When academic performance suffers, an educational diagnosis is done to help define the student’s academic strengths and learning needs and translate them into an individualized educational program (IEP). Because no single testing tool provides all the answers, a comprehensive evaluation involves multiple assessment tools including:
- Discussions with the child
- Interviews with the parents
- Observations in various settings
- Input from other professionals
- Background information
- Record reviews
- Diagnostic teaching
- Standardized and individually administered tests
Most of those assessment tools are readily understood; however, test results can be confusing to parents (and teachers) who may not know how to interpret the results.
Intelligence (IQ) test results generally remain constant over time, whereas achievement test scores rise as a child continues to progress. IQ, achievement, and various other tests are composed of subtests. The subtest scores are combined in order to develop composite or full-scale scores. An individual’s strengths and challenges generally are not reflected in his composite scores; however, they are reflected in the subtest scores. Consider three children, each with a composite IQ score of 100:
- Child A: Exceptionally high verbal comprehension and exceptionally low perceptual reasoning.
- Child B: Exceptionally low verbal comprehension and exceptionally high perceptual reasoning.
- Child C: Average verbal comprehension and average perceptual reasoning.
Despite having the same average composite IQ, each child clearly has different abilities and needs.
The subtests bring to light their specific strengths and deficits. They clarify what their IEP goals and objectives should be and what methodologies will be needed to address their unique learning styles.
Because the kinds of errors children make are critical to both diagnosis and learning, it is important to review the actual subtests within the test your child took and the answers he gave.
Questions about a student’s specific strengths and challenges are also not easily answered by group tests, such as group reading tests. For example, to assess a student’s reading skills, different tests are needed to measure various skills, such as phonemic awareness, oral reading, silent reading, word recognition, word attack, and reading comprehension.
In physical measurement we begin with zero and measure up to higher numbers. In contrast, psychological tests and educational achievement tests begin their measurements of aptitude in the middle (also referred to as the mean, average, or measure of central tendency) and measure out toward each end of the distribution curve.
Test scores are reported in different formats, including age equivalent scores (AE), which compare a child with other children his own age; grade equivalent scores (GE), which compare him with other children in the same grade; standard scores (SS), and percentile rank (PR).
To understand and be able to discuss your child’s test scores appropriately, it is helpful to familiarize yourself with the bell curve or normal distribution curve. A powerful tool, it is based on the premise that measured characteristics are distributed in a regularly occurring pattern in a given population, with most scores in the middle and a small number of scores at the low and high ends.
The bell curve may be used to make comparisons between one child’s score and the scores of peers in his own school or in different schools, or between one child’s score and the scores earned by older children, younger children, or children in different grades. It may also be used to measure the effectiveness of a class or program or to measure a child’s real progress or regression. All educational and psychological tests based on the bell curve report their scores as standard scores and percentile ranks.
To interpret test results, you need to know the testing instrument used and the mean (average) and standard deviation of the test. Standard deviation is a way to measure the distribution of scores, specifically the distance of individual scores from the mean.
On most educational and psychological tests, the mean is 100 and the standard deviation is 15 (Mean = 100; SD = 15). Standard scores are not like grades, with 100 as the highest score and 0 as the lowest. Rather, a child who has a standard score of 100 on a verbal, performance, or full-scale IQ test is scoring in the 50th percentile rank, as an average student of a given age. A standard score of 85 is at the 16th percentile rank, one standard deviation below the mean (low average); a standard score of 115 is at the 84th percentile rank, one standard deviation above the mean (high average).
On smaller subtests within psychoeducational tests, the mean is 10 and the standard deviation is 3 (Mean = 10; SD = 3). Therefore, a child who scores 10 on a subtest is scoring in the 50th percentile rank, as an average student of a given age. A subtest score of 7 is at the 16th percentile rank; a sub-test score of 13 is at the 84th percentile rank.
The average range is broad, spanning a distance from the 16th to the 84th percentiles, and the learning profiles of children within that average range are equally wide-ranging. Consequently, when you hear an evaluator say your child scored in the average range, recognize that’s just the beginning of the discussion that must follow.
This article is based on information presented by Donna A. Chauvin Quallen, M.Ed., C.A.S, at an event sponsored by SPED*NET, Special Education Network of Wilton (CT) Ltd. Quallen is a consultant, general and special educator, and former educational and special services administrator. Eve Kessler, Esq., an attorney with The Legal Aid Society, NYC, is President of SPED*NET Wilton (CT) and a Contributing Editor of Smart Kids.
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