Key Assessment Terms

• Percentile:

  • Describes how a student's performance compares to others. For example, being in the 70th percentile means the student performed better or as well as 70% of other individual who took the assessment, and 30% of others scored higher or preformed better.

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• Z-Score:

  • Shows how far a student's score is from the average (mean), using standard deviations. A z-score of 0 is average, while a positive or negative score shows how much higher or lower the student is compared to the average.

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• Standard Score:

  • A score that has been transformed to fit a standard scale, usually with an average (mean) of 100 and a standard deviation of 15. It allows comparison across different assessments.

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• Standard Deviation:

  • Measures how spread out scores are around the average. A smaller standard deviation means scores are close to the average, while a larger one shows more variation.

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• Scaled Score:

  • A type of standard score that has been adjusted to fit a smaller, specific scale, often used for subtests (e.g., on a scale of 1 to 20).

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• Raw Score:

  • The actual number of points or correct answers a student achieved on an assessment, before any adjustments or conversions to standard scores.

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• T-Score:

  • Similar to a standard score, but with a mean of 50 and a standard deviation of 10. It’s another way to see how a student compares to others.​​

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• Age Equivalent:

  • A score that reflects the age level at which the average student would earn a similar score. If a 9-year-old has an age equivalent of 6, their skills are comparable to those of a typical 6-year-old.

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• Grade Equivalent:

  • A score that reflects the grade level at which the average student would earn a similar score. A grade equivalent of 2.5 means the student is performing at the level of a typical second-grader in their fifth month of school.

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• Norm-Referenced:

  • An assessment that compares a student’s performance to that of a norm group, which is a large, representative sample of students.

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• Criterion-Referenced:

  • An assessment that measures a student’s performance against a specific set of standards or criteria, rather than comparing them to other students.

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• Composite Score:

  • A combined score from multiple subtests, providing an overall measure of a broader skill area, like overall language ability or cognitive function.

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• Validity:

  • Refers to whether a test actually measures what it is supposed to measure. A valid test accurately assesses the skill or trait it claims to.

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• Reliability:

  • Refers to how consistent a test’s results are over time or across different settings. A reliable test will yield similar results if administered multiple times under similar conditions.