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WECHSLER INTELLIGENCE SCALE FOR CHILDREN-3 RD EDITION (WISC-III)

WECHSLER INTELLIGENCE SCALE FOR CHILDREN-3 RD EDITION (WISC-III). PRESENTED BY LAURA KOHL. GENERAL INFORMATION. Primary Construct Assessed: General intelligence in children

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WECHSLER INTELLIGENCE SCALE FOR CHILDREN-3 RD EDITION (WISC-III)

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  1. WECHSLER INTELLIGENCE SCALE FOR CHILDREN-3RD EDITION (WISC-III) PRESENTED BY LAURA KOHL

  2. GENERAL INFORMATION • Primary Construct Assessed: General intelligence in children • Test Purpose: The WISC-III was designed to measure specific mental abilities that together reflect a child’s general intelligence

  3. GENERAL INFORMATIONContinued • Title: Wechsler Intelligence Scale for Children • Acronym: WISC-III • Author: David Wechsler • Publication Date: 1991 • Publisher: The Psychological Corporation • Previous Editions Publication Dates: 1949 and 1974 • Price: $520.00 per complete kit • Ages: 6-16.11 years • Norms: Based on 2200 children using a stratified random sampling procedure • Administration Time: Approximately 50-75 minutes

  4. GENERAL INFORMATIONContinued • Administration Type:The WISC-III is usually administered by a psychologist. This is an individually administered test. • Scoring & Interpretation Time: Time is approximately 30-40 minutes

  5. DEVELOPMENT OF THE WISC-III • Developed in response to research indicating that norms for intelligence tests become dated over time • In addition to re-norming, there were changes in test materials and administrative procedures as well • Pictures now more attractive and in color • Recommended order of administering subtests has changed

  6. DEVELOPMENT OF THE WISC-IIIContinued • One of main focal points is minimization of bias • Calculation of factor scores in addition to the IQ scores • Balance of the presentation of test items to include minorities and females • Maintain basic structure of WISC-R-73% overlap

  7. GENERAL SUBTEST INFORMATION • Battery of tests for 6-16.11 year olds: Evaluates intellectual abilities • 2 Scales: Verbal Scale and Performance Scale

  8. GENERAL SUBTEST INFORMATION- Continued • Administration time: Regular battery of 10 subtests requires 50-75 minutes and 3 supplementary subtests require an additional 10-15 minutes • Administer in one session: Test should be administered in one session. If it must be discontinued, reschedule during same week

  9. Picture Completion Information Coding Similarities Picture Arrangement Arithmetic Block Design Vocabulary Object Assembly Comprehension Symbol Search Digit Span Mazes WISC-III SUBTESTS

  10. SCORING • In scoring the WISC-III, raw scores for subtests are transmitted into scaled scores • Tables of scores are given for every 4 month interval between ages 6 and 16 years, 11 months • Subtest scaled scores have mean of 10 and standard deviation of 3

  11. SCORING Continued • Add scores together to produce overall verbal, performance and full scale score. • Using the norm tables, scores are converted to verbal, performance and full scale IQ scores • Mean 100 and standard deviation of 15 • 100 is average score

  12. FOUR FACTOR INDEXES • FACTOR I: Verbal Comprehension (Information, Similarities, Vocabulary, and Comprehension) • FACTOR II: Perceptual Organization (Picture Completion, Picture Arrangement, Block Design and Object Assembly) • FACTOR III: Freedom from Distractibility (Arithmetic and Digit Span) • FACTOR IV: Processing Speed: (Coding, Symbol Search)

  13. NORMATIVE INFORMATION • Ages: The sample of 2200 cases included 200 children from each of the 11 age groups ranging from 6 to 16.11 years • Gender: The sample included 100 males and 100 females in each age group • Race/Ethnicity: Proportions of Whites, Blacks, Hispanics and other race/ethnic groups were based on U.S. census data from 1988 • Geographic Region: U.S. was divided into 4 major geographic regions specified in the Census reports—Northeast, North Central, South and West

  14. SAMPLE CHARACTERISTICSContinued • Parent Education: Sample was stratified according to the following 5 education categories—8th grade or less, 9th through 11th grade, high school graduate or equivalent, 1-3 years of college, or 4 or more years of college

  15. RELIABILITY • Strong reliability overall: With 1.0 being a perfect correlation, subtest reliabilities are moderate to excellent (.61 to .92) • Consistency of IQ’s and Indexes: Very good to excellent (.80 to .97) • IQ and Index Stability: Mostly good to excellent (.74 to .95) • Interrater Reliability: Excellent for selected verbal subtests (all greater than .92)

  16. RELIABILITY Continued • Verbal IQ and Full Scale IQ Reliabilities:All exceeded .90 • Performance IQ Reliability:Range from .80 to .94

  17. VALIDITY

  18. CONVERGENT/DIVERGENT VALIDITY • The manual reports strong correlations between the WISC-III and the WPPSI-R, WISC-R, WAIS-R, Otis-Lennon School Ability Test, and the Differential Ability Scales

  19. PREDICTIVE VALIDITY • Studies in the manual and subsequent studies support the ability of the WISC-III to predict relevant outcomes. • The most important of these is the prediction of academic achievement in children.

  20. CLINICAL VALIDITY • The WISC-III goes well beyond its predecessor in providing support for clinical diagnosis, but most evidence to date shows that the WISC-III is not terribly sensitive to abnormal clinical conditions.

  21. LIMITING FACTORS • Common practice for students in special education to be assessed frequently—may result in higher scores due to practice effects • Caution must be used when interpreting scores—tests are limited measures of student’s assets overall • Verbal Scale is more closely related to academic achievement than performance scale

  22. STRENGTHS • Most widely used individually administered test of intellectual ability in children • Representative sample • Strong psychometric properties—reliability and validity are strong • Verbal and Performance Scale division—show individual strengths and weaknesses

  23. THE END

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