46-320-01 Tests and Measurements

1. 46-320-01Tests and Measurements Intersession 2006

2. Defining Intelligence • Psychometric approach • Information-processing approach • Cognitive approach

3. Spearman • Intelligence consists of one global factor (g) and specific factors • Positive manifold: all tests are influenced by g • Factor analysis • Half the variance in diverse mental ability tests is represented by g • Intelligence best represented by one score

4. Multiple Intelligences • gf-gc theory • Fluid (gf) • Reason, think, acquire new knowledge • Crystallized (gc) • Knowledge and acquired understanding

5. Binet • Binet: the capacity to: • Find and maintain a definite direction or purpose • To make necessary adaptations to achieve that purpose • For self-criticism so the adjustments can be made • Age Differentiation • Capabilities distinguish • 2/3 to 3/4 of children of a certain age • Independent of chronological age • General Mental Ability • Total product of all capabilities/elements of intelligence

6. 1905 Binet-Simon Scale • First major intelligence measure • 30 increasingly difficult items • Terms: idiot, imbecile, moron • Poor validation sample

7. 1908 Scale • Age scale • One score – verbal, language, and reading abilities • Mental age – 2/3 to 3/4 of items at age level

8. 1916 Stanford-Binet Intelligence Scale • Terman • Intelligence Quotient (IQ): • 16 maximum CA

9. 1937 Revision • Revisions in scoring, instructions • Performance items included • Alternate Forms L and M • IQ scores not equivalent across age

10. 1960 Scale • No alternate forms • Deviation IQ • Standard score: mean 100, sd 16 • New tables corrected for variability differences across ages • 1972: new normative sample, included nonwhites

11. Modern Stanford-Binet • Incorporated gf-gc theory • 1986: Age scale eliminated – 15 separate tests • Standard age scores, mean 50, sd 8

12. 1986 Administering the Test • Starting point: • CA used with score on Vocabulary test • Basal Age • Lowest level where 2 consecutive items are passed • Ceiling • At least 3 of 4 items are missed

13. Interpreting Results • Four area-content scores • Composite score • Mean 100, sd 16

14. 1986 Psychometric Properties • Reliability • .90 minimum – met by composite and area scores (both KR20 and test-retest) • Individual tests – some below this • Validity • Factor analysis: generally supports 4 group factors and g factor • Correlates well with other measures • Overall, meets expectations

15. 2 routing measures (verbal and nonverbal) 10 subtests total 5 factors: Fluid Reasoning; Knowledge; Quantitative Reasoning; Visual/Spatial Reasoning; Working Memory Return to age scale format Scaled scores: mean 10, SD 3 Standard Scores (Full-scale IQ, Nonverbal IQ, Verbal IQ, 5 factors): Mean 100, SD 15 2003 Fifth Edition

16. Psychometric Properties for 5th Edition • Normative sample: matches 2001 census • Included an extra sample for subpopulations • Reliability: • Full-scale IQ: .98 • Nonverbal IQ: .95 • Verbal IQ: .96 • Five Factors: .90 to .92 • Adequate to good reliability coefficients and interscorer agreement for subtests • Validity: full-scale IQ low to mid .8’s with Weschler scales

17. Wechsler • Critiqued Binet’s scale • Point scale • Credits assigned to each item • Group similar items – scores for each content area • Performance scale • Nonverbal intelligence • Directly compare verbal and nonverbal ability • Intelligence comprised of many elements, can be measured by summing these elements

18. Verbal Subtests • Vocabulary: Define words • Similarities: Relationship between two objects, concepts • Arithmetic: Simple arithmetic operations • Digit Span: Repeat sets of digits forwards/backwards • Information: General factual information • Comprehension: Social knowledge & practical information • Letter-Number Sequencing: Intermixed set of letters and numbers, repeat numbers then letters in ascending order

19. Performance Subtests • Picture Completion: Ability to see details • Digit Symbol-Coding: Visuomotor speed and scanning accuracy • Block Design: Reproduce designs with blocks • Matrix Reasoning: Complete visual patterns • Picture Arrangement: Arrange a set of visual images in correct story sequence • Symbol Search: Look for a target symbol in a set of symbols • Object Assembly: Assemble pieces of a puzzle

20. Scoring • Subtest raw scores converted to scaled scores (mean = 10, sd = 3) • *Age-adjusted norms • Client’s age • Reference-group norms • Standardization sample, age 20 to 34 • Convert subtest sum to deviation IQ (mean = 100, sd = 15)

21. Scaled Scores

22. Score Conversions

23. WAIS-III Scales • IQ scores: • FSIQ – Full Scale IQ • VIQ –Verbal IQ • PIQ – Performance IQ • Index Scores: • VCI – Verbal Comprehension Index • WM – Working Memory • POI – Perceptual Organization Index • PS – Processing Speed

24. Index Scores

25. WAIS-III IQ Scores

26. WAIS-III IQ Scores .3413 .3413 .1359 .1359 .0215 .0215 .0013 .0013 IQ = 55 70 85 100 115 130 145

27. WAIS-III IQ Descriptors • < 70 Extremely Low • 70 to 80 Borderline • 80 to 90 Low Average • 90 to 110 Average • 110 to 120 High Average • 120 to 130 Superior • >130 Very Superior

28. Interpretation • VIQ-PIQ Split • Possible L.D. (also ACID) • Strengths and Weaknesses • Compare Index scores • Compare subtest scores with mean score • Generate hypotheses

29. Psychometric Properties • Standardization: 13 age groups (16-17 to 85-89) • Reliability: • FSIQ: Test-retest .95; Split-half .98 • VIQ: Test-retest .94; Split-half .97 • PIQ: Test-retest .88; Split-half .94 • Not as good for individual subtests • SEM: FSIQ 2.29; VIQ 2.50; PIQ 3.75

30. WAIS-III Validity • With WISC-III • FSIQ: .93 • VIQ: .94 • PIQ: .86 • High correlations with WAIS-R

31. WISC-IV • 10 core and five supplemental subtests • Grouped into four indices: • Verbal Comprehension • Perceptual Reasoning • Working Memory • Processing Speed • No VIQ-PIQ