Wechsler’s Definition of IQ

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TM

Copyright © 1997 by The Psychological Corporation. All rights reserved.

Wechsler’s Definition of IQWechsler’s Definition of IQ

“Intelligence is the aggregate or global capacity of the individual to act purposefully, to think rationally and to deal effectively with his environment.”

– Global because it characterizes individual’s behavior as a whole

– Aggregate because it is composed of elements or abilities that are qualitatively differentiable

“Intelligence is the aggregate or global capacity of the individual to act purposefully, to think rationally and to deal effectively with his environment.”

– Global because it characterizes individual’s behavior as a whole

– Aggregate because it is composed of elements or abilities that are qualitatively differentiable

Wechsler, 1939Wechsler, 1939

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Goals of the WAIS–IIIGoals of the WAIS–III

Goal 1: Continuity and Familiarity

Goal 2: Updating of Norms

Goal 3: Extension of Age Range

Goal 4: Age-Corrected Norms

Goal 5: Improved Item Content

Goal 6: Improved Stimulus Materials

Goal 1: Continuity and Familiarity

Goal 2: Updating of Norms

Goal 3: Extension of Age Range

Goal 4: Age-Corrected Norms

Goal 5: Improved Item Content

Goal 6: Improved Stimulus Materials

Revisions and ChangesRevisions and Changes

33


Goals of the WAIS–IIIGoals of the WAIS–III

Goal 7: Improved Diagnostic and Descriptive Utility

Goal 8: De-emphasis on Performance Speed

Goal 9: Enhancement of Fluid Reasoning Assessment

Goal 10: Linkage with WMS–III and WIAT

Goal 11: Extensive Validity Studies

Goal 12: Enhancement of Scoring Rules

Goal 7: Improved Diagnostic and Descriptive Utility

Goal 8: De-emphasis on Performance Speed

Goal 9: Enhancement of Fluid Reasoning Assessment

Goal 10: Linkage with WMS–III and WIAT

Goal 11: Extensive Validity Studies

Goal 12: Enhancement of Scoring Rules

Revisions and ChangesRevisions and Changes

44


Basic Description of the WAIS–IIIBasic Description of the WAIS–III• Individual Administration• Assessment of Cognitive Functioning in Adults,

Aged 16–89 Years• Scale Composition

– 11 Subtests to Obtain IQ Scores– 11 Subtests to Obtain Index Scores– New Subtests: Matrix Reasoning, Symbol Search,

Letter–Number Sequencing– Optional Subtest: Object Assembly

• Individual Administration• Assessment of Cognitive Functioning in Adults,

Aged 16–89 Years• Scale Composition

– 11 Subtests to Obtain IQ Scores– 11 Subtests to Obtain Index Scores– New Subtests: Matrix Reasoning, Symbol Search,

Letter–Number Sequencing– Optional Subtest: Object Assembly

Goal 1: Continuity and FamiliarityGoal 1: Continuity and Familiarity

55


Demographic Stratification Variables

Demographic Stratification Variables

• Age

• Sex

• Race/Ethnicity

• Education Level

• Geographic Region

• Age

• Sex

• Race/Ethnicity

• Education Level

• Geographic Region

66


Stratification Variables: AgeStratification Variables: Age

16–17

18–19

20–24

25–29

30–34

35–44

45-54

55–64

65–69

70–74

75–79

80–84

85–89

WAIS–III

200 200 200 200 200 200 200 200 200 200 200 150 100

WMS–III

100 100 100 100 100 100 100 100 100 100 100 75 75

45–54

77


Structure of the ScaleStructure of the Scale

WAIS–III Levels of PerformanceWAIS–III Levels of Performance

FSIQFSIQFSIQFSIQ

Digit SpanDigit SpanArithmeticArithmeticLetter–Number Letter–Number

SequencingSequencing

VocabularyVocabularySimilaritiesSimilaritiesInformationInformationComprehensionComprehension

DigitDigit SymbolSymbol—Coding—CodingSymbol SearchSymbol Search

Block DesignBlock DesignMatrix ReasoningMatrix ReasoningPicture CompletionPicture CompletionPicture ArrangementPicture Arrangement

VIQVIQVIQVIQ PIQPIQPIQPIQ

VCIVCIVCIVCI WMIWMIWMIWMI POIPOIPOIPOI PSIPSIPSIPSI

88


WAIS–III Subtests for IQ ScoresWAIS–III Subtests for IQ Scores

• Vocabulary• Similarities• Arithmetic• Digit Span• Information• Comprehension

• Vocabulary• Similarities• Arithmetic• Digit Span• Information• Comprehension

• Picture Completion• Digit Symbol—Coding• Block Design• Matrix Reasoning• Picture Arrangement

• Picture Completion• Digit Symbol—Coding• Block Design• Matrix Reasoning• Picture Arrangement

Verbal PerformanceVerbal Performance

99


WAIS–III Subtestsfor Index Scores

WAIS–III Subtestsfor Index Scores

• Vocabulary

• Similarities

• Information

• Vocabulary

• Similarities

• Information

• Arithmetic

• Digit Span

• Letter–Number Sequencing

• Arithmetic

• Digit Span

• Letter–Number Sequencing

• Picture Completion

• Block Design

• Matrix Reasoning

• Picture Completion

• Block Design

• Matrix Reasoning

• DigitSymbol—Coding

• Symbol Search

• DigitSymbol—Coding

• Symbol Search

Verbal Comprehension

Verbal Comprehension

Perceptual OrganizationPerceptual

OrganizationWorkingMemoryWorkingMemory

ProcessingSpeed

ProcessingSpeed

1010


Summary of Verbal Subtest ChangesSummary of Verbal Subtest Changes

VocabularyVocabulary 3535 2525 00 88 3333SimilaritiesSimilarities 1414 1111 00 88 1919ArithmeticArithmetic 1414 1313 11 66 2020Digit SpanDigit Span 1414 1414 00 11 1515InformationInformation 2929 1818 11 66 1818ComprehensionComprehension 1616 1212 00 66 1818Letter–NumberLetter–Number Sequencing Sequencing —— —— —— 77 7 7

SubtestSubtest

Total Items

WAIS–R

Total Items

WAIS–R

Unchanged or Slightly Modified


Substantially Modified


New ItemsNew Items

Total Items

WAIS–III

Total Items

WAIS–III

1111


Summary of Performance Subtest ChangesSummary of Performance Subtest Changes

Picture CompletionPicture Completion 2020 88 22 1515 25 25Digit SymbolDigit Symbol —Coding —Coding 9393 9393 00 4040 133133Block DesignBlock Design 99 99 00 55 14 14Matrix ReasoningMatrix Reasoning —— —— —— 2626 28 28PicturePicture Arrangement Arrangement 1010 55 00 66 11 11Symbol SearchSymbol Search —— —— —— 6060 60 60Object AssemblyObject Assembly 44 33 11 22 5 5

SubtestSubtest

Total Items

WAIS–R

Total Items

WAIS–R





New ItemsNew Items

Total Items

WAIS–III

Total Items

WAIS–III

1212


Converting Raw Scores to Scaled ScoresConverting Raw Scores to Scaled Scores

SUBTESTSSUBTESTS Raw ScoreRaw Score

Picture Completion

Vocabulary

Digit Symbol–Coding

Similarities

Block Design

Arithmetic

Matrix Reasoning

Picture Completion

Vocabulary

Digit Symbol–Coding

Similarities

Block Design

Arithmetic

Matrix Reasoning

22 12 12 12

56 13 13 15

54 7 7 6

28 12 12 13

41 1 1 1 1 10

1 1 8 8 9

20 13 13 12

22 12 12 12

56 13 13 15

54 7 7 6

28 12 12 13

41 1 1 1 1 10

1 1 8 8 9

20 13 13 12

VERBAL PERF. VC PO WM PSVERBAL PERF. VC PO WM PS

Reference Group Scaled Scores

Reference Group Scaled Scores

Age-Adjusted Scaled ScoresAge-Adjusted Scaled Scores

1313


Converting Sums of Scaled Scoresto IQ and Index Scores

Converting Sums of Scaled Scoresto IQ and Index Scores

IQ/INDEX SCORESIQ/INDEX SCORES VIQ PIQ FSIQ VCI POI WMI PSIVIQ PIQ FSIQ VCI POI WMI PSI

Sums of Scaled Scores

IQ/Index Scores

Percentiles

Confidence Intervals

Sums of Scaled Scores

IQ/Index Scores

Percentiles

Confidence Intervals

62 55 117

101 106 103

53 66 58

96– 99– 99–106 112 107

62 55 117

101 106 103

53 66 58

96– 99– 99–106 112 1079595

1414

%%


Plotting Subtest Scores (IQ)Plotting Subtest Scores (IQ)

1515


Plotting Subtest Scores (Index)Plotting Subtest Scores (Index)

1616


Determining Strengths and WeaknessesDetermining Strengths and Weaknesses

13 9.57 3.43 2.10 5 <5%

12 9.57 2.43 2.77

8 9.57 –1.57 2.63

7 9.57 –2.57 2.40 W >25%

1 1 9.57 1.43 2.34

1 1 9.57 1.43 2.96

13 9.57 3.43 2.10 5 <5%

12 9.57 2.43 2.77

8 9.57 –1.57 2.63

7 9.57 –2.57 2.40 W >25%

1 1 9.57 1.43 2.34

1 1 9.57 1.43 2.96

SUBTESTSSUBTESTSScaled Score

Scaled Score

Vocabulary

Similarities

Arithmetic

Digit Span

Information

Comprehension

Vocabulary

Similarities

Arithmetic

Digit Span

Information

Comprehension

Mean ScoreMean Score

Difference from MeanDifference from Mean

Statistical Significance .0

5 Level

Statistical Significance .0

5 LevelStrength

(+)Strength

(+)Weakness

(–)Weakness

(–)

Frequency of Difference in

Standardization Sample



Total÷ No. of Subtests

Mean Score

Total÷ No. of Subtests

Mean Score

67 70 = 137

7 7 ÷ 14

9.57 10 9.79

67 70 = 137

7 7 ÷ 14

9.57 10 9.79Overall MeanOverall Mean

1717


Discrepancy AnalysisDiscrepancy Analysis

101 106 -5 8.48

110 111 -1 9.78

110 80 30 9.08 2.3%

111 79 32 12.13 2.6%

101 106 -5 8.48

110 111 -1 9.78

110 80 30 9.08 2.3%

111 79 32 12.13 2.6%

DISCREPANCY COMPARISONSDISCREPANCY COMPARISONS

Verbal IQ –Performance IQ

Verbal Comprehension – Perceptual Organization

Verbal Comprehension – Working Memory

Perceptual Organization – Processing Speed

Verbal IQ –Performance IQ

Verbal Comprehension – Perceptual Organization

Verbal Comprehension – Working Memory

Perceptual Organization – Processing Speed

Score1

Score1

Score2

Score2 DifferenceDifference

Statistical Significance .05 Level

Statistical Significance .05 Level





VIQ PIQ

VCI POI

VCI WMI

POI PSI

VIQ PIQ

VCI POI

VCI WMI

POI PSI

Digits Forward – BackwardDigits Forward – Backward 7 5 2 60%7 5 2 60%

FWD BKWD FWD BKWD

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Wechsler’s Definition of IQ