Which of the following is a measure of dispersion?

• A. Standard Deviation
• B. Mean
• C. Median
• D. Mode

Answer: (A)

Dispersion identifies how spread out data are. Among measures of dispersion, the standard deviation is the most informative because it quantifies how far each value tends to lie from the average, using all data points. It is calculated as the square root of the average squared deviations from the mean, so it shares the same units as the data and directly reflects the typical distance from the central value. A small standard deviation means observations cluster near the mean, while a large one indicates a wide spread.

In contrast, the mean, median, and mode describe central tendency—the typical value in the data—not how spread out the values are. They don't quantify variability, so they don't answer how dispersed the data are.