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


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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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Wechsler intelligence scale for children 3 rd edition wisc iii l.jpg

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

PRESENTED BY

LAURA KOHL


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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


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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


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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


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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


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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


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GENERAL SUBTEST INFORMATION

  • Battery of tests for 6-16.11 year olds: Evaluates intellectual abilities

  • 2 Scales: Verbal Scale and Performance Scale


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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


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Picture Completion

Information

Coding

Similarities

Picture Arrangement

Arithmetic

Block Design

Vocabulary

Object Assembly

Comprehension

Symbol Search

Digit Span

Mazes

WISC-III SUBTESTS


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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


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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


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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)


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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


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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


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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)


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RELIABILITY Continued

  • Verbal IQ and Full Scale IQ Reliabilities:All exceeded .90

  • Performance IQ Reliability:Range from .80 to .94


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VALIDITY


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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


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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.


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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.


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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


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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


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THE END


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