Technical Manual for Gibson Test of Cognitive Skills- Revised

Transcription

1 Technical Manual for Gibson Test of Cognitive Skills- Revised Normative Summary Sample Selection The Gibson Test of Cognitive Skills - Revised (GTCS) was normed on a sample of 2,305 children and adults (ages 5-22) in 24 states, including Arizona, Arkansas, California, Colorado, Florida, Georgia, Idaho, Illinois, Indiana, Kentucky, Louisiana, Massachusetts, Minnesota, Missouri, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Texas, Virginia, Washington, Wisconsin, and Wyoming. Norming sites were selected based on representation from the four primary geographic regions of the United States: Northeast, South, Midwest, and West. Tests were administered in two types of settings. First, the test was administered to all students in a Florida school. Second, test results were collected from psychologists, occupational therapists, speech therapists, behavioral optometrists, and PACE program providers in 24 states who use the Gibson Test of Cognitive Skills (formerly the Gibson Cognitive Test Battery) in their practices to screen students for learning problems. Demographics for age, geographical region, gender, race, and income are presented in Tables 1 3. Table 1. Demographics of Norming Sample by Age and Geographic Region West South Northeast Midwest Total Age n % n % n % n % n % Total

2 2 Table 2. Demographics of Norming Sample by Age and Gender Male Female Total Age n % n % n % Total Table 3. Demographics of Norming Sample by Race and Household Income Race Characteristic n % White Black/African American 83 4 Asian/Pacific Islander 32 1 Hispanic 60 3 Other 23 <1 Not Reported Household Income 1 Under 25, ,000 34, ,000-49, ,000-74, ,000-99, Over 100, Income estimated based on median per ZIP code Source: American Community Survey 5-Year Estimates

3 Reliability 3 Reliability of a test refers to the consistency with which the test measures the same trait, characteristic, or ability. Two types of reliability are reported for the GTCS: coefficient alpha and split-half. These metrics represent the estimates of the amount of error in the test scores. Coefficient Alpha Coefficient alpha represents the internal consistency reliability of the test, or how well the test items correlate with each other. For low-stakes educational testing and screening, the reliability coefficient should be at least.67. A desired reliability coefficient approximates or exceeds.80. Using item analysis, coefficient alphas were calculated for a sub-sample of 59 students from the norming group. In addition to an overall coefficient alpha for each test, coefficient alphas are reported for subgroups based on gender and three age intervals (Table 4). Overall coefficient alphas range from.78 to.93. The standard error of measurement (SEM) is also reported for each coefficient alpha, ranging from 1.1 to 2.6 (Table 5). Table 4. Coefficient Alphas for GTCS Tests by Subgroups Test Age 6-8 Age 9-11 Age Males Females Overall Word Attack Working Memory Visual Processing Auditory Processing Logic & Reasoning Processing Speed Table 5. Standard Error of Measurement (SEM) for GTCS Tests by Subgroups Test Age 6-8 Age 9-11 Age Males Females Overall Word Attack Working Memory Visual Processing Auditory Processing Logic & Reasoning Processing Speed Split-Half Split-half reliability is the estimation of test reliability determined by correlating the scores on two halves of the test. This method is frequently used when retesting the same students is not practical, or when practice effects are a possible threat. To calculate the split-half reliability estimate, the sum of the even numbered items was correlated with the sum of the odd numbered items. A Spearman-Brown formula was applied to the Pearson correlation for each subtest to predict the overall reliability of the test. Split-half reliability coefficients ranged from.68 to.97 (Table 6).

4 4 Table 6. Split-Half Correlation Coefficients for GTCS Test Age 6-8 Age 9-11 Age Overall Word Attack Working Memory Visual Processing Auditory Processing Logic & Reasoning Processing Speed Split-half correlation is not an appropriate analysis for a speeded test Validity Validity refers to a test s ability to measure what it is designed to measure. There are three types of validity reported: content validity, construct validity, and criterion concurrent validity. Content Validity Each GTCS test was developed following an extensive review of the literature and two decades of applied research on cognitive skills that are necessary for learning: memory, attention, processing speed, auditory processing and phonological awareness (segmenting, dropping, and blending), visual processing, logic & reasoning, and word attack skills. The tests were selected after extensive field use of similar tasks by clinicians using the Visual Information Processing (VIP) program and the Processing and Cognitive Enhancement (PACE) program. Subject matter experts were consulted during each phase of development and field-testing to ensure that the content of each test adequately represented the skill it aimed to measure. Construct Validity The individual GTCS tests were developed in alignment with intelligence factors identified by the Cattell-Horn-Carroll (CHC) theory of cognitive abilities (Table 7). Table 7. Construct Alignment of GTCS Tests and CHC Theory GTCS Subtest Skill Measured CHC Factor Processing Speed Processing Speed Processing Speed (Gs) Working Memory Working/Short-Term Memory Short-Term Memory (Gsm) Visual Processing Visual Processing Visual-Spatial Thinking (Gv) Auditory Processing Auditory Processing Auditory Processing (Ga) Logic & Reasoning Reasoning Fluid Reasoning (Gf) Word Attack Basic Reading Skills Reading-Writing Ability (Grw) 1 1 Grw is a broad ability identified in the Cattell-Horn-Carroll Gf-Gc Model

5 5 Criterion - Concurrent Validity Each test on the GTCS was correlated with other measures of the same skills to determine if the GTCS measures the skills as well as other standardized measures. Scores were collected from students in the norming group who were current clients of clinicians using the PACE program. The sample sizes are not consistent across criterion correlations because not all students were administered all tests. Correlation coefficients were attenuated based on reliability coefficients of the individual criterion tests, and corrected for possible range effects. The resulting correlations range from.77 to.98, indicating very strong relationships between the GTCS and other standardized criterion tests (Table 8). Table 8. Concurrent Validity between GTCS and Criterion Tests Test WRMT 1 Word Attack n = 1875 Working Memory n = 1521 Visual Processing n = 162 Auditory Processing n = 1591 Logic & Reasoning n = 94 Processing Speed n = 608 WA r uc =.89 r c =.98 DTLA 2 DS r uc =.53 r c =.75 WJ III 3 COG 22 r uc =.58 r c =.84 LAC 4 DTLA 5 r uc =.69 r c =.87 SR r uc =.49 r c =.77 WJ III 6 VM r uc =.62 r c =.83 Note. r uc = uncorrected correlation coefficient, r c = corrected correlation coefficient 1 WRMT WA = Woodcock Reading Mastery Tests: Word Attack 2 DTLA DS = Detroit Tests of Learning Aptitude: Design Sequence 3 WJ III COG 22: Woodcock-Johnson III - Tests of Cognitive Abilities: Visual Closure 4 LAC = Lindamood Auditory Conceptualization Test Revised 5 DTLA SR = Detroit Tests of Learning Aptitude: Symbolic Relations 6 WJ III VM = Woodcock-Johnson III Tests of Cognitive Abilities: Visual Matching

6 Normative Scores and Scoring Tables 6 Three types of normative scores are available for each subtest of the GTCS: standard scores, percentiles, and age-equivalents. Standard Scores (SS) The standard score (SS) is based on a distribution of scores from 50 to 150 with a mean of 100 and a standard deviation of 15. The standard score is determined from the raw score using conversion tables 9.1 through 10.5 based on the student s age. Choose the table that corresponds with the student s age. Locate the raw score under each test column and assign the standard score from the standard score column on the same row. For example, if a seven-year old student obtained a raw score of 14 on the Word Attack subtest, the student s standard score would be 119. Provide a SS for each test. Percentile Rank (%tile) Percentile rank is based on the location of the student s score compared to same-age students in the sample. It is the point in the distribution of scores that is at or below the scores of where a percentage of students fall. For example, a percentile rank of 83 means that the student scored as well as or better than 83% of the other students of the same age in the sample. Percentiles range from 1 to 99. It is important to note that the percentile rank is not the same as the percentage of items the student answered correctly. Percent correct is not a score option for the GT. Percentiles are located on the same tables as the standard scores by age group (pp. 7-61). Choose the table that corresponds with the student s age. Locate the raw score under each test column and assign the percentile from the percentile column on the same row. Provide a percentile for each test. Age-Equivalents (AE) An age-equivalent is an age that corresponds to the student s raw score. It is determined by calculating the mean scores of all students in each age group and plotting them on a graph to visually evaluate their correlations. It is important to note that the use of age-equivalents should be approached with caution. Because they are determined through manual smoothing, interpolation, and extrapolation, they are not as reliable as standard scores and percentiles. Choose the table that corresponds with the student s age. Locate the raw score under each test column and assign the age-equivalent for the student s raw score on each subtest. For each subtest, locate the raw score in the first column and the corresponding ageequivalent on the adjacent column.

7 Age 5 and Under <5 0 <5 0 <5 < < < <5 3 < < < < < <5 5 < < < < <5 7 <5 0 <5 1 < < < < < <5 0 <5 5 < < <5 7 < < < < < <5 12 <

8 8 13 < < <5 15 < < < < < < < <

9 > > > > > > > > > >16 > > > >16 > > > >16 > > > > >99 142

10 10 37 >16 31 > > >16 32 > > > > > > > > > > > > > > > >16 > >16 >99 142

11 AGE <5 0 <5 0 <5 0 <5 < <5 0 <5 1 <5 0 < < < < <5 5 < < <5 1 < <5 2 <5 1 < <5 3 < <5 4 < < <5 6 <5 2 < < <5 8 < < < <5 11 < <5 12 < < < < < < < < <

12

13 > > > > >99 140

14 >16 > >16 > >16 > >16 21 > >16 > >16 22 > >16 > >16 35 >16 23 > > >16 24 >16 24 >16 89 >16 > >16 90 >16 > >16 > >16 > >16 >99 142

15 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1 <5 1 <5 1 < <5 2 <5 2 <5 2 < <5 3 <5 3 < <5 4 <5 4 < <5 5-6 <5 5 < <5 7 < < <5 16 < < < <5 19 <5 2 < < < <

16

17 > > > >16 > > >16 > >16 22 > >16 > >16 >99 141

18 18 34 >16 > > >16 23 > >16 > > >16 89 >16 > >16 23 >16 90 >16 > >16 24 >16 > >16 >99 142

19 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1 <5 1 <5 1 < <5 2 <5 2 <5 2 < <5 3 <5 3 <5 3 < <5 4 <5 4 < < <5 5 < < < < <

20

21 > > >16 89 > >16 > >16 > >16 32 >16 16 >16 > >16 >99 140

22 22 > >16 23 >16 34 >16 > >16 24 >16 35 >16 24 >16 90 >16 17 >16 > >16 > >16 >99 142

23 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1 <5 1 <5 1 < <5 2 <5 2 <5 2 < <5 3 <5 3 <5 3 < <5 4-5 <5 4 < <5 5 < < < <

24

25 >16 89 > > > >16 23 > >16 15 >16 > >16 34 >16 16 >16 > >16 > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

26 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1 <5 1 <5 1 <5 1 < <5 2 <5 2 <5 2 < <5 3 <5 3 <5 3 < < <5 5 <5 4 < < <5 5 < < <

27

28 > > > > > >16 33 >16 23 > > > > > >16 16 >16 > > >16 > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

29 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1-2 <5 1 <5 1 <5 1 < <5 2 <5 3 < < < <5 5 <5 3 < < <5 7 <5 4 < < < <

30

31 > >16 21 > >16 22 > > > >16 15 > > >16 34 > >16 16 > >16 > > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

32 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1-3 <5 1 <5 1 <5 1 < <5 2 <5 4-6 < < <5 7-8 < < < < < <

33

34 > > > > > > > > >16 23 > >16 16 > >

35 > > > > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

36 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1-3 <5 1 <5 1 <5 1 < <5 2 <5 4-7 < < <5 8 < < < < < <

37

38 > > > >16 21 > > > > > > > > > > > >

39 39 38 >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

40 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1-3 <5 1 <5 1 <5 1 < <5 2 <5 4 < < < < <5 7 < < < < < < <

41

42 > > > > > >16 22 > > > > > > > >

43 > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

44 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1 <5 1-3 <5 1 <5 1 <5 1 < <5 4 < < < < <5 7 < < < < < < <

45

46 >16 32 >16 89 > > > > > > > > >16 23 > >

47 47 34 > > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

48 AGE <5 0 <5 0 <5 0 <5 0 <5 0 <5 < <5 1-2 <5 1-3 <5 1 <5 1 <5 1 < <5 4 < < < < <5 7 < < < < < < <

49

50 > > > > >16 89 > >16 22 > >16 33 >16 15 > > > > >

51 > > >16 24 >16 35 >16 24 >16 90 >16 17 >16 >99 142

52 AGE NA 0 NA 0 NA 0 NA 0 NA 0 NA < NA 1-3 NA 1-3 NA 1 NA 1 NA 1 NA NA 4-5 NA 4-6 NA 2 NA 2 NA 2 NA NA 6-7 NA 7-9 NA 3 NA 3 NA 3 NA NA 8-9 NA NA 4 NA 4 NA 4 NA NA 10 NA NA 5 NA 5 NA 5 NA NA 11 NA NA 6-11 NA 6-66 NA 6-8 NA NA 12 NA 12 NA 67 NA NA NA NA 21 NA 68 NA NA 13 NA 69 NA NA 22 NA 70 NA 9 NA NA 14 NA 71 NA NA 72 NA NA 24 NA 15 NA 10 NA NA NA 74 NA NA 16 NA NA NA 26 NA 11 NA NA NA 17 NA NA 77 NA NA NA 12 NA NA NA 79 NA NA NA NA 32 93

53 53 29 NA 81 NA NA NA NA NA NA 83 NA NA NA NA NA NA 20 NA NA 14 NA NA NA NA 32 NA 21 NA NA 88 NA NA NA NA NA NA NA

54 NA NA NA NA NA > NA 24 NA 35 NA 24 NA 90 NA 17 NA >99 142

55 AGE NA 0 NA 0 NA 0 NA 0 NA 0 NA < NA 1-3 NA 1-3 NA 1 NA 1 NA 1 NA NA 4-5 NA 4-6 NA 2 NA 2 NA 2 NA NA 6-7 NA 7-9 NA 3 NA 3 NA 3 NA NA 8-9 NA NA 4 NA 4 NA 4 NA NA 10 NA NA 5 NA 5 NA 5 NA NA 11 NA NA 6-12 NA 6-66 NA 6-8 NA NA 12 NA 13 NA 67 NA NA NA NA 21 NA 68 NA NA 69 NA 9 NA NA 22 NA 70 NA NA 15 NA 71 Na NA 10 NA NA 72 NA NA NA NA NA 74 NA NA 17 NA 11 NA NA NA NA 76 NA NA 12 NA NA 77 NA NA NA NA 28 NA NA 79 NA NA 13 NA NA 32 93

56 56 19 NA 81 NA NA 82 NA NA NA NA NA NA 14 NA NA NA 31 NA 85 NA NA NA NA 21 NA NA 32 NA NA NA 15 NA NA NA NA NA

57 57 23 NA NA NA NA NA > NA 24 NA 35 NA 24 NA 90 NA 17 NA > Last update 9/22/2015 GI37391CR