Standard Deviation

Standard Deviation (pronounced: /ˈstandərd/ /diːviːˈeɪʃ(ə)n/) is a statistical term that measures the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean (also known as the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range.

Etymology

The term "Standard Deviation" was first used in 1893 by the English statistician Karl Pearson. "Standard" refers to the standardizing of the dispersion of the values, and "Deviation" refers to the difference from the mean.

Related Terms

Mean: The average value of a set of numbers.
Variance: The square of the standard deviation. It is a measure of how data points differ from the mean.
Normal Distribution: A probability function that describes how the values of a variable are distributed. It is symmetric and its mean, median and mode are equal.
Z-Score: The number of standard deviations a given data point lies from the mean.
Population: In statistics, a population is the entire pool from which a statistical sample is drawn.
Sample: A subset of a statistical population that accurately reflects the members of the entire population.