M. W. Watkins, 2010, Structure of the Wechsler Intelligence Scale for Children-Fourth Edition among a national sample of referred students, Psychological Assessment, Vol. 22, pp. 782-787; M. W. Watkins, G. L. Canivez, T. James, K. & R. Good, in press, Construct validity of the WISC-IV(UK) with a large referred Irish sample, International Journal of School and Educational Psychology) supporting primary interpretation of the Full Scale IQ rather than the factor index scores.

Structural and Incremental Validity of the Wechsler Adult Intelligence Scale-Fourth Edition With a Clinical Sample

Structural and incremental validity of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008a) was examined with a sample of 300 individuals referred for evaluation at a university-based clinic. Confirmatory factor analysis indicated that the WAIS-IV structure was best represented by 4 first-order factors as well as a general intelligence factor in a direct hierarchical model. The general intelligence factor accounted for the most common and total variance among the subtests. Incremental validity analyses indicated that the Full Scale IQ (FSIQ) generally accounted for medium to large portions of academic achievement variance. For all measures of academic achievement, the first-order factors combined accounted for significant achievement variance beyond that accounted for by the FSIQ, but individual factor index scores contributed trivial amounts of achievement variance. Implications for interpreting WAIS-IV results are discussed.

Examination of the structural, convergent, and incremental validity of the Reynolds Intellectual Assessment Scales (RIAS) with a clinical sample.

Empirical examination of the Reynolds Intellectual Assessment Scales (RIAS; C. R. Reynolds & R. W. Kamphaus, 2003a) has produced mixed results regarding its internal structure and convergent validity. Various aspects of validity of RIAS scores with a sample (N = 521) of adolescents and adults seeking psychological evaluations at a university-based clinic were examined. Results from exploratory factor analysis indicated only 1 factor, and confirmatory factor analysis (CFA) indicated that the 1-factor model was a good fit and a better fit than the 2-factor model. Hierarchical factor analysis indicated the higher order, general intelligence factor accounted for the largest amount of variance. Correlations with other measures of verbal/crystallized and nonverbal/fluid intelligence were supportive of the convergent validity of the Verbal Intelligence Index but not the Nonverbal Intelligence Index. Joint CFA with these additional measures resulted in a superior fit of the 2-factor model compared with the 1-factor model, although the Odd-Item-Out subtest was found to be a poor measure of nonverbal/fluid intelligence. Incremental validity analyses indicated that the Composite Intelligence Index explained a medium to large portion of academic achievement variance; the NIX and VIX explained a small amount of remaining variance. Implications regarding interpretation of the RIAS when assessing similar individuals are discussed.

WAIS-IV and WISC-IV Structural Validity Alternate Methods, Alternate Results. Commentary on Weiss et al. (2013a) and Weiss et al. (2013b)

Weiss, Keith, Zhu, and Chen (2013a) and Weiss, Keith, Zhu, and Chen (2013b), this issue, report examinations of the factor structure of the Wechsler Adult Intelligence Scale–Fourth Edition (WAIS-IV) and Wechsler Intelligence Scale for Children–Fourth Edition (WISC-IV), respectively; comparing Wechsler Hierarchical Model (W-HM) and Cattell–Horn–Carroll Hierarchical Model (CHC-HM), subtest cross-loadings, and factorial invariance between clinical and normative groups from the respective standardizations. Both studies suffer from a number of theoretical, methodological, and practical problems that significantly limit conclusions and recommendations for practitioner interpretations of these instruments. Additional analyses and research are required to better inform practitioners for WAIS-IV and WISC-IV use.

Significant Factor Score Variability and the Validity of the WISC-III Full Scale IQ in Predicting Later Academic Achievement

The purpose of this study was to investigate the validity of the WISC-III (Wechsler, 1991) Full Scale IQ (FSIQ) scores in predicting later academic achievement given significant variability among any of the four WISC-III factor scores. Taken from an archival data set, the sample was composed of 6- to 13-year-old students who were twice evaluated for special education eligibility over approximately a 3-year retest interval. Participants were separated into two groups based on the presence or absence of significant factor score variability and then matched across groups on disability, FSIQ, age, sex, and ethnicity. The results of hierarchical multiple regression analyses indicated that the Full Scale IQ was a valid predictor of academic achievement scores even in the presence of significant factor score variability.

Construct Validity of the Kaufman Brief Intelligence Test, Wechsler Intelligence Scale for Children-Third Edition, and Adjustment Scales for Children and Adolescents.

The present study reports data supporting the construct validity of the Kaufman Brief Intelligence Test (K-BIT; Kaufman & Kaufman, 1990), the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; Wechsler, 1991), and the Adjustment Scales for Children and Adolescents (ASCA; McDermott, Marston, & Stott, 1993) through convergent and discriminant comparisons in a sample of 207 students receiving special education evaluations. Results were as hypothesized, with high and statistically significant correlations between the K-BIT and WISCIII, supporting convergent validity. Moderate and statistically significant correlations were obtained between the two intelligence measures (K-BIT and WISC-III) and measures of academic achievement (WIAT, WIAT-II, WJ-R ACH, or WJ-3 ACH) at levels typical of ability-achievement correlations. Correlations between the two intelligence measures (K-BIT and WISC-III) and the ASCA, a measure of child psychopathology, were low to near zero, supporting discriminant validity. Further discriminant evidence of construct validity was provided by the low to near zero correlations between the ASCA and the measures of academic achievement.

Factor structure of the Wechsler Intelligence Scale for Children-Fifth Edition: Exploratory factor analyses with the 16 primary and secondary subtests.

The factor structure of the 16 Primary and Secondary subtests of the Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V; Wechsler, 2014a) standardization sample was examined with exploratory factor analytic methods (EFA) not included in the WISC-V Technical and Interpretive Manual (Wechsler, 2014b). Factor extraction criteria suggested 1 to 4 factors and results favored 4 first-order factors. When this structure was transformed with the Schmid and Leiman (1957) orthogonalization procedure, the hierarchical g-factor accounted for large portions of total and common variance while the 4 first-order factors accounted for small portions of total and common variance; rendering interpretation at the factor index level less appropriate. Although the publisher favored a 5-factor model where the Perceptual Reasoning factor was split into separate Visual Spatial and Fluid Reasoning dimensions, no evidence for 5 factors was found. It was concluded that the WISC-V provides strong measurement of general intelligence and clinical interpretation should be primarily, if not exclusively, at that level. (PsycINFO Database Record

Construct Validity of the WISC-IV UK With a Large Referred Irish Sample

Irish educational psychologists frequently use the Wechsler Intelligence Scale for Children–Fourth U.K. Edition (WISC–IVUK) in clinical assessments of children with learning difficulties. Unfortunately, reliability and validity studies of the WISC–IVUK have not yet been reported. This study examined the construct validity of WISC–IVUK core subtest scores obtained from evaluations to assess learning difficulties in 794 Irish children (494 boys and 300 girls). One through four first-order factor models and indirect (higher-order) versus direct (bi-factor) hierarchical models were examined and compared using confirmatory factor analyses. The oblique four-factor Wechsler model provided the best fit to these data, but meaningful differences in fit statistics were not observed between this oblique four-factor model and rival indirect hierarchical and direct hierarchical models. For theoretical reasons, the direct (bi-factor) hierarchical model provided the best explanation of the WISC–IVUK factor structure. The general factor accounted for 63.7% of the common variance, whereas first-order factors each accounted for 8.6% to 9.6% of the common variance. Thus, the results with referred Irish children were similar to those from other investigations, further demonstrating the replication of the Wechsler Intelligence Scale for Children–Fourth Edition factor structure across cultures and the importance of focusing primary interpretation on the Full Scale Intelligence Quotient.