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

Per Schaeffer’s Senior Quantitative Analyst Rocky White, Fastenal stock has come within one standard deviation of its 50-day moving average. —Schaeffer's Investment Research, Forbes.com, 7 May 2025

When a model generates multiple potential outputs, standard deviation across those results may guide whether the model is confident in its answer or just guessing. —Christer Holloman, Forbes.com, 20 Apr. 2025

According to data from Schaeffer’s Senior Quantitative Analyst Rocky White, Vertex stock has pulled back to within one standard deviation of this moving average six other times over the past three years. —Schaeffer's Investment Research, Forbes.com, 9 Apr. 2025

For instance, the basal heights of children in India differed by more than a standard deviation from those of children in Haiti. —Manvir Singh, The New Yorker, 24 Mar. 2025

Word History

First Known Use

1895, in the meaning defined at sense 1

Rhymes for standard deviation

• abbreviation
• abomination
• acceleration
• accentuation
• accommodation
• accreditation
• acculturation
• accumulation
• acetylation
• adjudication
• administration
• adulteration

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