The Factorial Structure of Wechsler's Preschool and Primary Scale of Intelligence at Successive Age Levels

Abstract

SUMMARY.A factor analysis of the correlation matrix for the subtests of WPPSI was carried out for each of the age groups between 4 and 6+ years. The data were obtained from the WPPSI standardisation samples. In each analysis, three factors were extracted and two of these, after equimax rotation, were found to give patterns of loadings which were similar for all age groups. The rotated factors were identified as verbal intelligence, space performance and comprehension. Order analysis of the same data tended to support the notion that these factors could be also arranged into a circular order along with various tests of WPPSI.Using a likelihood ratio test for the Guttman ' circumplex ' structure, the correlation matrix for the 4-year age group was analysed and the result provides clear support for the postulated circular arrangement of the tests. The circumplex ordering of WPPSI suggests a systematic ordering according to the law of neighbouring variables and is found to be more parsimonious and less subjective in interpreting than the results emerging from the traditional factor analysis.INTRODUCTION THE present study was originally undertaken in order to examine the possibility of age-related trends in the pattern of mental abilities as reflected in the factorial structure of the Wechsler Preschool and Primary Scales ONpPSI), which had been administered to children aged 4 and 6$ years. For this purpose, the WPPSI data were factored by the iterative principal-axes method and three factors were retained for rotation by the equimax method.The study reported here aimed at answering the following questions : (a) With the principal-axes method can the first of the factors so obtained be identified with general intelligence and, if so, is this factor the same for all the age groups ? (b) Does this general factor account for il decreasing amount of common variance as the age level increases ? (c) With the method of equimax rotation how far do the factors obtained at one age level correspond with factors obtained at another ? If they are the same, do the factor loadings show any monotonic trend as a result of age change ? The final, and most important question was : (d) Do the WPPSI subtests conform to a circular ordering or ' circumplex ' (Guttman. 1954) ?The circumplex theory of Guttman (1 954) postulates that qualitatively different traits in a given domain can have an order among themselves without a beginning or an end. "A set of variables obeying such a law will be called a

Hierarchical factor structure of the Wechsler Preschool and Primary Scale of Intelligence—Revised.

“…These results were obtained on the standardization data by Carlson and Reynolds (1981), Hollenbeck and Kaufman (1973), Kaufman and Hollenbeck (1974), O'Grady (1990), Ramanaiah and Adams (1979), and Wall-Correspondence concerning this article should be addressed to John Blaha, Psychology Department, George Mason University, 4400 University Drive, Fairfax, Virginia 22030. brown, Blaha, and Wherry (1973), on emotionally disturbed children by Haynes and Atkinson (1984), and on above/below average reading children by Maxwell (1972). Those studies of the WPPSI standardization (Coates & Bromberg, 1973;Mukherjee, 1975) and samples such as educationally deprived and "normals" (Heil, Barclay, & Endres, 1978), and children with below-average reading (Maxwell, 1972), which extracted more than two factors found that only two factors were interpretable as Verbal and Performance with the remaining factor or factors being uninterpretable or denned by loadings from a single subtest or the factor or factors were inconsistent across age levels. Thus, it would appear that the Verbal and Performance factors remained invariant to changes in factor procedure or rotation method.…”