What term describes a measure of the spread of a data set?

• A. mean
• B. standard deviation
• C. median
• D. range

Answer: (B)

Spread reflects how far data points lie from each other or from a central value. The standard deviation is the common measure of this spread because it quantifies, on average, how far each value is from the mean. It does this by averaging the squared deviations from the mean and then taking the square root, which keeps the measure in the same units as the data. A small standard deviation means the data cluster tightly around the mean, while a large one indicates more variability. Unlike the range, which only uses the smallest and largest values, the standard deviation uses all data points to describe dispersion, making it a more informative and reliable gauge of spread. In practical terms, it helps distinguish between datasets that share the same average but differ in how concentrated or dispersed the observations are.