What is the coefficient of variation?

• A. Ratio of the standard deviation to the mean expressed as a percentage
• B. Ratio of the mean to the standard deviation
• C. Difference between highest and lowest values
• D. Sum divided by count

Answer: (A)

The main idea here is measuring how spread out data are relative to their average. The coefficient of variation expresses that as a ratio of the standard deviation to the mean, shown as a percentage. So you take the standard deviation, divide it by the mean, and multiply by 100.

This is the best answer because it standardizes dispersion by the data’s scale, letting you compare variability across different datasets or units. For example, if one group has a mean of 80 with an SD of 8, the CV is 10%, while another group with a mean of 40 and an SD of 6 has a CV of 15%. Even though the second group’s SD is smaller, its relative variability is greater.

The other options don’t describe the coefficient of variation: the ratio of the mean to the standard deviation would be a reciprocal of CV; the difference between highest and lowest values is the range; the sum divided by count is the mean.