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Standard Deviation Standard Deviation

Standard deviation (σ) is a measure of the dispersion in a set of data from its mean. The more dispersed or spread apart the data, the higher the deviation. Conversely, a low standard deviation indicates that the data points tend to be close to the mean. Standard deviation is calculated as the square root of the variance (variance is the average of the squared differences from the mean). Unlike variance, standard deviation is expressed in the same unit as the data.