What do Test Scores
Really Mean?
Rebecca Mann
rlmann@purdue.edu
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
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!
Norm vs. Criterion Referenced
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
Drivers License test
Content area placement exam (Algebra placement test)
Do not compare student to student
Wait until
KINDERGARTEN
THIS WEEK
WE TOOK A
TEST TO SEE
IF WERE
READY FOR
THE TEST
THAT TESTS
OUR TEST
SKILLS
Ability vs. Achievement
Ability Test
Measure of cognitive ability
Childs 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
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.
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
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.
Will this be
on the test?
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
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
68%
96%
From Get Off My Brain, by Randy McCutcheon, illustrated by Pete Wagner
Types of Scores
Raw
Percentile Ranks
Grade Equivalent Scores
Standard Scale Scores
Raw Score
The number of items a student
answers correctly
Allow students to be ranked, but
they do not allow you to compare
students
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
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 7
th
grade material. It
means the child reads 4
th
grade material
as well as the average 7
th
grader reads 4
th
grade material.
What is the test assessing???
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 10
th
grade
material. It means the child reads
material intended for 10 year olds as well
as the average 15 year old reads it.
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.
Standard Age Score
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
68%
96%
Standard scores
130 and above Very Superior
120-129 Superior
110-119 High Average
90-109 Average
80-89 Low Average
70-79 Borderline
69 and below Impaired (Mentally Retarded
range)
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 0 +2
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 childs true
score is somewhere between 125 and
135
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 students true score is within this range.
The higher the confidence (95 instead of 68),
the wider the range of scores
K-BIT
WISC-IV 5
rd
grade boy
Verbal Comprehension: 150
Perceptual Reasoning: 146
Working Memory: 97
Processing Speed: 88
Full Scale IQ: 127
WISC-IV 3
rd
grade boy
Verbal Comprehension: 110
Perceptual Reasoning: 137
Working Memory: 135
Processing Speed: 112
Full Scale IQ: 130
5
th
3
rd
Verbal Comprehension: 150 110
Perceptual Reasoning: 146 137
Working Memory: 97 135
Processing Speed: 88 112
Full Scale IQ: 127 130
http://www.hoagiesgifted.org/tests.htm
http://achieve.org/files/indiana_ISTEP_0.
pdf
