Construct Validity of the WISC–IVUKWith a Large Referred Irish Sample

Construct Validity of the WISC-V in Clinical Cases: Exploratory and Confirmatory Factor Analyses of the 10 Primary Subtests

Independent exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) research with the Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V) standardization sample has failed to provide support for the five group factors proposed by the publisher, but there have been no independent examinations of the WISC-V structure among clinical samples. The present study examined the latent structure of the 10 WISC-V primary subtests with a large (N = 2,512), bifurcated clinical sample (EFA, n = 1,256; CFA, n = 1,256). EFA did not support five factors as there were no salient subtest factor pattern coefficients on the fifth extracted factor. EFA indicated a four-factor model resembling the WISC-IV with a dominant general factor. A bifactor model with four group factors was supported by CFA as suggested by EFA. Variance estimates from both EFA and CFA found that the general intelligence factor dominated subtest variance and omega-hierarchical coefficients supported interpretation of the general intelligence factor. In both EFA and CFA, group factors explained small portions of common variance and produced low omega-hierarchical subscale coefficients, indicating that the group factors were of poor interpretive value.

Structural Validity of the WISC-IV for Students With ADHD

OBJECTIVE

To evaluate the structural validity of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV).

METHOD

Confirmatory factor analyses were applied to a sample of 233 students diagnosed with ADHD by school multidisciplinary evaluation teams to evaluate the relative fit of the following competing models: (a) one factor, (b) two oblique verbal and nonverbal factors, (c) three oblique verbal, perceptual, and combined working memory/processing speed factors, (d) four oblique verbal, perceptual, working memory, and processing speed factors, (e) a higher-order model with four first-order factors, and (f) a bifactor model with four domain-specific factors.

RESULTS

A higher-order four-factor model fit the data best, which was composed of a general intelligence factor and four domain-specific factors that matched the four factors specified in the WISC-IV technical and interpretive manual. Moreover, the general intelligence factor explained more than two times the total variance contributed by all four domain-specific factors combined.

CONCLUSIONS

Results substantiate previous research on the WISC-IV, indicating that the general intelligence factor contributes the most reliable information. Consequently, it is recommended that interpretation of the WISC-IV remain at the Full-Scale IQ score level.

Evidencia de validez de constructo para el WISC-IV con muestra brasileña

El objetivo fue analizar la estructura interna de la versión brasileña del WISC-IV, comparando el modelo de puntuaciones compuestas y cuatro dominios, constante en el manual del WISC-IV, con otros dos modelos, el de un factor general de la inteligencia y un modelo con base en la teoría CHC. Participaron 795 niños y adolescentes de diferentes regiones de Brasil, con edades entre 6 y 16 años. Los resultados mostraron que el modelo que mejor se ajustó fue el propuesto por el manual del WISC-IV. El modelo con base en la teoría CHC también presentó buen ajuste, pero con valores un poco inferiores a la propuesta original. El modelo de un factor general fue rechazado pues los índices de bondad de ajuste no fueron satisfactorios. Se sugieren futuras investigaciones que estudien la estructura del WISC-IV en otros países.

Structure of the Wechsler Intelligence Scale for Children - Fourth Edition in a Group of Children with ADHD

Objective: This study used confirmatory factor analysis to examine the factor structure for the 10 core WISC–IV subtests in a group of children (N = 812) with ADHD.

Method: The study examined oblique four- and five-factor models, higher order models with one general secondary factor and four and five primary factors, and a bifactor model with a general factor and four specific factors.

Results: The findings supported all models tested, with the bifactor model being the optimum model. For this model, only the general factor had high explained common variance and omega hierarchical value, and it predicted reading and arithmetic abilities.

Conclusion: The findings favor the use of the FSIQ scores of the WISC-IV, but not the subscale index scores.

Structural Validity of the WISC-IV for Students With Learning Disabilities

The structural validity of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) was evaluated using confirmatory factor analysis for a clinical sample of 1,537 students diagnosed with specific learning disabilities (SLD) by school psychologists in two large southwestern school districts. Results indicated that a bifactor model consisting of four first-order domain specific factors and a general intelligence breadth factor fit the data best. Consequently, the structural validity of the WISC-IV for students with SLD was supported by the results of the present study. The general intelligence factor contributed the most information, accounting for 48% of the common variance. Given this structure, it was recommended that score interpretation should emphasize the Full-Scale IQ score because of the marginal contributions of the first-order domain-specific factors and their low precision of measurement independent of the general factor.

Do the Autism Spectrum Quotient (AQ) and Autism Spectrum Quotient Short Form (AQ-S) Primarily Reflect General ASD Traits or Specific ASD Traits? A Bi-Factor Analysis

In the current study, we fit confirmatory bi-factor models to the items of the Autism Spectrum Quotient (AQ) and Autism Spectrum Quotient Short Form (AQ-S) in order to assess the extents to which the items of each reflect general versus specific factors. The models were fit in a combined sample of individuals with and without a clinical diagnosis of autism spectrum disorders. Results indicated that, with the exception of the Attention to Details factor in the AQ and the Numbers/Patterns factors in the AQ-S, items primarily reflected a general factor. This suggests that when attempting to estimate an association between a specific symptom measured by the AQ or AQ-S and some criterion, associations will be confounded by the general factor. To resolve this, we recommend using a bi-factor measurement model or factor scores from a bi-factor measurement whenever hypotheses about specific symptoms are being assessed.

Incremental validity of WISC-IV(UK) factor index scores with a referred Irish sample: predicting performance on the WIAT-II(UK.)

BACKGROUND

Subtest and factor scores have typically provided little incremental predictive validity beyond the omnibus IQ score.

AIMS

This study examined the incremental validity of Wechsler Intelligence Scale for Children - Fourth UK Edition (WISC-IV(UK) ; Wechsler, 2004a, Wechsler Intelligence Scale for Children - Fourth UK Edition, Harcourt Assessment, London, UK) and factor index scores in predicting academic achievement on the Wechsler Individual Achievement Test - Second UK Edition (WIAT-II(UK) ; Wechsler, 2005a, Wechsler Individual Achievement Test-Second UK Edition, Pearson, London, UK), beyond that predicted by the WISC-IV(UK) FSIQ.

SAMPLE

The sample included 1,014 Irish children (ages 6-0 to 16-9) who were referred for evaluation of learning difficulties.

METHOD

Hierarchical multiple regression analyses were used with the WISC-IV(UK) FSIQ (Block 1) and factor index scores (Block 2) as predictors and WIAT-II(UK) subtest and composite scores as dependent variables.

RESULTS

The WISC-IV(UK) FSIQ accounted for statistically significant and generally large portions of WIAT-II(UK) subtest and composite score variance. WISC-IV(UK) factor index scores combined to provide statistically significant increments in prediction of most WIAT-II(UK) subtest and composite scores over and above the FSIQ; however, the effect sizes were mostly small as previously observed (i.e., Canivez, 2013a, Psychol. Assess., 25, 484; Glutting et al., 2006, J. Spec. Educ., 40, 103; Nelson et al., 2013, Psychol. Assess., 25, 618). Individually, the WISC-IV(UK) factor index scores provided small unique contributions to predicting WIAT-II(UK) scores.

CONCLUSION

This, in combination with studies of apportioned variance from bifactor confirmatory factor analysis (Watkins et al., 2013, Int. J. Sch. Educ. Psychol., 1, 102), indicated that the WISC-IV(UK) FSIQ should retain the greatest weight in WISC-IV(UK) interpretation.