Iowa Tests (in Plain English)

The Iowa Tests of Basic Skills (ITBS) are standardized tests provided by the College of Education of the University of Iowa.  Following are some points that may help to better explain the purpose and outcomes of these tests.

Norm referenced (ITBS) vs. criterion referenced

-norm-referenced tests are designed to compare students (i.e., bell curve)

-better because students do not exist in isolation; at some point may be in another district; another state

-criterion referenced tests measure how well a student performs against an objective or criterion, rather than another student (i.e. classroom content tests)


Scores to watch for:

Percentile Rank (PR)

-this is the score that reflects performance

-tells the percent of students in a particular group that got lower raw scores on a test than the target student did

-shows student’s relative position or rank in a group of students who are in the same grade and who were tested at the same time of year

-if the student scored 75%ile, it means that she scored higher than 75% of the students in the group in which she is being compared; and that 25% of the students scored higher

-percentile ranks range from 1-99

-NPR (National Percentile Rank) indicates the child’s rank with other students in the nation; IPR (Iowa Percentile Rank) indicates your child’s rank with other students inIowa

Stanine (S)

-a rough grouping of percentile ranks that indicates the child’s relative position in a group; stanines range from 1-9 and can be interpreted using the following table:


Stanine                                    Interpretation              Percentile Rank

            1                      Below Average                       1-4

            2                      Below Average                       5-11

            3                      Below Average                       12-23

            4                      Average                                   24-40

            5                      Average                                  41-59

            6                      Average                                   60-76

            7                      Above Average                       77-88

            8                      Above Average                       89-95

            9                      Above Average                       96-99


Raw Score (RS)

-the number of questions a student gets right on a test

-by itself, this score has little or no meaning; meaning depends on the number of questions on the test, and how easy or hard they are

Percent Correct (PC)

-raw score divided by the total number of questions and the result is multiplied by 100

-like raw scores, these have little meaning by themselves

-do not confuse with percentile ranks; the two are very different

Grade Equivalent (GE)

-describes a student’s location on an achievement continuum, which is a number line that describes the lowest level on one end, and the highest level of knowledge on the other end

-a decimal number that describes performance in terms of grade level and month (6.4 is a score that means the child’s performance is typical of a student in the fourth month of the sixth grade)

-can be useful and convenient for measuring individual growth from year to year, and for estimating a student’s developmental status in terms of grade level

-only estimates a student’s developmental level, does not provide a prescription for grade

placement (i.e.; a fourth grader earning a GE of 6.2 should not be placed in a sixth grade class for reading)

Age Equivalent (AE)

-show typical age of the norm group that obtained a similar score

- (i.e.; a student with an AE of 8-7 means his performance is typical for a student who is 8 years, 7 months old)

-again, only provides an estimate of a student’s developmental level, and does not provide a prescription for grade placement

Standard Score (SS)

-like the GE, this describes the child’s achievement on a grade level scale

-compares the child’s performance to the “average” performance of grade level groups

-must be used only as a reference point

-the ITBS standard scale is: (grade number is first; standard scales score is second)

K [130]; 1 [150]; 2 [168]; 3 [185]; 4 [200]; 5 [214]; 6 [227]; 7 [239]; 8 [250]; 9 [260]

-for example, if a sixth grade student receives an SS of 226 on the Vocabulary test, it means he is performing like a typical sixth grader in vocabulary



- CompleteBattery; offers broadest range across all subject areas

- CoreBattery; focuses on critical content areas of reading, language arts, and math

CogAt: (Cognitive Abilities Test)

-measures developed reasoning abilities in three areas:  verbal; quantitative; and nonverbal

-measures preparedness for academic work- NOT the result of instruction in school

-CogAt is neither an intelligence test or an achievement test; it measures developed rather than innate abilities

Three Sections (each containing three subtests)

Verbal Battery:

-appraises verbal inductive and deductive reasoning skills, flexibility, fluency and adaptability in working with verbal materials and solving verbal problems

-students with high scores display an effective use of a variety of verbal strategies

-verbal abilities are important in reading comprehension, critical thinking, writing, and all verbal learning tasks

-generally expect children with high verbal abilities to perform well on reading tests

Quantitative Battery:

-assesses deductive and inductive reasoning skills, flexibility, and fluency at working with quantitative symbols and concepts

-abilities in this battery are related to high level problem solving mathematics and other disciplines

-generally expect children with high quantitative abilities to perform well on math tests

Nonverbal Battery:

-all three subtests use geometric shapes and figures that have little relationship to formal school instruction

-require no reading skills

-students with high scores on this battery have well-developed strategies for dealing with new materials and using them with flexibility and accuracy

Some things to watch for:

(NOTE:  all school administered standardized tests are pieces of your child’s academic picture.  Concerns should be addressed with the child’s teacher.  In some cases, may need follow-up with additional qualified professionals.)



-It must be remembered that there is much more to possible learning issues than a discrepancy between verbal and nonverbal abilities

-Look for patterns, either over the past few years, or by comparing scores of different standardized tests

Differences between Verbal and Nonverbal test scores (at the ~15 point level) MAY indicate:

(low verbal scores)

-weakness in ability to cognitively process verbal or ‘auditory’ information

-student performs well nonverbally, or with ‘hands on’ activities, but struggles to understand or remember information which is presented verbally

-this is not due to poor hearing, but is related to an assumed weakness in the brain’s ability to fully or efficiently process auditory information

-these students typically struggle with academic tasks which involve lectures or written instruction, and which provide limited visual or nonverbal information

-these students may have the most difficulty in the areas of reading and writing due to difficulty processing or expressing language-based information

-MAY signal a central auditory processing disorder (CAPD); may need further evaluation through formal cognitive assessment

(low nonverbal scores)

-underlying difficulties are believed to be a generalized weakness in the ability to process nonverbal information

-student performs well verbally (both receptive, listening, and speaking) but struggles to understand or remember information presented visually

-not due to poor vision, but rather to a weakness in the brain’s ability to fully or efficiently process nonverbal information

-these children may also demonstrate other social and behavioral characteristics; they frequently have difficulty accurately perceiving social situations, are confused with nonverbal communication, and have a general disinterest or avoidance of social situations

-students with nonverbal processing weakness typically struggle with academic tasks that involve complex or abstract displays (charts, graphs, maps, etc.)

-may also have difficulty with math and spelling, due to poor visualization, and struggle with hands-on activities (science labs, etc.)

-likely have strong reading and creative writing skills

-MAY signal a non-verbal learning disorder (NLD); may need further evaluation through formal cognitive assessment