title: Bifactor structure of the Wechsler Preschool and Primary Scale of Intelligence--Fourth Edition.
abstract: The Wechsler Preschool and Primary Scale of Intelligence--Fourth Edition (WPPSI-IV; Wechsler, 2012) represents a substantial departure from its predecessor, including omission of 4 subtests, addition of 5 new subtests, and modification of the contents of the 5 retained subtests. Wechsler (2012) explicitly assumed a higher-order structure with general intelligence (g) as the second-order factor that explained all the covariation of several first-order factors but failed to consider a bifactor model. The WPPSI-IV normative sample contains 1,700 children aged 2 years and 6 months through 7 years and 7 months, bifurcated into 2 age groups: 2:6-3:11 year olds (n = 600) and 4:0-7:7 year olds (n = 1,100). This study applied confirmatory factor analysis to the WPPSI-IV normative sample data to test the fit of a bifactor model and to determine the reliability of the resulting factors. The bifactor model fit the WPPSI-IV normative sample data as well as or better than the higher-order models favored by Wechsler (2012). In the bifactor model, the general factor accounted for more variance in every subtest than did its corresponding domain-specific factor and the general factor accounted for more total and common variance than all domain-specific factors combined. Further, the domain-specific factors exhibited poor reliability independent of g (i.e., ωh coefficients of .05 to .33). These results suggest that only the general intelligence dimension was sufficiently robust and precise for clinical use.
authors.affiliation: Department of Educational Psychology, Baylor University.
authors.forename: Marley W
authors.identifier: 0000-0001-6352-7174
authors.initials: MW
authors.lastname: Watkins
authors.affiliation: Department of Educational Psychology, Baylor University.
authors.forename: A Alexander
authors.identifier: 0000-0001-7007-7968
authors.initials: AA
authors.lastname: Beaujean
mesh_terms: D002648:Child; D002675:Child, Preschool; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D008960:Models, Psychological; D011594:Psychometrics; D015203:Reproducibility of Results; D014888:Wechsler Scales