## standard deviation

Statistics a measure of variability equal to the square root of the arithmetic average of the squares of the deviations from the mean in a frequency distribution

## standard deviation

noun

*Abbr.*

**SD**

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

## standard deviation

Noun

(*plural* standard deviations)

Origin

Coined by English mathematician Karl Pearson in 1894 in his paper "On the dissection of asymmetrical frequency curves".

## standard deviation - Computer Definition

In statistics, the average amount a number varies from the average number in a series of numbers.

## standard deviation - Investment & Finance Definition

The degree that a single value in a group of values varies from the mean (average) of the distribution. Standard deviation is a statistical measure that uses past performance of an investment or portfolio to determine the potential range of future performance and assess the probability of that performance. Standard deviations can be calculated for an individual security or for the entire portfolio.