variance(), variance_y(), and variance_x()

variance(summary StatsSummary1D, method TEXT) RETURNS BIGINT
variance_y(summary StatsSummary2D, method TEXT) RETURNS BIGINT
variance_x(summary StatsSummary2D, method TEXT) RETURNS BIGINT

Get the variance of the values contained in a statistical aggregate. In a two-dimensional stats_agg use the _y/ _x form to access the variance of the dependent and independent variables.

The method determines whether you calculate a population or sample variance. These values can be provided as their full names, or you can abbreviate them to pop or samp. These are the only four accepted values for the method argument. The default is sample.

For more information about statistical aggregate functions, see the hyperfunctions documentation.

Required arguments

NameTypeDescription
summaryStatsSummary1D/StatsSummary2DThe already constructed data structure from a previous stats_agg call

Optional Arguments

NameTypeDescription
methodTEXTThe method for the calculation 'population' or 'sample' (default)

Returns

ColumnTypeDescription
variance/variance_y/variance_xDOUBLE PRECISIONThe variance of the values in the statistical aggregate

Sample usage

SELECT variance_y(stats_agg(data, data))
FROM generate_series(0, 100) data;
variance_y 
------------
      858.5

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