*Z-Scores and Stanines*

*Z-Scores and Stanines*

December 28, 2015

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Z-Score

A common statistical way of standardising data on one scale so a comparison can take place is using a z-score. The z-score is like a common measure for all types of data. Each z-score corresponds to a point in a normal distribution.

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To find aÂ z-score for a specific result in a group of results:

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First, calculate the Mean for the group. Then calculate the Standard Deviation. Finally, calculate the z-score using the formula: (student result - Mean) / Standard Deviation.

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Stanine

Stanine scores are used in education to compare student performance over a normal distribution.

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Stanine scores convert raw test scores to a one-digit whole number to simplify test interpretation.

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Typically, stanine scores between 4 and 6 are considered average, scores of 3 or less are below average while scores of 7 or greater are above average.

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