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What do Test Scores Really Mean?

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Presentation on theme: "What do Test Scores Really Mean?"— Presentation transcript:

1 What do Test Scores Really Mean?
Rebecca Mann


3 Why test? School effectiveness Determine what students know and can do
Compare student achievement to achievement of similar students Compare student ability level and achievement

4 Norm vs. Criterion Referenced
Norm referenced Comparing a person's score against the scores of a similar group who have taken the same exam, called the "norming group." Examples California Achievement Test (CAT) Comprehensive Test of Basic Skills (CTBS) - "Terra Nova“ Iowa Test of Basic Skills (ITBS) Metropolitan Achievement Test (MAT) WISC Stanford-Binet Bell Curve – all students cannot be above average!

5 Norm vs. Criterion Referenced
Measure how well a person has learned a specific body of knowledge and skills Examples ISTEP and most state exams ITBS and Terra Nova Driver’s License test Content area placement exam (Algebra placement test) Do not compare student to student


7 Ability vs. Achievement
Ability Test Measure of cognitive ability Child’s ability to learn Achievement Test Measure of what an individual has learned There may be a discrepancy between ability and achievement scores Underachievement Learning Disability

8 Individual vs. Group Ability Tests
Individual intelligence tests are considered the most accurate measure of intelligence Wechsler Intelligence Scale for Children (WISC-IV) Wechsler Preschool & Primary Scale of Intelligence (WPPSI-III), Stanford Binet (SB-5) Woodcock-Johnson III (WJ-III) cognitive Individual IQ tests must be given by a school or counseling psychologist.

9 Individual vs. Group Ability Tests
Group intelligence tests are commonly used as screening measures Common group intelligence tests Otis-Lennon School Ability Test - OLSAT Cognitive Abilities Test – CogAT IQ scores are not given on group tests

10 Group Achievement Tests
Criterion-referenced Typically on grade level content, therefore difficult to know the level of mastery for a gifted child Grade-level achievement tests are only a measure of basic skills You cannot compare standard scores on achievement tests to IQ scores. 

11 Will this be on the test?

12 Ceiling The highest level of performance or score that a test can reliably measure WISC-IV = 160 Stanford-Binet IV = 165 CogAT = 150 OLSAT = 150

13 Standard Deviation a statistical measure of spread
One standard deviation is the range which includes 65% of all scores, two standard deviations includes 95% of all scores

14 68% 96%

15 From Get Off My Brain, by Randy McCutcheon, illustrated by Pete Wagner

16 Types of Scores Raw Percentile Ranks Grade Equivalent Scores
Standard Scale Scores

17 Raw Score The number of items a student answers correctly
Allow students to be ranked, but they do not allow you to compare students

18 Percentile Rank A percentile rank indicates the percentage of students in the same age or grade group whose scores fall below the score obtained by a particular student. 99 is the highest percentile rank possible. 50 is considered average Deals with percentage of persons not percentage of items

19 Grade Equivalent Score
Most misinterpreted test score If a 4th grader received a 7th grade equivalent score on a 4th grade reading achievement test, it DOES NOT mean the child is ready for 7th grade material. It means the child reads 4th grade material as well as the average 7th grader reads 4th grade material. What is the test assessing???

20 Age Equivalent Score Frequently misinterpreted
If a 10 year old received a 15 year old age equivalent score on a 4th grade reading achievement test, it DOES NOT mean the child is ready to tackle 10th grade material. It means the child reads material intended for 10 year olds as well as the average 15 year old reads it.

21 Stanine Stanine is short for standard nine. The name comes from the fact that stanine scores range from a low of 1 to a high of 9. For instance, a stanine score of 1, 2, or 3 is below average 4, 5, or 6 is average 7, 8, or 9 is above average The stanine scale is a normalized standard score scale consisting of nine broad levels designated by the numbers one through nine. Stanines are provided for both age and grade groups.

22 Standard Age Score Scale scores allow comparison of students
Raw Scores are converted to SAS based on chronological age Used for interpretation purposes Scale scores allow comparison of students Somewhat akin to an IQ score Uses means and standard deviation Mean = 100

23 68% 96%

24 Standard scores 130 and above Very Superior 120-129 Superior
High Average Average 80-89 Low Average 70-79 Borderline 69 and below Impaired (Mentally Retarded range)

25 Relationship Between CogAT Scores
Stanine 1 2 3 4 5 6 7 8 9 Percentile Rank 1-4 5-11 12-23 24-40 41-59 60-76 77-88 89-95 96-99 SAS 70 80 90 100 110 120 130 Standard Deviation -2 +2

26 Standard Measure of Error
The range inside which an individual subject's future scores are expected to fall, based on her current score The score +/- the standard measure of error is the estimated range in which the actual score lies 130 +/- 5 means that the child’s true score is somewhere between 125 and 135

27 Confidence Interval Using the standard measure of error
A range of values that indicates where the true score is likely to fall Often expressed in 68%, 90%, or 95% Such as: We can say with 68% confidence that a student’s true score is within this range. The higher the confidence (95 instead of 68), the wider the range of scores

28 K-BIT

29 WISC-IV – 5rd grade boy Verbal Comprehension: 150
Perceptual Reasoning: 146 Working Memory: Processing Speed: Full Scale IQ: 127

30 WISC-IV – 3rd grade boy Verbal Comprehension: 110
Perceptual Reasoning: 137 Working Memory: 135 Processing Speed: 112 Full Scale IQ: 130

31 5th 3rd Verbal Comprehension: 150 110 Perceptual Reasoning: 146 137
Working Memory: Processing Speed: Full Scale IQ:




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