standard deviation

noun

1

: a measure of the dispersion of a frequency distribution that is the square root of the arithmetic mean of the squares of the deviation of each of the class frequencies from the arithmetic mean of the frequency distribution

also : a similar quantity found by dividing by one less than the number of squares in the sum of squares instead of taking the arithmetic mean

2

: a parameter that indicates the way in which a probability function or a probability density function is centered around its mean and that is equal to the square root of the moment in which the deviation from the mean is squared

Examples of standard deviation in a Sentence

Recent Examples on the Web

On both counts, those factors are typically over two standard deviations higher than league average. —Tony Blengino, Forbes, 11 Oct. 2024

The main analysis compares the standard deviations—a measure of how much individual variation in response there is—for the changes in VO2max in the exercise group and the control group. —Alex Hutchinson, Outside Online, 12 Sep. 2024

Per data from Schaeffer's Senior Quantitative Analyst Rocky White, Ally stock is trading within one standard deviation of its 320-day moving average. —Schaeffer's Investment Research, Forbes, 2 Oct. 2024

If there’s true individual variation in response to exercise, then the standard deviation should be bigger in the exercise group than the control group. —Alex Hutchinson, Outside Online, 12 Sep. 2024

Word History

First Known Use

1895, in the meaning defined at sense 1

Kids Definition

standard deviation

noun

: the square root of the arithmetic mean of the squares of differences between the arithmetic mean of a frequency distribution and the values of the variable