Comparison of Waisiii and Waisr Factors

Some researchers argued that the WAIS-R is just a one-factor test, while other investigators, using diverse techniques, insisted on either two or three significant factors (Kaufman, 1990). As noted, a one-factor WAIS-R solution is fairly meaningless for clinical assessment; two- or three-factor solutions are each defensible as the best reduction of WAIS-R data (Leckliter et al., 1986). Kaufman (1990) concluded that examiners may choose to interpret either two or three WAIS-R factors, depending on the profile obtained by any given individual (i.e., the decision should rest on whether the small third dimension is interpretable for a given person).

In the first edition of this book, Kaufman (1990) reported that two-factor solutions of the WAIS-R offer outstanding support of the construct validity of the WAIS-R for normal and clinical samples, for males and females, for African Americans and Caucasians, and for different age groups spanning adolescence and old age. The WAIS-R's Verbal Comprehension dimension is defined by all six Verbal subtests, although the loadings for Digit Span are not as decisive as the loadings for the other five tasks. Similarly, the WAIS-R's Perceptual Organization is defined by the five Performance subtests. Two Performance subtests (Picture Completion and Picture Arrangement) have substantial loadings on the Verbal factor as well, but this tendency is stronger for the normal standardization sample than for the diverse clinical groups.

A third WAIS-R factor, historically labeled Freedom from Distractibility, but sometimes called Sequential Ability, Short-term Memory, Number Ability, Attention/Concentration, or Working Memory, was identified for various abnormal samples and for normal groups differing in gender, ethnic background (African Americans, Caucasians, Hispanics), and age (Kaufman, 1990). This third factor is composed of two WAIS-R subtests: Digit Span and Arithmetic.

Although Digit Symbol (-Coding) is associated with the third factor for the WISC-R, there is only weak and inconsistent support for its inclusion on the third WAIS-R factor. When three WAIS-R factors are rotated, Verbal Comprehension is defined by four subtests (all but the two "distractibility" tasks), and Perceptual Organization is defined by three: Block Design, Object Assembly, and Picture Completion. Neither Picture Arrangement nor Digit Symbol is consistently associated with any of the three factors, although both evidence interesting age-related trends for males and females (Kaufman, 1990).

Kaufman, Lichtenberger, and McLean (2001) compared the factor structure of the 11 subtests that are on both the WAIS-R and the WAIS-III to examine the continuity between the two versions of the test. As discussed in Chapter 3, the latest two versions of the WAIS are strikingly similar when only the 11 shared subtests are analyzed. Tables 3.5 and 3.6 in this book present the two- and three-factor solutions of both the WAIS-R and WAIS-III. The coefficients of congruence are striking, ranging from .984 to .996 on the three-factor solutions and surpassing .995 when two factors are rotated. With the addition of the new WAIS-III subtests, the four-factor model dominates the latest version of the test; however, like the WAIS-R, there is still strong support for the three-factor model of the WAISIII (Kaufman et al., in press; Ward et al., 2000).

Understanding And Treating Autism

Understanding And Treating Autism

Whenever a doctor informs the parents that their child is suffering with Autism, the first & foremost question that is thrown over him is - How did it happen? How did my child get this disease? Well, there is no definite answer to what are the exact causes of Autism.

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