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

The magnitudes of the changes were calculated in terms of standard deviations, which are used in statistics to convey how tightly a group of data points is clustered together.

From Los Angeles Times

"Our study proposed a simple yet objective method for determining hotspots using standard deviation values. This is the first time that this has been done."

From Science Daily

Above eight standard deviations is considered “very high.”

From New York Times

Funds' bonds allocation in November soared 18 points over the month to leave them net 19% overweight - almost 3 standard deviations above long-term averages.

From Reuters

Minor test deficits was defined as having a score of at least 0.5 standard deviations below the average score.

From Science Daily