Item response theory analyses of the Delis-Kaplan Executive Function System card sorting subtest

ABSTRACT

In the current study, we examined the dimensionality of the 16-item Card Sorting subtest of the Delis-Kaplan Executive Functioning System assessment in a sample of 264 native English-speaking children between the ages of 9 and 15 years. We also tested for measurement invariance for these items across age and gender groups using item response theory (IRT). Results of the exploratory factor analysis indicated that a two-factor model that distinguished between verbal and perceptual items provided the best fit to the data. Although the items demonstrated measurement invariance across age groups, measurement invariance was violated for gender groups, with two items demonstrating differential item functioning for males and females. Multigroup analysis using all 16 items indicated that the items were more effective for individuals whose IRT scale scores were relatively high. A single-group explanatory IRT model using 14 non-differential item functioning items showed that for perceptual ability, females scored higher than males and that scores increased with age for both males and females; for verbal ability, the observed increase in scores across age differed for males and females. The implications of these findings are discussed.

KEYWORDS:

• Item response theory
• exploratory factor analysis
• executive function
• differential item functioning
• multigroup analysis

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ Measurement invariance was investigated using the original standardization sample of the D-KEFS only. Dimensionality of EF was investigated using the original standardization sample and an independent sample of 174 male adolescents.

² In this paper, we use the term of factor to refer to latent variables in factor analyses and the term dimension to refer to latent variables in IRT analyses.

³ We used 0.32 as a good rule of thumb for the minimum loading of an item to consider it important/salient, which equates to approximately 10% overlapping variance with the other items in that factor in EFA.

⁴ Quartimin, Oblimin, and Varimax rotation methods were also tried. The same conclusions were reached in terms of the number of dimensions and the patterns of factor loadings.

⁵ Wald DIF test is asymptotically equivalent to LRT-LR DIF procedure.

⁶ Intercepts in the regression model of the explanatory model were fixed to 0 to identify the model.

Additional information

Funding

This work was supported by the National Center for Advancing Translational Sciences [UL1 TR000445]; National Institute of Child Health and Human Development [R01 HD 044073, U54 HD 083211, R01 HD 044073-14S1].