## variance

variance — aggregate function to return the variance of a range of values.

## DESCRIPTION

This function computes a value for each record returned by the query predicate, or from the specified column of a base table, and returns the variance of those values.

Variance is a measure of the dispersion of a set of data points around their mean value. It is a mathematical expectation of the average squared deviations from the mean. Variance measures the variability (volatility) from an average, and can be applied as a measure of risk. For example, this statistic can help determine the risk an investor might take on when purchasing a specific security.

The variance() function is calculated using the *unbiased* (or *n-1*) method, and is usually used when the incoming data represents a random sample. Use variancep() when the incoming data represents the entire population of data.

Expression * expr* must include the name of a column in a LiveView table, where that column's data type is int, long, or double. The returned
value is of type double.

## SEE ALSO

This LiveView aggregate function is based on the variance aggregate function in the StreamBase expression language.