How to Calculate a Standard Score

Use the standard score to help you curve test scores.
••• calculator image by Henryk Olszewski from Fotolia.com

Standard score is a statistics term. The standard score shows how far away from the mean a score falls. It is also known as a z-score. Using a z-score table, you can find where the score falls on the table and figure out what percentile the score falls in. This is a way of standardizing tests in order to curve the scores to fit around the mean. If everyone does poorly on a test, the score distribution will curve up to fit around the average score on the test.

    Find the mean and standard deviation of your data set. For example, assume you have a data set with a mean of 24 and a standard deviation of 5. You want to find the standard score of 28 in the data set.

    Subtract the mean from the data for which you want a standard score. In the example, 28 minus 24 equals 4.

    Divide the difference between the data and the mean by the standard deviation. In the example, 4 divided by 5 equals a standard score of 0.8. You can use this score on a z table to see where it falls as a percentage of the rest of the scores.

    Things You'll Need

    • Data set
    • Mean of data set
    • Standard deviation of data set

Related Articles

How to Find a Z Score
How to Find Standard Deviation on a TI 84 Plus
How to Calculate CV Values
How to Grade Using a Square Root Curve
How to Calculate Statistical Mean
How to Calculate a P-Value
How to Find the Z Score on a TI-83
Test Your Knowledge on Middle School Science
How to Report Z-Score Results
How to Convert T-Scores to Percentiles
How to Calculate Standard Errors
How to Calculate Sampling Distribution
Characteristics of Aquatic Plants
How to Calculate a Confidence Interval
How to Test for Acidity With Litmus Paper
How to Calculate the RMSE or Root Mean Squared Error
How to Calculate the Coefficient of Variation
How to Calculate an AFQT Score
How to Convert a Mean Score to a Percentage
How to Calculate Average Deviation From the Mean