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Learn About Standard Scores and What They Mean


Updated May 22, 2014

Normal Score Equivalents

What are Standard Scores?

Definition: Standard scores are used in norm-referenced assessment to compare one student's performance on a test to the performance of other students her age. Standard scores estimate whether a student's scores are above average, average, or below average compared to peers. They also enable comparison of a student's scores on different types of tests, as in diagnosing learning disabilities.

Common Types of Standard Scores:

  • Z-Scores: These scores are scaled on a number line ranging from -4 to 4 with zero being in the middle. On this scale, zero is average. Positive scores are above average, and negative scores are below average.
  • T-Scores: These scores range from 10 - 90 in intervals of 10 points. Fifty is average on this scale.
  • Stanines: The stanine scale is also called the standard nine scale. These scores range from 1 - 9 with five being average. Scores below five are below average. Scores above five are above average.

Some test publishers create their own scales of standard scores. Interpretations of those scales and what they mean are available through your child's examiner.

Back to Special Education and Learning Disability Terms

Standard scores help teachers determine how a child performs compared to other students. They also allow teachers to compare a student's performance on different tests.

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