Exploratory and confirmatory factor analyses of the WISC-IV with gifted students

These 2 studies investigated the factor structure of the Wechsler Intelligence Scale for Children-4th edition (WISC-IV; Wechsler, 2003a) with exploratory factor analysis (EFA; Study 1) and confirmatory factor analysis (CFA; Study 2) among 2 independent samples of gifted students. The EFA sample consisted of 225 children who were referred for a cognitive assessment as part of the application for gifted programming in their schools. The CFA sample consisted of 181 students who were tested the following year. All students included in the analyses were either accepted to school-based gifted programs following the assessment or were already participating in one. Across the 2 studies, there were approximately equal numbers of boys (205) and girls (201) with a mean age of 8-years-old. The mean composite scores for both samples varied from high average to superior and evidenced substantial differences among the index scores. In the EFA, the 2-, 3-, 4-, and 5-factor solutions were considered. The first 3 models, as well as an additional model reflecting the Verbal and Performance (V-P) IQ scores from previous versions of the WISC, were then compared using CFA. The CFA fit indices and parameter estimates supported the 4-factor, first-order WISC-IV model. This is the measurement model that includes the 4 index scores. Parameter estimates for the higher-order model reflecting g suggested that combining factors into a single, overarching score may not be the best way to represent the varying cognitive scores of gifted students.