StdDev

The StdDev function computes the standard deviation of a column or group. It measures the spread of a set of observations (numbers) around the mean and is calculated as the square root of the variance. A low standard deviation suggests data points are clustered near the mean, whereas a high standard deviation suggests data points are generally far from the mean.

Standard deviation is a useful measure of spread for symmetrical distributions with no outliers. It is expressed in the same units of measurement as the data and can help determine the statistical distribution of a dataset.

Syntax

StdDev(column)

Function arguments:

• column (required) - The column of numbers to be measured.

The underlying formula is as follows:

√(x_i-x)^2/n-1

where x_i is the value of one observation, x is the mean value of all observations, and n is the number of observations (sample size).

Example

StdDev([x])

• Return the sample standard deviation of non-null records in the x column for each group K.