Structural validity of the Spanish Wechsler Intelligence Scale for Children–Fourth Edition in a large sample of Spanish children with attention-deficit hyperactivity disorder

ABSTRACT

The factorial structure of the WISC-IV for 859 Spanish children diagnosed with ADHD was examined. A bifactor model with the four factors first identified by Wechsler (2003a) was the best fit to the data. The Coding and Symbol Search subtests were particularly poor measures of g but relatively strong measures of the Processing Speed factor. In contrast, the Block Design (BD) and Picture Concepts (PC) subtests were relatively strong measures of g but weak measures of the Perceptual Reasoning factor. In fact, 80% of the BD variance and 97.8% of the PC variance and was due to the general factor. Additionally, the Wechsler bifactor model was invariant across ADHD-Combined and ADHD-Inattentive groups, permitting a direct comparison of WISC-IV across children diagnosed with these subtypes of ADHD. Only the FSIQ exhibited robust estimates of reliability (ω = .85 and ω_h = .70). In contrast, the group factor scores were unreliable measures of their proposed underlying factors (ω_hs coefficients ranging from .14 to .50). It is unlikely that WISC-IV index score profiles can validly contribute to ADHD assessments. Consequently, clinicians must produce psychometric evidence to justify the interpretation of Wechsler score profiles for children with ADHD.

KEYWORDS:

• ADHD
• WISC-IV
• CFA
• bifactor
• intelligence
• validity
• invariance

Acknowledgments

Our appreciation to Almudena Hernández-Ruiz, Bonastre Gabasa-Gracia, Susana Lázaro-Mañes, and Ana Lozano-Monterde; all were members of Apunt Psicòlegs Mental Health Unit. We offer our special thanks to Juan Carlos Moyano-Gálvez.

Additional information

Notes on contributors

Javier Fenollar-Cortés

Javier Fenollar-Cortés, PhD, is a professor and clinical psychologist from the Department of Psychology at Universidad Loyola Andalucía (Spain). His teaching and research focus on ADHD and neurocognitive performance and cognitive profiles, in relation to improving ADHD conceptualization and diagnosis through clinical scales and neuropsychological tasks.

Carlos López-Pinar

Carlos López-Pinar is a clinical psychologist and PhD student from the Department of Psychobiology at the University of Valencia (Spain). His research interests involve individual differences in child psychopathology and professional issues in clinical psychology.

Marley W. Watkins

Marley W. Watkins, PhD, is professor and chairman of the Department of Educational Psychology at Baylor University. His research interests include professional issues, the psychometrics of assessment and diagnosis, individual differences, and computer applications.