WISC-IV Standardization Sample Research Articles

Diagnostic Utility of the WISC-IV GAI > CPI Cognitive Score Profile for a Referred Sample of Children and Adolescents with Autism

Individuals with autism spectrum disorder (ASD) are hypothesized to exhibit relative strengths in verbal and non-verbal reasoning and weaknesses in working memory and speed of information processing. The purpose of the present investigation was to determine the degree to which this cognitive profile as measured by the Wechsler Intelligence Scale for Children—Fourth Edition (WISC-IV; Wechsler 2003a) cognitive proficiency index (CPI; measure of working memory and processing speed) and general ability index (GAI; measure of verbal and non-verbal reasoning) could accurately distinguish between a referred sample of 79 school-aged students diagnosed with ASD and two non-clinical comparison groups: (a) 2200 children in the WISC-IV standardization sample and (b) 216 school-aged students referred for psychoeducational testing whose school-based evaluations did not result in a diagnosis. Results indicated that the ASD sample exhibited significantly lower mean scores on the CPI when compared to the two control groups. However, diagnostic utility statistics indicated that a randomly selected participant from the ASD subgroup would exhibit a larger difference between the GAI and CPI than a randomly selected participant from the two control groups 51.9–66.0% of the time. Consequently, the GAI > CPI cognitive score profile exhibits low diagnostic accuracy for individuals with ASD. Psychologists who work in applied settings are cautioned against using group trends to guide decision-making for individual clients.

Testing for multigroup invariance of the WISC-IV structure across France and Switzerland: Standard and CHC models

Measurement invariance of the WISC-IV factorial structure between French and Swiss samples was investigated by means of multi-group confirmatory factor analysis (MGCFA). The first sample was the French WISC-IV standardization sample described in the French WISC-IV technical manual (ages 6:0 through 16:11years), which included 1103 children (Wechsler, 2005). The French speaking Swiss sample included 249 children ranging in age from 8 to 12years old (124 males, mean age=10.16, SD=1.12 and 125 females, mean age=10.26, SD=1.17). Multigroup higher-order models were estimated to assess measurement invariance. In a first step, multigroup models were used to analyze the current four-factor structure. In a second step, multigroup higher-order models were conducted on a CHC-based model with five factors. For both the four-factor and the CHC-based models, results supported partial measurement invariance. Indeed, while configural and weak metric invariance criteria were met, intercept invariance was not demonstrated

Higher-Order Factor Structures for the WISC-IV: Implications for Neuropsychological Test Interpretation

Factor-analytic studies support a hierarchical four-factor model for the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) with a prominent general, third-order factor. However, there is substantial disagreement on which type of higher-order model best fits the data and how different models should guide test interpretation in clinical practice, with many studies concluding interpretation should primarily be focused on general indicators of intelligence. We performed a series of confirmatory factor analyses with the WISC-IV standardization sample (N = 2,200, ages 6–16 years) to examine model fit and reexamined models used to support test interpretation at the general level. Consistent with previous research, bifactor models were difficult to identify; however, compared with bifactor and hierarchical models, the correlated factors model with no general higher-order factor provided the best fit to the data. Results from this study support the basic four-factor model specified in the WISC-IV technical manual, with test interpretation primarily focused at the factor level, rather than the general level suggested in previous studies.

Discrepancy Score Reliabilities in the WISC-IV Standardization Sample

This investigation provides internal consistency reliabilities for Wechsler Intelligence Scale for Children—Fourth Edition (WISC-IV) subtest and index discrepancy scores using the standardization sample as the data source. Reliabilities range from .50 to .82 for subtest discrepancy scores and from .78 to .88 for index discrepancy scores. Thus, the reliabilities of the WISC-IV subtest and index discrepancy scores do not reach the ≥.90 criterion recommended for clinical decision making. However, 5 of the 66 subtest and 33 of the 36 index discrepancy score reliabilities are ≥.80, which is regarded as adequate when hypothesis generation is the goal instead of decision making.

A proposed method to estimate premorbid full scale intelligence quotient (FSIQ) for the Canadian Wechsler Intelligence Scale for Children–Fourth Edition (WISC-IV) using demographic and combined estimation procedures

Establishing a comparison standard in neuropsychological assessment is crucial to determining change in function. There is no available method to estimate premorbid intellectual functioning for the Wechsler Intelligence Scale for Children–Fourth Edition (WISC-IV). The WISC-IV provided normative data for both American and Canadian children aged 6 to 16 years old. This study developed regression algorithms as a proposed method to estimate full-scale intelligence quotient (FSIQ) for the Canadian WISC-IV. Participants were the Canadian WISC-IV standardization sample (n = 1,100). The sample was randomly divided into two groups (development and validation groups). The development group was used to generate regression algorithms; 1 algorithm only included demographics, and 11 combined demographic variables with WISC-IV subtest raw scores. The algorithms accounted for 18% to 70% of the variance in FSIQ (standard error of estimate, SEE = 8.6 to 14.2). Estimated FSIQ significantly correlated with actual FSIQ (r = .30 to .80), and the majority of individual FSIQ estimates were within ±10 points of actual FSIQ. The demographic-only algorithm was less accurate than algorithms combining demographic variables with subtest raw scores. The current algorithms yielded accurate estimates of current FSIQ for Canadian individuals aged 6–16 years old. The potential application of the algorithms to estimate premorbid FSIQ is reviewed. While promising, clinical validation of the algorithms in a sample of children and/or adolescents with known neurological dysfunction is needed to establish these algorithms as a premorbid estimation procedure.

Estimating Premorbid General Cognitive Functioning for Children and Adolescents Using the American Wechsler Intelligence Scale for Children—Fourth Edition: Demographic and Current Performance Approaches

Neuropsychologic evaluation requires current test performance be contrasted against a comparison standard to determine if change has occurred. An estimate of premorbid intelligence quotient (IQ) is often used as a comparison standard. The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) is a commonly used intelligence test. However, there is no method to estimate premorbid IQ for the WISC-IV, limiting the test's utility for neuropsychologic assessment. This study develops algorithms to estimate premorbid Full Scale IQ scores. Participants were the American WISC-IV standardization sample (N = 2172). The sample was randomly divided into 2 groups (development and validation). The development group was used to generate 12 algorithms. These algorithms were accurate predictors of WISC-IV Full Scale IQ scores in healthy children and adolescents. These algorithms hold promise as a method to predict premorbid IQ for patients with known or suspected neurologic dysfunction; however, clinical validation is required.

Orthogonal higher order structure of the Wechsler Intelligence Scale for Children--Fourth edition.

According to J. B. Carroll's (1993) 3-stratum theory, performance on any subtest reflects a mixture of both 2nd-order and 1st-order factors. To disentangle these influences, variance explained by the general factor should be extracted first. The 1st-order factors are then residualized, leaving them orthogonal to the general factor and each other. When these methods were applied to the WISC-IV standardization sample, the general factor accounted for the greatest amount of common (71.3%) and total (38.3%) variance. The largest contribution by a first-order factor was 6.5% of total variance. It was recommended that interpretation of the WISC-IV not discount the strong general factor.

Review of WISC-IV: Clinical Use and Interpretation: Scientist-Practitioner Perspectives.

AURELIO PRIFITERA, DONALD SAKLOFSKE, and LAWRENCEWEISS (Eds.) WISC-IV: Clinical Use and Interpretation: San Diego, CA: Academic Press, 2005, 432 pages (ISBN 0-12-564931-2, US$59.95 Hardcover) The purpose of this book is to introduce the Wechsler Intelligence Scale for Children, 4th Edition (WISC-IV) and describe its use in some common clinical populations. The title Scientist-Practitioner Perspectives leads the reader to believe that there will be an evidenced-based approach taken to the use of the WISC-IV in these special populations. This is a tall order given that the WISC-IV has only been released and there has been little research completed using it. Most of the evidence provided is based instead on the WISC-HI. The first three chapters are written by the editors and describe the changes that the WISC-IV brings from the WISC-III and provides a rationale for these changes. Specifically, the first chapter covers the change from Verbal IQ, Performance IQ, and Full Scale IQ to the four-factor model. The authors provide useful information and descriptions of each of the subtests and the factors. They also emphasize the importance of analyzing test scores within their clinical context, integrating all other information in the interpretation. The next two chapters cover the Full Scale IQ and each of the four factors and describe the General Ability Index (GAI) as an alternative to the FSIQ. The six subtests comprising the Verbal Comprehension Index and the Perceptual Organization Index are added to make the GAI. This is a useful measure to use when the Working Memory Index or Processing Speed Index is elevating or depressing the Full Scale IQ. Tables for the GAI are provided in Chapter 2. Chapter 4 describes the Process Approach and the WISC-IV Integrated. These first four chapters are useful in their descriptions of each aspect of the WISC-IV measure, but provide no critical evaluation of the measure. Chapters 5 and 6 present a three-tier model for the assessment of specific learning disabilities. The chapters are based on research by Beringer and others, using the WISC-III. The authors make the tenuous argument that because of the similarities between the WISC-III and the WISC-IV, one can confidently substitute the WISC-IV into this model of multilevel assessment. The case studies presented use the WISC-III as the IQ measure. Chapter 7 is a useful, well-written chapter on ADHD. The authors integrate theoretical models of ADHD with available research. Although this research is based mostly on the WISC-III, the authors do a good job of applying the research findings to the WISC-IV, pointing out differences between the WISC-III and the WISC-IV that may make generalization of some research findings difficult. For example, the authors note that research on the Freedom From Distractibility Index may not generalize to the WISC-IV because the new Letter-Number Sequencing subtest has been added to the index (now called Working Memory), and Arithmetic, which was previously a core subtest, is a supplemental one in the WISC-IV. They also report research findings from the WISC-IV standardization sample and draw comparisons to research on the WISC-III. The chapter ends with a case study where WISC-IV results are combined with results from other tests and questionnaires, to show how one might make an ADHD diagnosis. Chapter 8 focuses on the assessment of children who are Gifted. The authors report some research based on the WISC-III but are quick to point out the substantial changes to the WISC-IV and the difficulties in generalizing evidence gained from previous research. They use data from the WISC-IV standardization sample of Gifted children and relate it to previous research. They specifically discuss how the changes to the WISC-IV impact the diagnosis of Giftedness, including both pros and cons of the WISC-IV with respect to this population. The case study they present is one of a child who was previously identified as Gifted using the WISC-III and reassessed using the WISC-IV two years later. …