SOURCE
National Center for Educational Statistics

DEFINITION
For each different subject, NAEP creates a scale score based on statistical procedures called item response theory (IRT). IRT is a set of statistical procedures useful in summarizing student performance across a collection of test exercises requiring similar knowledge and skills. All NAEP subject area scales are produced using these procedures. In Math and Reading, NAEP creates a scale ranging from 0-500. In Science and Writing, NAEP creates a scale ranging from 0-300.

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DEFINITION: For each different subject, NAEP creates a scale score based on statistical procedures called item response theory (IRT). IRT is a set of statistical procedures useful in summarizing student performance across a collection of test exercises requiring similar knowledge and skills. All NAEP subject area scales are produced using these procedures. In Math and Reading, NAEP creates a scale ranging from 0-500. In Science and Writing, NAEP creates a scale ranging from 0-300.

SOURCE: National Center for Educational Statistics