standard deviation

noun

, Statistics.

1. a measure of dispersion in a frequency distribution, equal to the square root of the mean of the squares of the deviations from the arithmetic mean of the distribution.

standard deviation

noun

1. statistics a measure of dispersion obtained by extracting the square root of the mean of the squared deviations of the observed values from their mean in a frequency distribution

standard deviation

/ stăn′dərd /

1. A statistic used as a measure of the dispersion or variation in a distribution, equal to the square root of the arithmetic mean of the squares of the deviations from the arithmetic mean.

standard deviation

1. In statistics , a measure of how much the data in a certain collection are scattered around the mean . A low standard deviation means that the data are tightly clustered; a high standard deviation means that they are widely scattered.

Notes

About sixty-eight percent of the data are within one standard deviation of the mean.

Word History and Origins

Origin of standard deviation¹

First recorded in 1920–25

Example Sentences

I analyzed the regular-season standings for each of those teams by year since 19971 and translated each team’s winning percentage at the end of the regular season2 into a z-score to find how many standard deviations it was from the mean that season.

From FiveThirtyEight

Only the 1988 and 1981 seasons ended with a smaller standard deviation of team Elo ratings than 1982 did — which, in turn, helped set an uncertain tone for 1983 that didn’t let up all season.

From FiveThirtyEight

I translated each team’s winning percentage at the end of the regular season15 into a set of z-scores to find how many standard deviations a metropolitan area’s16 winning percentage was from the mean that season.

From FiveThirtyEight

One quick way to measure how much parity baseball has seen this year — relative to the same stage of previous seasons — is to look at the standard deviation of winning percentages.

From FiveThirtyEight

Our analysis shows that the standard deviation of Elo’s prediction errors drops steadily over the first five races of a season, then falls at a slower rate over the next few races before plateauing by midseason.

From FiveThirtyEight

And against the first target the accuracy observed was about .7 mils, in standard deviation.

From Project Gutenberg

For each measurement, the coefficient of variation, standard deviation and probable error were computed.

From Project Gutenberg

This is the estimated standard deviation of population where the estimate is made from area.

From Project Gutenberg

This is called the index of variability or "standard deviation."

From Project Gutenberg