Arc Guide to Special Education Evaluation Terms

Terms used in special education evaluations can be confusing. Test scores may be reported in a variety of ways including age equivalents, grade equivalents, raw scores, scale scores, subtest scores, and standard scores. These scores often show the age at which most people can do a skill or task. Scores may compare a student’s performance to others of the same age and may show the student’s position on that test relative to a group of similar-aged students. The goal of testing is to obtain a description of the knowledge and/or skill of the student.

This Arc Guide explains commonly used terms.

Average Score/Mean Score

Number or score that is obtained by adding up all the numbers and dividing by the amount of numbers. For example, 15 + 5 + 10 = 30, divided by 3, average is 10

Age Equivalent Score (AE)

Provides age at which most people can do a skill or task
Compares student’s performance to that age
Almost always used for tests of intellectual ability (IQ)

For example, if a 5 year old student gets a raw score of 20 on a test, and that is the average score for 5 year olds, the AE would be 5.

Bell Curve

An imaginary curve used to show scores on a test
This curve is graphically represented as a bell, with equal numbers on each side and approaching zero at the ends
Most individual scores would be at the top of the bell with a curve narrowing to the fewest individual scores on either end of the curve

Cluster Score/Composite Score/Index Score

An overall score made up of several subtests
Important to look subtest scores to identify areas of strength and need

Confidence Interval/Confidence Level

Also known as margin of error
The range in which a student’s scores will fall within a certain percentage most of the time
A measure of how the result/score is probably correct
Most confidence intervals are 95% or 99%

Criterion Reference

Determines whether or not a student meets a certain skill or content level (something the student does/does not do, and/or how much they do); is not compared to other students
Description of what a student should know or do at a specific age

Full Scale Score

Usually used for intelligence (IQ) tests
Overall score for several tests of verbal understanding, reasoning, memory and speed using spoken and picture prompts

Grade Equivalent Score (GE)

Compares the student’s performance on grade-level activities against the average performance of students at that grade levels

For example, a GE of 4.5 in math means the students solves math problems similar to the average 4th grader

Scores show an overall approximation of grade level abilities

Norm

Average level of ability or skill for most people
Scores often compared to others of the same age (age normed) or grade (grade normed)

Norm Referenced

Compares scores to the average student scores of the same age or grade level
Puts students in order in relation to others in a selected group

Percentile Rank

Divides everyone’s scores into 100 equal parts
Compares the student’s score to the students at a similar age.

For example, if a student obtains a percentile rank of 70, the student performed the same or better than 70% of the other students

Raw Score

An original student test score that has not been changed for interpretation or adjusted for position in relation to others’ scores
Describes tested number of items answered or done correctly

Scaled Score

Change of the raw score to a common scale that can be used for comparison to others’ scores

Standard Deviation (SD)/Standard Score

Measures the amount a specific score is from the average/mean score
In most educational and psychological tests, the mean/average is 100 and the standard deviation is 15. The mean is zero standard deviations.
A number indicating the difference a score is from a group
Indicates how widely individuals in a group vary (The more the group varies, the higher the standard deviation)
Average scores are between 85 –115

Standardized Test

Requires all test-takers to answer the same questions, in the same format, same instructions, same scoring to allow scores to be compared among students

Subscale/Subtest/Subtest Score

Short tests within a large test
Measures a specific ability/skill that is combined with other subtests
Two or more related subtests that test different parts of the same broad ability or skill

T scores

Used for social, emotional and behavioral tests such as the Behavior Rating Inventory of Executive Function (BRIEF) and Behavior Assessment System for Children (BASC) and are converted to percentile ranks
Have an average score of 50 and a standard deviation of 10
The farther away from 50 the score is, the more different it is from a usual score

For further information or advocacy services, contact The Arc Minnesota at 952-920-0855 or toll-free at 833.450.1494 or visit www.arcminnesota.org. (Please note: This document is not legal advice, and should not be construed as such. Thus, no information herein should replace the sound advice of an attorney.)