Purpose: Designed to as a “measure of a child’s intellectual and cognitive ability.”
Population: Children, aged 6 years 0 months through 16 years 11 months.
Score: Four Index Scales and a Full Scale Scores.
Time: (65 - 80) minutes for most children.
Author: David Wechsler.
Publisher: The Psychological Corporation.
Description: This fourth edition updates the WISC-III and provides subtest and composite scores representing intellectual functioning in general and specific cognitive abilities. The changes in the WISC-IV represent current research on cognitive development, intellectual assessment and cognitive processes. The revisions also include updated norms, additional subtests, and emphasis on scores reflecting discrete areas of cognitive functioning. New subtests include Word Reasoning, Matrix Reasoning, Picture Concepts, Cancellation, and Letter-Number Sequencing. Former WISC-III subtests that were dropped include Mazes, Object Assembly, and Picture Arrangement.
Scoring: Requires Subtest raw scores are converted into scaled scores that are summed into four index scores. The Verbal Comprehension Index (VCI) is composed of three subtests that are mostly verbal, the Perceptual Reasoning Index (PRI) uses three subtests that rely less on verbal skills, the Working Memory Index (WMI) consists of items requiring recall and repetition of letters and numbers, and the Processing Speed Index (PSI) uses non-verbal, timed search and coding tests. The optional subtests are not included in the index scores unless they replace a core test.
Reliability: The subtest reliability coefficients for internal consistency ranged from .79 to .90 with a median of .86. These coefficients showed substantial improvement from those of WISC-III subtests. The index scores reliability coefficient ranged from .88 PSI to .97 FS with a median of .92. These are identical to or slightly higher than WISC-III corresponding scales.
Validity: One of the manual reports strong correlations between WISC-IV metrics and comparable metrics from the WISC-III WPPSI-III, WAIS-III, Wechsler Abbreviated Scale of Intelligence (WASI; Wechsler, 1999), WIAT-II, Children’s Memory Scale (CMS; Cohen, 1997) Gifted Youth Version (Bar-On & Parker, 2000), and the Adaptive Behavior Assessment System-Second Edition (ABAS-II; Harrison & Oakland, 2003. Evidence of construct validity was also established using matched samples of clinical and non-clinical children.
Norms: One of the major goals was to update the norms to be more representative of the relevant population. The normative sample included 2200 children aged 6:0-16:11 and additional samples from special groups. The sample was stratified on demographic variables of age, sex, race/ethnicity, parent education level, and geographic region based on the March 2000 U.S. census data.
Suggested use: The WISC-IV is an appropriate instrument for practitioners and clinical researchers in assessing children’s intelligence and general cognitive functioning. When used with other assessment tools, it can be useful in identifying giftedness, mental retardation, and cognitive strengths and weaknesses. The test results can be useful in treatment planning, in placement and provision of clinical or educational services, and can add important information to a neuropsychological evaluation.