Which statistical measure describes dispersion around the mean?

• A. Standard deviation
• B. Variance
• C. Mean
• D. Median

Answer: (A)

When looking at how spread out data are around the average value, the standard deviation is the key measure. It represents the typical distance of observations from the mean, so a small standard deviation means the data cluster close to the mean, while a large one indicates a wider spread. The standard deviation is the square root of the variance, which is the average of squared deviations from the mean; variance also describes dispersion but uses squared units, making it harder to interpret directly. The mean and the median describe central tendency, not how spread out the data are. So the standard deviation is the best descriptor of dispersion around the mean.