What is standard deviation and how is it interpreted in test scores?

• A. The average score across all students.
• B. A measure of score dispersion around the mean; a small SD indicates scores are close to the mean.
• C. The difference between the highest and lowest scores.
• D. The most frequent score in the distribution.

Answer: (B)

Standard deviation tells you how spread out the test scores are around the average. It isn’t the average itself (that’s the mean), and it isn’t the range or the most frequent score. A small standard deviation means most students’ scores cluster near the mean, indicating consistent performance. A larger standard deviation shows more variability, with scores spread farther from the mean and a wider mix of high and low results. In practice, reporting the standard deviation alongside the mean gives a fuller picture of the test results: the mean provides the central tendency, while the standard deviation describes how spread out the scores are.